Research Collection
Doctoral Thesis
Synthesis and application of highly functionalised acylphosphane oxides
Author(s): Ott, Timo
Publication Date: 2008
Permanent Link: https://doi.org/10.3929/ethz-a-005867134
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ETH Library Dissertation ETH No. 18055
Synthesis and Application of Highly Functionalised Acylphosphane Oxides
A dissertation submitted to the ETH ZÜRICH for the degree of DOCTOR OF SCIENCES
presented by Timo Ott Dipl. Chem. born 24. February 1982 citizen of Ludwigshafen am Rhein, Germany
accepted on the recommendation of Prof. Dr. H. Grützmacher, examiner Prof. Dr. A. Mezzetti, co-examiner
Zürich 2008
Für Helga
"Just one more thing!"
Columbo
Danksagung Mein besonderer Dank gilt Prof. Dr. Hansjörg Grützmacher für die interessante Themenstellung und die vielen fruchtbaren Diskussionen. Ausserdem für die motivierende Unterstützung eigener Ideen und das entgegengebrachte Vertrauen. Prof. Dr. Antonio Mezzetti möchte ich für die freundliche Übernahme des Korreferats danken. Insbesondere bin ich für die ausführlichen Korrekturen und die konstruktive Kritik zu dank verpflichtet. Dr. Hartmut Schönberg danke ich für viele interessante Gespräche und Diskussionen und die schöne Zeit. Als nächstes möchte ich allen Kooperationspartnern danken, die unterstützend zur vorliegenden Arbeit beigetragen haben. Dies sind insbesondere die Ciba Holding AG, Prof. Dr. B. Meier und Prof. Dr. M. Reiher. Dr. Michael Wörle, Dr. Frank Krummeich, Dr. Heinz Rüegger, Dr. Jacco van Beek, Christian Mensing und Martin Colussi hatten immer ein offenes Ohr und "mal eben 5 (-120) Minuten Zeit", wenn es um Problemstellungen in der chemischen Analytik ging oder spezielle Experimente durchgeführt werden mussten. Dr. Céline Réthoré möchte ich für die wundervolle Zeit und die Unterstützung danken. Meinen Laborkollegen Friederike ("Fritzi") Tewes, Florian ("Puschl") Puschmann, Florian ("Karl") Auras, Dr. Simone Alidori, Federica ("Fede") Ricatto, Matthias Vogt, Dr. Carlos ("dos canones") Miro Sabatè, Judith Bräuer, Georgina Müller, Alex Huber, Katrin Prinz, Theodor ("Theo") Zweifel, Coen(radus) Hendriksen, Dr. Monica Trincado, Samuel Annen, Dr. Daniel Stein und den "Altdoktoranden", sowie den Kollegen aus anderen Arbeitsgruppen danke ich für die schöne Zeit in und ausserhalb des Laboratoriums, die anregenden Diskussionen und die Zerstreuung beim Tischfussball spielen. Matthias Vogt und Dr. Hartmut Schönberg danke ich zudem für die vielen gemeinsamen Stunden am Diffraktometer, Judith Bräuer, Gerogina Müller und Dr. Daniel Stein für die angenehme Laborzeit. Fede danke ich für die motivierenden Gespräche und die Zerstreuung in den Pausen während der "Schreibphase". Weiterhin möchte ich meinen "Forschungspraktikant(inn)en" und "Masterstudent(inn)en" Anna, Alex, Yves, Frederic, David, Elisabeth danken. Last but not least möchte ich den Busfahrern der ZVV danken, die mich nicht nur immer sicher zur ETH brachten, sondern auch massgeblich daran beteiligt waren, dass ich Céline kennengelernt habe.
CURRICULUM VITAE
Name: Timo Ott Family Status: unmarried Day of Birth: 24. Februar 1982 Place of Birth Ludwigshafen am Rhein, Germany Nationality: German
Formation
03/2006-10/2008: Dissertation, Swiss federal institute of technology (ETH Zürich), Switzerland, Institute of Inorganic Chemistry, Synthesis and Application of Highly Functionalised Acylphosphane oxides, Prof. Dr. H. Grützmacher.
07/2005-01/2006: Diploma Thesis, University of Karlsruhe (TH), Germany, Institute of Inorganic Chemistry, NHC-Stabilisierte Ruthenium-Komplexe und deren Anwendung in der Aktivierung von Distickstoff, Prof. Dr. U. Radius.
15. Juni 2005: Diploma Exam, Dipl. Chem.
2. Oktober 2003: Intermediate Diploma in Chemistry
10/2001-01/2006: Studies of Chemistry, University of Karlsruhe (TH).
22. Juni 2001: Abitur, Albert-Einstein-Gymnasium, Frankenthal/ Pfalz.
Further Education
10/2006-02/2007: „Entrepreneurship Course - Venture Challenge“, University of St. Gallen, Switzerland.
07/2003: Licence for the distribution of chemicals.
Publications
1) A simple straight forward synthesis of phenylphosphane and the photoinitiator bis(mesitoyl)phenylphosphane oxide (Irgacure 819), H. Grützmacher, J. Geier, D. Stein, T. Ott, H. Schönberg, R.H. Sommerlade, S. Boulmaaz, J.P. Wolf, P. Murrer, T. Ulrich, Chimia 2008, 62, 18-22. 2) Ethanol as a Hydrogen Donor: Highly Efficient Transfer Hydrogenations with Rhodium(I) Amides; T. Zweifel, J.V. Naubron, T. Büttner, T. Ott, H. Grützmacher, Angew. Chem. Int. Ed. Engl. 2008, 47, 3245-3249; Angew. Chem. 2008, 47, 3289- 3293. 3) Synthesis of polystyrene nanoparticles with a very small dispersity, T. Ott, H. Grützmacher, Patent 2008, patent pending. 4) Synthesis of BAPO functionalised Polymers, T. Ott, D. Stein, H. Grützmacher, Patent 2008, patent pending. 5) Oxidative cleavage of Rhodium Phosphide Bonds: Generation of Phosphinyl Radicals from 18 electron trigonal bipyramidal Rh(I) complexes, U. Fischbach, D. Stein, T. Ott, H. Grützmacher, to be submitted. 6) Investigation of the Formation of Phosphanoyl Radicals derived from bis(acly)phenylphosphane oxide, T. Ott, M. Vogt, H. Grützmacher, to be submitted. 7) A simple Synthesis of Functionalised Phosphanes, T. Ott, H. Grützmacher, to be submitted.
Public Presentations
1) Straight forward synthesis of functionalised acylphosphane oxides, 5th European Workshop on Phosphorus Chemistry, Regensburg, Germany, March 2008. 2) Straight forward synthesis of highly functionalised acylphosphane oxides and their application, Symposium der Anorganischen Chemie, Zürich, Switzerland, December 2007.
Zusammenfassung
Die vorliegende Arbeit beschreibt die Synthese von hochfunktionalisierten Acylphosphanoxiden und deren Anwendung als Photoinitiatoren. Neben der Funktionalisierung von Oberflächen und Polymeren durch das Aufbringen von photoaktiven Gruppen wurde insbesondere die Anwendung in der Emulsionspolymerisation getestet.
BAPO BAPO BAPO BAPO BAPO
FG FG FG FG FG Surface Polymer
Abbildung 1: BAPO-funktionalisierte Oberflächen und Polymere.
NaPH2 ist ein geeignetes Ausgangsmaterial für die Synthese von
Acylphosphanoxiden. Das Hauptproblem bei der Verwendung von NaPH2 ist dessen Schwerlöslichkeit und seine aufwendige Synthese. Deshalb haben wir eine einfache Synthesemethode ausgehend von elementarem roten oder weissen Phosphor entwickelt. Hierbei werden der Phosphor und das Natrium in flüssigem
Ammoniak bei Raumtemperatur zu einer Mischung aus [NaPH2(solv)x] und
2[NaNH2(solv)x] umgesetzt. Durch anschliessende Protonierung des NaNH2 wird das reine NaPH2 erhalten. Verwendet man für die Protonierung des
Reaktionsgemisches zwei äquivalente tert-Butanol, erhält man neuartige NaPH2- Alkoxidcluster, die sich durch hervorragende Löslichkeiten auszeichnen und selbst in Kohlenwasserstoffen löslich sind. Aus Toluol bzw. 1,2-Dimethoxyethan (dme) t lassen sich zwei verschiedene Alkoxid-Cluster [Na13(PH2)(O Bu)12] P6 und t [Na12(PH2)(O Bu)12][Na(dme)3] P7 kristallisieren, deren strukturelle Charakterisierung durch eine Kombination aus Pulsed Field Spin Echo NMR, Festkörper-NMR und Kristallstrukuranalysen durchgeführt werden konnte. Zusätzliche Berechnungen untermauern diese Untersuchungen. Es handelt sich - um zwei alkoxidstabilisierte Natrium-Cluster, in deren Zentrum sich ein PH2 -ion befindet (siehe Abbildung 2). Die 13 (in Cluster 1) bzw. 12 (in Cluster 2) Natriumatome sind auf den 20 Ecken eines pentagonalen Dodekaeders dynamisch fehlgeordnet.
Abbildung 2: Struktur des Clusters 1 und des Clusteranions 2.
Mit diesem neuartigen Ausgangsmaterial der formalen Zusammensetzung t NaPH2 x 2NaO Bu war es möglich, ausgehend von funktionalisierten Arylfluoriden neuartige tertiäre Arylphosphane zu synthetisieren, die als Liganden oder für funktionelle Materialien interessant sind. Durch leicht modifizierte Reaktionsbedingungen lassen sich auch primäre und sekundäre Arylphosphane synthetisieren, die nach den litreaturbekannten Methoden mit Acylchlorid, Base und Wasserstoffperoxid zu den entsprechenden Acylphosphanoxiden umgesetzt werden können. Zur gezielten Darstellung von hochfunktionalisierten Acylphosphanoxiden
konnten aus NaPH2 und Acylchloriden Natriumbis(acyl)phosphide dargestellt werden. Aus diesen wurden mit Elektrophilen, wie Alkylhalogeniden, Arylfluoriden, Epoxiden bzw. durch palladiumkatalysierte Kreuzkupplung mit Aryliodiden funktionalisierte Bis(acyl)phosphane (BAPs) synthetisiert. Diese BAPs können zu den entsprechenden funktionalisierten Bis(acyl)phosphanoxiden (BAPOs) mit Wasserstoffperoxid oxidiert werden. Durch Umpolung des Natriumbis(acyl)phosphides wurde auch eine neue Möglichkeit geschaffen BAPs mit nucleophilen Reagenzien, wie Grignardreagenzien darzustellen. Es war möglich, über 50 BAPOs mit verschiedensten Funktionellen Gruppen zu synthetisieren, die sich durch neuartige physikalische und chemische Eigenschaften auszeichnen (z.B. Löslichkeit in fluorierten Phasen, ionischen Flüssigkeiten, Wasser). Erstmals wurden die Kristallstrukturen von funktionalisierten BAPOs untersucht und verglichen. Die P–C(=O) -Bindungslängen sind mit zirka 1.9 Å sehr lang und verhalten sich direkt proportional zur Aktivität des Photoinitiators. Des Weiteren wurden photolytische und erstmals thermische Zersetzungsreaktionen der Acylphosphanoxide Irgacure 819 (BAPO) und Lucirin TPO (MAPO) untersucht. Für die photolytischen Zersetzungsreaktionen wurden Abfangreagenzien und erstmals Metallsalze verwendet. Die so gefundenen Zersetzungsprodukte (Phosphonate und Phosphinate) stimmen nicht mit denen aus den in situ – Untersuchungen in der Litreatur überein. Dies ist ein sehr wichtiges Ergebnis für die Anwendung der Photoinitiatoren. Bei den Untersuchungen zur thermischen Zersetzung von BAPOs wurden Umlagerungsreaktionen zu Phosphiniten und
Eliminierungsreaktionen zu P5Ph5 in quantitativen Ausbeuten beobachtet. Diese Beobachtungen sind grundlegend für weitere Anwendungen und eröffnen neue Einsatzmöglichkeiten. Ein weiterer wichtiger Aspekt dieser Arbeit sind die neu entdeckten lichtinduzierten Kondensationsreaktionen von BAPOs mit Aminen, Alkoholen und Phenolen zu Phosphonsäurederivaten, die eine neuartige Verwendung von BAPO-funktionalisierten Materialien zulassen und Anwendungen wie ortsaufgelöste, lichtinduzierte Kondensationsreaktionen auf Oberflächen ermöglichen. Als proof of principle wurde so Phenolphthalein auf BAPO- funktionalisierte Baumwolle kovalent gebunden. Das Ziel der Arbeit, BAPO-funktionalisierte Polymere zu synthetisieren, konnte auf verschiedenem Wege realisiert werden: a) durch das einsetzen von BAPO-funktionalisierten Monomeren zur Polymerisation, b) durch direkte Funktionalisierung von Polymeren mit Acylphosphiden zu BAPOs und c) durch Reaktionen zwischen Polymeren (oder Biopolymeren) mit funktionalisierten BAPOs. So konnten funktionalisiertes Polystyrol, Polynorbornen, verschiedene Silikone, Polythiophene und Biopolymere dargestellt werden. Für die so funktionalisierten Polymere wurde eine Reihe von Anwendungen gefunden: 1) Coatings für Oberflächen. 2) Ortsaufgelöste Radikalbildung auf Oberflächen. 3) Veredelung und Funktionalisierung von Textilien und Holz. 4) Photoinduzierte Gelbildung mit unpolaren Lösungsmitteln.
Erstmals wurden die beim photolytischen Zerfall erzeugten Acylradikale als Reduktionsmittel eingesetzt und so Metallnanopartikel erzeugt. Durch das Einsetzen von wasserlöslichen BAPOs zur photoinduzierten Emulsionspolymerisation konnten auf einfachem Wege Polystyrolnanopartikel (30- 100 nm) mit geringer Dispersität hergestellt werden. Durch das Anpassen der Reaktionsparameter ist es möglich, die Grösse und Grössenverteilung einzustellen. Die einfache Synthese solcher Partikel ist ohne grösseren Aufwand mit der klassischen Emulsionspolymerisation nicht möglich.
Abstract
In this thesis both the synthesis of highly functionalised acylphosphane oxides and their application as photoinitiators are described. Surface as well as polymer functionalisations with photosensitive groups were investigated, with the focus on the application in emulsion polymerisation (Figure 1).
BAPO BAPO BAPO BAPO BAPO
FG FG FG FG FG Surface Polymer
Figure 1: BAPO-functionalised surfaces and polymers.
NaPH2 serves as suitable starting material for the synthesis of
acylphosphane oxides. As NaPH2 is poorly soluble, the synthesis is rather time consuming. Therefore a simple method was developed for the synthesis, starting from elemental red or white phosphorus. Phosphorus and sodium are reacted in
liquid ammonia at room temperature to yield a mixture of [NaPH2(solv)x] and
2[NaNH2(solv)x]. In the following step NaNH2 is protonated with tert.-butanol and
pure NaPH2 is obtained. Depending on the solvent, two novel NaPH2-alkoxide clusters are formed, which exhibit excellent solubility, even in hydrocarbons. From t toluene cluster P6 [Na13(PH2)(O Bu)12] is obtained, whereas from dme cluster P7 t [Na12(PH2)(O Bu)12][Na(dme)3] is crystallised. Structural characterization was performed by combining Pulsed Field Spin Echo NMR, solid-state NMR and crystal structure analysis. Additional data from calculations supports the determined crystal structures. The composition of both species shows an alkoxide-stabilized sodium cluster bearing a PH2– ion in the center (Figure 2). The clusters consist of 13 and 12 sodium atoms respectively, which are positioned in the corners of a pentagonal dodecahedron and are dynamically disordered.
Figure 2: Structure of the cluster 1 and the cluster-anion 2.
t This novel precursor, which has the formal composition NaPH2 x 2NaO Bu renders possible the synthesis of novel tertiary aryl phosphanes, which may have highly interesting potential applications as ligands or in functional materials. Conveniently functionalised aryl fluorides can be used as starting materials. It is also possible to synthesise primary and secondary aryl phosphanes by slightly modifying the reaction conditions. These primary and secondary aryl phosphanes can be converted to acylphosphane oxides according to the method known from the literature, wherein acylchlorides, base and hydrogen peroxide react to give the corresponding acylphosphane oxides. For the selective synthesis of highly functionalised acyphosphane oxides, sodium bis(acyl)phosphides were prepared from NaPH2 and acylchlorides. Further employing electrophiles such as alkyl halogenides, aryl fluorides, epoxides, or palladium-catalysed crosscoupling with aryl iodides afforded functionalised bis(acyl)phosphanes (BAPs). In turn, these BAPs can be converted to the corresponding functionalised bis(acyl)phosphane oxides (BAPOs) by oxidation with hydrogen peroxide. Through Umpolung of sodium bis(acyl)phosphides a method was established to synthesise BAPs starting from nucleophilic reagents such as Grignard reagents. Over 50 BAPOs carrying wide range of functional groups, featuring novel physical and chemical properties were synthesised (i.e. solubility in fluorinated phases, ionic liquids, water).
For the first time, crystal structures of functionalised BAPOs were investigated and compared. The P-C(C=O) bond lengths are approximately 1.9 Å, which is very long and directly proportional to the activity of the photoinitiator. Furthermore photolytic and thermal decomposition of the acylphosphane oxides Irgacure 819 (BAPO) and Lucirin TPO (MAPO) were examined. Scavengers and for the first time metal salts were used to investigate the photolytical decomposition reactions. The decomposition products that were found (phosphonate and phosphinate) do not correspond to the once found in literature, obtained from in situ studies. This is a very important result with respect to the application of photoinitiators. In the thermal decomposition of BAPOs rearrangement reactions
afford phosphinites and elimination reactions take place to give P5Ph5 in quantitative yields. These observations are fundamental for further applications and give a whole new perspective. Another important aspect of results obtained in this work, are the newly found light-induced condensation reactions of BAPOs with amines, alcohols and phenols resulting in phosphonic acid derivatives. They allow a novel employment of BAPO-functionalised materials and can be applied in locally resolved, light-induced condensation reactions on surfaces. As proof of principle phenolphthaleine was covalently attached to BAPO-functionalised cotton wool following this procedure. The goal of this thesis to synthesise BAPO-functionalised polymers was reached in different ways: a) by using BAPO-functionalised monomers in the polymerisation, b) by directly functionalising polymers with acylphosphides to give BAPOs and c) by reaction of polymers (or biopolymers) with functionalised BAPOs. Functionalised polystyrene, polynorbornene, different silicones, polythiophene and biopolymers were prepared analogous to that way. For this type of functionalised polymers a range of applications was found:
1) Coatings for surfaces 2) Locally-resolved radical formation on surfaces 3) Refinement and functionalisation of textiles and wood 4) Photoinduced gel formation using apolar solvents
For the first time, acyl radicals generated in a photolytic decomposition were applied as a reductant to obtain metallic nanoparticles. By using water-soluble BAPOs for the photoinduced emulsion polymerisation, very small polystyrene nanoparticles exhibiting low dispersity might be easily obtained. Through adaption of the reaction parameters the size as well as size distribution of the particles can be attuned. The synthesis of such particles cannot be done according to the classical emulsion polymerisation procedure.
Table of Contents 19
1 INTRODUCTION...... 27
1.1 Photoinitiators ...... 28 1.1.1 Functionalised photoinitiators...... 30 1.1.2 Synthesis of functionalised acylphosphane oxides ...... 32 1.1.3 Photolytic decomposition of BAPOs...... 34
1.2 Application of functionalised BAPOs...... 35 1.2.1 BAPO-functionalised polymers...... 35 1.2.2 Synthesis of polymer nanoparticles...... 36
1.3 Phosphorus compounds as starting material for photoinitiators...... 40 1.3.1 Activation of elemental phosphorus ...... 40
1.3.2 The use of NaPH2 as precursor for phosphorus compounds...... 45 1.3.3 Synthesis of functionalised arylphosphanes ...... 46
Purpose ...... 49
2 ACTIVATION OF ELEMENTAL PHOSPHORUS AND INVESTIGATION OF NAPH2 ...... 51
2.1 Introduction...... 52
2.2 New routes to activate elemental phosphorus via nucleophilic degradation...... 53 2.2.1 Lithiumdiisopropylamide (LDA)...... 53 2.2.2 Magnesium diisopropylamide...... 55 2.2.3 Sodium tert-butoxide ...... 56 t 2.2.4 Crystal structure of (MesCO)2P-O Bu (B1a) ...... 57
2.2.5 Crystal structure of the Na3P7 containing cluster P5 ...... 58
t 2.3 Investigation of NaPH2-NaO Bu alkoxide clusters ...... 59 2.3.1 Alkoxide stabilized NaPH2-clusters ...... 59 2.3.2 PFGSE NMR experiments...... 65 2.3.3 Solid state NMR experiments...... 66 2.3.4 Theoretical studies ...... 68 2.3.5 Crystal structure of alkoxide packaged sodium selenide...... 69
2.4 A simple synthesis of functionalised primary, secondary, and tertiary arylphosphanes .70
2.5 Conclusion ...... 77
3 SYNTHESIS OF NEW FUNCTIONALISED ACYLPHOSPHANE OXIDES ....79 Table of Contents 20
3.1 Introduction...... 80
3.2 Synthesis of bis(acyl)phosphides ...... 81
3.3 Synthesis of functionalised bis(acyl)phosphane oxides ...... 83 3.3.1 Synthesis starting from bis(acyl)phosphides...... 83 3.3.2 Synthesis of alkyl-BAPOs (B4-B7) ...... 85 3.3.3 Synthesis of alkenyl- and alkinyl-substituted BAPOs (B8-B11) ...... 86 3.3.4 Synthesis of halogenalkyl-BAPOs (B12-B14) ...... 87 3.3.5 Synthesis of amino-, imino-, nitrilo-, azido- BAPOs and isonitrilo-BAP (B15-B20) ...... 88 3.3.6 Synthesis of hydroxy-, epoxy- and sugar- BAPOs (B21-B25)...... 89 3.3.7 Synthesis of sulfido-, phosphino-, phosphonato- and heterocycle containing- BAPOs (B26- B31) ...... 90 3.3.8 Synthesis of ketyl-, aldehyde- and acetal-BAPOs (B32-B37) ...... 92 3.3.9 Synthesis of carboxylic-, carboxylate-, ester-, and amido-BAPOs (B37-B46) ...... 93 3.3.10 Synthesis of alkoxysilane-BAPOs (B47-B49)...... 95 3.3.11 Synthesis of (per)fluorinated BAPOs (B50-B52) ...... 95 3.3.12 "Umpolung" of bis(acyl)phosphides...... 106 3.3.13 Straight-forward synthesis of Mes(Ph)P(=O)(MesCO) (B59)...... 107
3.4 Conclusion ...... 108
4 INVESTIGATION OF THE PROPERTIES OF BAPOS...... 111
4.1 Introduction...... 112
4.2 Discussion of the properties of functionalised BAPOs ...... 113 4.2.1 Comparison of MesBAPO-acetic acid (B38) and MeOBAPO-acetic acid (B39) ...... 113 4.2.2 Switching the UV activity by pH-control...... 114 4.2.3 Crystal structures of functionalised BAPOs...... 115 4.2.4 Crystal structure of (MesCO)2PCH2COOH (B38a) ...... 116
4.2.5 Crystal structure (MesCO)2P(=O)CH2COOH (B38) ...... 117 4.2.6 Crystal structure of (MesCO)2P(=O)CH2COOEt (B53) ...... 118
4.2.7 (MesCO)2P(=O)CH2CH2OH (B21)...... 119
4.2.8 Crystal structure of (MesCO)Ph2P(=O), (MAPO), (B3) ...... 120 4.2.9 Comparison of reactivity versus P–C=O bond lengths in BAPOs...... 121
4.3 Investigation of the formation of phosphanoyl radicals derived from bis(acyl)phosphane oxides ...... 122 4.3.1 The photolytic decomposition of bis(mesitoyl)phenylphosphane oxide (Irgacure 819)...... 122 4.3.2 Photolytic decomposition of Ph-BAPO in the presence of radical scavengers ...... 124 4.3.3 The photolytic decomposition of mesitoylpivaloylphenyl-phosphane oxide (BAPO*) ...... 130 Table of Contents 21
4.3.4 Photolytic decomposition reactions of BAPO* in the presence of scavengers ...... 131 4.3.5 The photolytic decomposition of bis(mesitoyl)methylphosphane oxide (Me-BAPO)...... 132 4.3.6 Decomposition reactions in the presence of scavengers...... 133 4.3.7 The photolytic decomposition of diphenylmesitoylphosphane oxide (MAPO) ...... 138
4.4 Light-induced condensation reactions with BAPOs ...... 138 4.4.1 Light-induced condensation...... 138
4.5 The thermal decomposition of Ph-BAPO (B2) and MAPO (B3) ...... 140 4.5.1 Thermal decomposition of Ph-BAPO (Irgacure 819)...... 141 4.5.2 Thermal versus photolytical decomposition of Ph-BAPO...... 143 4.5.3 Thermal decomposition of MAPO ...... 146
4.6 Conclusion ...... 147
5 SYNTHESIS OF BAPO-FUNCTIONALISED POLYMERS AND THEIR APPLICATION ...... 151
5.1 Introduction...... 152
5.2 Results and discussion ...... 155
5.3 Modification of polymers with BAPO groups (Method A) ...... 156 5.3.1 BAPO functionalised polystyrene ...... 156
5.4 Photoactive polymers functionalised with BAPO compounds (Method B) ...... 157 5.4.1 Synthesis of polymerisable BAPO monomers...... 157 5.4.2 BAPO functionalised polynorbornenes...... 158 5.4.3 BAPO functionalised polyacrylates ...... 160 5.4.4 BAPO functionalised polythiophenes ...... 161 5.4.5 BAPO functionalised polysiloxanes (polysilicones)...... 162 5.4.6 Ennoblement of textiles with BAPO-functionalised siloxanes and polysiloxanes ...... 163 5.4.7 Photoinduced gelation with non-polar liquids...... 169 5.4.8 Functionalisation of surfaces with thin films of BAPO functionalised silicones ...... 171 5.4.9 BAPO functionalised biopolymers ...... 174
5.5 Conclusion ...... 176
6 SYNTHESIS OF NANOPARTICLES ...... 179
6.1 Introduction...... 180
6.2 Synthesis of metal nanoparticles ...... 183
6.3 Synthesis of polystyrene nanoparticles ...... 185 Table of Contents 22
6.3.1 Emulsion polymerisation with water soluble BAPOs as initiators...... 185 6.3.2 Comparison of particle size and polymerisation time...... 186 6.3.3 Effect of the surfactant (sodium dodecylsulfate, SDS)...... 190 6.3.4 Effect of the initiator concentration ...... 191 6.3.5 Effect of the temperature...... 192 6.3.6 Further experiments ...... 192
6.4 Conclusion ...... 192
7 OUTLOOK ...... 195
8 EXPERIMENTAL PART...... 197
Starting materials ...... 201 3-(chloromethyl)thiophene...... 201 5-Norbornen-2-methylbromid ...... 202 5-Norbornene-2-(butyl-4-bromide)...... 202 sodium selenide, Na2Se (A6) ...... 203 Cellulose tosylate...... 204 6-Azido-6-deoxy Cellulose...... 204 1,4-Dichloro-1,4-diphenyl-2,3-diazabutadiene ...... 205 Diethoxy(methyl)(vinyl)silane...... 205
Chapter 2: ...... 206 General procedure for the nucleophilic degradation of P4...... 206
P4(s) + sodium tert-butoxide (P2)...... 207
Na3P7 from P4(solv.) + sodium tert.-butoxide (P5) ...... 207 (tert.-butoxyphosphinediyl)bis(mesitylmethanone) (B1a)...... 207
General procedure for [Na(PH2)(dme)]∞/[NaNH2] (red phosphorus) ...... 208
General procedure for [Na(PH2)(dme)]∞/[NaNH2] (white phosphorus)...... 208
[Na(PH2)(dme)]∞ (P8)...... 208 t [Na12(O Bu)12PH2][Na(dme)3] (P7) ...... 209 t [Na13(O Bu)12PH2] (P6)...... 209 [D9]-sodium tert-butoxide ...... 210 t [Na12(O Bu)10Se] (A5) ...... 210 Sodium-3,5-diphenyl-1,2,4-diazaphospholid (P9) ...... 210 t General procedure for the synthesis of arylphosphanes starting from NaPH2 x 2NaO Bu...... 211 tris(4-nitrophenyl)phosphane (P19)...... 213 (4-phenoxyphenyl)phosphane (P11) ...... 214 tris(4-vinylphenyl)phosphine (P20)...... 215 Table of Contents 23
(S)-2,2'-diphosphino-1,1'-binaphthyl (P21)...... 216 tris(4-iodophenyl)phosphine (P18) ...... 216 (4-bromophenyl)phosphine (P13)...... 217 (4-vinylphenyl)phosphine (P14)...... 218
Chapter 3 ...... 219 Sodium bis(mesitoyl)phosphide (P4)...... 219 sodium bis(2,6-dimethoxybenzoyl)phosphide (P31) ...... 220 sodium bis(2,6-bis(trifluoromethyl)benzoyl)phosphide (P32) ...... 221 sodium bis(perfluorooctanoyl)phosphide (P33)...... 221 bis(2,6-dimethoxybenzoyl)methylphosphane (MethylMeOBAP) (B4a)...... 222 bis(2,6-dimethoxybenzoyl)methylphosphane oxide (MethylMeOBAPO) (B4) ...... 222 1,3-di(bis(mesitoyl)phosphane oxide)propane (B5) ...... 223 cyclohexylphosphorylbis(mesitylmethanone) (B6) ...... 224 isopropylphosphorylbis(mesitylmethanone) (B7) ...... 224 Allylphosphorylbis(mesitylmethanone) (B8) ...... 225 (5-Norbornen-2-butyl)-4-bis(mesitoyl)phosphane oxide (B9)...... 226 ethyl 2-((bis(2,4,6-trimethylbenzoyl)phosphoryl)methyl)acrylate (B10)...... 227 (prop-2-ynylphosphoryl)bis(mesitylmethanone) (B11) ...... 227 ((4-bromobenzyl)phosphoryl)bis(mesitylmethanone) (B12) ...... 228 ((3-bromopropyl)phosphinediyl)bis(mesitylmethanone) (B13a) ...... 229 ((3-bromopropyl)phosphoryl)bis(mesitylmethanone) (B13)...... 230 ((3-chloropropyl)phosphoryl)bis(mesitylmethanone) (B14) ...... 230 ((3-aminopropyl)phosphoryl)bis(mesitylmethanone) (B15) ...... 231 3-(bis(2,6-dimethoxybenzoyl)phosphino)propylamine (B16)...... 232 (E)-((4-(benzylideneamino)phenyl)phosphoryl)bis(mesitylmethanone) (B17) ...... 233 3-(bis(2,4,6-trimethylbenzoyl)phosphoryl)propanenitrile (B18) ...... 234 ((2-isocyanatoethyl)phosphinediyl)bis(mesitylmethanone) (B19a) ...... 235 ((3-azidopropyl)phosphoryl)bis(mesitylmethanone) (B20) ...... 235 ((2-hydroxyethyl)phosphoryl)bis(mesitylmethanone) (B21) ...... 236 bis(2,6-dimethoxybenzoyl)hydroxyethylphosphanoxide (B22)...... 237 ((oxirane-2-ylmethyl)phosphoryl)bis(mesitylmethanone) (B23) ...... 237 ((2,3-dihydroxypropyl)phosphoryl)bis(mesitylmethanone) (B24) ...... 238 Acetyl protected BAPO-glucose (B25) ...... 239 ((2-mercaptoethyl)phosphoryl)bis(mesitylmethanone) (B26) ...... 239 (((1,3-dioxolan-2-yl)methyl)phosphinediyl)bis(mesitylmethanone) (B27)...... 240 ((3-(diphenylphosphino)propyl)phosphoryl)bis(mesitylmethanone) (B28) ...... 240 diethyl 2-(bis(2,6-dimethoxybenzoyl)phosphoryl)ethylphosphonate (B29) ...... 241 Table of Contents 24
((thiophene-3-ylmethyl)phosphinediyl)bis(mesitylmethanone) (thiophene-BAP) (B30a) ...... 242 ((thiophene-3-ylmethyl)phosphoryl)bis(mesitylmethanone) (B30) ...... 243 3-(3-(bis(2,4,6-trimethylbenzoyl)phosphoryl)propyl)-1-methyl-1H-imidazol-3-ium bromide (B31)..243 ((2-oxopropyl)phosphinediyl)bis(mesitylmethanone) (BAP-acetone) (B32a)...... 244 ((2-oxopropyl)phosphoryl)bis(mesitylmethanone) (BAPO-acetone) (B32)...... 245 ((4-acetylphenyl)phosphinediyl)bis(mesitylmethanone) (B33a) ...... 245 ((4-acetylphenyl)phosphoryl)bis(mesitylmethanone) (B33)...... 246 2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)acetaldehyde (BAPO-acetaldehyde) (B34) ...... 246 2-(bis(2,6-dimethoxybenzoyl)phosphino)acetaldehyde (MeOBAP acetaldehyde) (B35a)...... 247 2-(bis(2,6-dimethoxybenzoyl)phosphoryl)acetaldehyde (MeOBAPO acetaldehyde) (B35)...... 248 ((2-(1,3-dioxolan-2-yl)ethyl)phosphinediyl)bis(mesitylmethanone) (B36a)...... 249 (((1,3-dioxolan-2-yl)methyl)phosphoryl)bis(mesitylmethanone) (B36) ...... 249 3-(bis(2,4,6-trimethylbenzoyl)phosphoryl)propanal (B37) ...... 250 2-(bis(2,4,6-trimethylbenzoyl)phosphino)acetic acid (B38a) ...... 251 2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)acetic acid (BAPO-acetic acid) (B38) ...... 251 2-(bis(2,6-dimethoxybenzoyl)phosphino)acetic acid (MeOBAP acetic acid) (B39a) ...... 252 2-(bis(2,6-dimethoxybenzoyl)phosphoryl)acetic acid (MeOBAPO-acetic acid) (B39) ...... 252 11-(bis(2,4,6-trimethylbenzoyl)phosphoryl)undecanoic acid (BAPO-undecanoic acid) (B40) ...... 253 sodium 2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)acetate (B42)...... 254 methyl 2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)acetate (B43)...... 255 4-nitrophenyl 2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)acetate (B44) ...... 255 2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)acetamide (B45) ...... 257 2-(2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)ethyl)isoindoline-1,3-dione (B46) ...... 257 ((3-(triethoxysilyl)propyl)phosphoryl)bis(mesitylmethanone) (B47)...... 258 ((3-(diethoxy(methyl)silyl)propyl)phosphoryl)bis(mesitylmethanone) (B48)...... 259 ((3-(diethoxy(phenyl)silyl)propyl)phosphoryl)bis(mesitylmethanone) (B49)...... 260 ((perfluorooctyl)phosphoryl)bis(mesitylmethanone) (B50) ...... 261 ((perfluorophenyl)phosphoryl)bis(mesitylmethanone) (B51) ...... 262 bis(perfluorooctanoyl)perfluorooctanylphosphane (B52a) ...... 262 bis(perfluorooctanoyl)perfluorooctanyphosphanoxide (B52)...... 263 bis(2,4,6-trimethylbenzoyl)phosphinecarbonitrile (B56a) ...... 264 bis(2,6-dimethoxybenzoyl)-N-piperidinylphosphanoxide (B58)...... 264 mesityl(mesityl(phenyl)phosphino)methanone (B59a) ...... 265 mesityl(mesityl(phenyl)phosphoryl)methanone (B59) ...... 266
Chapter 4 ...... 267 Rearrangement of bis(2,6-dimethoxybenzoyl)hydroxyethyl-phosphanoxide to P34...... 267 Decomposition of Ph-BAPO in benzene: ...... 268 Table of Contents 25
Decomposition of Ph-BAPO in toluene ...... 269
Decomposition of Ph-BAPO in CCl4 ...... 269 Decomposition of Ph-BAPO in benzene in the presence of Diphenyldisulfide as scavengers...... 269 Decomposition of Ph-BAPO in benzene in the presence of methylphenyldisulfide as scavengers270 Decomposition of Ph-BAPO in benzene in the presence of TEMPO as scavenger ...... 271
Decomposition in the presence of [Cu(acac)2]: ...... 271
Decomposition in the presence of Ni(CF3COO)2:...... 271 Dimesityl diketone (A9):...... 271 BAPO* decomposition in benzene solution ...... 272 * BAPO decomposition in CCl4 solution...... 272 Decomposition of BAPO* in benzene in the presence of diphenyldisulfide as scavenger ...... 272 Decomposition of BAPO* in benzene in the presence of TEMPO as scavenger...... 273 Decomposition of Me-BAPO in benzene:...... 273 Decomposition of Me-BAPO in benzene in the presence of Diphenyldisulfide as scavengers ...... 273 Decomposition of Me-BAPO in benzene in the presence of TEMPO as scavenger...... 274
Decomposition of Me-BAPO in the presence of Cu(acac)2,...... 274 Decomposition of Me-BAPO in the presence of methylphenyldisulfide as scavengers...... 274 Thermal decomposition of Ph-BAPO in substance ...... 274 Thermal decomposition of a Ph-BAPO solution in p-Xylene...... 275 Thermal decomposition of MAPO, B3 ...... 275 Lithium diphenylphosphinite ...... 276 General procedure for light induced condensation reactions...... 276
Chapter 5 ...... 277 Poly(ethyl 2-((bis(2,4,6-trimethylbenzoyl)phosphoryl)methyl)acrylate (PM6) ...... 277 BAPO-cellulose (PM2)...... 278 General procedure for the synthesis of BAPO-functionalised silicones (PM7) ...... 278 (3-(Diethoxymethylsilyl)propyl)bis(mesitoyl)phosphane oxide, Diethoxydimethylsilan copolymer .279 Poly(3-(Triethoxysilyl)propyl)bis(mesitoyl)phosphane oxide ...... 279 Poly(3-(Diethoxyphenylsilyl)propyl)bis(mesitoyl)phosphane oxide ...... 280 Poly(3-(Diethoxymethylsilyl)propyl)bis(mesitoyl)phosphane oxide ...... 280 (3-(Diethoxyphenylsilyl)propyl)bis(mesitoyl)phosphan oxide, diethoxydimethylsilane copolymer ..280 (3-(Diethoxyphenylsilyl)propyl)bis(mesitoyl)phosphane oxide, Dimethoxydimethylsilane copolymer281 (3-(Diethoxymethylsilyl)propyl)bis(mesitoyl)phosphane oxide, Diethoxydimethylsilane copolymer281 (3-(Diethoxymethylsilyl)propyl)bis(mesitoyl)phosphane oxid, dimethoxydimethylsilan copolymer .282 (3-(Triethoxysilyl)propyl)bis(mesitoyl)phosphane oxide Triethoxy(vinyl)silane copolymer ...... 282 (3-(Triethoxysilyl)propyl)bis(mesitoyl)phosphane oxide Triethoxy(vinyl)silane copolymer ...... 283 (3-(Triethoxysilyl)propyl)bis(mesitoyl)phosphane oxide Triethoxy(vinyl)silane copolymer ...... 283 Table of Contents 26
(3-(Diethoxymethylsilyl)propyl)bis(mesitoyl)phosphane oxide Diethoxy(methyl)(vinyl)silane copolymer ...... 284 (3-(Diethoxymethylsilyl)propyl)bis(mesitoyl)phosphane oxide Diethoxy(methyl)(vinyl)silane copolymer ...... 284 (3-(Diethoxymethylsilyl)propyl)bis(mesitoyl)phosphane oxide Diethoxy(methyl)(vinyl)silane copolymer ...... 285 General procedure for light induced gelation of vinyl substituted BAPO-functionalised silicones ..286 BAPO-functionalised polynorbornene (PM5) ...... 286 BAPO-functionalised polystyrenes (PM3, PM4)...... 286 Functionalisation of cotton with BAPO-acetic acid...... 287 General procedure for the functionalisation of cotton with BAPOsiloxanes and -silicones...... 287 General procedure to perform a radical polymerisation on BAPO-functionalised cotton...... 288 Chemisorption of phenolphthaleine on BAPO-functionalised cotton during irradiation with ultraviolet light ...... 288 Synthesis of silver, copper and nickel (nano)particles ...... 288
Chapter 6 ...... 289 General emulsion polymerisation procedure...... 289
9 APPENDIX ...... 291 Abbreviations...... 292 Compounds ...... 295 Crystallography data...... 303
10 LITERATURE...... 315
Chapter 1
Introduction
Chapter 1 - Introduction 28
1.1 Photoinitiators
Photoinitiators are compounds that are able to initiate chemical reactions (e.g. polymerisation reactions) when they are irradiated with visible or ultraviolet light. During this irradiation process, they undergo a decomposition reaction under formation of highly reactive species. These react further with substrate molecules, e.g. monomers. The advantages of photo-initiated systems are a well-defined initiation / termination reaction, a wide range of possible scaffold geometries, and short reaction times1. Photoinitiators have many applications like coating and printing technologies, medical applications, or whenever reactive species have to be formed under very mild conditions at low temperature. They have to be compatible with the specific system and its application. Important criteria are2: 1) Compatibility with the polymerisable system. 2) Chemical and thermal stability in the dark and on storage. 3) Negligible effect on the properties of the cured film. 4) High initiating efficiency. 5) Relatively low cost. Many different classes of photoinitiators exist and are commercially available. The most important ones are acetophenone and benzophenone derivatives, oxime esters and acylphosphane oxides.3
Acetophenone- and benzophenone-type photoinitiators
Substituted acetophenone derivatives have been recognised as photoinitiators a long time ago (Figure 1). They have been commercially available and industrially applied for more than 25 years. Although they have many advantages (e.g. a low price and simple preparation), they have low quantum yields and intense UV light is necessary to induce their decomposition.3 Chapter 1 - Introduction 29
CH3 O CH 3 O OH O OH O CH 3 O N
H3C NMe2
Figure 1: Examples of Acetophenone-/ Benzophenone-Type Photoinitiators.
Oxime esters
Oxime esters are very efficient photoinitiators (Figure 2). Their main disadvantage is their low thermal stability. Nevertheless, they are used in electronical applications because of their high photoactivity.3
O O
N hv O N S S O O + O
-CO2, -C6H13CN
O
S +
Figure 2: An oxime ester-photoinitiator and its decomposition during irradiation.
Acylphosphane oxides
Mono-, bis-, and tris(acyl)phosphane oxides, R2P=O(COR’) (MAPOs),
RP=O(COR’)2 (BAPOs), P=O(COR’)3 (TAPOs) have many advantages and excellent properties compared to other classes of photoinitiators4 (Figure 3). Chapter 1 - Introduction 30
Specifically, they are efficiently excited with yellow to red light (λ = 350 – 440 nm) and undergo a very fast Norrish type I photo reaction, in which an acyl, R’CO●, and ● 5, 6, 7, 8 a phosphanoyl radical, RmP =O(COR’)n, are generated . The latter promotes the polymerisation reaction when suitable monomers are added.
O O O O P O O P O O O O P O O
Lucirin T PO Ir gacur e 819 Irgacure 1700
Figure 3: Examples for commercially available acylphosphane oxides
The absorption maxima of monoacylphosphane oxides (MAPOs) are shifted to lower wave numbers compared to bis(acyl)phosphane oxides (BAPOs). BAPOs are used whenever a light-absorption close to visible spectrum has to be used for photoinitiation. They are very reactive and efficient photoinitiators for any kind of coatings. However, they are more expensive and more difficult to synthesise than other photoinitiators like benzophenone derivatives. Nevertheless, their outstanding activity justifies complicated chemical reactions and more expensive starting materials3. Every BAPO molecule can generate up to four radicals during its decomposition, whereas only two radicals are formed by MAPOs under photolytic conditions. Tris(acyl)phosphane oxides are photoactive as well but not stable enough for industrial applications3.
1.1.1 Functionalised photoinitiators
Photoinitiators with functional groups are of high interest and have a wide range of applications. Functionalisation of surfaces and particles is one important example. Efficient photoinitiators allow local generation of radicals in order to perform highly spatially resolved chemical reactions. Another important application Chapter 1 - Introduction 31
is the synthesis of polymers carrying photosensitive groups. They are useful for coatings and manufacturing new materials (Figure 4).
PIG PIG PIG PIG PIG
FG FG FG FG FG
Surface Polymer PIG = Photoinitiating Group
Figure 4: Functionalisation of surfaces with photoinitiating groups.
Furthermore, functional groups impart different physical and chemical properties, like solubility and reactivity, to a photoinitiator. Many functionalised photoinitiators exist. Especially the acetophenone based ones are relatively easy to derivatise by standard chemical methodology. Nevertheless, their reactivity is relatively low, which is a major disadvantage,3 in particular for applications like surface functionalisation or other processes that require very active photoinitiators. One example are polymerisation processes, which are directly controlled by the concentration of the initiator and by its decomposition kinetics. Therefore, a high quantum yield is an absolutely necessary requirement for a photoinitiator. A further point is the wavelength of the absorbed light. For industrial applications, photoinitiators absorbing light in the UV/Vis range would be beneficial. As mentioned before, acetophenone and benzophenone derivatives absorb only highly energetic UV light. Therefore, to avoid expensive lamps and special equipment, more efficient functionalised photoinitiators are necessary. Since acylphosphane oxides have many advantages over other photoinitiating systems, we investigated functionalisation of this photoinitiator class. Chapter 1 - Introduction 32
1.1.2 Synthesis of functionalised acylphosphane oxides
Since phosphorus radicals are more efficient initiators than acyl radicals, BAPOs (Figure 5), which are able to generate functionalised phosphorus radicals are appealing candidates as photoinitiators (Figure 5).
O O O O O O O O O P P P
FG FG FG FG
FG FG
Figure 5: Three different possibilities to functionalise a BAPO. The one on the left is favored, because the functional group is directly connected to the reactive phosphorus radical after decomposition.
Even though acylphosphane oxides have several photochemical advantages, no standard procedure for the synthesis of functionalised BAPOs exist. Although a few functionalised BAPOs have been described in the literature, they carry their functionality at the acyl group. This kind of BAPOs is easier to synthesise, because commercially available dichlorophenylphosphane and metallation agents can be used as starting materials (Scheme 1). The few reported synthesis of BAPOs that carry a functional group at the phosphorus moiety start from functionalised dichlorophenylphosphane or functionalised phenylphosphane9. These starting materials are difficult to synthesise and to handle on large scales. The main problem of this method, though, is the intolerance of the dichlorophosphanyl group and metallation reagents to functional groups. Hence, only BAPOs carrying robust functional groups capable of surviving strongly reducing conditions can be synthesised following that pathway (Scheme 1)10. An example are polyether groups. Chapter 1 - Introduction 33
Cl Cl P +"4 M" O O O O "Ph-PM2" O -2 MCl R P R R P R FG +H2O2
H H P +R(C=O)Cl FG FG
base
FG R = bulky aryl or alky groups FG = H, -polyether
Scheme 1: The "classical" synthesis of functionalised Ph-BAPOs.
Another possibility to prepare functionalised acylphosphane oxides is the monoacylation of phenylphosphane derivatives and further functionalisation at the phosphorus atom. One example is the synthesis of mesitoylphenylphosphinic acid11. A very efficient synthetic method for alkyl- and aryl-BAPOs has been recently investigated in our research group12. This protocol starts from sodium bis(acyl)phosphide, which was prepared from red phosphorus, sodium and mesitoyl chloride. The sodium bis(mesitoyl)phosphide reacts via a nucleophilic substitution reaction with alkylhalogenides or with aryl iodides in a palladium catalysed cross coupling reaction to the corresponding bis(acyl)phosphanes. These phosphanes can be easily oxidised with hydrogen peroxide to the corresponding BAPOs. First investigations on the synthesis of functionalised BAPOs carrying protecting groups have been performed in previous work in our research group12, 13 (see 1.3.2). This work describes further investigations of the synthesis of highly functionalised BAPOs and the activation of the cheaper white phosphorus as starting material. Chapter 1 - Introduction 34
1.1.3 Photolytic decomposition of BAPOs
The photolytic decomposition of BAPOs are of high interest in terms of application. Each molecule of Irgacure 819 (B2) generates four radical species, their formation occurring in two steps (Scheme 2). These properties facilitate e.g. block-co-polymer synthesis14.
1
O hv O O P O P O O
Irgacure 819 (B2) 9 -1 k isc =8x10s
3 O O 10 -1 P + ka =1x10 s O Norrish type 1 O O P O
Scheme 2: The decomposition of Irgacure 819.
The decomposition mechanism of the acylphosphane oxides by irradiation with ultraviolet light is well known. In the first step, an excited singlet state is formed by absorbing photons, which undergoes a very fast intersystem crossing (isc) to a triplet state. The decomposition of the molecule in the triplet state gives a phenylmesitoylphosphanoyl and a mesitoyl radical. Depending on the system, these radicals undergo further reaction. The second acyl moiety can undergo an analogous decomposition reaction. However, these studies focused on the in-situ investigation of the radicals by physical methods such as EPR-spectroscopy15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28 or other special spectroscopic methods29, 30, 31, rather than on the nature of decay products. Chapter 1 - Introduction 35
The detailed knowledge of the decomposition products is of great importance especially for the application in polymerisation processes. Computational work on phosphanoyl radicals32 and their formation33 contribute to the understanding of these mechanisms. However, there are only a few publications in which these decomposition reactions have been studied in the presence of radical scavengers34, 35, 36, 37. Therein, the authors put their main focus on mono(acylphosphane) oxides. Especially these trapping reactions are of great importance in order to learn about the reactivity of phosphanoyl radicals. They might also open the way to the development of new applications beside polymerisation initiation, such as the use of phosphorus-centered radicals in hydrophosphination or selective addition reactions38, which allow a further modification of BAPO-functionalised surfaces and polymers.
1.2 Application of functionalised BAPOs
1.2.1 BAPO-functionalised polymers
The specific properties of nanometer-sized structures for materials that are important for molecular scale electronics39, magnetic storage devices, optoelectronics and biotechnology are increasingly investigated. There is a steady demand for concepts allowing the rationale synthesis of such materials eventually leading to the production of new materials with precise control of their features and functionality40. Among them, photosensitive polymers are of high interest. Currently they are applied in microlithography, holography41, coating technologies42, and as components for the synthesis of liquid crystals and nonlinear optical materials43. Specifically they are used for photo induced deposition processes on surfaces, solid-state topochemistry of polymers44, 45 and for the controlled synthesis of copolymers (e.g. brush polymers). For these and other possible applications, it is desirable to have photopolymers at hand that can be excited by light of moderate energy (that is, with wavelengths close to the visible range) and that the excitation proceeds with a Chapter 1 - Introduction 36
high quantum yield. To allow large scale (industrial) synthesis, simple and straight- forward synthetic routes to such photoactive polymers from cheap starting materials must be found. Another desirable property of these photoactive polymers is that the radical centres generated by light irradiation are able to undergo a range of well-defined reactions like initiation of polymerisations and / or selective trapping reactions with added substrates. Last but not least, all radical centres should be more or less evenly distributed along the polymer chain in order to allow the production of well-defined materials with controllable properties. In this work, the use of functionalised BAPOs for the synthesis of BAPO-functionalised polymers is investigated (see Chapter 5).
1.2.2 Synthesis of polymer nanoparticles
Polystyrene is one of the most important industrially produced polymers (annual production ~10 mio t/a). It is inert to many chemicals and solvents, can be easily machined, has many interesting physical properties and can be frothed up by heating in a closed vessel in the presence of a froth reagent like pentane. Since nanoparticles are known for their special properties, it is not astonishing that also polystyrene nanoparticles find several different application. They are used for coatings, the production of special polystyrene materials by squeeze ramming, as a substrate for other particles (e.g. metal nanoparticles46, 47, 48, 49) and as calibration substances in analytical laboratories, to mention only a few examples. Presently, they have also medical application, like for the production of protheses and micro-sized materials or as contrast agent in medical analysis50, 51, 52, 53. The production of monodisperse nanosized compounds is very difficult. Nanosized polymer particles can be prepared either by physical methods like evaporating droplets of polymer solutions54 or by direct synthesis of the particles with special polymerisation processes. Especially two kinds of radical polymerisation reactions are used thereto: Suspension polymerisation (SP) and emulsion polymerisation (EP). Suspension polymerisation is one common opportunity to synthesise particles in the range of 100 nm55 to several millimetres56. The water-insoluble monomer is mixed with an excess of water and Chapter 1 - Introduction 37
with an lipophile radical initiator, like organic peroxides, AIBN, or seldom a water- soluble initiator like potassium peroxodisulfate. This mixture is stirred vigorously to get small monomer droplets in the aqueous phase. Afterwards the reaction mixture is heated to initiate thermally the radical reaction. After the reaction is finished, a suspension of polymer particles is obtained. The polystyrene particles are normally sized in the μm scale but under optimized conditions with special stirrers and the use of supersonic bath it is possible to form particles with a size down to several hundred nanometers. Suspension polymerisation has many disadvantages though. The polydispersity of the polymer chains is very large and the molecular weight is in an average value in a range of 100.000 to 500.000, what is unfavourable for the material properties. Furthermore, the size of the polymer particles is very disperse. The second method is emulsion polymerisation. Herein, the polymerisation does not take place in the monomer drops like in the suspension polymerisation, but in micelles. Smaller polymer particles than in the suspension polymerisation are formed here. Their size is normally between 100 nm and 5 μm and has a smaller dispersity. The molecular weight is very high and usually in a range of 500.000 to 2 million. The polydispersity of the polymer chains is very small, which leads to good material properties. Analogously to suspension polymerisation, a water-insoluble monomer is mixed with an excess of water. The main difference to suspension polymerisation is the presence of a surfactant (e.g. sodium dodecylsulfate (SDS)) and the use of a water-soluble radical initiator (mostly common potassium peroxodisulfate). Because of the surfactant, the solubility of the monomer increases (e.g. 1% v/w for the system styrene / SDS)57. The concentration of the surfactant has to be higher than the crytical micelle concentration (cmc). After radicals are formed in the aqueous phase, they react with the monomer that is dissolved in extremely small amounts in the water (Figure 6). The surfactant forms a micelle around the oligomers in the water, which protects the polymerisation process against recombination reactions. Out of the monomer droplets, styrene gets dissolved in water in extremely small amounts and is Chapter 1 - Introduction 38
transported to the micelle-protected oligomers radicals by diffusion processes. While the polymer chains are growing and the polymer particle enlarges, the micelles get destroyed and latex particles are obtained. The Latex particles are still surrounded by absorbed surfactant molecules that charge the surface of the particles. As a result, the Latex is stable in water for a long time. To isolate the pure polymer particles it is necessary to neutralise their surface charge by adding acid, base or salts as sodium chloride. Alternatively, they can be obtained by centrifugation.
Figure 6: Schematic diagram illustrating the process of emulsion polymerisation58.
The emulsion polymerisation process is the most important technique to polymerise styrene in industry. The produced polymer has excellent properties and the use of water ensures that the reaction is well controlled. To enhance the Chapter 1 - Introduction 39
properties of the latex particles respectively the polystyrene, the emulsion polymerisation is often verified (e.g. optimized reaction conditions)59, 60. In the last 20 years, controlled radical polymerisation processes (living radical polymerisation) have been investigated. These new techniques have been applied to suspension and emulsion polymerisation processes. The most important are RAFT (reversible addition fragmentation transfer reaction)61, 62, NMP (nitroxide-mediated polymerisation) / TEMPO-mediated63, 64, 65, 66, 67 and ATRP (atom transfer radical polymerisation)68. These methods slow down the very fast radical polymerisation reaction by stabilizing the radicals. Higher molecular weight and smaller polydispersity are the consequence. The disadvantage is that toxic, expensive, coloured or malodorant chemicals61 have to be used like heavy metal salts, sulphur containing compounds and TEMPO. In addition, many other variations of the emulsion polymerisation process have been investigated. The reaction can be performed in strong magnetic fields69, in the presence of microwaves70, 71, without any surfactant under special conditions,72, 73 or co-surfactants or special organic solvents (e.g. alcohols, alkanes) can be added to get a polymerisation in miniemulsion74, 75, 76. Another disadvantage of the “classical” emulsion polymerisation is that the initiation occurs thermally. Large amounts of water have to be heated up. However, the reaction is affected by the temperature. To solve this problem, other initiator systems have been used, like radioactive77, 78 or photochemical initiation, which allows to perform the polymerisation at lower temperature. Since most of the commercial available photoinitiators are not or sparingly soluble in water, only in the presence of dispersions agents, or have a bad quantum yield79, 80, 81, 82, the main focus of photo-induced reactions is on inverse emulsion polymerisation. Herein, a concentrated aqueous monomer solution (e.g. acryl amide) is mixed with a diluted solution of the photoinitiator in a non-polar solvent (e.g. toluene). The size of the particles and the dispersity is normally larger than in the regular emulsion polymerisation83. Therefore, a good water-soluble photoinitiator, which has good quantum absorption and an absorption maximum Chapter 1 - Introduction 40
close to visible light would be the solution. Water-soluble BAPO-acetic acid and its salts achieve this purpose (see chapter 3).
1.3 Phosphorus compounds as starting material for photoinitiators
1.3.1 Activation of elemental phosphorus
The amorphous red and the allotrope white phosphorus modifications (Figure 7) are in principle an ideal starting material for phosphorus compounds. They are cheap, not malodorant and no useless metal halogenide waste is produced as with halogenphosphanes as starting material. In industrial application, white phosphorus is preferred because of its price and its physical properties. Therefore, the activation of phosphorus has been investigated since the early decades of phosphorus chemistry and it is still an important field in research. P
P P P
Figure 7: Structure of white phosphorus.
So far, no efficient method exists to activate elemental phosphorus in order
to synthesise phosphanes easily and in good yields. PCl3, prepared on a large scale from elemental phosphorus and chlorine, is still the most common starting material for the synthesis of phosphanes. During the production of these phosphanes, a large amount of sodium chloride is formed. This synthetic route is uneconomic and not environmentally friendly. In general, the two main problems of phosphorus activation are the poor reactivity of red phosphorus and the strong reactivity of white phosphorus. Red phosphorus is relatively inert, whereas white phosphorus reacts so fast and often so exothermically that it is not possible to control the chemical reaction and to get defined products. Another problem is the bad solubility of both phosphorus Chapter 1 - Introduction 41
modifications. Two ways are promising for the activation of white phosphorus: activation with (transition) metal complexes and degradation or disproportionation by nucleophilic attack. Many activation reactions of white phosphorus with metal complexes have been reported, however none catalyses the synthesis of phosphanes. Aluminium(I) and gallium(I) compounds are very active in the activation of white phosphorus84, 85, 86 . They form cage structures with P4. Other compounds of main group 87 elements that contain no metals but react specifically with P4 are carbenes and silylenes88, 89, 90. Very promising are the investigations using transition metal
complexes to activate P4. White phosphorus is able to coordinate in different modes as shown in Figure 8. The phosphorus-phosphorus bonds become weak, and a degradation of the bonds takes place. Many activation reactions have been performed with late transition metals but only a few promise a synthetic application until now.
P P PP P P P P P P P P P P P P M M M M
Figure 8: Frequent coordination modes of white phosphorus91.
Two interesting new routes for the functionalisation of white phosphorus are the one of Peruzzini et al. and Cummins et al.. Peruzzini et al. described an activation reaction with rhodium and iridium hydrides. The activation product is 92 able to react with H2 to give PH3 (Scheme 3).
Chapter 1 - Introduction 42
P H H2 PH 3 P P P P P P H P P P P P P Rh Rh M thf, 40°C, -H P H 2 P P H P P P P PH M=Rh,Ir 3
P H2 P H P P P H P P P P P Ir P P P P P H Ir thf, 70°C P Ir -EtH P P H P P P
Scheme 3: Activation of white phosphorus with Ir- and Rh-hydrides.
The main problem is the atom economy, though, as only one mol PH3 is
formed per mol P4. Another system discovered by Peruzzini and co-workers based on a ruthenium cyclopentadienyl complex has the same disadvantage93.
Hydrolysis affords one equivalent of PH3 and three equivalents of unknown phosphorus compounds.
Cummins et al. activated white phosphorus to a P2-unit that can be split by reduction with sodium amalgam to give a niobium(V)phosphide. The phosphide can be easily transformed to tBuCP (Scheme 4). The reaction product of * niobium(V) phosphide with Mes NPCl is able to form "P2" species at 65°C. In
contrast, the formation of "P2" units starting from P4 normally requires temperatures 94, 95 above 1100°C . These two examples cannot give an overview of P4 activation with transition metals, but they show excellently its importance. Chapter 1 - Introduction 43
t H CH2 Bu Ar t t CH Bu H BuH2C Ar 2 t N Bu N Ar N Ar P 2 Nb Ar 0.5 P4 t N N Nb Nb N CH2 Bu N P t t N CH2 Bu Ar t BuH2C N CH2 Bu Ar Ar t CH2 Bu Ar
Na/Hg tBu - O P t t N(Ar)CH2 Bu t N(Ar)CH2 Bu + P Nb BuCOCl t Na BuH2C(Ar)N Nb t BuH2C(Ar)N t N(Ar)CH2 Bu t N(Ar)CH2 Bu
Mes*NPCl
O * t Mes N N(Ar)CH2 Bu P Nb P t BuH2C(Ar)N N(Ar)CH tBu Nb N(Ar)CH tBu 2 t 2 BuH2C(Ar)N + tBuCP t N(Ar)CH2 Bu Mes* N t N(Ar)CH2 Bu 65°C t BuH2C(Ar)N Nb N(Ar)CH tBu Ar=C H -3,5-Me " 2 6 3 2 +"P2
Scheme 4: Activation of P4 with a niobum hydride complex.
After the activation reactions, we will discuss now the nucleophilic degradation reactions of white phosphorus. The degradation occurs stepwise as shown in Scheme 5. All steps include more or less a disproportionation reaction96. The first investigations on nucleophilic degradation reactions with hydroxides and
sodium alkoxides of P4 were performed one hundred years ago. Since then, these experiments have been verified and revised several times97, 98, 99, 100, 101. Furthermore, many different nucleophiles have been used to study the degradation reactions and to find a way to use white phosphorus as a precursor for phosphanes. Sodium thiolates102, 103, lithium amides97, Grignard- and Chapter 1 - Introduction 44
organolithium compounds104, 97 , potassium and lithium phosphides105, 106, 107, 108 are only some of the reported "classical" nucleophiles.
P - - (1) m/4 P P +X X-Pm P
P P - - P P +X XP P (2) P P
P - 2- (3) P P +4X 2 (X-P-P-X) P P - - - n/4 P P +2X (X-P-X) +Pn-1 (4) P
P - P - o/4 P P +3X X X +Po-1 (5) P X
Scheme 5: Nucleophilic degradation/ disproportionation of white phosphorus by nucleophilic attack
In the first step of the degradation, the anion attacks the P4 unit and a
substituted P4-anion is formed (Scheme 5 (2)). This can be either linear or cyclic. 2– After a second attack of an anion, P2X2 units are formed (Scheme 5 (3)). Another
possibility is the disproportionation of P4, which is favored by charge-delocalizing nucleophiles and nucleophiles with large counterions (low charge density, e.g. – – – Ph2PO , CN or (Me2N)2PO ). A polyphospha-anion and a monophospha-anion are formed (Scheme 5 (4), (5)) 97. Last but not least, metals can be used to activate elemental phosphorus. Unfortunately, the reactions between phosphorus and metals are very often not selective, or polyphosphides are formed109. Hence, the resulting metal phosphides
are normally not used directly as a reagent. After their hydrolysis, PH3 is formed that is used as a phosphination reagent. Alkali metal phosphides can be prepared from the pure metal and white phosphorus by heating in an inert solvent like xylene. Red phosphorus has to be melted together with the metal directly. Chapter 1 - Introduction 45
Only a few publication report the direct synthesis of phosphanes starting from alkali phosphides. Cahor, Letts and Collie prepared tetraalkylphosphonium 110 111 salts starting from Na3P , Peterson synthesised Me4PI out of Na3P . Becker
obtained P(TMS)3, which is a very important precursor for phosphorus compounds from the reaction of white or red phosphorus with a potassium / sodium alloy112. For the synthesis of BAPOs starting from elemental phosphorus, the phosphorus activation and degradation reactions had to be investigated. The precursor sodium bis(mesitoyl)phosphide was studied by D. Stein13. It was prepared starting from NaPH2, which has many disadvantages because of its physical properties, stability and solubility.
1.3.2 The use of NaPH2 as precursor for phosphorus compounds
Sodium phosphide, NaPH2, is a very versatile starting material in organophosphorus chemistry. Early publications describe the reduction of white
phosphorus, P4, with sodium or lithium in liquid ammonia to the diphosphanediide 113, 114 Na2(P2H2) 2 NaNH2 . Careful addition of ammonium bromide or water in the
presence of an excess of alkaline metal gave NaPH2 as a thermally unstable, pyrophoric substance that is insoluble in organic solvents. Indications for the
composition of NaPH2 were only obtained by reaction with alkyl iodides, which gave the corresponding primary phosphanes in about 60% yield115, 116.
This synthesis of NaPH2 was refined by Brandsma et al. by adding tert- butanol in diethylether in the course of the reduction. Subsequent addition of alkyl halides gave the corresponding alkylphosphanes in 77 % yield117, 118, 119, 120.
MPH2 (M = Li – K) is also obtained when phosphane, PH3, reacts with
ammonia solutions of alkaline metals. The poor solubility of NaPH2 can be overcome to a certain extent by the addition of crown-ethers121. To the best of our 122 knowledge, [LiPH2(dme)], prepared from PH3 and nBuLi is the only structurally characterised alkaline dihydrogenphosphide known to date123. None of the above mentioned synthesis is really practical, nor do they give
stable solutions of MPH2. The insolubility of simple inorganic salts - caused by their high lattice energy – can be overcome by “alkoxide packaging”. For example, Chapter 1 - Introduction 46
t 124 insoluble hydrides become soluble as “super aggregates” like [Li33H17(O Bu)16] and MH/M(OtBu) mixtures were successfully used in N-heterocyclic carbene synthesis125. We reported that NaOH can be encapsulated and solubilised in form t 126 of the 21-vertex tert-butoxide cage [Na11(OH)(O Bu)10] .
D. Stein found in earlier investigations that NaPH2 can be synthesised starting from sodium, red phosphorus and tert-butanol in liquid ammonia / dme (1:1) as solvent mixture13 (Scheme 5). The crude product of the synthesis has t the theoretical formula NaPH2 x 2 NaO Bu and is not a uniform compound. An
alkoxide clusters was crystallised from an concentrated solution of NaPH2 x 2 NaOtBu. Therefore, it is not wondering that in the presence of NaOtBu, the
solubility of NaPH2 increases dramatically. This new material can be used as precursor for sodium bis(mesitoyl)phosphide that can be used for the synthesis of BAPOs. Besides investigating the phenomenon of the increasing solubility, the improvement of the synthesis is discussed in this work. A new way to use white phosphorus as a starting material had to be found as well. The advantage of employing white instead of red phosphorus is its lower price and easier handling on an industrial scale.
NH3(l) dme t 2 BuOH t P+3Na [NaPH2(solv)x] + 2 [NaNH2(solv)x] NaPH2 x2NaOBu T=291K -NH3 p=7bar t Scheme 6: Synthesis of NaPH2 x 2 NaO Bu starting from sodium and phosphorus
1.3.3 Synthesis of functionalised arylphosphanes
As mentioned before, functionalised primary and secondary arylphosphanes, can be used as starting materials for the synthesis of BAPOs. Beside these applications, functionalised and in particular tertiary ones have many applications. They are widely used for the synthesis of transition metal complexes because they control their performance in catalysts127. In recent years, phosphanes have been also applied as interesting components of electronic materials128. Chapter 1 - Introduction 47
While arylamines are routinely prepared on a large scale by simple nucleophilic aromatic substitution by using ammonia or amides as nucleophiles under relatively harsh conditions (high temperatures and / or pressures),129 more sophisticated methods have to be used for the preparation of arylphosphanes, which are thermally intrinsically less stable than amines. A number of such methods exist. The nucleophilic substitution of halogeno-substituted phosphanes,
RnP(Hal)3-n, with organometallics (R’M; M = Li, MgX, ZnX, R’ = organyl group) is among the most popular methods.130, 131 Primary or secondary phosphanes132, 133, 134, 135, 136 can be quite conveniently coupled under basic conditions with alkyl halides to give tertiary phosphanes. Phenyl- and (diphenyl)lithiumphosphide,
[PhPHLi] and [Ph2PLi], are frequently employed in these reactions because they are readily available from the following reaction137, 138:
PhnPHm + nBuLi [PhnPHm-1Li] + nBuH
Ph3P + 2 Li Ph2PLi + LiPh When aryl halides are to be used in these reactions, [Pd]° catalysed cross- coupling reactions have been developed, in analogy to the Hartwig-Buchwald coupling between aryl halides and amines139, 140(Scheme 7).
I O 0 LnPd +L ONa ONa -L P O
PPh I 2 L Pd LnPd n Ar Ar
L=PPh ,BINAP,dba 3 HNEt3I Ph2P-H, NEt3
Scheme 7: Palladium catalysed cross-coupling of phosphanes139.
Phosphane, PH3, and its metal derivatives, PHnMm (n = 2 – 0, m = 1 – 3), 141, 142, 143, 144, 145, 146, 147, 148 or silylated phosphanes149 have been used for the Chapter 1 - Introduction 48
preparation of alkyl and aryl substituted phosphanes115, 116, 117, 118, 119. However, none of these protocols allowed the synthesis of functionalised phosphanes because of the often strongly basic and / or nucleophilic reaction conditions or the need of higher temperatures and prolonged reaction times. Exceptions are the
synthesis of the water-soluble tris(sulfonylphenyl)phosphane, (NaO3S-C6H4)3P (TPPS), and various pyridylphenylphosphanes, which Stelzer et al. prepared from
PH3 / dmso / KOH mixtures using the corresponding aryl fluorides as substrates141, 142, 143, 144, 145 (Scheme 8).
SO3Na F
KOH, dmso, PH3 3 -3KF,-3H2O P SO3Na NaO3S SO3Na
Scheme 8: Synthesis of tris(aryl)phosphanes starting from arylfluorides and PH3.
The synthesis of functionalised arylphosphanes, starting from NaPH2 x 2 NaOtBu is discussed in this work (see Chapter 2).
Purpose
The goal of this thesis was the synthesis of functionalised BAPOs and their application in the functionalisation of polymers and surfaces. In the first step, the synthesis of the precursor for the BAPO-synthesis had to be improved. Therefore, the activation of elemental white and red phosphorus had to be studied, the
synthesis of NaPH2 had to be improved and the properties of NaPH2 in the presence of tert-butoxide had to be studied as well. In the next step, these investigations were applied in the preparation of functionalised arylphosphanes and bis(acyl)phosphides to use them for the preparation of BAPOs with a wide range of functionalities. To design BAPOs for special application, it was necessary to study their reactivity, photolytically and thermal decomposition reactions. Methods to perform light induced and selective reactions in high yields on surfaces had to be investigated. They would afford locally resolved surface functionalisation of BAPO- functionalised surfaces by adding special reagents and local irradiation. Starting from functionalised BAPOs, the preparation of BAPO-functionalised polymers had to be investigated. Their properties had to be studied and characterised. Finally, other applications of the synthesised BAPOs were investigated, especially in order to use them as photoinitiators for polymerisation reactions.
Chapter 2
Activation of elemental phosphorus and investigation of
NaPH2
Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 52
2.1 Introduction
In order to synthesise new functionalised acylphosphane oxides we investigated the activation of white and red phosphorus. No efficient method exists to activate the insoluble, inert red or the very reactive white phosphorus. Many systems have been investigated (see Chapter 1), but the activation with transition metal complexes, with alkali metals or the nucleophilic degradation does not give useful results for the synthesis of phosphanes in general. A problem of the red phosphorus is its undefined structure, the bad reactivity and insolubility. The problem of the activation of white phosphorus is the strong reactivity and unselective reactions to non-defined products or very stable Zintl-anions, which can not be transformed to phosphanes easily. The state-of-the-art is the production of halogenphosphanes starting from the elements or of PH3 by hydrolysis of metal phosphides as starting material. During the synthesis of phosphanes from these kinds of starting materials, the production of metal halide and the physical and
chemical properties of PH3 are serious problems. Furthermore, other "standard"
starting materials in order to prepare phosphanes (e.g. P(TMS)3) have many disadvantages. They are toxic, gaseous, extremely sensitive to oxygen and moisture, and their starting materials are expensive. They can not be used in an industrial scale.
The activation of white phosphorus, P4, has been investigated for many years. Many degradation reactions have been reported several decades ago, but the products were not determind97. In the first part of this chapter, we describe the nucleophilic degradation with amides and tert-butoxide. Afterwards we report the
reactivity and characterisation of the NaPH2-alkoxide cluster that were used as starting materials for BAPOs in the previous work from D. Stein13. Finally, we t discuss the use of NaPH2 x 2 NaO Bu in the synthesis of bis(acyl)phosphides and functionalised arylphosphanes as starting materials for BAPOs (see Chapter 1)13.
NaPH2 is a versatile starting material in organophosphorus chemistry, but its insolubility has always been a big problem. "Alkoxide-packaging" was found as a new phenomenon in previous work but was not studied sufficiently. Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 53
2.2 New routes to activate elemental phosphorus via nucleophilic
degradation
2.2.1 Lithiumdiisopropylamide (LDA)
The reaction of lithium diisopropylamide (LDA) with white phosphorus (P4) is described in the literature97. The analytical data from these investigations in literature are limited to elemental analysis, though. Different structures of the product, like 4-membered rings with amino-substituents, have only been assumed, but no further investigations have been reported.
thf P4 + 2 N [Li2P16(thf)8] Li P1,43%
Scheme 9: Nucleophilic degradation of P4 with LDA.
In our investigations, white phosphorus was dissolved in thf and two equivalents of LDA were added subsequently at room temperature (Scheme 9). The solution became red immediately. After adding an excess of n-hexane, a red oil precipitated. The oil crystallises in n-hexane in one week into red crystals that are suitable for X-ray analysis. The X-ray analysis shows the structure of
[Li2P16(thf)8] (P1). The yield calculated on P4 is about 43%. 2– The cluster anion P16 has been known for more than 25 years, but its synthesis is time-consuming and starts from "non-common" starting materials like 150 151 152 Na3P7 or Li3P7 and P2H4 , which have to be synthesised themselves as 2– well. Furthermore, in these synthesis the P16 anion was only obtained in a mixture 2– with polyphosphides. The synthesis with LDA is the first synthesis to give P16 in a reaction that is easy to perform in relatively good yields. The 31P NMR spectra and
the structure fit with the investigations of [Li2P16(thf)8] P1 from Baudler et al. (Figure 9)152. The NMR-signals are broad at room temperature. At -30°C the mulitiplicity of the different atoms can be seen clearly. This is a new simple straight-forward Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 54
synthesis of a compound that can be used as precursor for many other polyphosphides.
2– Figure 9: ORTEP plot of P16 in [Li2P16(thf)8] (P1) (thermal ellipsoids at 50% probability, the cation is omitted for clarity). Selected bond lengths [Å] and angles [°]: P1–P4: 2.034(2), P1–P3: 2.081(3), P1–P2: 2.167(6), P3–P7: 2.217(5), P2–P5: 2.281(4), P5–P6: 2.94(5), P6–P7: 2.351(5), P9–P4: 2.575(5), P8–P3: 2.152(4), P8–P9: 2.115(6), P3–P7–P5: 105.24(2), P7–P5–P6: 64.89(4), P1–P2–P5: 95.75(3), P4–P3–P7: 62.09, P9–P8–P3: 105.13(3), P8–P3–P7: 95.43(5), P8–P9– P4: 103.81(4).
P6,7 P2 P3,4 P5 P8,9 P1
31 2– Figure 10: P NMR spectrum of P16 . Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 55
2.2.2 Magnesium diisopropylamide
The reaction of white phosphorus with magnesium amides has not been reported in the literature. Magnesium-phosphorus bonds are less stable than lithium-phosphorus bonds. Therefore, the investigation of this reaction is interesting in terms of finding new ways to activate white phosphorus. White phosphorus reacts with less than one equivalent magnesium 2– diisopropylamide to P16 . With one equivalent in thf or dme it gives a red unidentified oil A1, which shows two signals in the 31P NMR spectrum. A doublet of doublets of doublets at δ = 102.29 (J1 = 547, J2 = 270 Hz, J3 = 101 Hz) and a triplet of doublets at δ = -207.99 (J1 = 208 Hz, J2 = 101 Hz).
N Mg N N ,thf MeI thf i P4 + Mg A1 A2 [MeP(NPr2)2] N
MesCOCl
Na O O
P +?(Signalat95.5ppm)
P4 i Scheme 10: Nucleophilic degradation of P4 with Mg(N Pr2)2.
Figure 11: 31P NMR spectrum of A1. Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 56
This oil reacts with a second equivalent of magnesium diisopropylamide to a red unidentified microcrystalline powder A2. All attempts to get single crystals failed. The 31P NMR spectrum shows a doublet of doublets at δ = -0.27 (J1 = 274 Hz, J2 = 208 Hz). A minor product gives a second set of signals with the same multiplicity and coupling constants at δ = -1.21 ppm (Figure 12).
Figure 12: 31P NMR spectrum of A2.
i Compound A2 reacts with methyl iodide to MeP(N Pr2)2 and mesitoyl
chloride to a mixture (1:1) of (MesCO)2PNa and a non-identified product that gives a signal at 95.5 ppm in the 31P NMR spectrum.
2.2.3 Sodium tert-butoxide
t thf P4(s) + NaO Bu Na2P16 (P2)
O thf MesCOCl P + t A3 4(solv.) NaO Bu P O O excess Na
P5 B1a,60%
t Scheme 11: Nucleophilic degradation of P4 with NaO Bu.
The reaction of white phosphorus with sodium tert-butoxide has not been reported in the literature. An 1 M solution of sodium tert-butoxide in thf dissolves Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 57
one equivalent of white phosphorus by forming Na2P16 (P2). The analytical data fit to the ones of the literature152. If the white phosphorus is dissolved in thf before it is added to the sodium tert-butoxide solution, an unidentified compound A3 is formed, which shows two very broad signals at δ = 59.3 and -39.8 in the 31P NMR t spectrum. By adding sodium, this compound reacts to [Na3P7(NaO Bu)6(dme)3] (P5) (Figure 14). This alkoxide cluster P5 crystallises out of the solution in a yield of about 60%. The unknown product reacts with mesitoyl chloride to t [(MesCO)2PO Bu] (B1a), which can be crystallised out of the solution by evaporation of the solvent. This kind of an "umgepolt" BAP might be interesting for the synthesis of functionalised bis(acyl)phosphane oxides (BAPOs) by electrophilic substitution. t The alternative synthesis of (MesCO)2P-O Bu starting from sodium bis(mesitoyl)phosphide (P4) is quite complicated.13 Therefore, this route is interesting for the synthesis of new photoinitiators.
t 2.2.4 Crystal structure of (MesCO)2P-O Bu (B1a)
White crystals of B1a are formed from a concentrated thf solutions upon evaporating the solvent during several days in a yield of 58% (Figure 13). The two bond lengths of P–C(=O) are 1.8983(6) Å and 1.8938(6) Å, which is in the range of the one of BAP-acetic acid (1.8628(2)) (see Chapter 4). The bond length P–OtBu is in the typical range of tert-butyl phosphinites153. Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 58
Figure 13: ORTEP plot of BAP-OtBu (B1a) (thermal ellipsoids at 50% probability, hydrogen atoms omitted for clarity). Selected bond lenghts [Å] and angles [°]: P1– O1: 1.6166(4), P1–C5: 1.8938(6), P1–C15: 1.8983(6), O1–C1: 1.5117(6), O2–C15: 1.2335(6), C5–O3: 1.2452, C5–P1–O1: 100.71(2), C15–P1–O1: 100.54(2), C15– P1–C5: 100.86(3), O3–C5–P1: 117.76(4), P1–C15–O2: 116.59(4).
2.2.5 Crystal structure of the Na3P7 containing cluster P5
t The [(Na3P7)2(NaO Bu)6(dme)6] cluster crystallises out of the concentrated thf solution. Its core is a planar hexagonal ring of corner linked sodium triangles 3- that alternate in their orientation. On both sides of this 6-membered ring, a P7 unit is located in such a way that the three sodium atoms on the same side of the ring coordinate to the negatively charged phosphorus atoms. Every sodium triangle is stabilized by a tert-butoxy group, which is centred over the triangle. The sodium 3- ions that compensate the negative charge of the P7 anion are coordinated by 3- dme. The bond length of the P7 cluster corresponds to the ones published in the literature154.
Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 59
t Figure 14: ORTEP plot of [(Na3P7)2(NaO Bu)6(dme)6] (P5) (thermal ellipsoids at 50% probability, hydrogen atoms omitted for clarity). Selected bond lenghts [Å] and angles [°]: P1–P2: 2.1792(16), P1–P3: 2.1822(15), P1–P4: 2.1819(15), P4–P7: 2.1822(15), P2–P5: 2.1513(14), P3–P6: 2.1462(15), P7–P5: 2.2746(15), P5–P6: 2.2495(16), P6–P7: 2.2606(15), Na1–P4: 2.9647(18), Na1–P2: 3.1368(18), Na2– P3: 3.1631(18), Na2–P4: 2.9764(18), Na3–P2: 3.0214(18), Na3–P3: 3.0097(19), P1–Na6: 3.2018(18), Na3–Na7: 3.4542(20), Na3–Na6: 3.4604(20), Na6–Na7: 3.2016(22), Na6–Na5: 3.2300(22), Na5–Na4: 3.2281(22), Na5–Na6–Na7: 57.00(4), Na4–Na5–Na6: 128.64(6), Na5–Na1–Na4: 57.00(4), Na1–Na5–Na4: 64.57(5), Na1–Na4–Na5: 58.43(4), P1–P2–P5: 97.97(3), P1–P3–P6: 97.80(6), P3– P1–P4: 101.57(6), P5–P6–P7: 60.57(5), P6–P7–P5: 59.47(5).
t 2.3 Investigation of NaPH2-NaO Bu alkoxide clusters
2.3.1 Alkoxide stabilized NaPH2-clusters
t In earlier investigations D. Stein found that NaPH2 forms with NaO Bu a very t stable [Na13(PH2)(O Bu)12] (P6) alkoxide cluster that has very good solubilities in hydrocarbons. Since only the crystal structure was known13, we had to investigate Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 60
the properties of this alkoxide cluster (e.g. stability, synthesis) and to search for t other NaPH2-NaO Bu clusters. It was possible to synthesise another completely t new types of alkoxide clusters: [Na(dme)3][Na12(PH2)(O Bu)12] (P7). These two clusters serve as thermally stable and hydrocarbon soluble sources of the nucleophile PH2 . Both the red and white modifications of phosphorus react with three equivalents of sodium, dissolved in a mixture of liquid ammonia and dme (1:1) at 13 room temperature, to a mixture of [NaPH2(solv)x] (P8) and [NaNH2(solv)x] . The only difference is the reaction time, which is of two hours for the red phosphorus and of one hour for the white phosphorus. If only two equivalents of sodium are used, Na3P7 (P3) is obtained (Scheme 12).
NH3(l) dme P+3Na [NaPH2(solv)x] + 2 [NaNH2(solv)x] T=291K 7bar t Filtration of 2 BuOH dme solution -NH3
t [NaPH2(dme)]x P8 NaPH2 x2NaOBu P10
NaOtBu (excess), toluene, recryst. toluene, 80°C dme, toluene, NaPH +12NaOtBu [Na (PH )(OtBu) ] P6 recryst. 2 80°C 13 2 12 toluene, dme 60°C
t recryst. = recrystallisation [Na(dme)6][Na 12(PH2)(O Bu)12] P7
Scheme 12: Synthesis of NaPH2 and its clusters starting from elemental phosphorus.
The [NaPH2(solv)x] (P8) can be isolated by filtering off the insoluble
[NaNH2(solv)x] in a yield of 78 %. After evaporating the solvent, crystalline P8 remains. The pale yellow product shows one 31P NMR resonance at δ = -301.8, which splits into a triplet with J = 147 Hz in the 1H-coupled spectrum and a resonance at δ = -1.37 in the 1H NMR spectrum proving the formation of the – dihydrogenphosphide anion PH2 . Another method to destroy sodium amide is its Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 61
protonation to ammonia with tert-butanol. In this case a composite with the t theoretical formula "NaPH2 x 2 NaO Bu" (P10) is formed in a yield >90 %. It is soluble in hydrocarbons and ethers (thf, diethyl ether, toluene, benzene, dme) and can directly be used for the synthesis of phophorus compunds. It shows in the 31P NMR spectrum a signal at δ = -285.3 (J = 146 Hz). By evaporating a + t concentrated dme solution of P10, [Na(dme)3] [Na12(PH2)(O Bu)12] (P7) crystallises in big colourless cubes with an edge length up to 3 mm. When toluene t is used as a solvent [Na13(PH2)(O Bu)12] (P6) crystallises in colourless cubes with an edge size up to 5 mm. When crystals of P7 are dissolved in toluene and heated up to about 60°C, t [Na13(PH2)(O Bu)12] (P6) is formed. Crystals of the latter compound react immediately to P7 by dissolving them in dme.
P7 P6
Scheme 13: Solvent dependent equilibrium of the NaPH2 clusters.
Another possibility to synthesise the cluster P6 is the direct reaction of pure t NaPH2 or [NaPH2(dme)x] (P8) with the stoichiometric amount of NaO Bu in toluene at 80°C. After cooling down the solution to room temperature, colourless crystals of t [Na13(PH2)(O Bu)12] P6 are formed. The NMR spectroscopic analysis shows the – 31 signals of the PH2 ion in the proton-coupled P NMR spectrum at δ = –307.7 ppm Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 62
(J = 145.0 Hz) and a doublet at δ = –2.24 ppm in the 1H NMR spectrum (J = 145.0 Hz). for
t Figure 15: The structure of [Na13(PH2)(O Bu)12] P6 and its space-filling model.
The X-ray-structure of P6, as observed from D. Stein, shows that twelve – tert-butoxy groups form an icosahedron and fully encapsulate the central PH2 anion13 (Figure 15). The thirteen sodium cations are statistically distributed on the twenty corners of a pentagonal dodecahedron (Figure 15). The disorder persists even at 120 K and the line widths of NMR experiments point to a fast dynamic process rather than static disorder. Compound P6 can be viewed as a neutral anion-aggregate155, 156, 157 showing charge alternation form the inside to the – + t – outside of one PH2 , thirteen Na , and twelve BuO .The outer surface of the cluster is completely covered by the lipophilic tBu groups, which explains its relatively high solubility (> 20% by weight) in hydrocarbon solvents. – The X-ray diffraction data of P7 show that the anion [Na12(PH2)(OtBu)12] has the same structure as P6 (twelve sodium cations disordered on the dodecahedral shell) (Figure 16). Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 63
– Figure 16: Plot of the X-ray structure of [Na12(PH2)(OtBu)12] (P7) measured at 30 K with an Oxford helium cooling system. (blue = sodium, red = oxygen, purple = + phosphorus, black = carbon). The hydrogen atoms and the [Na(dme)3] cation are omitted for clarity.
– The X-ray-structure of the cluster anion [Na12(PH2)(OtBu)12] (P7) is analogous to the one of [Na13(PH2)(OtBu)12] (P6). The sodium atoms form a – disordered icosahedron around the PH2 anion. Over each of the twelve 5- membered rings, a tert-butoxide ion stabilizes the cluster. As in the t [Na13(PH2)(O Bu)12] (P6) cluster, the sodium cage and the tert-butoxide anions are disordered. There are no significant differences in the volume of the cluster; even though there is one sodium atom less in the sodium cage. The angles and the distances between the different atoms of the disordered dodecahedral cage fit to the angles and the atom distances of P6 as well. This concept complements nicely the chemistry seen with other covalently 158, 159, 160. constructed container molecules and supra-molecular capsules C60,
which is able to encapsulate for example He and H2 is a classical example for this phenomenon161. Compared with the discussed system, the main difference is the Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 64
2- fact that the H2 in C60@H2 is freely rotating, whereas the PH has not enough space in the sodium cage to undergo free rotations. This is shown by a simulation
using the 100 % Van-der-Waals-radii of C60@H2 and "Na12@PH2" in Figure 17. – Moreover, the two H atoms of the PH2 -ion are irregularly "covered" by sodium ions in the model.
- Figure 17: Models with the 100% van-der-Waals-radii of the atoms: a) PH2 encapsulated by 12 sodium and b) C60@H2 (cut through the C60 molecule).
Both P7 and P6 are air-sensitive but not pyrophoric, thermally stable (P7: 109 °C; P6: 112 °C), and can be stored under argon at room temperature for at least a couple of months. When crystals of the anionic cluster P7 are dissolved in 31 [D8]toluene or [D6]benzene and warmed up to 60°C, the P NMR resonance of the neutral aggregate P6 is observed. Vice versa, a dme solution of the neutral aggregate P6 shows the signal of ion pair P7. However, in toluene solutions with about 10% dme, both compounds are observed separately indicating no or very slow exchange on the NMR time scale. The remarkable stability of the clusters P7 and P6 is also reflected by their reactivity: No reaction takes place when 1,4-dichloro-1,4-diphenyl-2,3- diazabutadiene (A4) is added to a toluene solution of P6. However, adding a few drops of thf immediately causes a strongly exothermic reaction. A broadened signal in 31P NMR spectrum at δ = 65 indicates the formation of the 2,5-diphenyl- 162, 163, 164 3,4-diazaphospolide P9. Thus, [Na(dme)[P(CPh)2N2]∞ (P9) was obtained in a straight-forward manner in high purity. Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 65
NN NN thf +NaPH x2NaOtBu 2 P (P9) ClCl Na+
NN NN toluene t +NaPH2 x2NaOBu P (P9) ClCl Na+ t Scheme 14: Synthesis of a diazaphospholide P9 from NaPH2 x 2 NaO Bu.
2.3.2 PFGSE NMR experiments
Further evidence for the remarkable stability of the aggregates was obtained from Pulsed Field Gradient Spin Echo experiments (PFGSE NMR)165, 166, 167. In a - t – [D8]toluene solution of P7 (or P6) the diffusion rate of the O Bu and the PH2 groups are identical (D = 6.11 x 10-10 m2s-1), which strongly suggests that they are incorporated within the same species. However, the estimated hydrodynamic 3 radius, rH = 6.52 Å, and molecular volume, VH = 1162 Å , are smaller than the estimated volume from the solid-state structure (1850 Å3). The PFGSE NMR experiments with the ion pair P7 show that the dme molecules move at a much higher rate (D = 22.4 x 10-10 m2s-1). Therefore, P7 reacts in hydrocarbons as solvents according to:
+ t – t [Na(dme)3] [Na12(PH2)(O Bu)12] (P7) [Na13(PH2)(O Bu)12] (P6) + 3 dme
In thf-d8, however, both P7 and P6 are degraded to smaller aggregates that are more open. PFGSE NMR measurements show that now the averaged diffusion – -10 2 -1 t – -10 2 -1 rates of the PH2 (D = 10 x 10 m s ) and BuO groups (D = 8.21 x 10 m s ) are different. A further specification concerning the size of the species in solution cannot be made with certainty. A thf-d8 solution of P6 shows a triplet at δ = -297.9 (J = 158 Hz) in the proton coupled 31P NMR spectrum and a doublet at δ = -0.72 1 1 – (d, JPH = 158 Hz) in the H NMR spectrum. The same spectra for the PH2 unit are
obtained when [NaPH2(dme)]x is successively reacted with up to four equivalents of NaOtBu. An electro spray ionisation (ESI) mass spectrum of a thf solution of P7 Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 66
t shows a highest peak at m/z = 532, suggesting that species like [Na5(PH2)(O Bu)4] may be present.
2.3.3 Solid state NMR experiments
In a collaboration with Prof. B. Meier, solid state NMR experiments of the t – t two clusters [Na12(PH2)(O Bu)12] (P7) and [Na13(PH2)(O Bu)12] (P6) were performed to investigate and to prove the motion of the sodium cations168. A description of the NMR theory for the measurements of the 23Na spectra can be found in the literature169, 170, 171, 172. A clear proof of fast motion of the sodium cations was obtained from 23 t temperature-dependent one-dimensional Na spectra of the [Na13(PH2)(O Bu)12] (P6) shown in Figure 18.
Figure 18: Temperature correlated 23Na-NMR solid state spectrum of t [Na13(PH2)(O Bu)12] (P6) (left) and its 12-site exchange simulation (right).
The strong changes in the spectra indicate the averaging of the quadrupolar interaction. At low temperature, a broad lineshape is obtained. Just above 100 K the lineshape narrows dramatically and reach a minimum at around 150 K. At higher temperatures, the line shape broadens further and shifts its centre, after which it narrows once more (Figure 18). Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 67
The changes of the spectrum as a function of temperature can be explained well by a model of fast exchange of the sodium sites on an icosahedron. Figure 18 shows a 12-site exchange simulation for a system of 12 sodium nuclei. The only exchange that is allowed, is the one between the five nearest neighbours in the icosahedron. The simulation shows two regions of coalescence and narrow lines in between the two coalescence regions at the highest rates, which is expected for the case of a strong quadrupolar interaction. However, the exact 23Na lineshape is not reproduced by the exchange simulation. Significant broadening is found
experimentely due to short T1 at high temperatures. The discrepancy of the data at low temperature is not yet understood. However, it was not possible to measure the temperature-dependent 1D t spectrum for the [Na(dme)3][Na12(PH2)(O Bu)12] (P7) cluster in a reasonable amount of time, due to the strong broadening of the lines close to room temperature because of the strongly decreasing signal noise to ratio. It was possible to estimate the activation energy of the sodium exchange in 23 both complexes from the Na T1 relaxation times. Figure 19 shows the T1 values for both complexes as a function of temperature. A minimum was found for t t [Na13(PH2)(O Bu)12] (P6) at around 210 K. For the [Na(dme)3][Na12(PH2)(O Bu)12] (P7) complex, no minimum has been observed yet at room temperature. At higher
temperatures, the T1 decreased but the temperature could not be measured reliably and the data were discarded. In the regime of extreme narrowing, the slope 173 of the T1 curve can be used to estimate the activation energy . Assuming that t this is possible for the [Na(dme)3][Na12(PH2)(O Bu)12] (P7) data too, values of 28 t and 9 kJ/mol were estimated for [Na(dme)3][Na12(PH2)(O Bu)12] (P7) and t [Na13(PH2)(O Bu)12] (P6) complexes, respectively. Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 68
23 Figure 19: T1 relaxation times of Na nuclei in the sodium cages (above: t t [Na13(PH2)(O Bu)12] (P6); below: [Na(dme)3][Na12(PH2)(O Bu)12] (P7)). (Solid lines are plotted to guide the eye).
In summary, it was shown that the sodium cations in the two different t clusters are in fast motion. The motion in the [Na13(PH2)(O Bu)12] (P6) is faster than t the one in [Na(dme)3][Na12(PH2)(O Bu)12] (P7).
2.3.4 Theoretical studies
Theoretical studies were performed in a collaboration with M. Reiher to t – t prove the stability of [Na12(PH2)(O Bu)12] (P7) and [Na13(PH2)(O Bu)12] (P6) and to - investigate the stability of analogous clusters in which the PH2 is removed from the sodium cage, or less bulky groups like methylate, hydroxide and fluoride replace the stabilising, bulky tert-butoxy groups174. Calculations with the program package Turbomole showed that both – t [Na12(PH2)(OtBu)12] (P7) and [Na13(PH2)(O Bu)12] (P6) are stable in the vapour phase. Energies for eight different regioisomers of the cluster, with different occupancy of the Na+ sites were calculated. The energy gaps between the different t [Na13(PH2)(O Bu)12] (P6) regioisomers are smaller than the gaps calculated for the Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 69
t – [Na12(PH2)(O Bu)12] (P7) cluster anion. This is in agreement with the solid state NMR experiments, which evidence that the speed of the sodium motion is higher in t [Na13(PH2)(O Bu)12] (P6). – Further calculations showed that the clusters are stable even if the PH2 -ion is removed. This is a very surprising result, because it means that sodium alkoxides are able to form empty cages and should be able to encapsulate neutral molecules or atoms. Another important result is that also clusters in which the stabilising tert-butoxide is substituted by smaller anions like methoxide, hydroxide, or even fluoride would be stable. Experiments to synthesise these compounds were not performed until now, because the experimental investigations concentrated on the synthesis of NaPH2. However, these results might open a new field in cluster science.
2.3.5 Crystal structure of alkoxide packaged sodium selenide.
– For comparison with the alkoxide packaged cluster containing PH2 a
selenide cluster was synthesised from Na2Se (A6). The insoluble sodium selenide A6, which can be easily prepared from the elements in liquid ammonia, was heated up to 100°C for 12 h in toluene in the presence of 12 equivalents NaOtBu t analogously to the synthesis of [Na13(PH2)(O Bu)12] (P6) starting from NaPH2.
t NH3, NaO Bu (excess), t 2Na+Se Na2Se [Na12(Se)(O Bu)10] A5 -35°C, 2 h toluene, 80°C, 12 h
Scheme 15: Synthesis of an alkoxide packaged selenide cluster.
After filtration, the reaction solution was cooled down in the fridge. White t crystals of [Na12(O Bu)10Se] (A5) were obtained. The X-ray-study shows that the selenium atom is in a quadratic antiprism of sodium cations, which is fused with a cube of sodium ions. The cluster is stabilized by tert-butoxide anions that are localised over every face of the cube and alternately over every second triangular face of the quadratic antiprism (Figure 20). Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 70
Figure 20: ORTEP plot of A5 (thermal ellipsoids at 50% probability, hydrogen atoms omitted for clarity). Selected bond lenghts [Å] and angles [°]: Na1–Na2: 3.1527(8), Na2–Na3: 3.0831(7), Na3–Na4: 3.0888(8), Na1–Na4: 3.1141(7), Na5– Na6: 3.1106(8), O1–Na1: 2.2895(2), O1–Na5: 2.2381(2), Na5–Se1: 2.4226(1), Na6–Se1: 2.9168(2), Na1–Se1: 2.3063(2), Na2–Se1: 2.3739(2), Na3–Se1: 2.3063(1), Na4–Se1: 2.3704(7), Na1–Na2–Na3: 89.35(2), Na2–Na3–Na4: 91.22(2), Na1–Se1–Na3: 135.98(6), Na1–Se1–Na2: 84.68(5).
2.4 A simple synthesis of functionalised primary, secondary, and tertiary arylphosphanes
In the preceding paragraphs, we have described a refined protocol for the synthesis of a sodium phosphide reagent that has formally the composition t NaPH2 2NaO Bu. This material can be obtained by reaction of elemental phosphorus (red or white) in a 1 : 1 (by vol.) mixture of dimethoxyethane (dme) and liquid ammonia with 3 equivalents of sodium and two equivalents of tert-butanol in t the temperature range of –78 °C to –33 °C. This NaPH2 2NaO Bu reagent has some outstanding properties: (i) it is soluble in many organic solvents, (ii) in the solid state and in solution it is thermally rather stable, and (iii) the reactivity can be controlled by the polarity of the solvent. That is, in toluene almost no reactivity is Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 71
– observed while in ethereal solvents this “PH2 ” reagent becomes highly reactive. In this paragraph, we describe the application of these findings to the synthesis of primary, secondary and tertiary phosphanes. t The reaction between NaPH2 2NaO Bu (P10) and aryl fluorides of the type FG-Aryl-F (FG = functional group) leads to a remarkably wide variety of functionalised phosphanes under very mild conditions. The reaction proceeds stepwise as shown in a simplified manner in Scheme 16, which ignores any possible protonation-deprotonation equilibria between the phosphides and phosphanes on one side and and tert-butoxide and tert-butanol on the other. Depending on the stoichiometry and reaction conditions, primary, secondary, or tertiary phosphanes can be obtained (Figure 21). Not all of the compounds prepared by this method were isolated, but every compound was characterised by NMR spectroscopy and mass spectrometry. F
PH2 F FG t t NaPH2 x2NaOBu x2NaOBu + -NaF P10 FG FG -NaF t F - BuOH
FG FG FG + t P PH xNaOBu FG -NaF -tBuOH
FG FG
Scheme 16: Synthesis of functionalised phosphanes from aryl fluorides
The reaction conditions and yields are listed in Table 1. Fluorobenzene itself does not react, probably because it is not sufficiently activated. Also chloro-, bromo-, or iodoarenes do not react under the reaction conditions employed. However, the fluoroarenes that are further substituted with electron drawing Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 72
substituents react rapidly at ambient temperature and give the tertiary phosphanes. Bulky or little activated fluoroarenes like 4-phenoxy-fluorobenzene (Table 1) only give the primary phosphane P11, which was isolated as a colourless oil. When primary or secondary phosphanes were prepared from more activated t fluoroarenes, it was of advantage to cool a toluene solution of NaPH2 2NaO Bu to about 0 °C and to add the fluorobenzene to this solution. With the exception of 1,3,5-trifluorobenzene, no reaction was observed at this stage. Only when thf is added to this mixture, the reaction was triggered and the primary phosphanes P11, P12, P13 or secondary phosphanes P14, P15, P16, P17 (Table 1) were formed. t The activated 1,3,5-trifluorobenzene does react with NaPH2 2NaO Bu in toluene, but the addition of thf is needed to complete the reaction. Many of the phosphanes shown in Figure 21 were synthesised for the first time. Tris(iodophenyl)phosphane P18 (31P NMR, δ = –4.3) is a slightly yellow oil, which can be stored under exclusion of light. Tris(p-nitrophenyl)phosphane P19 (31P NMR, δ = +5.7) was obtained in 70% yield as slightly yellow oil, which can be stored under exclusion of light at temperatures below –18 °C for several days. Decomposition via “self-oxidation” of the trivalent phosphorus center is rather slow under these conditions (about 50% after one week at 0 °C). Tris(p- vinylphenyl)phosphane P20 (31P NMR, δ = –7.8) was easily prepared in high yield (80%) and may find interesting applications in coordination chemistry like related ortho-vinylphenyl-substituted phosphanes.175 Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 73
O
PH2 PH2 PH2 PH PH O SO 3H Br P11 P12 P13 P14 P15 O COOH
I I NO2
PH PH P
P COOH P16 P17 P18 I O2N P19 NO 2
F F COOH
P P
PH2 PH2 P
P20 P21 P22 F HOOC P23 COOH F F F3C CF3 F
P F P F P F
F P25 F P26 P24 CF3 F
MeSO2 SO2Me SiMe3
P P P
SO2Me Me3Si SiMe3 P27 P28 P29 + sec. phosph. P30
Figure 21: Structural formulae of the arylphosphanes prepared in this work. Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 74
Table 1: Starting materials, solvents and yields of the phosphanes synthesised t from “NaPH2 (NaO Bu)2”.
Phosphane Starting Method Yield Phosphane Starting Solvent Yield / Literature Material [%] Material [%] F F P11[d] P20[e] thf 60[b] thf 80[b] Ref.176 Ref.177 O
F toluene/ toluene/ [d] OTs P12 [a] [c] [b] thf 70 P21 OTs thf 90 Ref.144
SO 3H
F toluene/ F [d] [e] P13 thf [b] P22 [a] 80 thf 90 Ref.178 Ref.179 Br OTf F toluene/ P14[d] P23[e] thf 90[a] thf 60[a] Ref.180 Ref.181 F COOH F toluene/ F P24[e] P15[c] thf 90[a] thf 40[b] Ref.182 CF3 O F F toluene/ toluene/ P25[e] P16[c] thf 80[b] thf 90[b] Ref.183 F F
Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 75
F F P27[e] P17[c] thf 40[a] thf 70[a] COOH Ref.184
F F
P18[c] thf 80[b] P28[c] thf 90[a]
I SO 2Me F F P29[e] P19[c] thf 70[b] thf 50[a] Ref.185
NO2 SiMe 3 All reactions were performed at ambient temperature, T = 298 K, reaction time is less than two hours. For further details see the experimental part. OTs = p-Me- [a] 31 [b] C6H4-SO3; OTf = CF3SO3. Yields determined by P NMR. Isolated yield. In cases were yields were < 60%, the corresponding primary and/or secondary phosphane was observed as further product. [c] This work. [d] Reported but not isolated. [e] Reported and available as substance.
Instead of the fluoroarenes, tosylates or triflates can be used in the reaction with t NaPH2 2NaO Bu. This procedure has the advantage that the p-MeC6H4SO3
(TsO) or CF3SO3 (OTf) derivatives are easily available through the reaction of the corresponding hydroxyl compounds with tosyl chloride or trifluoromethylsulfonyl chloride. Examples are the synthesis of phosphanes P21 and P22. Especially the high-yield (90%) synthesis of the enantiomerically pure stereoisomer S-P21 as slightly yellow, almost odourless crystalline powder from simple basic chemicals (that is P21-binaphtol, tosylchloride, elemental phosphorus, sodium, tert-butanol
and ammonia) is remarkable. This parent phosphane of the family of C2-symmetric ones can be stored without decomposition for several months. Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 76
Other phosphanes like tris(p-carboxyphenyl)phosphane (P23) or the series of fluoroarene substituted phosphanes P24, P25, P26 can be conveniently prepared by the method described here. A special case is observed with the reactions of the various difluorosubstituted benzenes because, irrespectively of the isomer, the tris(meta- fluorophenyl)phosphane P12 is obtained in 90% yield (Scheme 17).
F F
F NaOtBu F -NaF F -HOtBu 1/3 [NaPH2 xNa(OtBu) ] F n P F -HOtBu F F F t NaO Bu P26 -NaF -HOtBu F
t Scheme 17: Regioselectivity of the reaction from NaPH2 x 2NaO Bu with difluorobenzenes to P26.
While in all other substitution reactions leading to the products of Figure 21 an “ipso-substitution” typical for a nucleophilic aromatic displacement reaction was observed (that is, the leaving and incoming group are bound to the same carbon atom), the formation of P26 indicates a different mechanism. We believe that, in the case of the activated 1,2-, 1,3- and 1,4-difluorobenzenes, the NaPH2 2NaOtBu reagent behaves as a strong base and deprotonates the arene. The corresponding fluorophenyl anion eliminates immediately fluoride and forms a fluorobenzyne. 1,2- and 1,3-difluorobenzene will both lead to 2-fluorobenzyne, whereas the 1,4-difluoro isomer will give 3-fluorobenzyne as reactive intermediate. The strong withdrawing effect of the fluoro substituent will lead to a charge
alternation in the C6-ring and polarize the C≡C triple bond in the way shown in – Scheme 17. Indeed, preferential nucleophilic attack of a phosphide, “PR2 “, with R Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 77
= H and/or 3-F-C6H4, should lead to the meta-substituted isomer exclusively. It is likely that a similar “arine” mechanism is also valid in reactions with other polysubstituted fluroarene like 1,3,5-tris(fluoro)benzene, which gives phosphane P25.
2.5 Conclusion
2- Three ways to synthesise P16 starting from different nucleophiles were 3- found. Furthermore, different ways for the synthesis of P7 were investigated. Even though it was possible to prepare sodium bis(mesitoyl)phosphide (P4) starting from white phosphorus and magnesium diisopropylamide, it was not possible to perform this reaction in order to get a good yield for the synthesis of bis(acyl)phosphane oxides (BAPOs). The reaction of red or white phosphorus with sodium metal in dme / ammonia solution at room temperature, followed by addition of tert-butanol, gives a t white powder with the empirical formula NaPH2 x 2NaO Bu (P10). P10 crystallises t t as [Na(dme)3][Na12(PH2)(O Bu12)] (P7) from dme and as [Na13(PH2)(O Bu12)] (P6) from a toluene solution. They are two of the rare examples of ternary ionic aggregates that were structurally characterised in the solid state and in solution. Like a “Jack-in-the box”, these clusters spring open upon addition of small amounts of thf and the highly nucleophilic PH2– is released, allowing the simple and straight- forward synthesis of organophosphorus compounds, which become easily available from readily available chemicals. t A new application of the NaPH2 2NaO Bu reagent was developed in order to prepare primary, secondary and tertiary arylphosphanes. These phosphanes have many application and the primary and secondary ones can be used as starting materials for acylphosphane oxides (see Chapter 3). Under very mild reaction conditions, a wide range of fluoroarenes can be reacted to give tertiary phosphanes. In most cases the fluoro-substituent in the starting arene is simply substituted by a phosphanyl group (ipso-substitution), although other mechanism may operate as well in special cases (“arine”-mechanism). The reaction tolerates a Chapter 2 - Activation of elemental phosphorus and investigation of NaPH2 78 remarkable wide range of further functionalities like nitro-, methylsulfonate- and carbonyl-groups, chloro-, bromo-, iodo-, and unsaturated carbon-carbon bonds, which allows the synthesis of previously unknown highly functionalised phosphanes. These may be of high value not only as ligands for transition metal complexes but also as molecular building blocks for modern materials.
Chapter 3
Synthesis of new functionalised acylphosphane oxides
Chapter 3 - Synthesis of new functionalised acylphosphane oxides 80
3.1 Introduction
After the description of the synthesis of NaPH2 and its "alkoxide packaging" in Chapter 2, we describe here its use as a starting material in the preparation of new highly functionalised acylphosphane oxides (BAPOs) (Scheme 19). In his PhD-thesis D. Stein described the preparation of sodium bis(mesitoyl)phosphide (P4)13 and the synthesis of a few non-functionalised BAPOs. Furthermore, he synthesised a BAPO-functionalised ester and a BAPO- functionalised di-alkylphosphonate but it was not possible to deprotect these compounds in order to prepare the BAPO-functionalised acids.
NH3, t dme, +2HOBu t Pred +3Na 2[NaPH2(solv)x] + 4 [NaNH2(solv)y] [NaPH2 x2NaOBu] 293 K -NH3 P10 solution precipitate R=-Me,iBu, P8 Na MesCOCl O O -C2H4P(=O)(OEt)2, O 1) H2O/ toluene O O 1 -CH2COOEt Mes P Mes 2) R -X, thf Mes P Mes 3) H2O2/EtOH R P4 Scheme 18: Synthesis of BAPOs described by D. Stein.
The ultimate goal of the studies reported in this thesis is to prepare highly functionalised BAPOs with new physical and chemical properties as starting materials for new materials, the functionalisation of surfaces and BAPO- functionalised polymers. Therefore, it was necessary to improve the synthesis and to develop new bis(acyl)phosphides. Furthermore, the synthesis of functionalised BAPOs had to be investigated. In this chapter, we describe new ways and starting materials to prepare functionalised BAPOs starting from bis(acyl)phosphides. The "Umpolung" of bis(mesitoyl)phosphide was investigated as a new principle for the synthesis of BAPOs. Finally, the use of functionalised mono(acyl)phosphane oxides was tested as an alternative concept of phosphorus based photoinitiators. Chapter 3 - Synthesis of new functionalised acylphosphane oxides 81
3.2 Synthesis of bis(acyl)phosphides
NH3, dme, 2P +4Na 2[NaPH (solv) ]+4[NaNH (solv) ] red or white 293 K 2 x 2 y solution precipitate P8 +2HOtBu -NH3
t [NaPH2 x2NaOBu] P10
Cl O Cl O 2 MesCOCl O O 2C F COCl 2 2 7 15 F3C CF3
Na Na Na Na O O O O O O O O CF3 O O CF3 Mes P Mes P P C7F15 P C7F15 O O CF3 F3C
67%, P4 87%, P31 58%, P33 87%, P32
1) H2O/ toluene 2) R1-X, thf 3) H2O2/EtOH
O O R1 =alkyl O 2 R =alkyl,aryl R2 P R2 X = halide R1
Scheme 19: Synthesis of bis(acyl)phosphides and their use for the synthesis of BAPOs.
Sodium bis(mesitoyl)phosphide (P4) was prepared in a previous work13 by t the reaction of mesitoyl chloride and NaPH2 x 2NaO Bu (P10) in toluene, thf or Chapter 3 - Synthesis of new functionalised acylphosphane oxides 82 dme (Scheme 19). The pure product was isolated by filtering off the insoluble sodium chloride and evaporating the filtrate in vacuo. Because of very small sodium chloride particles in the dispersion, combined with the high viscosity of concentrated solutions, the filtration takes a long time. Since degassed distilled water does not react with sodium bis(mesitoyl)phosphide (P4), even not after stirring for several days, it can be used to extract the sodium chloride. Degassed distilled water dissolves the sodium chloride, and the bis(mesitoyl)phosphide is extracted in the organic phase. In the case of the water-soluble thf or dme, toluene has to be added. According to this observation, it is possible to use degassed solvents to synthesise BAPOs starting from sodium bis(mesitoyl)phosphide instead of distilled ones. However, the BAPOs and the isolated bis(acyl)phosphides are more difficult to crystallise than with absolute solvents under inert conditions. Both are pure according to the NMR spectra, but small residues of water seem to disturb the crystallisation. The sodium bis(acyl)phosphides of 2,6-dimethoxybenzoic acid (P31), 2,6- trifluoromethylbenzoic acid (P32) and of perfluorinated octanoic acid (P33) were synthesised as precursors for BAPOs with other absorption, solubility and reactivity properties. They are pale yellow powders except the perfluorinated one, which is a pale yellow oil. With fluorinated acylphosphides, it is very important to cool the solution of the acyl halide down to -78°C before adding the solution of NaPH2 x 2NaOtBu (P10) dropwise, otherwise P10 would react with the fluorinated group.
Chapter 3 - Synthesis of new functionalised acylphosphane oxides 83
3.3 Synthesis of functionalised bis(acyl)phosphane oxides
3.3.1 Synthesis starting from bis(acyl)phosphides
Six different methods were investigated to prepare functionalised BAPOs starting from sodium bis(acyl)phosphides (Scheme 20).
O O O O R1 P R1 R1 P R1 R2 R2 R2 F F 2 I-CHR2 O O X-CH2R 2 2 R1 P R1 F R Na O O F F 2 F F O O Cl-CH2R R1 P R1 NaI F F I R1 P R1 R2 R2 ,[Pd0] S
O O O R2 R1 P R1 O O O O
R1 P R1 R1 P R1
R2 OH SH
R1,2 = Aryl, Alkyl X=Cl,Br,I,OTf
Scheme 20: Different ways for the synthesis of bis(acyl)phosphanes (BAPs).
The reactivity of sodium bis(mesitoyl)phosphide in nucleophilic substitution reactions with alkyl halides and triflates depends markedly on the solvent. Especially dme activates the phosphide but has the disadvantage of dissolving sodium iodide as well as sodium bromide formed in the reaction. Because the driving force is the precipitation of sodium halide during the reaction, it is important to use a mixture of different solvents in these cases. A mixture of toluene and dme was found to be an ideal solvent mixture for unreactive electrophiles, but thf can be Chapter 3 - Synthesis of new functionalised acylphosphane oxides 84 used as well. If an alkyl chloride is not reactive enough to undergo a nucleophilic substitution, an in situ Finkelstein reaction can be performed in thf, dme, or acetone by adding a catalytic amount of sodium iodide to the reaction mixture. The phosphide is thermally stable without any decomposition reaction up to 80°C. Therefore, it is possible to accelerate the reaction by heating up the mixture to 60°C.
Na Na O O O O O O Na P O O P
O O C7F15 P C7F15 P33 P4 P31
Figure 22: Bis(acyl)phosphides that were used to synthesise functionalised BAPOs.
Other electrophiles that can be used for the reaction with sodium bis(acyl)phosphides are epoxides, thiiranes and aryl fluorides (Scheme 20). Alternatively, a palladium(0) catalysed cross coupling reaction can be used to prepare arylBAPOs from aryl iodides with 1-5 mol% [Pd(dba)2] or [Pd(PPh3)4] in toluene at 80°C in a closed Schlenk flask (see below). The corresponding products are bis(acyl)phosphanes (BAPs). They are yellow oils or white powders and not light sensitive. They can be oxidised either by adding one equivalent of hydrogen peroxide (10%) solution to the phosphane in toluene and heating it up for 12 hours to 40 - 60°C or by adding one equivalent of hydrogen peroxide (10-30%) to a solution of the phosphane (BAP) in ethanol and heating it up to 40°C for 2 hours. The oxidation is quantitative in most cases. If a heterogeneous system with toluene / water is used, it is necessary to work up the reaction mixture by washing with sodium hydrogen carbonate solution (2%), brine, distilled water and by drying with sodium or magnesium sulfate. No work-up is necessary with the "ethanol method". After removing the solvent, the pure BAPO is obtained (Scheme 21). Chapter 3 - Synthesis of new functionalised acylphosphane oxides 85
1)H2O2 (10%), O O O O toluene/ water, O O O H2O2 (10%) O 1 1 12 h R1 P R1 R P R R1 P R1 2) NaHCO3 (2%) ethanol, 4h R R2 2 3) brine R2 4) Na2SO4 BAPO BAP BAPO (bis(acyl)phosphane) oxide (bis(acyl)phosphane) (bis(acyl)phosphane) oxide
Scheme 21: Oxidation of BAPs to BAPOs (ethanol versus toluene as solvent).
Solid BAPOs can be recrystallised from thf / n-hexane (or pentane) to give a pale yellow crystalline powder. Sometimes pentane gives better results than n- hexane. The crystallisation can be accelerated with ultrasonic waves or by cooling down the solution in the freezer or with a dry ice / acetone bath. Finally, it is important to prepare first a functionalised starting material for the reactions with the bis(acyl)phosphide instead of functionalising a BAPO. Many different BAPOs have been prepared. They are summerised in Table 2 at the end of this chapter.
3.3.2 Synthesis of alkyl-BAPOs (B4-B7)
The alkyl-BAPOs (B4 - B7) were synthesised as model substrates of the functionalised BAPOs. A typical synthesis is shown Scheme 22. They can be prepared from primary alkyl iodides, -bromides, or triflates. The alkyl chlorides are not reactive enough and do not react with the bis(acyl)phosphides. In this case, an in situ Finkelstein reaction with sodium iodide in thf, dme, or acetone has to be performed. For the reaction with alkyl iodides, it is important to cool down the reaction mixture with an ice-bath. If the reaction mixture becomes too warm, the BAP decomposes. Sodium bis(2,6-dimethoxybenzoyl)phosphane reacts so exothermically with methyl iodide that the BAP decomposes immediately. In this case, methyl triflate was used to synthesise the BAPO. With primary dibromoalkanes, di-BAPO-functionalised molecules can be prepared.
Chapter 3 - Synthesis of new functionalised acylphosphane oxides 86
Na 1) Br Br O O thf, toluene 50°C, 24h 2 P O O 2) H2O2, ethanol, O O 40°C, 2h P P O O
P4 62%, B5 Scheme 22: Synthesis of a di-BAPO-functionalised alkane. For the synthesis of secondary alkylBAPOs, it is necessary to use the secondary alkyl iodides as electrophiles, because the other halogenalkanes do not react. The reactions were performed with cyclohexyl iodide and isopropyl iodide in toluene. It was necessary to heat the reaction mixture up to 60°C for 2 days. The
BAPs were oxidised with H2O2 (10%) in toluene to the corresponding BAPOs B6 and B7. Tertiary alkyl halides do not react at all with sodium bis(mesitoyl)phosphide
(P4), even if the reaction conditions were optimised for SN1 reactions. Beside the fact that secondary and tertiary alkyl halides are less reactive than primary ones, the steric hindrance seems to be the main problem in this case.
3.3.3 Synthesis of alkenyl- and alkinyl-substituted BAPOs (B8-B11)
Alkenyl- and alkinyl-BAPOs are suitable compounds for the synthesis of polymers. Furthermore, they can be used for further functionalisation of BAPO- molecules. Reactions were performed with allyl bromide, 2-(bromomethyl)-acrylic ethyl ester and (bromobutyl)norbornene to prepare the alkenyl-BAPOs B8, B9, B10. Propargyl bromide was used for the synthesis of the alkinylBAPO B11 using sodium bis(mesitoyl)phosphide (P4) as precursor. The reactions work well and relatively fast, but it is important that the electrophile is not too bulky. For the synthesis of a norbornene substituted BAPO, it was necessary to synthesise the 4- bromobutylnorbornene first, because the commercial available bromomethyl derivative reacts extremely slowly. All described alkenyl- and alkinyl-BAPOs are pale yellow oils. Chapter 3 - Synthesis of new functionalised acylphosphane oxides 87
Br O O O P 1) Mg, thf Br Mes Mes 2) Br-C3H6-Br, Li2CuCl4,thf 1) P4,thf,12h 2) H2O2, toluene
51% B9, 75%
Scheme 23: Chain extension of bromomethylnorbornene to prepare BAPO-butyl- norbornene.
3.3.4 Synthesis of halogenalkyl-BAPOs (B12-B14)
The halogenalkyl functionalised BAPOs B12, B13 and B14 have been synthesised from bis(mesitoyl)phosphide P4 as substrate and p-bromo- benzylbromide, 1,3-dibromopropane, or 1-bromo-3-chloropropane as reagents. The 1,3-propanediyl derivatives were used to avoid the elimination of HBr. Since bromoaryl functionalities do not react with bis(mesitoyl)phosphides, it is easy to prepare the corresponding p-bromophenyl BAPO. For the reactions with 1-bromo- 3-chloro-propane and 1,3-dibromopropane, it is very important to cool the reaction mixture down to 0°C and to add subsequently a diluted solution of the phosphide to a solution of the halogenalkane (Scheme 24), otherwise the bis(BAPO)alkane B5 is obtained (Scheme 22).
Na 1) 10 Br Br O O toluene 0°C -> 50°C, 24h O P O 2) H2O2,toluene P Br 40°C, 12h O
P4 81%, B13
Scheme 24: Synthesis of 3-bromopropylBAPO B13.
Halogen-functionalised BAPOs are interesting as precursors for a wide variety of functionalised BAPOs. Chapter 3 - Synthesis of new functionalised acylphosphane oxides 88
3.3.5 Synthesis of amino-, imino-, nitrilo-, azido- BAPOs and isonitrilo- BAP (B15-B20)
Bromoalkylammonium salts were found as the best precursors to prepare the new class of aminoBAPOs. 3-Bromopropylammonium bromide reacts with sodium bis(mesitoyl)phosphide (P4) or with bis (2,6-dimethoxybenzoyl)phosphide (P31) to the corresponding products B15 and B16, which are isolated as yellow oils. p-Iodoaniline reacts with benzaldehyde to the corresponding imine A7, which undergoes easily a palladium catalysed cross coupling to the iminoBAPO B17 (Scheme 25).
Na O I O O P O 1) P O NH2 O
+ toluene, P4 12h, rt N [Pd(PPh3)4], toluene, N I 12h, 40°C
2) H2O2, toluene A7 40°C, 12h 91%, B17
Scheme 25:Synthesis of the first "iminoBAPO".
Investigations to cleave the imine to the amine with diluted acids (HCl (2%),
H2SO4 (2%), acetic acid, trifluoroacetic acid and tetrafluoroboronic acid) remained inconclusive. A good precursor for the preparation of a BAPO-alkyl nitrile is 4- bromobutyronitrile, which reacts with bis(mesitoyl)phosphide in almost quantitative yield to give B18 as a yellow oil. The cheaper 3-bromopropionitrile does not react to the phosphane. The reason is that the elimination of HBr is preferred over the nucleophilic substitution. The BAP-alkyl isonitrile B19a was prepared starting from 2- bromoethylisonitrile and sodium bis(mesitoyl)phosphide (P4). The oxidation with Chapter 3 - Synthesis of new functionalised acylphosphane oxides 89 hydrogen peroxide gives decomposition of the isonitrile-functionality instead of the corresponding BAPO B19. Since bromoalkylazides are not very stable and difficult to prepare and purify, 3-azidopropylBAPO B20 was synthesised starting from 3- bromopropylBAPO B13 and sodium azide with dmso as solvent (Scheme 26). The product was obtained as a yellow oil after purification.
dmso, NaN3, O O O 70°C, 12h -NaBr O P Br P N3 O O
B13 35%, B20
Scheme 26: Synthesis of 3-azido-BAPO.
3.3.6 Synthesis of hydroxy-, epoxy- and sugar- BAPOs (B21-B25)
MesBAPO and MeOBAPO substituted ethanol (B21, B22) were prepared by treating 2-bromoethanol with sodium bis(mesitoyl)phosphide (P4) and sodium bis(2,6-dimethoxybenzoyl)phosphide (P31), respectively, in thf. The pure compounds are white crystalline powders. The crude products are yellow oils that can be recrystallised from thf / n-hexane. The purified white powder is stable over several months. Another possibility to synthesise a 2-hydroxyethylBAPO (BAPO- ethanol) is the reaction of sodium bis(mesitoyl)phosphide (P4) with oxirane in dme / toluene during 10 days at 70°C in a closed Schlenk flask followed by hydrolysis with ammonium chloride solution (5%). The BAPO-functionalised epoxide B23 is easily prepared starting from epibromohydrine and sodium bis(mesitoyl)phosphide (P4) in thf because the nucleophilic substitution is faster than the nucleophilic attack on the oxirane ring. The product is a pale yellow oil. Chapter 3 - Synthesis of new functionalised acylphosphane oxides 90
Na O Br O O O O 1) ,thf P P O 2) H2O2,toluene 40°C, 12h O P4 49%, B23
Scheme 27: Synthesis of a BAPO-functionalised epoxide.
An acetyl protected sugar-BAPO B25 was synthesised starting from tetra-O- acetyl-α-pyranosylbromide and BAPO-ethanol. The deacetylation was not performed, but already the acetylprotected "sugarBAPO", a yellow oil, is water- soluble.
3.3.7 Synthesis of sulfido-, phosphino-, phosphonato- and heterocycle containing- BAPOs (B26-B31)
Thiirane reacts with sodium bis(mesitoyl)phosphide (P4) in a mixture of dme and toluene in two days to the thioethanol functionalised BAP B26a. After hydrolysis with an ammonium chloride solution (5%), the phosphane was oxidised with one equivalent of hydrogen peroxide (10%) at 0 °C. BAPO B26 can be isolated in a yield of about 30% since the oxidation of the phosphane is faster than that of the thiol functionality. For this reason, the BAP B26a should be used as compound for functionalisation, in analogy to the 2-isonitriloethyl-BAP B19a. After the thiol has reacted with other reagents or is coordinated, it can still be oxidised, depending obviously on the particular system. The reaction of 3-bromopropyl- BAPO B13 with alkali hydrogensulfide works in principle, but also in this case the yield is very low because the sulfide anion attacks the BAPO-group. 3-Bromopropyl-BAPO B13 reacts with potassium diphenylphosphide to 3- (diphenylphosphino)propyl-BAPO B28. Here the nucleophilic phosphide reacts with the BAPO group as well. Therefore, the resulting yellow oil is obtained in only 30% yield after purification. 2-Bromoethylphosphonic diethylester reacts with sodium bis(2,6- dimethoxybenzoyl)phosphide (P31). It was not possible to deprotect the Chapter 3 - Synthesis of new functionalised acylphosphane oxides 91 corresponding BAPO B29 by common methods, like adding trimethylsilyl bromide, because the BAPO group reacts with it. The direct synthesis of the BAPO- phosphonate is not possible. 2-Chloroethylphosphonic acid reacts with sodium bis(mesitoyl)phosphide (P4) to a mixture of different compounds. The synthesis of the thiophene-BAPO B30 is shown in Scheme 28. The four-step synthesis is an easy way to prepare the functionalised BAPO B30 in very good yield. The thiophene-BAPO is a yellow oil that is stable for more than one year when stored in the fridge under argon.
HO Cl Mes Mes O O SOCl , 2 P P O toluene, P4,thf,NaI H2O2 (10%) O O 40°C S RT, 2 h S Mes Mes S S B30a 83%, B30
Scheme 28: Synthesis of BAPO-functionalised thiophene.
The imidazolium-BAPO salt B31 can be obtained from 3-bromopropyl BAPO and methylimidazole in toluene. The yellow imidazolium BAPO bromide precipitates after one hour. The pure product is obtained by filtration, as the starting material stays in solution. The product, a pale yellow powder, is water soluble and hygroscopic (Scheme 29).
O O
N P N O O O P Br toluene, 50h, 12h N O Br N B13 91%, B31
Scheme 29: Synthesis of a BAPO imidazolium salt. Chapter 3 - Synthesis of new functionalised acylphosphane oxides 92
3.3.8 Synthesis of ketyl-, aldehyde- and acetal-BAPOs (B32-B37)
Bromoacetone reacts immediately with sodium bis(mesitoyl)phosphide (P4) in toluene to BAPO-acetone B32. Bromoacetone can be easily synthesised from bromine, acetone and an oxidant, like potassium chlorate. However, bromoacetone is a lacrimatory. Therefore, it is a very dangerous reagent.
Na O O O O O 1) Br ,toluene P P O 2) H2O2,toluene 40°C, 12h O P4 93%, B32
Scheme 30: Synthesis of the first "KetylBAPO" (BAPOacetone).
To avoid the use of bromoacetone, p-iodoacetophenone can be used as starting material to perform a palladium catalysed cross coupling with sodium bis(mesitoyl)phosphide (P4) to the BAPO B33. The disadvantage of this method is the expensive palladium, especially for large-scale synthesis. BAPO acetaldehydes B34 and B35 can be synthesised starting from aqueous chloroacetaldehyde solution and the bis(acyl)phosphides P4 and P31. Because of the water resistance of sodium bis(mesitoyl)phosphide (P4) and sodium bis(2,6-dimethoxybenzoyl)phosphide (P31), the aqueous solution of 2- chloracetaldehyde can be used directly. However, the reaction mixture has to be worked up as soon as possible after the reaction is finished to avoid hydrolysis of the product. A BAPO-substituted acetal can be prepared from bromoalkyl acetals. 2-(2- Bromoethyl)dioxalane does not react with sodium bis(mesitoyl)phosphide in thf in the predicted way, though. Instead, HBr is eliminated and the resulting vinylacetal undergoes immediately anionic polymerisation (Scheme 31). The white non- soluble polymer forms a thin film in the flask. Chapter 3 - Synthesis of new functionalised acylphosphane oxides 93
Br O (MesCO)2PNa O OO O O O O O O
Scheme 31: Elimination of HBr and polymerisation of the resulting vinylacetal186.
To avoid HBr-elimination, 2-(3-bromopropyl)dioxolane was used, which reacts nicely to the corresponding BAP B36a and is then oxidised to BAPO B36. Many different experiments to deprotect the acetal were performed. With trifluoroacetic acid, the BAPO-acetal B36 is deprotected successfully to BAPO B37, but the acid slowly reacts with the BAPO group as well. Therefore, the yield of BAPO aldehyde B37 is only 23%.
3.3.9 Synthesis of carboxylic-, carboxylate-, ester-, and amido-BAPOs (B37-B46)
Bromoacetic acid reacts with sodium bis(mesitoyl)phosphide (P4) or bis(2,6- dimethoxybenzoyl)phosphide (P31) in thf and thf / dme to the corresponding BAP- acetic acid B38a and MeOBAP-acetic acid B39a, which are isolated as white crystalline powders. For the synthesis of MeOBAP-acetic acid B39a it is necessary to add a small amount of dme, otherwise protonation of the phosphide takes place instead of nucleophilic substitution (Scheme 32).
O Na O O O O O O O O O O BrCH CO H, BrCH CO H, O P 2 2 P 2 2 P thf/ dme thf H O O O O O OHO O B39a P31 B57a Scheme 32: Solvent effect of the nucleophilic substitution of P31 with
BrCH2COOH Chapter 3 - Synthesis of new functionalised acylphosphane oxides 94
After oxidation with hydrogen peroxide and evaporation of the solvent after MesBAPO-acetic acid (B38) and MeOBAPO-acetic acid (B39) are obtained as white crystalline powders. 11-Bromo-undecanoic acid reacts with sodium bis(mesitoyl)phosphide (P4) to the corresponding 11-BAP undecanoic acid B40a and can be oxidised to B40 with hydrogen peroxide. The alkali salts of these BAPO-carboxylic acids can be prepared by stirring vigorously with an alkali carbonate or a hydrogen carbonate solution. The pure BAPO-carboxylic acids are soluble only in small amounts in cold water. At higher temperatures, the insolubility increases dramatically. Therefore, they can be recrystallised from water. MeOBAPO- acetic acid B39 and its alkali salts B41 are also more soluble in polar solvents than the mesitoyl derivative B42. However, the alkali salts are quite soluble in water and alcohols. Bromoalkylcarboxylic esters were used to prepare the corresponding BAPO esters. Methyl- and ethyl bromoacetate react rapidly with sodium bis(mesitoyl)phosphide to the corresponding BAPs, which were then oxidised with hydrogen peroxide. The method that uses ethanol / hydrogen peroxide is preferred because the product has not to be recrystallised several times. The methyl- (B43) and ethyl-BAPOacetates (B53) crystallise easily to give big, pale yellow crystals that are suitable for X-ray analysis (see Chapter 4). p-Nitrophenylbromoacetate reacts with sodium bis(mesitoyl)phosphide (P4) to the corresponding BAP B44a in good yield. This BAP-acetic p-nitrophenylester is only stable for several hours because the nitro group oxidizes the phosphane. Therefore, it has to be oxidised immediately by hydrogen peroxide in toluene at 0°C. The oxidation was not performed in ethanol to avoid the generation of the ethylester. The "active ester"- BAPO B44 can be used to functionalise, for example, biopolymers. BAPO amides were prepared directly from sodium bis(mesitoyl)phosphide (P4) and bromoacetic amide. N-(2-bromopropyl)phthalimide reacts with sodium bis(mesitoyl)phosphide to give the corresponding BAP B46a and can be oxidised in toluene with hydrogen peroxide to the phthalimide BAPO B46. Hydrazine was tried for the deprotection to the amine, but the yield of the corresponding amine Chapter 3 - Synthesis of new functionalised acylphosphane oxides 95 was very low. Free ammonia and hydrazine react with the BAPO-group to mixtures of different unknown products.
3.3.10 Synthesis of alkoxysilane-BAPOs (B47-B49)
3-Chloropropylalkoxysilanes react very slowly with sodium bis(mesitoyl)phosphide (P4) in dme, thf, toluene, or toluene / dme mixtures. The reaction time is shortened by adding sodium iodide but is still relatively long. The problem was solved by forming the 3-iodopropylalkoxysilanes with a Finkelstein reaction in acetone. The corresponding BAPs of 3-iodopropyl-triethoxysilane B47a, 3-iodopropylmethyldiethoxysilane B48a and 3-iodopropylphenyldiethoxysilane B49a are obtained in good yields as yellow oils. The oxidation was performed in toluene / hydrogen peroxide (10%) in the presence of potassium carbonate to avoid condensation reactions. The BAPOs B47, B48 and B49 are pale yellow oils.
Na O O O O 1) I Si(OEt3) P thf, 50°C, 3h P O 2) H2O2,K2CO2, toluene, 40°C, 12h OEt Si EtO OEt P4 92%, B47
Scheme 33: Synthesis of a tris(alkoxy)silane BAPO.
3.3.11 Synthesis of (per)fluorinated BAPOs (B50-B52)
Perfluorinated BAPOs are a completely new class of photoinitiators and open new fields of application, in particular, photoinduced reactions in fluorous phases and in multiphasic systems. The BAPO B50 with a perfluoro octyl group was easily obtained starting from 1-bromoperfluorooctane and sodium bis(mesitoyl)phosphide (P4) in thf. An alternative synthesis is the nucleophilic aromatic substitution of hexafluorobenzene with sodium bis(mesitoyl)phosphide (P4) in thf. Oxidation with hydrogen peroxide in ethanol gave B51. Chapter 3 - Synthesis of new functionalised acylphosphane oxides 96
In order to synthesise a perfluorinated BAPO, it is necessary to prepare a perfluorinated bis(acyl)phosphide. Sodium bis(perfluorooctanoyl)phosphide (P33) t was prepared from NaPH2 x 2NaO Bu and perfluoroctanoyl chloride. It reacts with 1-bromoperfluorooctane to give the first perfluorinated BAP B52a , which is a pale yellow oil and soluble in ethanol. Upon oxidation the perfluorinated BAPO B52 is formed as a pale yellow oil.
Na O O O O 1) thf, 0°C->rt, 16h C7F15 F15C7 +Br-C8F15 P C F P C F 7 15 7 15 2) H2O2,ethanol, C8F17 O 40°C, 12h P33 95%, B52
Scheme 34: Synthesis of the first perfluorinated BAPO.
Upon irradiation with UV light, it decomposes more slowly than non- fluorinated BAPOs. The absorption F-BAPO
1.8 maximum is in the range of other 1.6 1.4 BAPOs. It is slightly soluble in alcohols 1.2 1 0.8 and very soluble in perfluorinated 0.6 Absorbtion 0.4 0.2 solvents, e.g. perfluorodecaline. The 0 200 250 300 350 400 450 absorption maximum is in the range of Wavelength (nm) other BAPOs (Figure 23).
Figure 23: UV-spectrum of the first perfluorinated BAPO B52 in acetonitrile. Chapter 3 - Synthesis of new functionalised acylphosphane oxides 97
Table 2: Overview of synthesised BAPOs. (* = Yield was determind by NMR)
Yield Starting Material Product (%)
O O O O
P31 Me-OTf P 78 O H3C O O B4
P4 Br Br O O 62 O O P P O O B5
I P4 O 62* O P
O B6
O O P4 57* I P O B7
O O
P4 Br P 76 O B8 Chapter 3 - Synthesis of new functionalised acylphosphane oxides 98
Yield Starting Material Product (%)
O O
P Br P4 O 75
B9
O O Br P
P4 O 61 O O O O B10
O O
P4 Br P 86
O B11
Br O
P4 O P 84 O Br Br B12
P4 Br Br O 90 O P Br O B13 Chapter 3 - Synthesis of new functionalised acylphosphane oxides 99
Yield Starting Material Product (%)
P4 Br Cl O 62 O P Cl O B14
O P4 Br NH3Br 54* O P O
H2N B15
O O O O P31 Br NH3Br 45* O P O O H2N B16
I N O P4 P N 91 (p-iodoaniline, O O benzaldehyde) B17
O O
P4 Br P 80 N O
CN B18 Chapter 3 - Synthesis of new functionalised acylphosphane oxides 100
Yield Starting Material Product (%)
N P4 Cl C O O 73 O P
N=C=O B19a
B13 NaN3 O 35 O P N3 O B20
O O OH P4 Br P 76 O OH B21
O O O O P31 Br OH 76 O P O O HO B22
O O Br P4 O P 49 O
O B23 Chapter 3 - Synthesis of new functionalised acylphosphane oxides 101
Yield Starting Material Product (%)
O O OH OH P4 P 64 Br O HO OH B24
O O
H P H O Br O CH O H3C O 3 H H O B21 O O O 32* O O H H O H H C O O CH3 O CH3 3 CH3 H H O O O O O H
O CH3 CH3 B25
P4 S 29 O O P SH O B26
O B13 KPPh2 O 37 P P O B28
O O O O O P P31 P O O 74 O Br O O P EtO OEt O B29 Chapter 3 - Synthesis of new functionalised acylphosphane oxides 102
Yield Starting Material Product (%)
O Cl P4 S O P 83
O S B30
O O
P N O B13 N 91
N Br N B31
O O P4 O 93 Br P O O B32
O O
P4 O P 78 O I
O B33
O O Cl O P4 P 76 (40% in water) O H O B34 Chapter 3 - Synthesis of new functionalised acylphosphane oxides 103
Yield Starting Material Product (%)
O O Cl O O O P31 P 82 O (40% in water) O O O H B35
O Br O P4 P 67 O O O O O B36
O O
B36 - P 23 O H
O B37
O O OH Br P4 P 87 O O HO O B38
O O O O OH Br P31 P 78 O O O O OH O B39 Chapter 3 - Synthesis of new functionalised acylphosphane oxides 104
Yield Starting Material Product (%)
OH Br P4 8 O 82 O O O P OH O 8 B40
O O
B38 - P 100 O NaO O B42
O O P4 Br CH3 O 77 O P O O OMe B43
O O NO P O 2 P4 O O 57 Br O O
NO2 B44
NH 2 O P4 Br O 87 O P O
O NH2 B45 Chapter 3 - Synthesis of new functionalised acylphosphane oxides 105
Yield Starting Material Product (%)
O O O Br P P4 N O O 76 N O O B46
O I O O Si P P4 O 92 O O O Si O O B47
O O
O P O P4 Si O 88
CH3 O Cl Si O Me B48
O O
O P P4 Si O 89 Cl O
O Si O B49
P4 Br-C8F17 O 82 O P O C8F17 B50 Chapter 3 - Synthesis of new functionalised acylphosphane oxides 106
Yield Starting Material Product (%)
F O F F F F F P O P4 F 63 O F F F F B51
O O C F F C P33 Br-C8F17 7 15 P 15 7 95 C8F17 O B52
3.3.12 "Umpolung" of bis(acyl)phosphides
As described above, we prepared several BAPOs from sodium bis(acyl)phosphides and electrophiles by nucleophilic substitution. However, some functionalised BAPOs, e.g. that carry a heteroatom directly at the phosphorus atom can be more easily synthesised by electrophilic substitution at the phosphorus atom. Hence, an "Umpolung" is necessary to synthesise a convenient starting material. We first studied the reaction of sodium bis(mesitoyl)phosphide (P4) and halogens. However, the phosphide decomposes upon reaction with elemental bromine and chlorine instead of giving the chlorophosphane (MesCO)2P–X (X = halogene).
Moreover, other halogenation reactions (e.g. with CCl4 or I–Br) did not work either. In previous experiments, D. Stein found that iodine oxidises the phosphide P4 to 13 the dimer [(MesCO)2P–P(MesCO)2] . Eventually, the reaction with bromine cyanide was successful and yielded a suitable precursor for electrophilic substitution. Cyanobis(mesitoyl)phosphane (B56a) reacts e.g. with methylmagnesiumbromide to Me-BAP (B54a) (Scheme 35). Chapter 3 - Synthesis of new functionalised acylphosphane oxides 107
O O O O Br-CN, MeMgBr P4 P P thf, 5 min CN thf Me 69%, B56a 54%, B54a
Scheme 35: "Umpolung" of sodium bis(mesitoyl)phosphide (P4).
Another method for an "Umpolung" was developed with sodium bis(2,6- dimethoxybenzoyl)phosphide (P31), which can be easily protonated by adding acetic acid (Scheme 36). The resulting phosphane (B57a) (31P NMR: δ = 11.0) was oxidised with air in the presence of 2-propanol to the secondary phosphane oxide B57. Subsequently, it was treated with 1,2-dichloroethane, triethylamine and piperidine to give the piperidyl BAPO B58. Na O O O O O O O O
CH3COOH P P H air, iPrOH O O O O P31 B57a
O O O O O O CH2Cl2,NEt3,C2H4Cl2, O O N O H P P O 0°C H O O N O O B58 B57
Scheme 36: Umpolung of sodium (2,6-dimethoxybenzoyl)phosphide.
3.3.13 Straight-forward synthesis of Mes(Ph)P(=O)(MesCO) (B59)
Finally, to investigate the use of monoacylphosphane oxides (MAPOs), we prepared [Mes(Ph)P(=O)(MesCO)] (B59). It is a very active photoinitiator, for which the following synthesis was developed. Mesitylene magnesium bromide (A8) was prepared by a standard Grignard reaction and treated with PCl3 to give the dichloromesitylphosphane (P36). After reducing the chlorophosphane with sodium, hydrolysis with tBuOH gave mesitylphosphane (P37), which, in the presence of the Chapter 3 - Synthesis of new functionalised acylphosphane oxides 108 resulting sodium tert-butoxide, reacts with mesitoyl chloride to mesitoylmesitylphosphide P38. After a cross coupling reaction with phenyl iodide 31 and [Pd(PPh3)4] in thf, the phosphane B59a ( P NMR: δ = 8.6) is formed. The oxidation with hydrogen peroxide (10%) in toluene gave a brown oil in a yield of 52%. Br PCl2 PH2 1) Mg, Et2O t 2) PCl 2Na,2HOBu 3 +2NaOtBu
P36 P37
Na O 1) Ph-I, [Pd(PPh3)4] + MesCOCl P P -NaCl, -HOtBu 2) H2O2, toluene O O
37%, B59 P38
Scheme 37: The synthesis of MAPO B59.
Pure microcrystalline yellow B59 (31P NMR: δ = 24.6 ppm) can be obtained by purification by flash chromatography (ethyl acetate / heptane (1:4)) or by recrystallisation from acetonitrile. It is very important to store the product under light exclusion in the fridge, as it decomposes very rapidly. Therefore, as our goal was to find photoinitiators that can be industrially applied and used for the functionalisation of surfaces, MAPOs are not suitable because they generate only two radicals per molecule. Furthermore, some derivatives seem to be very photosensitive. This would be problematic for an industrial application.
3.4 Conclusion
A number of BAPOs with common functional groups were prepared. With them, it is possible to perform a further functionalisation of the BAPOs. Moreover, we synthesised different BAPOs such as acrylates, siloxanes and diols, that can be used for polymerisation and polycondensation processes. Chapter 3 - Synthesis of new functionalised acylphosphane oxides 109
Photoinitiators that are able to coordinate to metal atoms are interesting for the functionalisation of metal surfaces. Thiols and phosphanes are good ligands for the late transition metals. Phosphonates are able to react with aluminium oxide on the passivated surface of aluminium and to coordinate many transition metals (e.g. Fe, Mn, Co, Ni). Thiophene derivatives have also coordinating properties and can be used as starting materials for conducting polymers (see chapter 4). Imidazolium salts have two important properties. They can be used as ionic liquids and are the precursors for N-heterocyclic carbenes and their metal complexes. Furthermore, we obtained the first perfluorinated BAPO and the first water-soluble BAPOs. This opens the way to new applications. Before discussing some examples thereof in Chapter 5 and Chapter 6, we describe the structures and properties of the newly prepared BAPOs in the next chapter.
Chapter 4
Investigation of the Properties of BAPOs
Chapter 4 -Investigation of the properties of BAPOs 112
4.1 Introduction
In chapter 3 we discussed the synthesis of new highly functionalised BAPOs. This chapter describes the study of their properties, molecular structures, photolyticall and thermal decomposition processes. The crystal structures reported here are the first ones of functionalised acylphosphanes and acylphosphane oxides. Even if the study of the structure of photoinitiators in the solid state is necessary to understand their reactivity, crystal structures of the commercially available BAPOs and MAPOs were not known before. Grützmacher et al. published for the first time a crystal structure of a BAPO, the non-functionalised Ph-BAPO (B2) in 2008.187 Furthermore, we investigated the reactivity of the radicals generated photochemically from BAPOs in the presence of scavengers to find selective reactions and to use BAPO-functionalities for light induced addition or condensation reactions with small molecules. This method would open new ways in grafting small molecules or particles on surfaces. Many investigations on the formation of radicals derived from BAPOs and MAPOs have been reported (see chapter 1), but herein the authors put their main focus on irradiation experiments with an in-situ determination of decompiosition products. Finally the thermal decomposition of the commercially available Ph-BAPO and MAPO has never been reported before. These investigations are promising for new application for all kind of BAPOs and MAPOs. Chapter 4 -Investigation of the properties of BAPOs 113
4.2 Discussion of the properties of functionalised BAPOs
4.2.1 Comparison of MesBAPO-acetic acid (B38) and MeOBAPO-acetic acid (B39)
O O O O O O P P O O O HO O O HO O B38 B39
Figure 24: The formulas of MesBAPO-acetic acid (B38) and MeOBAPO-acetic acid (B39).
MeOBAPOs and MesBAPOs are the first water-soluble BAPOs and therefore the first water-soluble photoinitiators with high quantum yield in combination with an absorbtion maximum in the UV / Vis range. Hence, some chemical and physical properties have to be discussed. The polarity of MeOBAPOs and MesBAPOs is quite different. The MeOBAPO- acetic acid (B39) is much more polar than MesBAPO-acetic acid (B38). The result is a different solubility in organic solvents. Thus, is very good soluble in alcohols, acetonitrile and water, but almost insoluble in non-polar solvents like benzene or alkanes, whereas MesBAPO-acetic acid (B38) is hardly soluble in water but highly soluble in benzene and toluene. Furthermore, the absorption properties are different (Figure 25). The maximum absorption of MeOBAPO-acetic acid (B39) is at 264 nm, the one of MesBAPO-acetic acid (B38) at 370 nm.
Chapter 4 -Investigation of the properties of BAPOs 114
Figure 25: UV-spectra of MesBAPO-acetic acid (B38, left) and MeOBAPO-acetic acid (B39, right).
4.2.2 Switching the UV activity by pH-control
MeOBAPO-ethanol B22 (31P NMR: δ = 26.5) is a photoactive pale yellow oil, which is soluble in polar solvents like thf, ethanol and dmso. By changing the pH value with hydrochloric acid, acetic acid, trifluoroacetic acid, sodium hydrogencarbonate, or triethylamine, an equilibrium with the colourless phosphorane P34 is established (31P NMR: δ = -227.9) (Scheme 38). The four- membered ring and its ring-tension stabilize the phosphorane according to the investigations of Turnblom et al.188. Decomposition takes place when the solution of the phosphorane is warmed up to 40-60°C or if an excess of acid is added. An explanation might be a Wittig-analogous reaction, for example to bis(mesitoyl)phosphinic acid and ethene. O O HO O O O P OH POO Acid O O Base O O O O O
B22 P34
Scheme 38: Equilibrium of BAPO-ethanol with the corresponding phosphorane. Chapter 4 -Investigation of the properties of BAPOs 115
The analogous reaction with MesBAPO-ethanol B21 is not observed. This can be explained with a stabilisation of the "hydroxyphosphorane" P34 via a hydrogen bonding to the methoxygroups, which are absent in B21. This kind of such a "switchable" photoinitiators is a completely new system, which has an enormous potential for application.
4.2.3 Crystal structures of functionalised BAPOs
The best method to obtain crystals from BAPOs in a good quality for single crystal X-ray diffraction is to evaporate a concentrated solution of the BAPOs and BAPs in n-hexane over several days. The crystals of BAPO-acetic acid (B38) were obtained by cooling down a warm concentrated aqueous solution from 40°C to room temperature during two hours in a water bath. All crystals of BAPs and BAPOs are pale yellow or colourless when they are very small. Their solutions are pale yellow, independently of the solvent. Chapter 4 -Investigation of the properties of BAPOs 116
4.2.4 Crystal structure of (MesCO)2PCH2COOH (B38a)
Figure 26: ORTEP plots of BAP-acetic acid and its dimer (B38a) (thermal ellipsoids at 50% probability, hydrogen atoms omitted for clarity). Selected bond lenghts [Å] and angles [°]: P1–C1: 1.8351(2), P1–C3: 1.8628(2), P1–C30: 1.8841(2), C3–O1: 1.2113(2), C30–O2: 1.2078(2), C2–O3: 1.3042(2), C2–O4: 1.2293(2), C1–P1–C3: 101.79(8), C1–P1–C30: 101.33(9), C3–P1–C30: 108.71(8), O1–C3–P1: 118.00(1), O2–C30–P1: 115.78(2), C2–C1–P1: 117.17(1), C1–C2– O4: 121.71(2), C1–C2–O3: 115.23(2), O4–C2–O3: 123.03(2).
In the solid state, BAP-acetic acid (B38a) forms dimers with intermolecular hydrogen bonds between two carboxylic groups. The distance between two oxygen atoms of the two different carboxyl groups in the dimer is 2.65 Å, which is in range of typical hydrogen bonding. The torsion angle between the two acyl groups at the phosphorus is quite small (52.80°). A reason is the -stacking of the two mesitoyl rings, which are 3.83 Å apart. The P-CH2 bond length corresponds to 189 the P-CH2 bond length in Ph2PCH2COOH, which is 1.855 Å . The P–C(=O) bond Chapter 4 -Investigation of the properties of BAPOs 117 lengths (1.8628(2) and 1.8841(2) Å) are slightly shorter than the one in Ph-BAPO, which is 1.896 Å.
4.2.5 Crystal structure (MesCO)2P(=O)CH2COOH (B38)
Figure 27: ORTEP plots of BAPO-acetic acid (B38) and its dimer (thermal ellipsoids at 50% probability, hydrogen atoms omitted for clarity). Selected bond lenghts [Å] and angles [°]: P1–O1: 1.4754(2), P1–C1: 1.7954(3), P1–C3: 1.8775(3), P1–C13: 1.8831(4), C3–O2: 1.2110(4), C13–O3: 1.2092(4), C2–O4: 1.3127(4), C2–O5: 1.1923(4), O1–P1–C13: 112.81(1), O1–P1–C3: 120.21(2), O1– P1–C1: 112.94(2), O4–C2–O5: 125.03(3), O3–C13–P1: 117.87(3), O2–C3–P1: 110.38(2), P1–C1–C2: 109.49(2). Chapter 4 -Investigation of the properties of BAPOs 118
The BAPO-acetic acid (B38) was crystallised from water by cooling a concentrated solution at 40°C down to room temperature. It forms dimers in the solid state. Two molecules are connected by a hydrogen bonding from the carboxyl group of molecule one to the P=O of the second molecule and vice-versa. This might be a reason why it is poorly soluble in water. The length of the hydrogen bond is 2.638 Å. The shorter bond length, compared to the hydrogen bonding of the phosphane B38a (2.65 Å) indicates a stronger bonding. The torsion angle between the two mesitoyl groups is 72.00°. The P1-C1 distance of 1.878 and 1.883 Å is in the range of the one in Ph-BAPO.
4.2.6 Crystal structure of (MesCO)2P(=O)CH2COOEt (B53)
Figure 28: ORTEP plot of ethyl BAPO-acetate (B53) (thermal ellipsoids at 50% probability, hydrogen atoms omitted for clarity). Selected bond lenghts [Å] and angles [°]: P1–C1: 1.8650(2), P1–C5: 1.9426(2), P1–C15: 1.9411(2), P3–O1: 1.5177(2), C15–O2: 1.2439(2), C5–O3: 1.2441(2), C2–O4: 1.3316(2), C2–O5: 1.2294(3), C1–P1–C5: 103.15(9), C1–P1–C15: 101.83(9), C5–P1–C15: 101.31(9), O1–C5–P1: 114.51(9), O2–C15–P1: 111.32(2), C2–C1–P1: 110.15(1), C1–C2– O4: 112.85(2), C1–C2–O5: 123.15(2), O4–C2–O5: 123.98(2). Chapter 4 -Investigation of the properties of BAPOs 119
Ethyl BAPO-acetate is the BAPO with the longest P–C(=O) bonds known (1.943 and 1.941 Å). As it decomposes faster than other BAPOs like Ph-BAPO, a correlation with the length of the P–C(=O) bond is possible. Even if this bond is quite long, there are many other compounds known with an even longer P–C bonds190. The torsion angle between the acyl groups is 75.24°, which is less than in Ph-BAPO (B2), but larger than the one of BAPO-acetic acid and BAPO-ethanol. The methyl BAPO-acetate (B43) is less reactive and has shorter P–C(=O) bonds (1.904 and 1.885 Å)191 than ethyl BAPO-acetate (B53). The torsion angle between the acyl groups is 86.49°.
4.2.7 (MesCO)2P(=O)CH2CH2OH (B21)
Figure 29: ORTEP plots of BAPO-ethanol and its dimer (B21) (thermal ellipsoids at 50% probability, hydrogen atoms omitted for clarity). Selected bond lenghts [Å] and angles [°]: P1–O1: 1.5030(1), P1–C13: 1.8143(1), P1–C1: 1.8376(1), P1–C3: 1.8639(1), C1–C2: 1.5694(1), C2–O4: 1.4290(1), C13–O3: 1.2645(1), C13–P1– O1: 112.28(4), C1–P1–O1: 115.22(4), C3–P1–O1: 117.87, C1–P1–C13: 100.38, C3–P1–C13: 102.49(5).
The solid state structure of BAPO-ethanol shows intermolecular hydrogen bonding with a second molecule to form dimers. Here, the two hydroxy groups bond to the two P=O groups in the dimer. The O…O distance is 2.669 Å, which is in the range of a typical hydrogen bond. The torsion angle between the acyl groups is 66.99°, the smallest one for all crystallographically analysed BAPOs. Chapter 4 -Investigation of the properties of BAPOs 120
4.2.8 Crystal structure of (MesCO)Ph2P(=O), (MAPO), (B3)
Figure 30: ORTEP plot of MAPO (B3) (diphenylmesitoylphosphane oxide) (thermal ellipsoids at 50% probability, hydrogen atoms omitted for clarity). Selected bond lenghts [Å] and angles [°]: P1–O1: 1.4785(2), P1–C1: 1.8821(3), P1–C11: 1.7893(3), P1–C17: 1.7864(3), C1–O2: 1.2202(3), C1–C2: 1.4850(3), O1–P1–C1: 115.5(1), C1–P1–C11: 99.01(1), C1–P1–C17: 105.22(1), C11–P1–C17: 108.86(1), P1–C1–O2: 116.82(2), C2–C1–O2: 124.34(2).
The crystal structure of the commercially available photoinitiator diphenylmesitoylphosphane oxide, (MAPO, B3) was determind for comparison with the BAPOs reported above. It is the first time that a photoactive monoacylphosphane oxide is investigated by X-ray crystallography. Crystals were obtained by evaporation of a concentrated thf solution of B3 within two days. The P1–C1 bond length of 1.8821(3) Å is slightly shorter than the P–acyl distance in Ph-BAPO (B2) (1.895 and 1.896 Å). It is remarkable that all the C-P bond lengths in acylphosphane oxides are relatively long as compared to other known bond lengths of phosphane oxides. The C-P bond length in O=PPh3 is 1.808 Å for example192. However, there are phosphorus compounds with bond lengths longer than 2 Å190. Chapter 4 -Investigation of the properties of BAPOs 121
4.2.9 Comparison of reactivity versus P–C=O bond lengths in BAPOs
The reactivities of the BAPOs were estimated with an irradiation experiment. A 5 mM benzene solution (0.5 mL) was irradiated with a middle preasure Hg-lamp for 5 s in an NMR tube. Then the reaction mixture was analyised by 31P NMR spectroscopy. Afterwards the same sample was irradiated again. The procedure was repeated after 10 s, 30 s, 60 s and 5 min. With these experiments a ranking of the decomposition rate of the BAPOs was determined by the integration of the unreacted BAPO signals (1 = after 30 s irradiation with a UV lamp 100% decomposition, 8 = after 30 s irradiation with a UV lamp 25% decomposition).
Table 3: Comparison of bond length, torsion angles and reactivity of BAPOs.
d(P-CO2) d(P-CO3) torsion angle [°] relative reactivity Compound in Å in Å CO1 vs. CO2 1= most reactive MAPO (B3) 1.882 - - 8 Ph-BAPO (B2)187 1.896 1.895 77.35 7 Me-BAPO (B54) 13 1.887 1.885 67.52 6 BAPO* (B55) 13 1.898 1.891 73.55 5 BAPO-ethanol B21) 1.863 1.8143 66.99 4 BAPO-acetic acid (B38) 1.883 1.878 72.00 3 Methyl BAPO-acetate (B43) 1.904 1.885 86.49 2 Ethyl BAPO-acetate (B53) 1.9426 1.9411 75.24 1
The tendency of the P–C(=O) bond length of the different BAPOs in Table 3 corresponds with their reactivity: the longer the distances are, the more reactive they are. Therefore, the MAPO B3 is less active than Ph-BAPO (B2) for example. No other correlation between other spectroscopic data (e.g. UV, IR) was found. Furthermore the molecular structure of the BAPOs discussed above was optimized by MM2 calculations in order to find a correlation between structure and the bond length of the P–C=O bonding. These calculations gave a quite good value for P–C(=O) distances and therefore for the reactivity of the BAPOs. This is Chapter 4 -Investigation of the properties of BAPOs 122 the first step to find a model for the optimization of the structure of photoinitiators by calculations. In conclusion only the P–C(=O) distances give an idea about the reactivity of the BAPOs. Since many different features like hydrogen bonds, electronic effects and bulky substituents influence the substances, it is very difficult to find a model to predict the absorption properties. Other BAPOs have to be crystallised systematically.
4.3 Investigation of the formation of phosphanoyl radicals derived from bis(acyl)phosphane oxides
4.3.1 The photolytic decomposition of bis(mesitoyl)phenylphosphane oxide (Irgacure 819)
The decomposition of pure bis(mesitoyl)phenylphosphane oxide (B2) in ultra-violet light was investigated in different solvents. From a solution in benzene, the crystalline tetramer D1 (Scheme 39) was easily isolated by simple concentration. The product is similar to the one isolated by recombination reactions of benzoyl radicals generated by electroreduction193. A single crystal X-ray diffraction analysis demonstrated that the trans isomer of D1 is formed. In contrast to the observations of Kolczak et. al.5 no benzil derivative was detected.
O O +2R1 Mes O 2 Mes O O O O R1 hexamethylbenzil (A9) not detected by 13CNMR D1
Scheme 39: Recombination of mesitoyl radicals R1. Chapter 4 -Investigation of the properties of BAPOs 123
Since D1 is formed from mesitoyl radicals, it should be possible to use benzil as a scavenger for mesitoyl radicals. The irradiation experiments of Irgacure 819 (B2) in a benzene solution after 5-60 min under ultraviolet light in the presence of benzil does not yield the expected diphenyl derivative of D1, though. In contrast, dimesityl diketone A9, which can be easily synthesised in a Grignard reaction from oxalic acid dimethylester and magnesium mesityl bromide (Mes–MgBr), reacts with one equivalent of Irgacure 819 (B2) in benzene readily to give D1 under UV irradiation (Scheme 40). Furthermore, two other decomposition products were identified in situ. PhPO(OH)-O-PO(OH)Ph (D2) was identified by its characteristic peak at δ = 7.1194 in the 31P NMR spectrum. Because of the formation of the phosphonic acid dimer D2, we assume a two-step splitting mechanism of B2. Another decomposition product that was found by 31P and 1H NMR spectroscopy is phenylmesitoylphosphinic acid (Ph(MesCO)P(=O)OH, D3) (31P NMR: δ = 17.7).
O O O O HO OH O hv P P P ++O D1 O C6H6 P O OH
B2 D3,20% D2,50% + 30 % non-identified phosphorus compounds
Scheme 40: Decomposition of Ph-BAPO in a benzene solution without any scavengers under inert gas conditions.
In experiments with different irradiation times of the Ph-BAPO solution a phosphorus compound with a chemical shift at δ = 36.4 was detected by 31P NMR spectroscopy. After longer irradiation times this signal became smaller and a signal at δ = 43.2 increased. Both compounds were not isolated and characterised. Using toluene as reaction medium, only traces of the tetramer D1 but a large amount of mesitoyl aldehyde (D4) were obtained. Moreover, PhPO(OH)-O- PO(OH)Ph (D2) was observed by NMR spectroscopy. In the case of carbon tetrachloride as solvent, PhP(=O)Cl2 (D5) is formed in a yield of 40%. The carbonyl Chapter 4 -Investigation of the properties of BAPOs 124 radicals recombine to a very small amount of mesitoyl chloride (D6) and the tetramer D1 as main product.
4.3.2 Photolytic decomposition of Ph-BAPO in the presence of radical scavengers
Using thiols as scavengers, which have been used as trapping agents for similar decomposition reactions in the past,29 the irradiation experiments with Irgacure 819 (B2) lead to a mixture of five different compounds. In contrast to this observation, we obtained in the reaction with diphenyldisulfide only the mesitoyl thioester D7 and the phenyl phosphonic thioester D8.
O O O S S P O hv P +2Ph2S2 2 S + O C6H6
B2 D7 D8
Scheme 41: Ph2S2 as trapping reagent for radicals.
By using the asymmetric methylphenyldisulfide, it was shown that the reaction does not occur in an insertion manner, but rather via a two-step cleavage of the acylic groups (Scheme 42). In this reaction, the main products are the mesitoyl thiomethylester D9, the phosphonic dithiopheneylester D8 and the asymmetric phosphonic thioester D10. Chapter 4 -Investigation of the properties of BAPOs 125
O O S S CH P S 3 + D9 O S S O P CH 45%, D8 hv, 3 P O +MeSSPh C D O 6 6 45%, D10 O O S S B2 H3C P CH3 S +
D7 10%, D11
Scheme 42: The trapping reaction with MeSSPh and the yield of the phosphorus compounds.
Minor products are the mesitoyl thiopheneylester D7 and the phosphonic dithiomethylester D11. The overall product distribution indicated that the thiophenyl radicals prefer to recombine with the phosphorus radical instead of the mesitoyl radical. Steric effects of the mesitoyl group might be the explanation. 2,2,6,6-Tetramethylpiperidineoxyl (TEMPO) is a common radical scavenger. A 0.5 M benzene solution of Irgacure 819 (B2), in which two equivalents of TEMPO were dissolved, was irradiated for 5 minutes with a UV lamp (Scheme 43). The phenylphosphonic di(TEMPO)ester D12 and the tetramer D1 are formed in almost quantitative amounts. The ester D13 is a by-product in very low concentration because of steric effects and stoichiometry.
O O hv, N O N P O N +2 O P O O + D1 N + O C6D6 O
B2 80%, D12 D13 Scheme 43: Trapping reaction with TEMPO Chapter 4 -Investigation of the properties of BAPOs 126
Since allylic compounds like safrole do not polymerize because of hydrogen transfer, they can be used as scavengers for radicals. An excess of safrole forms the phosphane oxide D14 in a diluted solution of Irgacure 819 (B2) in benzene.
O O O H hv, P O P + O O + C6D6 O O O 2 excess B2 D14 D4
Scheme 44: Trapping reaction with safrole.
Instead of “classical” scavengers, it is also possible to use metal salts in order to trap reaction products that have coordinating properties. After irradiation of a Cu(acac)2 / Irgacure 819 (B2) (1:2.5) solution in thf, green crystals of D15 were obtained within 12 h.
P O O O O O O hv, O Cu Cu P +2.5Cu(acac)2 O O thf O O O O P B2
D15,41%
Scheme 45: The decomposition of Ph-BAPO in the presence of [Cu(acac)2] in thf.
[Cu(Ph(MesCO)PO2)(acac)]2 (D15) is a dimer with two copper centres bridged by two phosphinic acid ligands and containing two chelating acetylacetonato ligands. The coordination of the copper atoms is almost square planar (sum of angles: 363.26°). The distance between the two copper atoms is Chapter 4 -Investigation of the properties of BAPOs 127
4.99 Å. In a similar experiment with Me-BAPO B54, a coordination polymer D16 was obtained (see below). The bond length and the distances between the ligand and the copper atoms are in the typical range of copper(II) complexes.
Figure 31: ORTEP plot of D15 (thermal ellipsoids at 50% probability, hydrogen atoms omitted for clarity). Selected bond lenghts [Å] and angles [°]: P1–O1: 1.5048(7), P1–O2: 1.5044(6), P1–C1: 1.8377(9), P1–C7: 1.8667(10), Cu1–O2: 1.9458(7), Cu2–O1: 1.9772(9), Cu2–O10: 1.8727(7), Cu2–O9: 1.8743(6), C7–O5: 1.2416(1), O9–Cu2–O10: 93.22(3), O1–Cu2–O10: 88.41(3), O1–Cu2–O9: 160.42(3), O1–P1–O2: 120.81(4), C1–P1–O1: 111.44(5), C1–P1–O2: 105.28(4), C1–P1–C7: 103.77(5), P1–C7–O5: 117.75(7).
Although the reaction was performed under argon atmosphere D15 was formed in a relatively high yield. This result is surprising because we have no Chapter 4 -Investigation of the properties of BAPOs 128 explanation for the formation of the [(MesCO)P(=O)O–] ligand, as water and oxygen were absolutely excluded during the reaction. D15 is stable against UV irradiation. An explanation might be the strong absorption of the metal compounds itself, even if similar arylmesitoylphosphinic salts (especially their alkali salts) are used as water-soluble photoinitiators195.
In a similar experiment with [Ni(CF3COO)2] the yellow tetranuclear complex D17 was formed. This is a prove that also the second acyl group can be split off to form the diphosphonate [–OP(=O)(Ph)–O–P(=O)(Ph)–O–].
F F F
O P thf O O O O O Ni P hv, P O thf O B2 O +2.5Ni(CF3COO)2 Ni O Ni thf thf O O O O O P O O P Ni O thf P O O F F F
Scheme 46: Decomposition of Ph-BAPO in thf in the presence of Ni(CF3COO)2.
The structure of the nickel salt D17 is a tetranuclear nickel cluster with three different kinds of chelating ligands and thf as a fourth, non-chelating ligand (Figure – – 32). The [Ph(MesCO)P(=O)O ] (D3) and the CF3COO ligands are coordinating two different nickel atoms in a bridging fashion. They form a dinuclear nickel unit with a Ni-Ni distance of 3.01 Å. Both nickel atoms are in an octahedral environment. Furthermore, the nickel atoms are coordinated by one thf molecule each. The two dinuclear units are linked by two bridging di(phenylphosphonato) ligand D2. The distance of the nickel atoms between the two different dinuclaer units is 4.99 Å. Chapter 4 -Investigation of the properties of BAPOs 129
Figure 32: ORTEP plot of D17 (thermal ellipsoids at 50% probability, hydrogen atoms, the phenyl rings of [–O–P(=O)Ph–O–P(=O)Ph–O–] and the C atoms of the thf are omitted for clarity). Selected bond lenghts [Å] and angles [°]: Ni1–O1: 2.0936(3), Ni1–O2: 2.1096(3), Ni1–O3: 2.0600(3), Ni1-O10: 2.0270(3), Ni1–O11: 1.9891(3), Ni2–O1: 2.0790(3), Ni2–O2: 2.0535(3), Ni2–O4: 2.0338(3), Ni2–O5: 2.0855(3), Ni2–O7: 2.0674(3), Ni2-O9: 2.0372(3), P2–O2: 1.5166(3), P2–O8: 1.5877(3), P1–O6: 1.4670(3), P1–C9: 1.8669(6), C1–O3: 1.2449(6), C1–O4: 1.2598(6), C9–O5: 1.2376(5), O3–C1–O4: 130.32(5), C9–O5–Ni2: 117.30(3), O2– Ni1–O3: 87.03(1), O2–Ni2–O5: 166.94(1), O5–Ni2–O7: 89.98(1), O2–P2–O8: 107.67(2), Ni1–O1–Ni2: 96.36(1).
This is the first known organometallic crystal structure containing a di(phenylphosphonic) ligand, which might be very interesting as a chelating or bridging ligand, and this method might reveal powerful to generate it in situ. As the diphosphonate D2 can be formed from the phosphinic acid D3, this suggests that the two mesitoyl radicals are cleaved independently. As the dimer D18 was detected in the EI mass spectra, the following reaction scheme can be assumed (Scheme 47). Chapter 4 -Investigation of the properties of BAPOs 130
O O O O hv, oxidation 2 P OH P O P HO P O P OH -H2O O O O -2MesCO O D3 D18 D2
Scheme 47: Predicted mechanism for the condensation of D3. The oxidation reaction is unknown.
Unfortunately, because of the complexity of the mixtures of products obtained, it was not possible to investigate all the decomposition products of Irgacure 819 (B2) in a pure benzene solution, neither to investigate the oxidation of the decomposition products to phosphonic acids.
4.3.3 The photolytic decomposition of mesitoylpivaloylphenyl- phosphane oxide (BAPO*)
The unsymmetrical BAPOs with two different acyl groups are a completely new substance class and a new family of photoinitiators13. In this paragraph, we describe photolysis experiments of mesitoylpivaloylphenylphosphane oxide (B55) under different conditions. Its decomposition is very interesting because an independent cleavage of the acyl groups might be possible. One acyl group was cleaved first and the second one afterwards under other conditions, for example another wavelength. This new concept is very interesting, especially for the synthesis of block copolymers. In a typical irradiation experiment of mesitoylpivaloylphenylphosphane oxide (B55) in benzene under argon atmosphere, the tetramer D19 was detected by EI- mass spectroscopy (Scheme 48). The phosphorus compounds that are formed during the irradiation are the same found in the decomposition reaction of Ph- BAPO (B2). Additionally, pivaloyl aldehyde (D20) and mesityl aldehyde (D4) were formed in toluene solution. Tolyl radicals (Ph–CH2•) are resonance-stabilised radicals. Therefore, in this case hydrogen atoms can be more easily abstracted Chapter 4 -Investigation of the properties of BAPOs 131 from the solvent than in a benzene solution. Surprisingly, diphenylphosphonic acid (D2) and phenylmesitoylphosphinic acid (D3) were detected by 31P NMR spectroscopy although all experiments were performed under argon atmosphere and water-exclusion with distilled solvents. Moreover, the experiments were reproduced. Therefore, the BAPO* undergoes a disproportionation reaction analogously to Ph-BAPO (B2) (see above).
O O O O +2Mes O 2 O O O D19 R2 D21
O O O HO OH O P P hv, C6D6 ++O D19 P P O O O OH 15 %, D3 55 %, D2 + 30 % non-identified phosphorous compounds
Scheme 48: The decomposition of BAPO* in a benzene solution and the recombination of the acyl radicals.
4.3.4 Photolytic decomposition reactions of BAPO* in the presence of scavengers
When a tetrachloromethane solution of BAPO* (B55) was irradiated with UV light, dichlorophenylphosphane oxide (D5), pivaloyl chloride (D22) and mesitoyl chloride (D6) were formed, according to the 31P NMR spectra of the reaction solution (Scheme 49). With diphenyldisulfide as scavenger, the phenylphosphonic dithiophenylester D8, the corresponding mesitoyl thiopheneylester D7, and pivaloyl thiophenylester D23 were obtained. When TEMPO was used as scavenger, the corresponding phosphonic diester D12, pivaloyl ester D24, and mesitoyl ester D13 were detected by 31P NMR spectroscopy and EI-mass spectroscopy. Chapter 4 -Investigation of the properties of BAPOs 132
O Cl Cl P + R-COCl N O N
D22, D6 CCl4,hv O P O
D5 O O TEMPO, hv P D12 O O + PhS SPh P Ph2S2 O + R-COSPh hv D55 R D23, D7 O N
D8 R=Mes,tBu D13, D24 Scheme 49: Investigation on the decomposition of BAPO* in the presence of scavengers.
4.3.5 The photolytic decomposition of bis(mesitoyl)methylphosphane oxide (Me-BAPO)
After studying the decomposition of Ph-BAPO (B2) and BAPO* (B55), we decided to focus on the properties of an alkyl-BAPO under UV irradiation as a model for the functionalised alkyl-BAPOs reported in chapter 3. The only alkyl- BAPO, which has been investigated until now is the commercially available Irgacure 1700. However, in these publications the authors put their main focus on in-situ investigations (see chapter 1).
O O O O P O O O
Figure 33: Structure of Irgacure 1700.
Solutions of bis(mesitoyl)methylphosphane oxide (Me-BAPO, B54) in an inert solvent such as benzene decomposed under UV irradiation to 70% MePO(OH)-O-PO(OH)Me (D25) and 30% unknown compounds (Scheme 44). Chapter 4 -Investigation of the properties of BAPOs 133
Similar to the decomposition of Ph-BAPO (B2), the tetramer D1 was formed by the recombination of mesitoyl radicals in almost quantitative yields. When toluene was used as reaction medium, only traces of the tetramer D1 were observed, but a large amount of mesitoyl aldehyde D4 was formed. In addition, D25 was detected by 31P NMR spectroscopy. In the case of carbon tetrachloride as solvent, dichloromethylphosphane oxide (MeP(=O)Cl2) is formed in a yield of 55%. The carbonyl radicals form a very small amount of mesitoyl chloride D6 and the tetramer D1 as main product.
O O O hv, C6H6 O O CH3 HO OH + D1 P P + P P O CH O 3 O OH H3CCH3 B54 20%, D26 50%, D25
+ 30 % non-identified phosphorus compounds
Scheme 50: Decomposition of Me-BAPO solution in benzene upon UV irradiation
4.3.6 Decomposition reactions in the presence of scavengers
Using thiols as scavengers, the irradiation with Me-BAPO (B54) leads to a mixture of many different compounds. However, we observed a remarkable result in the reaction with diphenyldisulfide, as it gave the mesitoyl thioester D7 and the phenyl phosphonic thioester D27 in a quantitative yield (Scheme 51).
O O O O O S S P hv P +2Ph2S2 2 S +2 Me C6H6 CH3
B54 quant., D7 quant., D27 Scheme 51: Ph2S2 as trapping reagent for radicals formed by Me-BAPO.
By using unsymmetrical disulfide scavengers like methylphenyldisulfide, it was shown that the reaction occurs not in an insertion manner but rather by a two- step cleavage of the acyl groups. If the reaction were an insertion, the Chapter 4 -Investigation of the properties of BAPOs 134 unsymmetrical disulfide D28 would be the main product. Instead, the main products are mesitoyl thiomethylester (D9), the phosphonic dithiophenylester D27 and the asymmetric phosphonic thioester D28 (Scheme 52), which corresponds to the analogous reaction with Ph-BAPO (B2).
O O S S CH P S 3 + CH3 D9 O O O 60%, D27 O hv, S S P CH P + MeSSPh 3 CH3 Me C6H6 35%, D28 B54 O O S S H C P CH S + 3 3 Me
D7 5%, D29
Scheme 52: Products of the trapping reaction with MeSSPh (yields determined by 31P NMR spectroscopy).
The mesitoyl thiopheneylester D7 and the phosphonic thioester D29 are minor products, most probably because of steric effects of the mesitoyl group. Indeed, the thiophenyl radicals prefer to recombine with the phosphorus centered radical rather than with the mesitoyl radical.
Since we were able to show (e.g. with unsymmetric disulfides) that the photolytical decomposition reaction of a BAPO is a two step splitting mechanism, we propose the mechanism shown in Scheme 53. Since the monoacylthiophosphinic acids [(MesCO)PhP(=O)S-Ph] were not detected, we assume that they might be very potent initiators. This has to be investigated in the future. Chapter 4 -Investigation of the properties of BAPOs 135
Ph O S S O S P O O O Ph S ,hv R Mes 2 2 Ph2S2,hv S + P Mes P Ph + C H O O R 6 6 O R C6H6, -MesCOSPh R=Ph,Me S Ph
Scheme 53: A forecasted two step splitting mechnanism during the reaction of a BAPO to a dithiophosphonic ester with a disulfide.
The trapping reaction with 2,2,6,6-tetramethylpiperidinoxyl (TEMPO) gives similar results as with Irgacure 819 (B2). A 0.25 mM benzene solution of Me-BAPO containing two equivalents of TEMPO was irradiated for 15 minutes with a UV- lamp. The phosphonic ester D30 and the tetramer D1 were formed in almost quantitative yield. The ester D13 is a by-product in a very low concentration because of steric effects (Scheme 54).
O O N O N O O O P N O N + +D1 Me hv, C6H6 O P O Me B54 D30 D13
Scheme 54: Trapping reaction of B54 with TEMPO.
Irradiation of a diluted solution of Me-BAPO in benzene in the presence of an excess of safrole led to the phosphane oxide D31 after 10 min. Allylic compounds react with radicals to give very stable allyl radicals. Therefore, hydrogen atoms can easily be transfered from an excess of the allylic compound. This is the reason, why allylic compounds cannot be polymerised by radical polymerisation. Chapter 4 -Investigation of the properties of BAPOs 136
O O O O H O hv, P + Mes P Mes + O CH3 Me C6D6 O O O B54 2 D31 D4
Scheme 55: Safrole as scavenger for trapping experiments with Me-BAPO (B54)
In addition, the decomposition of Me-BAPO in the presence of metal salts was performed to trap the phosphorus compounds and crystallise the resulting complexes. The copper complex D16 was obtained by irradiating a diluted solution of Cu(acac)2 and Me-BAPO (B54) in thf. By layering the thf solution with n-hexane, light green crystals were obtained, which contain a copper salt of methylmesitoyl- phosphinic acid (D26).
O O hv, P + 2.5 Cu(acac)2 [(Me(MesCO)P(=O)O)2Cu]x thf O CH 3 32 %, D16
Scheme 56: The decomposition of Me-BAPO in the presence of Cu(acac)2.
This result shows that the mesitoyl groups are cleaved independently. However, it is not clear whether only one mesitoyl group is cleaved because of the pale green colour of the copper salt D16 or because mesitoylmethylphosphinic acid D3 is not photoactive. Chapter 4 -Investigation of the properties of BAPOs 137
C3
C2 O3 O1 O7 P1 O2 Cu1 O8 C1 P2 Cu2 O6 O9 O5 O4
Figure 34: ORTEP plot of D16 (thermal ellipsoids at 50% probability, hydrogen atoms omitted for clarity). Selected bond lenghts [Å] and angles [°]: P1–O1: 1.555(12), P1–O2: 1.468(12), Cu2–O2: 1.983(11), Cu1–O1: 1.919(13), P1–C1: 1.872(10), C2–O3: 1.299(12), P1–C2: 1.907(12), P1–P2: 3.826(11), Cu1–Cu2: 5.081(12), P1–C2–O3: 115.83(10), P1–O2–Cu2: 135.26(12), O2–Cu2–O8: 84.44(12), O2–Cu2–O4: 94.43(14), O2–Cu2–O9: 164.90(12), O4–Cu2–O9: 88.72(12), O2–P1–C2: 105.88(12), C2–P1–O1: 100.79(11), C1–P1–C1: 107.72(11).
[(Me(MesCO)P(=O)O)2Cu]x (D16) is an inorganic polymer containing 8- membered 1,5-corner-linked rings. The rings are fused at the Cu(II) ions. The coordination of the copper by four phosphinato ligands is almost square planar (sum of the angles: 368.78°). Two of the ligands form a bridge to the next copper atoms. The copper-oxygen distances are Cu1–O1: 1.919(13) and Cu2–O2: 1.983(11) for the mononegative bidendate bridging ligand. The distances for the other Cu–O bonds in a ring are similar because of symmetry. The structure Chapter 4 -Investigation of the properties of BAPOs 138
corresponds to the polymeric diethylphosphinic acid copper salt [(Et2P(=O)O)2Cu]x from J.Trotter et al.196
4.3.7 The photolytic decomposition of diphenylmesitoylphosphane oxide (MAPO)
A toluene solution of diphenylmesitoylphosphane oxide (MAPO, B3) in toluene was irradiated for 10 minutes. Then, pure diphenylphosphinic acid crystallised out of the solution upon 10 days. Furthermore, the recombination product D1 of the mesitoylradicals was detected. The analytical data for both compounds are in agreement with the literature, including their crystal structures197, 198.
4.4 Light-induced condensation reactions with BAPOs
The studies of the decomposition reactions of acylphosphane oxides discussed above show that they are not only interesting for starting radical (polymerisation) reactions but also for performing light induced condensation reactions. A number of different products, which were formed and isolated by using trapping reagents, show that it is easy to transform an acylphosphane oxide in a phosphonic ester, thioester, or other phosphane oxides by simple irradiation. With disulfides, they react to the thiophosphonic acid, with TEMPO to the phosphonic ester and with safrole to the alkylphenylphosphane oxides. Thinking of using acylphosphane oxides for the functionalisation of surfaces or macromolecules, it would be very interesting to transform selectively their functionality by irradiation. It would be then possible to "write" on a surface to save information or to get area resolved functionalities, e.g. for producing DNA chips.
4.4.1 Light-induced condensation
As discussed in the previous paragraph, some of the trapping reagents, especially the symmetric disulfides that were used to investigate the Chapter 4 -Investigation of the properties of BAPOs 139 decomposition, react in quantitative yields with BAPOs during UV irradiation. However, since these reagents have several disadvantages, new compounds had to be found to perform these reactions. It is not only necessary to have a selective reaction in a quantitative yield, but also to use readily available functional reagents. Therefore, disulfides and TEMPO derivatives are not very useful. We found that alcohols undergo selective photoinduced reactions with BAPOs to give phosphonicesters, mesitoyl aldehyde and mesitoyl esters. As shown in Scheme 57, different alcohols were successfully tested.
FG FG FG OH O FG O O O H O O P O + + O P toluene, hv O
FG= Br, Cl, -COOEt, -H D36a-d D37a-d D4
Scheme 57: Light induced condensation reaction with functionalised alcohols.
When phenols are used instead of aliphatic alcohols, diphenyl phosphonates and mesitoyl aldehyde are formed in quantitative yield. This photoinduced condensation reaction can be used to functionalise surfaces. As proof of principle, BAPO-functionalised cellulose was irradiated in a solution of phenolphthaleine, which was then bonded covalently to the cellulose, as prolonged washing did not remove it (see chapter 5).
Chapter 4 -Investigation of the properties of BAPOs 140
FG FG H O O FG OH O + 2 O P toluene, hv O P O O
D38a-d D4 FG= -Br, -OMe, -H, -COOEt, -"phenolphthaleine"
Scheme 58: Photo-induced condensation reactions of BAPO functionalities and phenols. Another interesting photo-induced condensation reaction was performed with secondary amines. Aliphatic amines reacted quantitatively with a solution of Ph-BAPO in toluene under UV irradiation to phenylphosphonic amides, which have not only interesting properties themselves, but they are also good precursors for other phosphorus compounds199.
H O NR2 O HNR2,hv R2N P O +2 toluene O P O
D39 D4 R=ethyl,n-propyl
Scheme 59: Photo induced condensation reaction of BAPOs with secondary amines.
Me-BAPO (B54) and BAPO* (B55) showed the same reactivities and formed the analogous phosphonates and amides.
4.5 The thermal decomposition of Ph-BAPO (B2) and MAPO (B3)
The decomposition of BAPOs in UV light was thoroughly studied in the last 27 years (see chapter 1). In contrast, the thermal decomposition has never been Chapter 4 -Investigation of the properties of BAPOs 141 investigated before, even though Ph-BAPO (Irgacure 819, B2) and MAPO (B3) are commercially available compounds that are produced in a large scale by Ciba and BASF SE. A thermally induced rearrangement reaction is the (frequently Lewis- acid catalysed) Michaelis-Arbuzov-rearrangement, by which P(III) alkoxides are transformed into O=P(V) oxides.200
R O P P R' R R OR' R
Scheme 60: The Michaelis-Arbuzov-rearrangement.
4.5.1 Thermal decomposition of Ph-BAPO (Irgacure 819)
The melting point of Ph-BAPO (B2), measured with a standard melting point apparatus is 128.9°C. The DTA curve in Figure 35 shows that an endothermic process takes place at this temperature. Since the curve is not symmetric, the measured signal for the endothermic process is not only the melting of Ph-BAPO (B2). Therefore, a chemical reaction must occur as well. The TG curve shows no mass loss. A rearrangement is the only explanation for this result.
Chapter 4 -Investigation of the properties of BAPOs 142
Figure 35: Thermoanalytical data of Ph-BAPO (B2)
Actually, pure Ph-BAPO B2 decomposes when it is heated up for 12 hours under inert gas, as can be seen in Figure 35.
O O O 140°C, P P O P + O P melt, 12h P P O
>95%, D33
B2 >95%, D32
Scheme 61: Thermal decomposition of Ph-BAPO (B2) upon melting.
31 The P NMR spectra of the decomposition products indicate that P5Ph5 (D32) and mesitoyl anhydride (D33) were obtained in nearly quantitative yield. The mesitoyl anhydride (D33) was crystallised easily by evaporating a concentrated thf solution (Scheme 61). Chapter 4 -Investigation of the properties of BAPOs 143
Furthermore, we investigated whether this reaction is a solid state phenomenon or if it also takes place in solution. To study the decomposition of Ph- BAPO (B2) in solution, p-xylene was used as solvent. After 12 h at 140°C, the rearrangement product D34 was formed in nearly quantitative yield. The reaction is an anti-Michaelis-Arbuzov reaction201, 200.
O 140°C, O O P p-Xylene, 12h P O O O
B2 >90%, D34
Scheme 62: Thermal decomposition of Ph-BAPO (B2) in p-xylene solution.
These results are very interesting for synthesising new functionalised phosphites and polyphosphanes starting from functionalised BAPOs. Furthermore, they explain why accurate temperature control is necessary during the synthesis of the BAPOs.
4.5.2 Thermal versus photolytical decomposition of Ph-BAPO
The following Scheme 63 gives an overview of the different photolytical and thermal decomposition products of Ph-BAPO (B2) determined in this work and the one determined by in-situ investigations in literature (see chapter 1).5 Therefore, photolytical decomposition products described in the literature are different from the one determined in this work using scavengers. 31 Only D34 ( P NMR (C6D6) δ = 98.7) was determined in the thermal decomposition of B2. Therefore, the decomposition products from the in-situ investigations undergo further chemical reactions. Surprisingly, the photolytical decomposition products undergo an oxidation or disproportionation reaction to phosphonates and phosphinates during the reaction. The oxidant was not determined, but around 30% non-identified Chapter 4 -Investigation of the properties of BAPOs 144 phosphorus compounds were detected by 31P NMR spectroscopy after photolysis. The reactions were performed under argon atmosphere with distilled benzene and reproduced several times. Therefore, it can be excluded that the decomposition products were oxidised by air or water. In the thermal decomposition in substance, the phosphorus is reduced to 31 Ph5P5 (D32) ( P NMR (C6D6) δ = -0.3 (m)) and the mesitoyl anhydride is formed. Similar disproportionation reactions possibly occur also during photolysis and can lead to the oxidation of the in-situ formed decomposition products and form the phosphonic and phosphinic acids and their derivative (D2, D3, D18). The formation of D1 can be explained by the reaction of the benzil derivative
(MesCO)2 (A9) with mesitoyl radicals (see above).
Chapter 4 -Investigation of the properties of BAPOs 145
O O PP O O O O P O P O O O P O O
D34 O
in-situ determined O O photo decomposition products described O in the literature
D33 Determined thermal decompostition O products described O O P in this work O P O O B2 photo Determined D34 decompostition P P products described P in this work P P
D32 O O O O
D1 O O P OH P OH HO P O O O D2 D3 O O P O P + 30% non-identified O O P-compounds
D18
Scheme 63: Overview of decomposition products derived from Ph-BAPO. Chapter 4 -Investigation of the properties of BAPOs 146
4.5.3 Thermal decomposition of MAPO
In the next step, the thermal decomposition of MAPO (B3) was investigated.
Figure 36: Thermoanalytical (DTA) data of MAPO (Diphenylmesitoylphosphane oxide
The decomposition product was for both cases diphenylmesitoylphosphinite 31 D35 ( P NMR (C6D6) δ = 101.9). It is obtained as a white crystalline powder after melting MAPO (B3) for 12 h. Hence, an anti-Michaelis-Arbuzov-reaction takes place as observed for B2.
O 140°C, xylene, 12h O P P or: melt, O 140°C, 12h O
B3 quant., D35
Scheme 64: The thermal decomposition product of MAPO.
In order to find new applications of the thermal decomposition reactions, the reactivity of the decomposition product D35 was investigated. With phenyl lithium, the diphenylphosphinite A10 and the corresponding mesitylphenylketone A11 were formed. Chapter 4 -Investigation of the properties of BAPOs 147
O OLi O PhLi P P + O
D35 A10 A11
Scheme 65: PhLi forms the corresponding phosphinite from the decomposition product.
Since phosphinites and their tautomeric secondary phosphane oxides (SPOs) are useful ligands for catalysis202, this reaction is a new opportunity for synthesising new and solid state bounded catalysts. That also BAPO functionalised surfaces undergo such a reaction assumed.
4.6 Conclusion
Comparison of the data of the investigated BAPOs showed that only the bond length of the P–C(=O)-bond has an effect on the reactivity of the BAPOs. The photolytically decomposition of Ph-BAPO (B2), BAPO* (B55) and Me- BAPO (B54) were studied in this work. Especially the alkyl-BAPOs are interesting because the functionalised BAPOs discussed in chapter 3 are mainly such compounds. Me-BAPO was used as a model substrate for them. The above results show that the acyl groups of the investigated BAPOs are cleaved independently. The tetrameric decomposition product D19, which is obtained by irradiation of BAPO* (B55), shows that the pivaloyl radicals recombine first. This implies that the pivaloyl radicals are formed before the mesitoyl radicals. The experiments to form metal salts from the decomposition products of Me-BAPO (B54) and Ph-BAPO (B2) were particularly useful to prove the independent cleavage of the acyl groups. The diphosphonic acids and the monoacylphosphinic acids were detected in the 31P NMR spectra of the decomposition reactions of Me-BAPO, BAPO* and Ph- BAPO in a benzene solution. Since all experiments were performed under inert Chapter 4 -Investigation of the properties of BAPOs 148 gas conditions, no explanation for the oxidation process of the phosphorus was found. As about 30% of non-identified phosphorus products were detected in the 31P NMR spectrum, the reaction must be a disproportionation reaction.
Even though it was possible to detect [PhP(=O)(SPh)2] in the experiments with Ph2S2 as scavenger, the experiments with the unsymmetrical methylphenyldisulfide indicate that no insertion occurrs, but rather a stepwise reaction. Safrole was used as a scavenger for phosphorus radicals. To our knowledge, it has never been used as a scavenger for radicals before. It forms only very small amounts of oligomers and the trapping product in a rather good yield for Me-BAPO (B54) and the Ph-BAPO (B2). During the reaction with safrole, a secondary radical is formed which is stabilized by the electron rich phenyl ring. Before a polymerisation reaction can take place, a H-atom transfer generates the saturated product and an allyl radical, which can recombine with other phosphorus radicals. Alcohols and especially phenols undergo photo-induced condensation reactions with BAPOs to form phosphonic esters in high yield. Experiments were performed with different alcohols and phenols and BAPO* (B55), Me- (B54) and Ph-BAPO (B2). As proof of principle for the use of this reaction for the light- induced functionalisation of surfaces and macromolecules, phenolphthaleine was grafted on BAPO-functionalised cellulose (PM2) (see chapter 5). Another important result is the photo-induced condensation with secondary amines to form amides. Phosphonic amides can be used as precursors for many other compounds. Also, amido groups can easily be transferred to other functional groups. Furthermore, phosphonic amides have many interesting properties themselves and can be used for e.g. enoblement of fabrics203. It is the first time that the thermal decomposition reaction of acylphosphane oxides were investigated. Ph-BAPO (B2) forms in a meltery at 140°C P5Ph5 and mesitoyl anhydride. However, it forms in a p-xylene solution at the same temperature the anit-Michaelis-Arbuzov product D34. Surprisingly, for the MAPO B3 no difference exists between the decomposition performed in p-xylene or in a Chapter 4 -Investigation of the properties of BAPOs 149 meltery. In both cases the phosphinite D35 was formed. This result is interesting for new applications and the synthesis of new phosphorus compounds. In the next chapter we discuss the application of the results from chapter 3 and 4 as new concepts for synthesis and application of BAPO-functionalised polymers.
Chapter 5
Synthesis of BAPO-functionalised polymers and their application Chapter 5 - Synthesis of BAPO functionalised polymers and their application 152
5.1 Introduction
The main goal of this thesis is the preparation of BAPO-functionalised polymers and the functionalisation of surfaces and materials with BAPO groups. In this chapter we describe the synthesis of BAPO-functionalised polymers and some applications, which exploits the results reported in chapter 2 and 3. The BAPO- functionality is, as mentioned before, a highly photolabile chromophore. Comparable oligo- or polymers with BAPO functions have not been described in the literature before. The polymers prepared are listed below. a) BAPO-functionalised polystyrenes
Due to its very good physical and chemical properties, polystyrene is one of the most important industrially produced polymers. A wide variety of derivatives is likewise commercially available. These can be used to synthesise BAPO- functionalised polystyrene derivatives. b) BAPO-functionalised polynorbornenes
Polynorbornenes, obtained by a ring opening metathesis polymerisation (ROMP), are unsaturated polymers that are used due to their unusual physical properties for special applications like e.g. bulletproof and shock absorbing materials204. c) BAPO-functionalised polyacrylates
Polyacrylates (e.g. PMA, PMMA) are transparent and robust polymers, which are important to produce stress resistant materials used for outdoor applications (i.e. building constructions) and all sort of packaging204.
Chapter 5 - Synthesis of BAPO functionalised polymers and their application 153 d) BAPO-functionalised polythiophenes
Polythiophene is known for its excellent properties as conducting organic polymer205. Many functionalised polythiophenes have been synthesised206. Conducting polymers and their thin films have a high potential for fabricating low cost integrated circuits for large-area electronic devices207, 208. Under this aspect, a BAPO functionalised polythiophene is highly interesting. First, a further functionalisation of the conducting polymer by irradiation with light is possible. Second, the surface reaction between the phosphoranyl radicals that form upon irradiation and surface bonded groups (i.e. OH, NHR, Si-H, etc.) will lead to a fixation and immobilisation of the thin film. Thirdly, the phosphoranyl radicals formed upon the photo-decomposition from the BAPO groups do react with the sulphur atom of thiophenee rings. As a result, a thiophene based conducting polymer with a high content of BAPO groups in the side chains looses its conductivity after intensive irradiation with UV light. Consequently, conducting paths can be easily created within the film by using a simple lithographic method. e) BAPO-functionalised polysiloxanes
Polysiloxanes (silicones) belong to the most popular inorganic polymers with an impressively wide range of applications and their quantity of production increases steadily. Silicones are chemically very robust, inert to many organic solvents and strong acids and have remarkable physical properties, which are less common for purely organic polymers. Silicones are not toxic and not flammable, which makes them ideal polymers for medical purposes and as protecting coatings. Silicones functionalised with photosensitive groups may further enlarge the range of applications of these interesting macromolecules. However, only very few silicones with photoactive groups have been synthesised until now. Most frequently cinnamic acid derivatives were incorporated as photosensitive chromophores.209, 210, 211 BAPO functionalised silicones are unknown.
Chapter 5 - Synthesis of BAPO functionalised polymers and their application 154 f) BAPO-functionalised biopolymers, in particular cellulose materials
Cellulose containing materials (wood, cotton, starch etc) are readily available and renewable biopolymers. Their functionalisation with BAPO groups, which are especially sensitive to cleavage by light in the visible range, would be highly desirable for the manufacturing of functionalised cellulose materials. Especially when the photoinitiator is covalently linked to the biopolymer, durable and robust coatings can be expected. A simple method to achieve this is reported in the following. Furthermore, our investigations relate to concepts and the application of these and related materials in the following fields: g) Surface coatings and site-specific surface structuring
Surfaces can be easily coated with many different polymers by special techniques (e.g. by spin coating). Therefore, BAPO functionalised polymers are very promising. With coating technology and a corresponding BAPO-functionalised polymer, it is possible to produce thin films on surfaces. On these coatings, locally resolved radicals can be generated. This is very interesting for many applications, for example surface modification, structuring of surfaces, and further functionalisation of surfaces or covalent grafting of molecules in combination with special irradiation techniques, these ideas are very promising. h) Ennoblement of textile fabrics, wood, and related materials
Cotton consists of cellulose, which is a polymer of β-glycosidic linked glucose units. Although many different methods exist to functionalise cotton (e.g. reactive dyeing), there is a steady demand for further technologies. Especially a permanent and durable functionalisation or coating would be of high value in clothing and for outdoor applications. Under this aspect, a covalent linking of BAPO units to the cotton fibre surface would be highly desirable. Because of the known efficiency of BAPO derivatives to generate radicals and initiate radical polymerisation reactions leading to polymers with high molecular weights, only few Chapter 5 - Synthesis of BAPO functionalised polymers and their application 155
BAPO groups on the cotton surface would be necessary to achieve an efficient coating. i) Photo induced gel formation processes
Gelation is a fascinating phenomenon, because large amounts of a liquid can be absorbed by a small amount of a solid. Many substances are known to promote gel formation with polar solvents. Most prominent examples are flour and amylum, which are used in daily cooking and baking procedures. These compounds are able to bind to polar solvents by dipolar interactions and hydrogen bonds. Three dimensional, non ordered networks are generated, which are able to encapsulate large amounts of solvent molecules. The gel formation can be influenced by a number of factors like pH, temperature etc.212, 213. The very weak van der Waals interactions within non-polar liquids do not allow to form easily three dimensional networks through intramolecular interactions. To the best of our knowledge, no efficient compound is known for the gelation of unpolar solvents. Such gels may have a variety of highly interesting applications (sensoring and purification for analytical purposes, drug storage and delivery in medical applications and fragrance chemistry, etc.). Hence, a simple method allowing the formation of gels with non-polar liquids is highly desirable. As discussed below, BAPO functionalised vinylsilicones allow this type of gelation process using visible light as promoter.
5.2 Results and discussion
A simple straight-forward approach to light sensitive BAPO-functionalised polymers (method A) consists in the reaction of a performed polymer with reactive groups (halides, tosylates, and related fugitive groups) with sodium bis(mesitoyl)phosphide P4 and subsequent oxidation of the acylphosphido substituted polymers. The alternative method B to photoactive polymers with BAPO functions consists of (i) preparing a monomeric BAPO compound with a suitably Chapter 5 - Synthesis of BAPO functionalised polymers and their application 156 polymerisable group R, and (ii) its incorporation into an oligo- or polymer either by polymerising the BAPO monomer itself or by performing a co-polymerisation reaction in the presence of other monomers. By this approach a very wide range of organic, inorganic, and hybrid polymers is accessible. By either of these methods, BAPO containing oligo- and / or polymers are obtained, which can be further processed under the action of visible light from various sources (sunlight, LEDs, halogen, argon and related lamps, UV/vis Hg- photo lamps, etc.) The preparation and processing of various BAPO containing polymers is described in the following examples.
5.3 Modification of polymers with BAPO groups (Method A)
5.3.1 BAPO functionalised polystyrene
Poly(bromomethylstyrene) reacts with sodium bis(mesitoyl)phosphide
Na[P(COMes)2] (P4) to give the functionalised polystyrene PM3. The BAPO- functionalised polymer shows a very broad signal at δ = 26.3 in the 31P NMR spectrum. The chemical shift is in the range of a an alkyl-BAPO. The polymer has an incorporation of BAPO groups of about 20% as determined by elemental analysis.
1) [(MesCO)2P]Na, toluene/ thf, 72 h, 60°C
2) H2O2 O Br P n O O n PM3
Scheme 66: Synthesis of BAPO-functionalised polystyrene P1 by nucleophilic substitution of polybromomethylstyrene. Chapter 5 - Synthesis of BAPO functionalised polymers and their application 157
An alternative route for the synthesis of a similar polymer is the palladium catalysed cross coupling of poly(p-iodostyrene) and sodium bis(mesitoyl) phosphide P4 in the presence of [Pd(PPh3)4] (5 mol%). This reaction gives rise to polymer PM4 with an incorporation of about 10% of BAPO groups after 72 hours. The polymer gives a signal at δ = 9.3 in the 31P NMR spectrum, which is in the typical range of an ary-BAPO.
1) [(MesCO)2P]Na, [Pd(PPh3)4] toluene, 72 h, 85°C
2) H O 2 2 O I O P n O
n PM4
Scheme 67: Synthesis of BAPO-functionalised polystyrene PM4 by palladium catalysed cross coupling of poly (p-iodostyrene).
Under irradiation of a toluene solution with light in the 300 nm to 500 nm range, BAPO groups decompose as anticipated under UV irradiation. This opens interesting applications in coating processes.
5.4 Photoactive polymers functionalised with BAPO compounds (Method B)
5.4.1 Synthesis of polymerisable BAPO monomers
The polymerisable BAPO monomers B9-11, B30, B47-49 shown in Scheme 68 were synthesised according to chapter 3. Chapter 5 - Synthesis of BAPO functionalised polymers and their application 158
Na O O 1) Na 2) 2 ROH 2MesCOCl P Pn or PCl3 NaPH2x(NaOR)2
P4 1) R-X 2) H2O2 O O O P R
O O O O O P O P P O O O EtOOC B9 B10 B11 O O O O P P O O
(EtO)2RSi S
R=Me,Ph,OEt B30 B47-49
Scheme 68: General procedure for the synthesis of BAPO functionalised monomers and some examples.
5.4.2 BAPO functionalised polynorbornenes
A BAPO functionalised poly(norborene) PM5 was synthesised for example by copolymerising BAPO-n-butylnorbornene (B9) (20 mol%) with norbornene (80%) in a ring opening metathesis polymerisation (ROMP) promoted by a Grubbs type I catalyst (1 mol%), which proved to be very efficient. Complete conversion was achieved within one hour. The GPC (gel permeation chromatography) analysis gives a molecular mass of Mn = 235’677, Mw = 452’363 g/mol, and a Chapter 5 - Synthesis of BAPO functionalised polymers and their application 159 dispersity of 1.92. The ratio between B9 and norbornene (nb) can be widely varied (B9: nb 100 : 0 to 0.1 : 100).
O O O O P P O O +
PCy3 Cl Ru Cl Ph PCy3 x y z (Gr ubbs I,1mol%) Cy = cyclohexyl +CH2Cl2,1h
Figure 37: BAPO functionalised polynorbornene PM5.
The photoactivity of polymer PM5 and the possibility to prepare thin photoactive films, which allow the simple generation of structured surfaces, was demonstrated in the following experiment. A drop of a 5 % (by mass) solution of the copolymer PM5 in chloroform was placed on a silicon wafer to give a thin film. A copper net (0.14 mm mesh) was placed as a mask on this thin film. Subsequently a few drops of ethylacrylate were added on top of the net. After irradiation with a UV lamp for 10 minutes, the poly(acrylate) platelets were exclusively formed on the silicon wafer surface at positions where the ethylacrylate had contact to the photoactive polymer and which had been exposed to the light. After removing the copper net, a structured coating was obtained (Figure 38), which is an accurate image of the copper net mask. The dark square spots correspond to the poly(acrylate) platelets while the bright lines correspond to non- covered silicon, which was masked by the copper net. Chapter 5 - Synthesis of BAPO functionalised polymers and their application 160
Figure 38: Structured silicon surface obtained by site-selective photo- polymerisation of ethyl acetate using BAPO functionalised polynorbornene P3. Dark regions correspond to poly(ethylacrylate), bright lines to the non-covered silicon surface.
5.4.3 BAPO functionalised polyacrylates
The polymer poly(BAPO)methacrylate (PM6), was synthesised by radical polymerisation of a suitable BAPO monomer like B10. The oligo- / polymerisation reaction was initiated thermally with AIBN (azobisisobutyrodinitrile) at 60°C in toluene (Scheme 69). The progress of the oligo- / polymerisation reaction was 1 31 followed by H and P NMR spectroscopy where characteristic broad signals (P = 26.9) indicate polymer formation. A further analysis of the polymer by MALDI-TOF experiments shows signals of oligomers (M2)n with n = 2 - 10. These results are further confirmed by a GPC analysis. Chapter 5 - Synthesis of BAPO functionalised polymers and their application 161
BAPO O O AIBN (7mol%), P 60°C toluene O O O O
O n PM6
Scheme 69: Synthesis of BAPO functionalised polymethacrylate PM6; BAPO =
PO(COMes)2.
A copolymerisation with a second, sterically not hindered acrylate or even an olefin like styrene is possible and allows to easily prepare a wide range of BAPO functionalised acrylates and related polymers like acrylate / styrene copolymers.
5.4.4 BAPO functionalised polythiophenes
We prepared the thiophene BAPO B30 as a yellow oil according to the described procedure in chapter 3. Electrochemical oxidation under standard conditions (see below) gave oligo- / polymers PM1 as shown in Scheme 70.
O Mes Mes O O O electrochemical P P O oxidation Mes O Mes S S n PM1
Scheme 70: Synthesis of BAPO-polythiophene PM1.
The electrochemical behaviour of monomer B30 was investigated by cyclic voltammetry (CV; platin electrode in thf, potential referenced versus Fc/Fc+). It clearly shows that the monomer B30 is oxidised to oligo- / polymers. A first electrochemical cycle shows a non reversible oxidation step at a potential of E1 = -0.293 V. In the second cycle the integral of the oxidation curve becomes bigger indicating an increase of current. This behaviour is continuously observed and the Chapter 5 - Synthesis of BAPO functionalised polymers and their application 162 current wave steadily increases with the number of electrochemical cycles. At the same time, the oxidation potential is shifted to lower values (i.e. E2 = -0.238 V, E3
= -0.183, E4 = -0.172). Such a behaviour is typical for the formation of a conducting polymer and indicates an increase of the electrode surface through the deposition of the conducting polymer. The oxidation potentials are in the typical range of thiophene oligomers214. A control experiment using Ph-BAPO B2 as substrate shows that the BAPO group is not oxidised within the investigated potential range (-2.5 – +2.0 V).
5.4.5 BAPO functionalised polysiloxanes (polysilicones)
Suitable monomeric precursor molecules for BAPO functionalised silicones are B47 - B49, which can be conveniently synthesised from sodium bis(mesitoyl)phosphide (P4) and siloxyalkylhalides following the general synthetic scheme introduced above. A large variety of polymers and copolymers PM7 can be easily synthesised with excellent yields and short reaction times.
O O O O P P 2R OEt HClaq. 5%, O + 1 O 1 Si R ROEt toluene O O Si Si OEt R1 O Si R2 1 OEt Si B47-B49 R PM7 R1 O R2 R1,R2 =Me,Ph,OEt
Scheme 71: Synthesis of BAPO functionalised silicones PM7.
For example, a toluene solution of one of the monomers B47 - B49 is stirred vigorously with diluted hydrochloric acid (1-5%). Higher HCl concentration can decompose the BAPO. Strongly oxidising acids like sulphuric acid cannot be used. After the polycondensation, the polysiloxane remains dissolved in the toluene solution, which allows a very simple work-up and isolation of the polymer by separation of the organic phase from the aqueous hydrochloric acid. Subsequently, Chapter 5 - Synthesis of BAPO functionalised polymers and their application 163 the toluene solution is washed with aqueous sodium hydrogen carbonate and dried over sodium sulfate. The polysiloxane (silicone) remains as viscous oil or solid after evaporation of the toluene. Following this procedure, copolymers with a wide range of (commercially available) alkoxysilanes were synthesised with a different ratio of monomers (for details: see below and experimental part). The obtained light sensitive silicones are mostly pale yellow oils. When the (triethoxy)propylBAPO B47 was used as a monomer, cross-linked silicone polymers are obtained. Especially under vacuum or by gently warming (30-60°C), these materials are obtained in solid form. The molecular weight lies between 200’000 and 500’000 g/mol and the polydisperisity is in a range of Q = 1.5 to 2.0. To impede solidification of the synthesised silicones through cross-linking condensation reactions, trimethylethoxysilane can be added.
5.4.6 Ennoblement of textiles with BAPO-functionalised siloxanes and polysiloxanes
It is known that alkoxysilanes are able to react with hydroxy groups of 215 cellulose under extrusion of an alcohol to give cellulose-O-SiR3 linkages. Consequently the siloxysubstituted BAPO monomers B47 - 49 and the silicone polymers PM7 shown in Scheme 71 should be suitable reagents for the binding of BAPO units to the surface of cotton fibres and textiles. Subsequently, the cotton fiber may be easily further modified photolytically (Scheme 72).
FG FG FG FG FG FG FG FG BAPO BAPO FG hv FG cotton P P
Scheme 72: Functionalised cotton fiber by polymerising functionalised monomers on its surface. Chapter 5 - Synthesis of BAPO functionalised polymers and their application 164
To test this idea and as a proof of principle, experiments were performed which allow the polymerisation and simultaneous grafting of a fluorinated acrylate,
H2C=CH(COOC8F17) (AC8) and thereby lead to waterproof cotton fabrics. The siloxy BAPOs B47 - 49 were dissolved in dichloromethane (6.5%), and pieces (about 6 10 cm) of virgin (untreated) cotton fabrics were impregnated with this solution. Subsequently, the off-white to very pale yellow cotton fabrics were air- dried and then placed in a 5% (by weight) n-hexane solution of 1H,1H,2H,2H- heptadecafluorodecyl acrylate (AC8).
Table 4: Analytical data of some BAPO functionalised silicone copolymers PM7 that were tested for water proofing of cotton textiles. (Mn = number average molecular mass, Mw = weight average molecular mass, Mw/Mn = polydispersity)
Copolymer with Monomers homopolymer Me2Si(OEt)2 (10/90)
Mn= 245079 Mn= 1544 BAPO–C3H6–SiMe(OEt)2 PM8 Mw= 407486 PM11 Mw= 2139 (B48) Mw/Mn= 1.66 Mw/Mn= 1.38
Mn= 155675 Mn= 165588 BAPO–C3H6–SiPh(OEt)3 PM9 Mw= 294401 PM12 Mw= 315434 (B49) Mw/Mn= 1.89 Mw/Mn= 1.91
Mn= 256278 Mn= 243679 BAPO–C3H6–Si(OEt)3 PM10 Mw= 468595 PM13 Mw= 448975 (B47) Mw/Mn= 1.83 Mw/Mn= 1.84
In the next step, the cotton pieces in this solution were irradiated for 10 minutes using a standard high-pressure Hg-lamp, or halogen lamps, or an array of LED’s to initiate the polymerisation of the acrylate. The BAPO containing silicone polymers PM7 (Scheme 71) were applied in the same way [i.e. as 6% (by weight) solutions in dichloromethane] (see Table 4 for a listing of some analytical data of the polymers which were used). The functionalised cotton was intensively washed with dichloromethane for one hour at room temperature in a shaking machine to Chapter 5 - Synthesis of BAPO functionalised polymers and their application 165 wash off all polymeric material that was not covalently bound. This procedure was repeated three times with fresh portions of dichloromethane. In all cases, completely colourless cotton samples were obtained. The water-repellency of the treated cotton textiles was tested by simply placing a droplet of distilled water on the cotton fabric. The results are listed in Table 5. Every treated cotton fabric showed a water-repellent effect with respect to virgin cotton (entry 1). In the experiments with the monomers B48 and B49, only a slight water-proofing effect was observed (entries 2, 3) and the water droplet was absorbed by the fabric in about a few seconds. A satisfying result was obtained with the silicone produced form the tri(ethoxy)silane B47 (entry 4). The water droplet rolls off the surface and only a small wet point remains on the cotton fabric. A very good result was obtained with the silicone copolymer which was obtained by cocondensation of 10 equivalents of B48 with 90 equivalents of Me2Si(OEt)2 (entry 5). In this case a waterproof textile was obtained, which is not wetable (i.e. from which the water droplet rolls off immediately leaving no wet point) and which kept this property for at least 1 year. Both the R1 group in the BAPO containing siloxy monomer B47 - 49 and the 2 2 R group in the diethoxysilane, (R )2Si(OEt)2, used in the condensation reaction has a profound effect on the water repellent properties. Specifically, a phenyl substituent either as group R1 and / or R2 lowers the water repellency. Probably the increased steric hindrance at the silicon center hampers the reaction between the remaining ethoxy substituents and the hydroxyl groups of the cotton fabric and thereby prevents covalent linkage. Indeed, it is important that a small amount of alkoxy (here ethoxy) groups remains in the silicone polymer after the condensation reaction. The copolymer listed in entry 5 contains 0.031% of ethoxy groups (with respect to the number of silicon centers (= monomer units) determined by 1H NMR spectroscopy). Likewise, the homopolymer obtained from B47 (entry 4) contains silicon bonded ethoxy groups, which allow the covalent linking. Unfortunately, quantification was not possible because of the very large signals in the NMR spectra of the polymer.
Chapter 5 - Synthesis of BAPO functionalised polymers and their application 166
Table 5: Water resistance of cotton fabrics, which were treated with a BAPO functionalised silicone and irradiated in presence of the perfluorinated acrylate AC8.
BAPO functionalised silicone (90% copolymers were synthesised from entry Monomer remarks 10% B47-B49 and 90% of 2 (R )2Si(OEt)2 Immediate absorption 1 virgin cotton of water droplet.
BAPO BAPO BAPO Me Me Me Absorption of water 2 B48 Si Si Si droplet after a few EtO O O OEt seconds. n PM8 BAPO BAPO BAPO Ph Ph Ph Absorption of water 3 B49 Si Si Si droplet after a few EtO O O OEt seconds. n PM9
OEt BAPO OEt EtO O O OEt No absorption of water Si Si Si droplet. The droplet EtO sticks slightly to the 4 B47 BAPOn O BAPO surface but drains off Si at an ≈60° angle EtO leaving a small wet BAPO m point. x PM10
BAPO Me BAPO Me No absorption of water Me Me Me Me droplet. The droplet B48, Si Si Si Si rolls of immediately 5 Me Si– 2 EtO O O O OEt leaving no wet point. (OEt) n m 2 x Effect persists for at least 1 year. PM11 Chapter 5 - Synthesis of BAPO functionalised polymers and their application 167
BAPO functionalised silicone (90% copolymers were synthesised from entry Monomer remarks 10% B47-B49 and 90% of 2 (R )2Si(OEt)2
BAPO Me BAPO Me Ph Me Ph Me B49, Si Si Si Si The waterdrop is 6 Me2Si– EtO O O O OEt absorbed after around (OEt) n m three seconds. 2 x
PM12
BAPO Ph BAPO Ph Me Ph Me Ph B48, Si Si Si Si After 5 seconds the 7 Ph2Si– EtO O O O OEt waterdrop was (OEt) n m absorbed. 2 x
PM13
BAPO Ph BAPO Ph Ph Ph Ph Ph B49, Si Si Si Si After 5 seconds the 8 Ph2Si– EtO O O O OEt waterdrop was (OEt) n m absorbed. 2 x
PM14
Generally better results were obtained with silicone copolymers. On one side this may be due to the water repellent effect of the polysilicone by itself. On the other hand a too high concentration of BAPO groups at the surface leads to efficient radical recombination reactions of the surface radicals, which lowers the amount of the grafted perfluorinated polymer. This is also indicated by the smaller increase of the weight of the textile after the treatment. Figure 39 shows pictures from scanning electron microscopy (SEM) of a virgin cotton fabric (top) and the cotton fabric treated according to entry 5 in Table
5 (copolymer from B48 / Me2Si(OEt)2 (10 : 90), AC8) (bottom). The waterproofing effect can be easily seen in the photograph shown on the right side of the figure. A droplet of coffee is not absorbed even after prolonged exposure times. Chapter 5 - Synthesis of BAPO functionalised polymers and their application 168
Another possibility for the functionalisation of cotton is its treatment with BAPO-acetic acid (B38) in a dichloromethane solution in the presence of dicyclohexyl carbodiimide (DCC) as coupling reagent at 40°C for several hours. Since the water repellent effect of this cotton after irradiation in a 1 M n-hexane solution of AC8 is less than with the silicones, it was not further investigated.
Figure 39: SEM picture of virgin cotton and after functionalisation with a BAPO- functionalised polymer PM7 [10 eq. B48 / 90 eq. Me2Si(OEt)2] and polymerising perfluorinated acrylate AC8 on the surface. Top: Virgin cotton fiber; bottom: treated cotton fiber; right: coffee droplet on treated cotton fabric.
In the same manner, wood samples were functionalised. Also here the BAPO functionalised silicones gave very good results (Figure 40). For further details see Ref.216 Chapter 5 - Synthesis of BAPO functionalised polymers and their application 169
Figure 40: Wood after treatment with a BAPO-silicone PM7 and functionalisation with a perfluorinated acrylate (left: white fir, right: beech).
5.4.7 Photoinduced gelation with non-polar liquids
A BAPO functionalised silicone with vinyl groups is able to form a cross- linked silicone polymer when irradiated by visible light. The synthesis of such polymers is straight-forward and simply involves the cocondensation reaction of the BAPO alkoxysilanes B47 - 49 with a commercially available ethoxyvinylsilane like tri(ethoxy)vinylsilane, (EtO)3Si-CH=CH2, or di(ethoxy)methylvinylsilane,
(EtO)2MeSi-CH=CH2.
Figure 41: Gelation of a benzene solution of a BAPO-functionalised vinylsilicone.
The synthesis of the silicone polymers is performed according to the general procedure outlined in Scheme 71 (5% aqueous HCl / toluene). The resulting BAPO-vinyl-silicones are soluble in non polar solvents like benzene or toluene. After irradiation with a UV/Vis Hg-lamp, a gel is formed within a few minutes. Figure 41 shows a sample of a slightly yellow silicone-gel in benzene. Chapter 5 - Synthesis of BAPO functionalised polymers and their application 170
The amount of benzene which can be encapsulated in an irradiated BAPO- vinyl-silane depends on the ratio between the siloxy substituted BAPO monomer B47, the (ethoxy)vinylsilane and the structure of the latter. In a typical experiment, the BAPO-vinyl-substituted silicone was dissolved in benzene and irradiated for several minutes. Depending on the monomer, different amounts of benzene were gelated. The maximal capacity was investigated with iterative experiments. The results are listed in Table 6 and Table 7.
Table 6: Absorption capacity of cross-linked silicones upon UV / Vis-irradiation.
Capacity Nr. Monomer 1 Monomer 2 ratio Polymer (mL benzene / 1g silicone) 1 50:50 PM15 70 (EtO)3Si–C3H6-BAPO (EtO)3Si–HC=CH2 2 25:75 PM16 45 B47 A10 3 5:95 PM17 50
The best result is obtained with a silicone copolymer obtained by condensing a 1 : 1 mixture of (EtO)3Si–C3H6-BAPO (B47) and (EtO)3Si–CH=CH2 (A10). 70 mL of benzene per gram of silicone were absorbed after irradiation with UV/Vis light (Table 6, entry 1). Lowering the amount of B47 in the copolymer leads to a decrease of encapsulated benzene. However, there is not a linear correlation between the B47 / A10 ratio and the benzene bound in the gel. For example, the cross-linked co-polymer obtained (entry 3), can bind with only 5% of B47 still 50 mL of benzene. A certain degree of cross-linking must be present already before the radiation process in order to achieve a good gel forming performance. This is clearly demonstrated by the experiments listed in Table 7. Here, di(ethoxy)- substituted silane (B48) and methylvinylsilane (A11) were used in the polycondensation reaction leading to linear polysilicones. In all cases, significant smaller amounts of benzene were encapsulated after UV / Vis-irradiation of a benzene solution of the silicone copolymer. Again, decreasing the amount of B48 Chapter 5 - Synthesis of BAPO functionalised polymers and their application 171 in the silicone copolymer leads to a lowering of bound benzene (12 mL per gram of silicone at B48: (EtO)2MeSi-HC=CH2 ratios below 25 : 75, entries 2, 3 in Table 7).
Table 7: Absorption capacity of linear silicones after irradiation.
Capacity Nr. Monomer 1 Monomer 2 ratio Polymer (mL benzene/ 1g silicone
1 (EtO)2MeSi-C3H6- 50:50 PM18 40 (EtO)2MeSi-HC=CH2 2 BAPO 25:75 PM19 12 A11 3 B48 5:95 PM20 12
After evaporation of the solvent under vacuum, the gel is converted into a white powder, which is able to swell in non-polar solvents (e.g. chloroform, benzene, toluene, ethylacetate) but remains unaffected by polar solvents (e.g. dimethylformamide, dimethylsulfoxide, water, ethanol). Although the absorption capacity drops to about 30% of its initial capacity, this is still significantly more than amylum, which is capable of absorbing about 100% of its own weight. In summary, a remarkable simple and straight-forward method for the photochemical formation of gels with apolar substances was developed through the synthesis of BAPO-functionalised poly(vinyl)siloxanes. Both sufficient cross- linking through the polycondensation reaction in the formation of the silicone copolymer and in the photochemical process must be achieved in order to obtain a material which has the capacity of binding high amounts of an apolar liquid. These properties are achieved by (i) the use of tri(alkoxy)silanes in the polycondensation reaction and (ii) a sufficiently high content of BAPO groups in the silicone copolymer.
5.4.8 Functionalisation of surfaces with thin films of BAPO functionalised silicones
As with the BAPO functionalised poly(norborene) PM5 (see above), the BAPO-functionalised polysilicones PM7 listed in Table 4 and Table 5 can be used Chapter 5 - Synthesis of BAPO functionalised polymers and their application 172 for surface functionalisation and site-specific structuring. The highly cross-linked homopolysiloxane [O3Si-C3H6-BAPO]x (PM10) obtained by the polycondensation reaction of (EtO)3Si-C3H6-BAPO (B47) is able to form solid thin films on a surface by simply adding a drop of a diluted chloroform solution on the surface and evaporating the solvent. With other BAPO functionalised silicones liquid films are produced. If this experiment is performed with a standard silicon wafer, the result can be detected conveniently investigated by SEM.
To a silicon wafer coated with a thin film of [O3Si-C3H6-BAPO]x (PM10), a few drops of ethyl acrylate were added. The half of the silicon wafer was covered with an aluminum foil to protect this part against light. In the next step, the silicon wafer was irradiated with a high-pressure UV/Vis Hg-mercury lamp to initiate the polymerisation process. Figure 42 shows the result. The upper half of the left picture shows the silicon wafer that was covered with the aluminium foil. Here, the thin film of [O3Si-C3H6-BAPO]x is visible. The bottom of the left picture shows the part of the silicon wafer which was exposed to light. This part is completely covered by poly(ethylacrylate).
Figure 42: Polymerisation of ethyl acrylate on a thin film of [O3Si-C3H6-BAPO]x (PM10). The upper part shows the thin film and the lower part the organic polymer. Chapter 5 - Synthesis of BAPO functionalised polymers and their application 173
In a second experiment, a copper net was placed on the thin film on the silicon wafer. Acrylonitrile was dropped on this assembly, which was subsequently irradiated for several minutes. After the copper net was removed, the sample was subjected to a SEM analysis (Figure 43). A structured surface consisting of micrometer-sized “pots” of poly(acrylonitrile) are seen where the sample was exposed to light. These “micro-bowls” have a diameter of about 50 μm and they are around 30 μm deep. An explanation of this effect can be given as follows. First concave shaped droplets of the liquid acrylonitrile are formed by the capillary forces in the holes of the copper net. The phosphoranyl radicals that are generated in these holes on the silicon surface under irradiation lead to a very fast polymerisation reaction and solidification of this initial structure. This result, in combination with the one discussed above for the BAPO functionalised poly(norborene) PM5, clearly shows that BAPO-functionalised polymers can be effectively used for the preparation of various nanostructured surfaces.
Figure 43: “Microbowls” generated by light induced polymerisation on a thin film of BAPO functionalised silicone PM7 and a copper net. Chapter 5 - Synthesis of BAPO functionalised polymers and their application 174
5.4.9 BAPO functionalised biopolymers
According to a published procedure, the primary hydroxyl functions of cellulose powder were tosylated and subsequently reacted with sodium azide in a simple nucleophilic substitution reaction to give azidocellulose217. BAPO functions can be covalently added to this material via a [2+3] cycloaddition with the propargyl-BAPO compound B11 (Scheme 73). This “click reaction” is performed at room temperature and the resulting triazol heterocycles are chemically robust and ensure a durable covalent binding of BAPO functions.
HOH HOTos H O TosCl/ TEA H O O O HO O HO O H OH 0°C->RT H OH H H 24h H H O Mes Mes NaN3/dmf O O 100°C, 24h O P O P O N Mes HN3 Mes N B11 H O HN O HO O H O dmso, RT, 24h H OH O HO O H H H OH H H
Scheme 73: Synthesis of photoactive polymer "BAPO-cellulose" PM2 by using "click"-chemistry.
The elemental analysis shows that 52% of the cellulose units are functionalised with a photoactive BAPO group. Remarkably, the green BAPO- functionalised cellulose is soluble in dmso to form a yellow solution. After irradiation of the solution or the solid, complete fading of the colour is observed and colourless cellulose materials are obtained, which indicates the efficient and quantitative photolytic cleavage of the BAPO functions. In order to prove that a BAPO-functionalised cellulose can be further modified by binding functional groups in a photoreaction, the following experiment ● was performed. Phosphoranyl radicals, R2PO , react very efficiently with various hydroxyl groups to give esters of the type R2PO-OR (see: chapter 4). It should Chapter 5 - Synthesis of BAPO functionalised polymers and their application 175 therefore be possible to graft covalently alcohols and related compounds to BAPO- functionalised cellulose. HO OH
O OH O O O O O O O O Mes P Mes O -H+ thf, hv O +H+ O O O Cellulose -MesCHO O O (pale green) Mes P Mes P
Cellulose Cellulose (colourless) (red)
Scheme 74: Suggested reaction between BAPO-functionalised cellulose and phenolphthaleine during UV / Vis irradiation.
BAPO-cellulose was suspended in a colourless phenolphthaleine solution in thf and irradiated with a middle-pressure Hg-lamp. A light green material was obtained (see left picture of Figure 44), which was intensively washed for 12 hours with thf and ethanol to remove the phenolphthaleine that was not cellulose-bound in the photoreaction but only physically adsorbed. In a control experiment, the BAPO-functionalised cellulose was treated in the same way but not exposed to light. After drying the samples with phenolphthaleine treated, one drop of diluted sodium hydroxide solution was added. The colour of the photolysed BAPO- cellulose material turned immediately to red, indicating a covalent grafting of the chromophores. On the contrary, the colour of sample from the control experiment kept its green colour. In summary, it is possible to functionalise macromolecules and surfaces by light induced condensation reactions of covalently fixed BAPO- functionalities.
Chapter 5 - Synthesis of BAPO functionalised polymers and their application 176
Figure 44: Durable light induced binding of phenolphthalein to a BAPO- functionalised cellulose (PM2). Left: non-irradiated BAPO-functionalised cellulose. Right: BAPO-functionalised cellulose after irradiation in the presence of phenolphthaleine. The phenolphthaleine is covalently crafted to the cellulose.
5.5 Conclusion
Two different methods were developed to prepare BAPO-functionalised polymers. In method A the starting material is a functionalised polymer on which the BAPO group was introduced. In method B the functionalised BAPOs (described in chapter 3) were used as monomers for polymerisation or copolymerisation processes. It was possible to prepare different kinds of organic, inorganic and biopolymers. Potential applications were tested. Very promising are the investigations for photosensitive coatings, the enoblement of textiles, photo-induced gelation experiments and the enoblement of wood. These kinds of polymers and application are new and outstanding results. Such kind of photopolymers with such photo active groups were completely unknown before. In each of these methods, BAPO containing oligo- and / or polymers are obtained that can be further processed under the action of visible light from various sources (sunlight, LED’s, halogen, argon, and related lamps, UV/Vis Hg- photolamps, etc.). As a proof of principle phenolphthaleine was grafted covalently on BAPO- functionalised cotton. This is one example for many promising application. With Chapter 5 - Synthesis of BAPO functionalised polymers and their application 177 analogous reactions it should be possible to create highly functionalised surfaces and to graft molecules locally resolved on surfaces. This opens new ways for example for storage media or DNA-chips.
Chapter 6
Synthesis of nanoparticles Chapter 6 - Synthesis of nanoparticles 180
6.1 Introduction
The interest in nanoparticles has been increasing in the recent period218, 219, 220. Especially silver nanoparticles are known for their antibacterial properties221. In future, work has to be concentrated on the morphological control and the fixation of metal nanoparticles on surfaces and polymers222, 223. Nevertheless, also new methods for environmentally friendly techniques have to be investigated to produce large amounts of nano scale materials. They are synthesised by reducing metal salts or by physical methods224. Especially chemical methods that use stoichiometric amounts of a reducing reagent have the disadvantage that the metal particles cannot be completely separated from the oxidised waste. Enviroment pollution is the consequence. Polymer nanoparticles are of highly interest as well (see chapter 1). Polystyrene nanoparticles have been prepared by various methods. However, none of these methods yields nanoparticles of small dispersity and in a range between 10 and 100 nm. Normally special methods have to be used to produce such particles. Many disadvantages, like expensive, toxic, malodorant, or coloured chemicals, or high reaction temperatures have to be accepted. Water-soluble BAPOs might be helpful to solve this problem because they are very potent initiators. Other photoinitiators for emulsion polymerisation exist, but they have a relatively low quantum yield and, therefore, they are no alternative to the "classical" initiators, e.g. sodium dodecylsulfate (SDS). Since the kinetics of such a polymerisation is very important and especially in the beginning many radicals are needed to form a latex with small particles, water-soluble BAPOs are very promising. Table 8 gives an overview of all known methods to prepare polystyrene nanoparticles in a range between 10-200 nm. These methods have many disadvantages because special conditions are necessary. Therefore, a process with BAPO-acetic acid was investigated as a new initiator to solve this problem. Chapter 6 - Synthesis of nanoparticles 181
Table 8: Overview of emulsion polymerisation processes to get polystyrene nano particles (EP = emulsion polymerisation). Size Method Comment / Disadvantage Ref. 110- RAFT Coloured agent, CS2 (toxic!) 62 200 nm Coloured agent, ultrasonic, 125°C, 53 nm TEMPO dodecylbenzenesulfonic acid sodium salt, 63 styrene / divinylbenzene system 70- TEMPO/NMP ultrasonic, 125°C, SDBS 225 170 nm
70- 226 TEMPO ultrasonic, 125°C 170 nm
~100 nm TEMPO. 135°C large dispersity 227 10- Surfactant free yield for particles <100nm is <20%, large 72 500 nm EP dispersity surfactant mixture (SDCS, SLS) 2% 5-500 nm 70°C 228 K2S2O5, process for butylacrylate! until 35nm pure styrene, below 16- Microwave EP copolymerisate. KPS, acetone-water, 229 350 nm latex was obtained by removing acetone. Emulsifier free >25 nm AIBN, water-acetone 230 EP surfactant + cosurfactant + thermal 5-50 nm Microemulsion initiator. overview, large amounts of 231 surfactant. 40 nm- Ultrasonic EP 70°C AIBN, DBP, cosurfactant necessary 55 2.5 μm 50- EP, γ-ray γ-ray 77 250 nm Chapter 6 - Synthesis of nanoparticles 182
Size Method Comment/ Disadvantage Ref. 40 mL styrene, MeOH, water, pH = 10 14 nm EP (NaOH), 1 g ammonium persulfate for 232 100 g styrene 50- 65°C, SDS, sodium lauryl sulfate, very EP 233 500 nm large dispersity
200 nm EP copolymerisation styrene, MMA 234 200- EP KPS, ultrasound waves, large dispersity 235 250 nm 200- EP Polyvinylpyrrolidone, emulsifier free, KPS 57 1000 nm
30-60 nm ATRP CuCl, polyethylenglycole 236 KPS, microwave conditions, 15-50 nm EP 237 emulsifier free, 63°C 20- 135°C, KPS, N2 pressure, large TEMPO 238 100 nm dispersity KPS, 70°C, copolymerisation (Styrene / 40-60 nm Microwave EP 239 Butylacrylate) 100 nm- Suspension PM, CuCl + Ligands (e.g. bipy) 68 5 μm ATRP 25- prepolymerisation, latex that is stable for Miniemulsion 240 500 nm 12 month, Mw= 3.000-200.000 Polymer is dissolved, mixed with water Evaporation of 5-80 nm and then evacuated under vigorous 54 droplets stirring 100 nm - γ-rays-induced, copolymerisation with a surfactant 78 10 μm 60Co monomer
59-64 nm EP KPS, surfactant free, >70°C 241 Chapter 6 - Synthesis of nanoparticles 183
Size Method Comment/ Disadvantage Ref. Dibenzylketone as intiator, SDS, toluene/ 30- Photo induced water, PD = 2.6-2.2, small molecular 242 60 nm microemulsion weight 30- 243 TEMPO large dispersity 200 nm 1-100 nm Photo induced 244 very large dispersity microemulsion dispers perfluorinated compounds, initiator: 245 Photo induced organic peroxides, silfides, ketones and EP others 20-30 nm Microemulsion KPS, AIBN, 70°C 246
6.2 Synthesis of metal nanoparticles
Acyl radicals are known to act as reducing agents. Ph-BAPO (B2) and MAPO (B3) are able to reduce metal salts with a relatively high redox potential. Thus, silver triflate was reduced by irradiation in the presence of Ph-BAPO (B2) in thf solution. Silver nanoparticles are formed, and after several days elementary silver precipitates. Also copper(I) triflate and nickel(II) trifluoroacetate give analogous results. After one day the elementary metal precipitates. All blank tests without Ph-BAPO were negative. However, it is more interesting for application to use a catalytic process. Only a catalytic amount (5 mol%) of Ph-BAPO (B2) is necessary to reduce silver triflate to elemental silver under hydrogen atmosphere (p(H2) = 1 bar). Without any addition of ligands or stabilizers, particles in the range of 2-50 nm (Figure 45) are obtained. XRD experiments indicate the presence of silver. Phosphorus signals are coming from the decomposition products of Ph-BAPO (B2). The TEM / XRD analysis was performed on a carbon covered copper net. This is the explaination Chapter 6 - Synthesis of nanoparticles 184 for the presence of carbon and copper in the XRD spectrum. Further investigations and analytical measurements (e.g. AAS, ED) were performed by J. Bräuer247.
HAADF Detector
1 2
100 nm
EDX HAADF Detector Area 1 EDX HAADF Detector Area 2 300 C C 100
Ag 80 200 Ag Ag
Si 60 Cu Si Si P Counts P Counts SiP O P S Cu S 40 O 100 Ag Cu S F Cu Cu Cu Ag Cu S Ag 20 F Cu Ag Ag Ag Ag Ag Ag Cu Ag Ag Cu 0 0 2 4 6 8 10 0 2 4 6 8 10 Energy (keV) Energy (keV)
Figure 45: TEM / XRD experiments of silver nanoparticles prepared by the reduction of silver triflate with Ph-BAPO under hydrogen atmosphere.
In an other experiment, BAPO-functionalised cotton PM2 (chapter 5) was treated with a silver triflate solution (5%) in thf. In the next step the cotton was irradiated with a UV lamp. The green colour of the functionalised cotton PM2 disappears. By analysing the cotton with SEM, small particles with a good electron conductivity were found. These particles are the pale spots in Figure 46. They are silver nanoparticles, which cannot be removed by washing the cellulose. An Chapter 6 - Synthesis of nanoparticles 185 evidence for the presence of silver in the washed cotton was the classical chemical analysis with nitric acid disintegration and the reaction with chloride anions.
Figure 46: BAPO-functionalised cotton with accumulated silver particles.
6.3 Synthesis of polystyrene nanoparticles
6.3.1 Emulsion polymerisation with water soluble BAPOs as initiators
In principle, all water-soluble BAPO derivatives should be able to initiate an emulsion polymerisation process. BAPO-acetic acid (B38), MeOBAPO-acetic acid (B39), BAPO-undecanoic acid (B40) and 1N-BAPOpropyl-2N- methylimidazoium bromide (B31) were investigated in order to perform an emulsion polymerisation process. We found out that they initiate the polymerisation of styrene and methyl methacrylate (MMA) in such a system. Styrene, degassed water, sodium dodecylsulfate (SDS) and the photoinitiator were mixed and stirred under irradiation. Subsequently, the reaction mixture was stirred in the dark for 72 h to complete the reaction. The Chapter 6 - Synthesis of nanoparticles 186 polymerisation process with BAPO-acetic acid, which can be synthesised easily, was optimised with respect to the yield and particle size of polystyrene.
The molecular masses (Mw and Mn) of the polystyrene are in the range between 2.0 - 6.0 million, as determined by GPC. The polydispersity Mw / Mn is between 1.03 and 1.38, and, thus, very small. The molecular weight and the polydispersity are not discussed here, because the main focus is on the particle size and there is no direct dependency between particle size and the molecular weight. Finally, the GPC system used is not suitable to give exact, reliable results for molecules with a molecular weight higher than two millions. In the following investigations BAPO-acetic acid sodium salt (B42) was used as photoinitiator.
6.3.2 Comparison of particle size and polymerisation time
To study the effect of the irradiation time on the particle size, samples were taken out of the reaction mixture continuously during irradiation with UV light. This polystyrene samples were put in a flask under argon atmosphere and stirred in the dark for 72 hours minus the irradiation time. After 72 h, the reaction was quenched by adding one drop of an aqueous hydroquinone solution (1%). The yield of polystyrene increases very steeply during the first hour of irradiation time, whereas the particle size increases continuously. Light scattering experiments showed that the dispersity of the particles is getting bigger during the irradiation. Figure 47 shows the depending of particle size and yield on the irradiation time.
Chapter 6 - Synthesis of nanoparticles 187
Addition of hydroquinone after 72 h reaction time
Yield (%)/ Yield Size (nm) 120 Particle size 110 100 90 80 70 60 50 40 30 0 2000 4000 6000 8000 10000 Time (s)
Figure 47: Particle size and yield against irradiation time. The size is the hydrodynamic radius of the particles as measured by light scattering.
The hydrodynamic size of the particles is approximately two times larger in the light scattering experiments than the size detected by scanning electron microscopy (Figure 48). This has two reasons. The first one is that even small amounts of large particles influence the light scattering to a large extent. The second one is that the light scattering measures the hydrodynamic radius, which is always bigger than the real one.
Chapter 6 - Synthesis of nanoparticles 188
Figure 48: Polystyrene particles after 60 minutes (3600 s) irradiation time. The average particle diameter is about 45 nm and around 20 nm smaller than the result of the light scattering measurements.
In the second series of experiments, the samples were not stirred in the dark after the irradiation to complete the reaction. Samples were taken out of the reaction mixture and the reaction was immediately quenched with an aqueous hydroquinone solution (1%wt). The yields are smaller, which indicates that the reaction is still proceeding after the initiation / irradiation period. It is noticeable that the diameter of the polystyrene particles remains nearly constant throughout the reaction. An equilibrium between initiation and termination reactions explains this result.
Chapter 6 - Synthesis of nanoparticles 189
Addition of hydroquinone directly after sample taking
Yield (%)/ Yield size (nm) Particle Size 110
100
90
80
70
60
50
40
30 0 2000 4000 6000 8000 10000 Time (s)
Figure 49: Particle size and their yield against irradiation time. The reaction was stopped by adding hydroquinone immediately after the irradiation time. The size is the hydrodynamic radius of the particles as measured by light scattering.
Figure 50: Polystyrene particles after 60 minutes (3600 s) irradiation time. Chapter 6 - Synthesis of nanoparticles 190
For both experiments, it is peculiar that the yield is higher for extremely short irradiation times than for irradiation times that are a little bit longer. An explanation is the recombination of radicals, which takes place if the radical concentration is high enough.
6.3.3 Effect of the surfactant (sodium dodecylsulfate, SDS)
In the next step, the focus was put on the effect of the surfactant concentration. In a typical experiment sodium BAPO-acetate (B42) (20 mg), styrene (10 g), degassed water (33.5 mL) and a variable amount of SDS as surfactant were mixed. The emulsion was stirred vigorously and irradiated during 10 minutes. Then, the reaction was quenched with hydroquinone. The surfactant concentration and yield are directly proportional (Figure 51). In addition, the SDS concentration is direct proportional to the particle size.
Particle size Yield (%)/ Yield S ize (nm)
70
60
50
40
30
20
10
0 0.1 0.2 0.3 0.4 0.5 0.6 0 SDS concentration (g)
Figure 51: The effect of the surfactant (SDS = sodium dodecylsulfate) concentration on the yield and the size of the polystyrene particles. Chapter 6 - Synthesis of nanoparticles 191
6.3.4 Effect of the initiator concentration
The effect of the concentration of the photoinitiator has been investigated in a typical experiment according to the general procedure in the experimental part. sodium dodecylsulfate (SDS) (100 mg ), styrene (10 g), degassed water (33.5 mol) and a variable amount of photoinitiator (sodium BAPO-acetate (B42)) were mixed. The reaction mixture was stirred vigorously. The irradiation time was 10 minutes, after which the reaction was quenched with hydroquinone. As Figure 52 shows, an extremely small amount of photoinitiator is sufficient to get a yield about 30%. The yield increases with the initiator concentration and has a maximum at an initiator concentration of 10 mg / 10 g styrene. When the radical concentration becomes too high, recombination reactions overweigh the polymerisation. The particle size decreases parallel to the yield because of the recombination reactions.
Yield (%)/ Particle size Size (nm) Yield 70
60
50
40
30
20
10
0 0 2 4 6 8 10 12 14 16 18 20 Initiator concentration (mg)
Figure 52: The effect of the initiator concentration on the particle size and the yield of the emulsion polymerisation. Chapter 6 - Synthesis of nanoparticles 192
6.3.5 Effect of the temperature
A typical experiment (see the general procedure) was performed at different temperatures by mixing sodium dodecylsulfate (SDS) (100 mg), styrene (10 g), degassed water (33.5 mL) and sodium BAPO-acetate (B42) (10 mg). The reaction mixture was stirred vigorously and irradiated for 10 minutes, before quenching with hydroquinone. Experiments were performed at temperatures between 0°C and 80°C. Astonishingly, the temperature has only a small effect on the reaction. The dispersity of the particle size becomes smaller at lower temperatures. This is not surprising, because initiation and termination reactions are more well behaved at low temperature, which is an important reason for using photoinitiators for emulsion polymerisation.
6.3.6 Further experiments
The emulsion polymerisation was performed with acrylates and methacrylates as well. They form a latex, but the polymers where not further analysed. One new application of polystyrene nanoparticles was tested. Latex, synthesised in analogy to the general procedure with 40 nm particles was used to impregnate wood of a silver fir and a beech tree. Afterwards the wood was water resistant. This can be an easy and environmental friendly procedure to protect wood, without any silicones, perfluorinated agents, or other chemicals.
6.4 Conclusion
It was possible to synthesise metal silver, copper, and nickel nanoparticles starting from silver triflate, copper(I) triflate, nickel trifluoroacetate. As reducing agent Ph-BAPO and its decomposition products can be used. Furthermore, it was possible to work under hydrogen atmosphere by using only a catalytical amount of Ph-BAPO (B2). Silver nanoparticles were obtained in a size between 2 and 50 nm. this method is very promising for the synthesis of other metal nanoparticles. Chapter 6 - Synthesis of nanoparticles 193
The emulsion polymerisation with BAPO-acetic acid as initiator is a powerful method to synthesise monodisperse polystyrene nanoparticles. Only by changing the reaction parameters, particles having size between 20 and 110 nm can be prepared. The isolated particles are re-dispersible in water. In the diameter range between 40 and 70 nm it is possible to get nearly quantitative yields. The molecular weight of the polystyrene is very high (1-5 mio.). The polydispersity is relatively small (1.05-2.0). Table 8 (see: Introduction Chapter 6) gives an overview of other polymerisation methods to synthesise polystyrene. Although there are some methods to synthesise polystyrene particles in nano scale, no method exist that combines all advantages of the emulsion polymerisation (EP) as efficiently as the BAPO-acetic acid initiated one. No additives (like additional surfactants for the microemulsion polymerisation) are necessary, no poisonous, expensive, malodorant, radioactive chemicals and explosive initiators (e.g. AIBN, DBP) have to be used, the reaction can be performed at room temperature and the resulting latex is stable for more than one year. Furthermore, the reaction can be performed in standard laboratory glassware. No special equipment like ultrasonic or microwave is necessary. Actually, intensive sun light, white or blue LEDs and halogen lamps are able to start the polymerisation reaction.
Outlook
We described in this work the design of highly functionalised and very active photoinitiators, prepared starting from elemental phosphorus. The first applications were investigated, but this is only the beginning of a new field in using photoinitiators for the functionalisation of materials and surfaces. In the future, we have to concentrate on new applications for BAPO- functionalised materials and surfaces. Therefore, it is very important to investigate additional methods to functionalise such materials and surfaces. Especially the direct functionalisation of metal surfaces with BAPO groups is very promising. Furthermore, many alternative routes for the functionalisation of polymers and biopolymers (e.g. with 3-aminopropyl-BAPO (B15), 3-azidopropyl-BAPO (B20), acetone-BAPO (B32)) are possible and should be investigated. Moreover, technical processes to prepare polymers with functionalised BAPOs have to be developed, especially the living polymerisation processes that were investigated in the last ten years. Potential products like polymer nanoparticles are promising for many applications.
At the same time, methods have to be developed to prepare NaPH2 under mild conditions, without high pressure, toxic ammonia gas and relatively expensive dme. A one-pot procedure that can be performed in large scales would allow saving much time during the synthesis of BAPO derivatives.
Experimental Part
Experimental Part 198
General techniques: All manipulations of air or moisture sensitive compounds were performed on a standard vacuum line in flame-dried flasks under an atmosphere of argon. The argon was provided by PANGAS and further purified with an MBraun 100 HP gas purification system. Solvents were distilled under argon from sodium (toluene), sodium / benzophenone (thf, dioxane, dimethoxy ethane, diethyl ether), sodium / benzophenone / tetraglyme (n-hexane), sodium- potassium alloy (benzene), calcium hydride (methylene chloride, chloroform, acetonitrile), phosphorus pentoxide (acetonitrile). Air sensitive compounds were stored and weighed in gloveboxes (M Braun: lab master 130 or 150B-G). Reactions in small quantities were performed within a glovebox. Cyclic voltammetric investigations were performed using Princeton Applied Research potentiostat / galvanostat model 263A or model 283. The measurements were performed on an apparatus designed by Heinze et al.[163] Working electrode: planar platinum electrode (approximate surface area 0.785 mm2); reference electrode: silver; counter electrode: platinum wire. At the end of each measurement, ferrocene was added as internal standard for calibration (-0.352 V vs. Ag / AgCl). EPR spectroscopic investigations were performed in collaboration with the group of Prof. Koppenol at the laboratory of inorganic chemistry at the ETH Zürich. Electron paramagnetic resonance spectra were obtained with a Bruker EMX 080 (Bruker, Karlsruhe, Germany) equipped with a microwave-bridge ER 041 XG and the dielectric mixing resonator ER 4117 D-MVT. The instrument settings used in a typical experiment were: gain = 8 × 104; resolution = 1024 points; measurement field = 3465 G; measurement time = 81.9 s; microwave power = 0.507 mW; modulation amplitude = 0.5 G; frequency = 9.751 GHz. Data acquisition and analysis were carried out with ACQUISIT software (Bruker). The samples were brought into the cavity by means of a regular NMR tube. IR spectra were recorded on a Perkin-Elmer-Spectrum 2000 FT-IR-Raman spectrometer with KBr beam splitter (range 500 – 4000 cm–1). Solution spectra were measured in a 0.5 mm KBr cell, for solid compounds, the ATR technique was Experimental Part 199 applied. The absorption bands are described as follows: strong (s), very strong (vs), middle (m), weak (w), or broad (br). Mass spectra of organic compounds were recorded on a Finnigan MAT SSQ 7000 mass spectrometer using electron ionization. GC-MS measurements were performed on a Finnigan MAT GCQ combined with a MAT SSQ 7000 mass spectrometer using electron ionisation. Melting points were determined with a Büchi melting point apparatus and are not corrected. Samples were prepared in glass capillaries. Solution NMR spectroscopy: NMR spectra were recorded on Bruker Avance 700, 500, 400, 300, 250, 200 spectrometers at room temperature (if not indicated differently). Temperatures below room temperature were reached by evaporation of liquid nitrogen. The temperatures used for the kinetic simulations were measured correctly by replacing the sample NMR tube of the sample with a tube in which a thermo coupler was fitted. The chemical shifts (δ) are measured 248 according to IUPAC and expressed in ppm relative to TMS, CFCl3 and H3PO4 for 1H and 13C, 19F and 31P respectively. Coupling constants J are given in Hertz [Hz] as absolute values, unless specifically stated. Where a first order analysis is appropriate, the multiplicity of the signals is indicated as s, d, t, q, or m for singlets, doublets, triplets, quartets, or multiplets respectively. Otherwise the spin systems are specified explicitly. Quaternary carbons are indicated as Cquat, aromatic as
Caryl, when not noted otherwise. Line shape simulations were performed with the MEXICO program package.249 Solid State NMR spectroscopy: 31P CP MAS solid-state NMR spectra were acquired at room temperature on a Bruker Avance 500 instrument operating at a 1H Larmor frequency of 500 MHz. Conventional cross-polarisation and magic- angle-spinning techniques were implemented using 4 mm rotors, with which rotational frequencies of >11 kHz were achieved. The strength of the magnetic field was adjusted such that the 13C carboxylate resonance of glycine appeared at 176.0 ppm. In consequence referencing of all isotopes might be achieved as for the solution NMR using the unified Ξ scale. Chemical shifts are expressed relative Experimental Part 200
to H3PO4. CP MAS spectra were simulated using the SIMPSON program package250. Pulsed Field Gradient Spin Echo Experiments (PFGSE): All the measurements of the self-diffusion coefficients were performed on the Bruker AVANCE 500 spectrometer equipped with a microprocessor controlled gradient unit and a multinuclear BBI probe head with an actively shielded Z-gradient coil. The sequence used was the standard three pulses Stimulated Echo. The gradients were of sine-shape, their length (δ) 2 ms and the strength varied systematically in the course of the experiments. The time between the midpoints of the gradients (Δ) was 100 ms. The spectra were acquired using 32 K points and a recycle time of 30 seconds. The logarithmic values of the normalised intensities were plotted as a function of the square of the gradient strength and fitted with the standard linear regression algorithm. The diffusion coefficients reported in the various tables were estimated using the diffusion so efficient of HDO in D2O as a reference. The hydrodynamic radii were calculated from the values of the experimental diffusion coefficients using the Stokes-Einstein equation reported below:
rH=kT/6πDη where k is the Boltzmann constant (1.38*10-23 J K-1), T is the temperature expressed in K, η is the viscosity in Kg s-1 m-1 taken from the standard literature and rH the hydrodynamic radius in m. The measured diffusion coefficients and the resulting hydrodynamic radii and volumes are:
-10 2 -1 3 P6 [D8]thf: D = 5.80*10 m s , rH = 8.53 Å, VH = 2600 Å -10 2 -1 3 - P6 [D8]Toluene: D = 6.11*10 m s , rH = 6.52 Å, VH = 1162 Å (PH2 /OtBu) -10 2 -1 3 - P7 [D8]Toluene: D = 6.11*10 m s , rH = 6.52 Å, VH = 1162 Å (PH2 /OtBu) t -10 2 -1 3 NaO Bu [D8]thf: D = 9.02*10 m s , rH = 4.42 Å, VH = 361 Å t -10 2 -1 3 NaO Bu [D8]Toluene : D = 6.67*10 m s , rH = 5.97 Å, VH = 893 Å
Experimental Part 201
UV/Vis spectra were recorded on a UV/vis/NIR lambda 19 spectrometer in 5 mm quartz cuvettes (200 – 1000 nm). X-ray crystallographic measurements were performed on Bruker SMART 1K, SMART APEX and OXFORD XCalibur platforms with graphite-monochromated
Mo-Kα radiation (α = 0.71073 Å). The reflex intensities were measured by CCD area detectors. The collected frames were processed with the proprietary software SAINT251 for the Bruker Diffractometer or XCalibur for the Oxford Diffractometer and an absorption correction was applied (SADABS252). Solution and refinement of the structures was performed with SHELXS-97253 and SHELXL-97254 respectively. In general, all non-hydrogen atoms were refined with anisotropic displacement parameters. Hydrogen atoms were placed in their idealized positions and allowed to ride on the respective carbon atoms. Associated crystallographic data and other experimental details are summerised in the crystallographic tables in the appendix. UV-Lamp: The UV lamp for irradiation experiments was a standard middle pressure mercury lamp. Chemicals: basic chemicals were ordered at ABCR, Acros, Aldrich, Fluka, Lancaster, or STREM. TEMPO and its derivatives, mesitoyl chloride and mesitoyl esters were disposed by Ciba SC.
Starting materials
3-(chloromethyl)thiophene
3-hydroxythiophene (1.00 g, 0.90 mL, 8.77 mmol) was dissolved in Cl S CH2Cl2 (10 mL). The solution was cooled down to 0°C and stirred
vigorously. SOCl2 (1.9 mL, 83.1 g, 26 mmol) was added dropwise. The ice bath was removed and the reaction mixture was stirred at room temperature for one hour. Subsequently, the solvent was removed under vacuum. The remaining oil was dissolved in diethyl ether. Afterwards the solution was washed with an aqueous sodium hydrogencarbonate (2%) solution, brine and dried Experimental Part 202 with sodium sulfate. After evaporating the diethyl ether, the pure product was obtained (Yield: 0.88 g, 67%, 5.88 mmol).
1 H NMR: (300.1 MHz, C6D6): = 4.16 (s, 2 H, ClCH2), 6.73 (s, 1 H, S-CH), 6.82 (br., 1 H, CH4), 7.2 (br., 1 H, CH5). 13 2 5 C NMR: (62.9 MHz, C6D6): = 40.4 (CH2), 125.7 (C H), 126.8 (C H), 127.6 (C4H), 139.6 (C3H).
5-Norbornen-2-methylbromid255
In a thick walled Schlenk flask, equipped with a young valve Br dicyclopentadiene (7.5 mL, 56 mmol, 1 eq.), allyl bromide (11.6 mL, 135 mmol, 1.2 eq.) and hydroquinone (40 mg, 0.36 mmol, 0.3 mol-%) were stirred for 18 h at 180-190°C. Afterwards the excess of allyl bromide was destillated off by heating the black liquid product up to 100°C. After the distillation at 10 mbar, the colourless product was obtained (Yield: 67%, 75.4 mmol, 14.1 g).
1 3 4 H NMR (250 MHz, CDCl3): = 6.20 (dd, 1 H, JHH = 3.0 Hz, 5.7 Hz, CH ), 5.99 3 5 8 8 (dd, 1H, JHH = 2.9 Hz, 5.7 Hz, CH ), 3.21 (m, 1H, CH ), 3.02 (m, 2H, CH ), 2.98 6 3 1 2 (m, 1H, CH ), 2.87 (m, 1H, CH ), 2.53 (m, 1H, CH ), 1.94 (m, 1H, CH exo), 1.49 (m, 7 7 2 3 1H, CH ), 1.29 (m, 1H, CH ), 0.59 ppm (ddd, 1H, JHH = 2.7 Hz, JHH = 4.3 Hz, 11.8 2 Hz, CH endo). 13 5 4 7 6 C NMR (62.9 Hz, CDCl3): = 138.2 (C ), 131.6 (C ), 49.7 (C ), 45.5 (C ), 43.1 (C3), 42.1 (C1), 38.3 (C8), 32.8 ppm (C2).
5-Norbornene-2-(butyl-4-bromide)
Br In a 250 mL three neck bottle magnesium turnings (5.2 g, 214 mmol, 2.35 eq.) were mixed with thf (10 mL). Whilst stirring 5- norbornene-2-methylbromide (17 g, 90.8 mmol, 1.03 eq.) that was dissolved in thf (25 mL) was added dropwise. After stirring for one hour the excess of magnesium turnings were filtered off. The solution was added dropwise to a mixture of 1,3- Experimental Part 203
dibromopropan (17.9 g, 88 mmol, 1 eq.), Li2CuCl4 (0.1 M in thf) (9 mL, 0.9 mmol, 0.01 eq.) and thf (35 mL). After complete addition of the Grignard reagent, the black solution was stirred for one hour more. The reaction mixture was hydrolyzed with acetic acid (20%). Diethylether (40 mL) was added and the organic phase was washed with saturated sodium hydrogencarbonate solution (30 mL) and distilled water (30 mL). The organic layer was dried over magnesium sulfate and the solvent was evaporated in vacuo at room temperature. The product was distilled at 20 mbar and 140°C. A colourless oil is obtained (Yield: 10.31 g, 45 mmol, 51%).
1 3 4 H NMR (300 MHz, CDCl3): = 6.10 (dd, 1H, JHH = 3.1 Hz, 5.7 Hz, CH ), 5,91 (dd, 3 5 3 11 1H, JHH = 2.8 Hz, 5.7 Hz, CH ), 3.39 (t, 2H, JHH = 6.8 Hz, CH2 ), 2.75 (m, 1H, 3 6 1 2 CH ), 2.75 (m, 1H, CH ), 1.98 (m, 1H, CH ), 1.83 (m, 1H, CH exo), 1.83 (m, 2H, 10 7 9 8 CH2 ), 1,39 (m, 2H, CH2 ), 1,39 (m, 2H, CH2 ), 1.09 (m, 2H, CH2 ), 0.49 ppm (ddd, 2 3 2 1 H, JHH =2.6 Hz, JHH = 4.1 Hz, 11.2 Hz, CH endo). 13 5 4 7 6 C NMR (75 MHz, CDCl3): = 137.1 (C ), 132.2 (C ), 49.7 (C ), 45.4 (C ), 42.6 (C3), 38.7 (C1), 34.0 (C2), 33.9 (C11), 33.1 (C10), 32.5 (C8), 27.2 ppm (C9).
sodium selenide, Na2Se (A6)
In a 250 mL Schlenk flask sodium (5 g, 21.7 mmol, 2 eq.) was added. Afterwards the Schlenk was cooled down in liquid nitrogen and around 50 mL of liquid ammonia were condensed from a gas cylinder. The solution was stirred with a glass covered magnetic stirrer. After fully dissolving the sodium, the solution was allowed to warm up to -35°C. Afterwards selenium (8.52 g, 10,85 mmol, 1 eq.) was added in small portions. It is important to wait until the selenium reacted with the sodium, before adding the next portion. As the reaction is exothermic, the Schlenk flask should not be closed during the course of the complete reaction in order to prevent an explosion of the flask, because the reaction is very exothermic. After the addition of the complete amount of selenium, the reaction gave a grey suspension. The ammonia was evaporated by warming the flask up to room temperature. A white powder was obtained, which was dried in vacuo for several Experimental Part 204 hours. It is spontaneously inflammable under air. Selenium waste can be oxidised with a diluted solution of bromine in methanol. The yield of Na2Se is quantitative.
Cellulose tosylate256
To the solution of 20.2 g of air-dry cellulose in dma / LiCl (4.3% w/w), a mixture of triethylamine (59.4 mL, 427.2 mmol) and dma (40.6 mL) was added while stirring. After cooling to about 8°C, a solution of p-toluenesulfonyl chloride (40.7 g, 213.6 mmol) in dma (60 mL) was added dropwise within 30 min. The homogeneous reaction mixture was stirred for 24 h at 8°C, and then slowly poured into ice water (5 L). The precipitate was filtrated off, carefully washed with a mixture of distilled water (15 L) and ethanol (2 L) and finally suspended in acetone (1 L) in order to dissolve impurities. Susequentely, water (3 L) was added to separate the cellulose from the acetone by filtration. After filtration and washing with ethanol, the sample was dried at 50°C under vacuum (Yield: 75 %), degree of substitution (DS) = 1.36 (based on sulphur analysis).
13C NMR (DMSO-d6): = 144.7-127.4 (tosylate aromatics), 105-65 (cellulose backbone), 20.7(CH). IR (goldengate, [cm-1]): 3523 (v, OH), 3072 (v), 2891 (v, CH), 1598, 1500, 1453 (v,
C-Carom.), 1364 (SO2), 1177 (v, SO), 814 (w).
6-Azido-6-deoxy Cellulose
Sodium azide (7.49 g, 0.115 mol) was added to a solution of tosyl cellulose (7.0 g, 0.023 mol; DS (degree of substitution) = 0.92) in dmf (120 mL) and the reaction mixture was stirred at 100 °C for 24 h. Isolation was carried out by precipitation of the mixture in water (600 mL) and filtration of the polymer. After washing five times with water (250 mL), five times with of ethanol (250 mL), and drying at 60°C under vacuum the product, 6-azido-cellulose was obtained. Degree of substitution (DS): 0.88 (calculated from N-content determined by elemental analysis).
Experimental Part 205
EA: Calc.: C 38.92, H 4.90, N 20.88%; Found C 37.94, H 5.10, N 19.41%. IR (goldengate, [cm-1]): 3 435 (OH), 2 953 (C–H), 2 113 (N3), 1 733 (C–O), 1 223 (C–O–C). 13C NMR (dmso-d6): = 51.05 (C-6, AGU), 60.44–79.7 (C-2–C-5, AGU), 99.76– 104.10 (C-1, AGU). 1H NMR (dmso-d6): = 5.54–4.39 (AGU).
1,4-Dichloro-1,4-diphenyl-2,3-diazabutadiene257
Benzalazin (1,4-diphenyl-2,3-diazabutadiene) (5 g, 24 mmol, 1 eq.) was dissolved in glacial acetic acid (75 mL). The solution was stirred and chlorine gas was induced for two hours. The separated, flesh-coloured product was isolated by filtration and dried under vacuum. Additional product can be isolated from the filtrate by fractional crystallisation (4.68 g, 16.8 mmol, 70%).
1 3,4,5 H NMR (300.13 MHz, CDCl3): δ = 7.43 – 7.57 (m, 6 H, Ph CH ), 8.14 ppm (m, 4 H, Ph CH2,6). 13 2,3,5,6 4 C NMR (75.5 MHz, CDCl3): δ = 128.6 (s, Ph C ), 131.8 (s, Ph C ), 133.7 (s, Ph C1), 144.2 ppm (s, C=N).
Diethoxy(methyl)(vinyl)silane258, 259
Dichloro(methyl)(vinyl)silane (6.5 mL, 0.05 moL, 1 eq.) and degassed dichloromethane (7.5 ml) were added to a 100 ml Flask equipped with a reflux condenser and a dropping funnel under argon atmosphere. The solution was stirred and heated to 50 °C. A mixture of degassed ethanol (5.8 mL, 0.10 mol, 2 eq.) and degassed dichloromethane (15 mL) was added dropwise over a period of 20 min. Gaseous hydrochloride acid was formed in the process. The reaction mixture was stirred at 50 °C for 48 h. After distillation under argon atmosphere, diethoxy(methyl)(vinyl)silane was obtained as a colourless liquid (72%, 5.77 g, 0.036 mol).
Experimental Part 206
1 H NMR (300 MHz, C6D6): δ = 6.08 (m, 3H, CH=CH2), 3.81 (q, J = 7.0 Hz, 2H,
OCH2CH3), 1.45 (t, 3H, J = 7.0 Hz, OCH2CH3), 0.21 (s, 3H, Me).
Chapter 2:
General procedure for the nucleophilic degradation of P4
White phosphorus (0.5 g, 4.03 mmol, 1 eq.) was stirred with thf (20 mL) in a Schlenk flask. A certain amount of the nucleophile was added and the solution was stirred for two hours.
P4 + 2 lithium diisopropylamide (P1) A deep red solution was formed immediately. By adding n-hexane a red oil precipitated, which crystallised to red crystaline powder (Yield: 43 % [Li2P16(thf)8], NMR-spectrum: see chapter 2, the analytical data correspond to literature151).
P4 + 0.5 magnesium diisopropylamide (P1) A deep red solution was formed immediately. The 31P NMR spectrum shows the 2- 151 signals of P16 (analytical data correspond to Ref. ).
P4 + 2 magnesium diisopropylamide (A1) A deep red solution was formed immediately. By adding n-hexane a red powder was obtained, which was filtered off and washed with n-hexane before drying it in the vacuum. 31 1 2 3 P NMR (121.3 MHz, C6D6): δ = 102.29 ppm (J = 547.32, J = 270.77 Hz, J = 101.09 Hz), -207.99 ppm (td, J1 = 208.06 Hz, J2 = 101.09 Hz).
P4 + 2 magnesium diisopropylamide (A2) A deep red solution was formed immediately. By adding n-hexane a red powder was obtained, which was filtered off and washed with n-hexane before drying it in the vacuum. Experimental Part 207
31 1 2 P NMR (121.3 MHz, C6D6): δ = -0.27 ( J = 274.1 Hz, J = 208.3 Hz).
P4(s) + sodium tert-butoxide (P2)
NaOtBu (3.09 g, 32.2 mmol, 2 eq.) was dissolved in thf (15 mL). White phosphorus (0.5 g (16.1 mmol, 1 eq.) was added to the solution, which was stirred vigorously.
The solution became red immediately. After adding an excess of n-hexane, Na2P16 precipitations as a red oil (analytical data correspond to Ref.151).
Na3P7 from P4(solv.) + sodium tert.-butoxide (P5)
NaOtBu (3.09 g, 32.2 mmol, 2 eq.) was dissolved in thf (15 mL) and white phosphorus (0.5 g, 16.1 mmol, 1 eq.) was dissolved in thf (25 mL). The solutions were mixed together and stirred vigorously. The solution became orange immediately. After adding an excess of n-hexane an orange non-identified product precipitations. The precipitate was filtered off. Afterwards the precipitate was dried under vacuum and dissolved in thf. An excess of sodium metal was added. The t solution was not stirred. After 5 days pale yellow [(Na3P7)2(NaO Bu)6] (P5) crystallised in a yield of 60%.
31 P NMR (101.3 MHz, C6D6): = -121.1 (br.).
(tert.-butoxyphosphinediyl)bis(mesitylmethanone) (B1a)
NaOtBu (3.09 g, 32.2 mmol, 2 eq.) was dissolved in thf (15 mL) and white phosphorus (0.5 g, 16.1 mmol, 1 eq.) was dissolved in thf (25 mL). The solutions were put O together and stirred vigorously. The solution became orange P O O immediately. After adding an excess of n-hexane an orange non-identified product precipitated. The precipitate was filtered off. Afterwards it was dried under vacuum and dissolved in thf. The solution was cooled down to 0°C in an ice bath and it was stirred vigorously. Mesitoyl Experimental Part 208 chloride (5.87 g, 32.2 mmol, 2 eq.) was added dropwise. The colour became yellow immediately. After 20 minutes, the reaction was completed. The product was recrystallised from thf / n-hexane. For NMR-data: D. Stein, Dissertation.13
General procedure for [Na(PH2)(dme)]∞/[NaNH2] (red phosphorus)
In a thick-walled 100 mL Schlenk flask equipped with a teflon valve, sodium (1.73 g, 75 mmol, 3 eq.) and red phosphorus (0.78 g, 25 mmol, 1 eq.) were suspended in dme (20 mL). Under agitation using a glass-mantled magnetic stirring bar, liquid ammonia (20 mL) was condensed into the flask at -78°C and the mixture was warmed to 15°C and stirred for 90 min behind an explosive-proof shield. The initially blue solution turned yellow and the pressure in the flask rose to 7 - 8 bar. The ammonia was slowly evaporated and the dme removed in vacuo.
The crude product is a mixture of [Na(PH2)(solv)] and [NaNH2(solv)] which was suspended in dme.
General procedure for [Na(PH2)(dme)]∞/[NaNH2] (white phosphorus)
In a thick-walled 100 mL Schlenk flask equipped with a teflon valve, sodium (1.73 g, 75 mmol, 3 eq.) and white phosphorus (0.78 g, 25 mmol, 1 eq.) were suspended in dme (20 mL). Under agitation using a glass-mantled magnetic stirring bar, liquid ammonia (20 mL) were condensed into the flask at -100°C. Afterwards, the reaction mixture was slowly warmed up to 15°C. It was stirred for 90 min behind an explosive-proof shield. The initially blue solution turned yellow and the pressure in the flask rose to 7 - 8 bar. The ammonia was slowly evaporated and the dme removed in vacuo. The crude product is a mixture of
[Na(PH2)(solv)] and [NaNH2(solv)] which was suspended in dme.
[Na(PH2)(dme)]∞ (P8)
The pure [Na(PH2)(dme)]∞ can be obtained by filtration of the dme suspension of
[Na(PH2)(DME)]∞ / [NaNH2] and evaporation of the filtrate (2.8 g, 20 mmol, 78 %).
The residue in the filter is NaNH2. Experimental Part 209
M.p. 62 °C. 1 - H NMR (250.1 MHz, [D8]thf): δ = 1.37 (d, 2 H, J = 147.1 Hz, PH2 ). 31 1 - P{ H}-NMR (101.2 MHz, [D8]thf): δ = -288.4 (s, PH2 ). 31 - P NMR (101.2 MHz, [D8]thf): δ = -288.4 (t, J = 145.3 Hz, PH2 ).
t [Na12(O Bu)12PH2][Na(dme)3] (P7)
t a) [Na(PH2)(dme)]∞/[NaNH2] was suspended in dme. After addition of BuOH (3.71 g, 50 mmol, 2 eq.) within 5 min at -78°C the flask was slowly warmed up to 20°C. At -30°C colourless crystals of P7 were formed from the solution after two days.
t b) 0.25 g [Na13(O Bu)12PH2] (P6) were recrystallised in dme (1 mL). Colourless crystals were formed from the solution after 2 days. In the NMR-Spectrum the reaction is quantitative.
M.p. 109 °C. 1 1 - H NMR (300.13 MHz, [D8]-Toluene): δ = –2.24 (d, 2 H, JP,H = 145.0 Hz, PH2 ),
1.47 (s(br.), 108 H, OC(CH3)3), 3.31 (s, 6 H, O-CH3), 3.47 (s, 4 H, CH2). 31 1 - P NMR (121.49 MHz, [D8]-Toluene): δ = –307.7 (t, JP,H = 145.0 Hz, PH2 ). 13 C NMR (75.47 MHz, [D8]-Toluene): δ = 36.3 (s, OC(CH3)3), 66.1 (s, OC(CH3)3).
t [Na13(O Bu)12PH2] (P6)
t a) NaO Bu (2.13 g, 22 mmol, 12 eq.) and [Na(PH2)(DME)]∞ (0.27 g, 1.8 mmol, 1 eq.) were stirred for 10 min at 80°C in toluene (10 mL). After filtration over celite, the solution was cooled down to -30°C. In the NMR-spectrum, the reaction is quantitative. Large colourless crystals were formed by cooling down the solution (1.6 g, 1.3 mmol, 71.5 %). b) [Na(PH2)(DME)]∞/[NaNH2] was suspended in 20 mL toluene. After addition of tBuOH (3.71 g, 50 mmol, 2 eq) within 5 min at -78°C the flask was slowly warmed up to 20°C. At -30°C colourless crystals were formed after two days. Experimental Part 210
M.p.: 112 °C. 1 H NMR (300.13 MHz, [D8]-Toluene): δ = 1.48 (s(br.), 108 H, OC(CH3)3), –2.20 (d, 1 - 2 H, JP,H = 142.3 Hz, PH2 ). 31 1 - P NMR (121.49 MHz, [D8]-Toluene): δ = –292.3 (t, JP,H = 142.3 Hz, PH2 ). 13 C NMR (75.47 MHz, [D8]-Toluene): δ = 36.5 (s, OC(CH3)3), 66.1 (s, OC(CH3)3).
[D9]-sodium tert-butoxide
[D9]tBuOH (1 mL) was stirred with an excess of sodium in a Schlenk flask under argon. After the complete reaction of [D9]-tBuOH with sodium, toluene (3 mL) was added to dissolve the sodium tert.butoxide. The sodium was filtered off and the solution was evaporated at room temperature in vacuo. The pure product was obtained in an almost quantitative yield.
t [Na12(O Bu)10Se] (A5)
Na2Se (2.75 g, 22 mmol, 12 eq.) and [Na(PH2)(DME)]∞ (0.27 g, 1.8 mmol, 1 eq.) were stirred for 90 min at 100°C in toluene (10 mL). After filtration over celite, the solution was cooled down to room temperature. Large colourless crystals were formed by cooling down the solution (1.8 g, 1.4 mmol, 79.4 %).
Sodium-3,5-diphenyl-1,2,4-diazaphospholid (P9)
t To a solution of [Na13(O Bu)12PH2] (5 mL, 0.180 g, 1.49 mmol, 1 eq.) in thf (5 mL) a solution of 1,4-dichloro-1,4-diphenyl-2,3-diazabutadien (0.397 g, 1.43 mmol, 0.96 eq.) in thf (1 mL) was added. After stirring for 1 h the solvent was evaporated and the residue was suspended in n-hexane (10 mL). After filtration the crude product was obtained as a slightly yellow powder. Colourless, air-sensitive single crystals of [Na(dme)[P(CPh)2N2]∞ (P9) were obtained by storing a dme solution layered with n-hexane for several days at -18 °C (0.34 g, 1.1 mmol, 66%).
M.p.: 138°C. Experimental Part 211
1 8 H NMR (250.13 MHz, d -thf): δ = 3.19 (s, 6 H, DME, OCH3), 3.36 (s, 4 H, DME, 4 3,5 2,6 OCH2), 6.99 (t, 2 H, Ph CH ), 7.14 (t, 4 H, Ph CH ), 7.91 ppm (d, 4 H, Ph CH ). 13 8 C NMR (62.89 MHz, d -thf): δ = 58.0 (s, DME, OCH3), 71.7 (s, DME, OCH2), 5 4 3 2,6 125.1 (d, JC,P = 2.0 Hz, Ph C ), 125.7 (d, JC,P = 10.0 Hz, Ph C ), 127.6 (s, Ph 3,5 2 1 1 C ), 140.8 (d, JC,P = 23.3 Hz, Ph C ), 178.8 ppm (d, JC,P = 45.2 Hz, PCN). 31P{1H}-NMR (101.25 MHz, d8-thf): δ = 66.5 ppm (s).
General procedure for the synthesis of arylphosphanes starting from t NaPH2 x 2NaO Bu
There are two different ways to synthesise arylphosphanes starting from aryl t fluorides, aryl triflates, aryl tosylates and NaPH2 x 2NaO Bu. The first procedure (a) describes the synthesis with very reactive, electron poor aryl fluorides, especially for the synthesis of primary and secondary phosphanes. The second procedure (b) describes the synthesis using less reactive aryl fluorides for the preparation of primary and secondary phosphanes and in general the synthesis of tertiary phosphanes.
t a) NaPH2 x 2 NaO Bu (300 mg, 1.20 mmol, 1 eq.) was dissolved in toluene (5 mL). One or two equivalents of aryl fluoride for the synthesis of the corresponding primary or secondary arylphosphane were added dropwise under vigorous stirring. After the aryl fluoride is added three drops of thf were added with a syringe. Depending on the reactivity of the aryl fluoride, the reaction takes place immediately or during two hours. To quench the reaction degassed ammonium chloride solution (5 %) was added. The phosphane was extracted with diethylether. The organic ether phase was washed with brine and dried with sodium sulfate. After evaporation of the solvent the pure product remains.
t b) NaPH2 x 2 NaO Bu (300 mg, 1.20 mmol, 1 eq.) was dissolved in thf (5 mL). One, two or three equivalent aryl fluoride for the synthesis of the corresponding primary, secondary or tertiary phenylphosphane was added dropwise under vigorous stirring. After the aryl fluoride is added completely the solution is stirred over night. Experimental Part 212
To quench the reaction degassed ammonium chloride solution (5 %) was added. The phosphane was extracted with diethylether. The organic ether phase was washed with brine and dried with sodium sulfate. After evaporation of the solvent, the pure product is obtained.
t Table 9: Analytical data for phosphanes starting from NaPH2 x 2 NaO Bu.
Method 31P NMR Phosphane EI-MS Yield/ % (C6D6)/ppm
O -71.4 PH A J = 57.7 466.01 (M+) 90 Hz
O
CF3
+ F3C P B -5.8 466.05 (M ) 50
CF3
O S O
B -6.3 496.20+) (M 90 P O O S S O O
SO3H
A -124.1 189.99+) (M 70
PH2 Experimental Part 213
P B 3.2 412.14 (M+) 70
HO O O OH - B 40 37.4 P H
CO2H
B -5.2 60 P
HO2C CO2H
SiMe3
B -6.0 478.12+) (M 50 P
Me3Si SiMe3
tris(4-nitrophenyl)phosphane (P19)
t O2N NO2 NaPH2 x 2 NaO Bu (522 mg, 2.10 mmol, 1 eq.) was dissolved in thf (3 mL) in a 50 mL Schlenk flask. Under P cooling with ice water p-fluoronitrobenzol (888 mg (6.30 mmol, 3 eq.), which was dissolved in thf (2 mL) was added dropwise to the NaPH x 2NaOtBu solution NO 2 2 via a syringe. The reaction mixture was then stirred for 2 h at room temperature. Afterwards, the reaction was quenched by addition of 5 mL degassed and deionized H2O. The product was extracted with diethylether (15 mL). After removal of the aqueous phase, the organic phase was washed twice with an aqueous Experimental Part 214
degassed ammonium chloride solution (5 %) (10 mL) and dried over NaSO4. The dried organic phase was filtered and the filtrate concentrated under high vacuum to yield a pale yellow oil (Yield: 70%, 1.47 mmol, 583.7 mg).
31 P NMR (101.3 MHz, C6D6): δ = -5.66 (br.) 1 2 3 H NMR (250 MHz, C6D6): δ = 7.75 (m, 2 H, C H), 8.28 (m, 2 H, C H). 13 3 2 C NMR (62.9 MHz, C6D6): δ = 121.3(PhC ), 125.9 (PhC ) (d, J = 10.0 Hz), 143.6 (PhC1), 148.4 (PhC4). IR (goldengate, [cm-1]): 791 (s), 1011 (s), 1091 (s), 1258 (m, N=O st.), 1344 (m,
NO2 st. sy.), 1496 (m, NO2 st as), 1592 (m), 2159 (w), 2962 (w). MS (EI, m/z): 397.05 (M+).
(4-phenoxyphenyl)phosphane (P11)
t For the synthesis of (4-phenoxyphenyl)phosphane, NaPH2 x 2 NaO Bu PH2 (328 mg, 1.32 mmol, 1 eq.) was dissolved in thf (5 mL) in a 50 mL Schlenk flask in the glovebox. Under cooling with ice water, 1-fluoro-4-
O phenoxybenzene (248 mg, 1.32 mmol, 1 eq.) was added dropwise to t the NaPH2 x 2 NaO Bu solution via a syringe through a septum. The reaction mixture was stirred for 4 h at room temperature and subsequently the reaction was then quenched by addition of 10 mL degassed brine. The product was extracted with diethyl ether (8 mL) and the aqueous phase was removed. Further, the organic phase was washed twice with degassed aqueous ammonium chloride solution (5 %) (10 mL) and dried over NaSO4. The organic phase was filtered off and the filtrate concentrated under high vacuum to yield a colourless oil, transparent liquid (Yield: 61%, 0.79 mmol, 159.6 mg).
31 1 3 P NMR (101.3 MHz, C6D6): δ = -122.3 (tt, J = 188 Hz, J = 8.01). 1 4 H NMR (250 MHz, C6D6): δ = 6.69 (m, 1 H, Ph'C H), 6.78 (d, J = 6.67 Hz, 4 H, O- C-CH), 6.97 (t, 3J = 8.1 Hz, 2 H, Ph'C3H), 7.16 (d, 3J = 8.10 Hz, 2 H PhC2H), 4.3 (d,
J = 204.1 Hz, PH2). Experimental Part 215
13 3 2 1 C NMR (62.9 MHz, C6D6): δ = 116.7 (PhC ), 118.4 (Ph'C ), 120.6 (d, J = 12.58 Hz, PhC1), 123.1 (Ph'C3), 125.4 (Ph'C4), 129.8 (PhC2), 157.3 (PhC4 + Ph'C1). EA: [C]: 71.24 % (calculated: 71.28 %), [H]: 5.44 % (calculated: 5.48 %) IR (goldengate, [cm-1]): 690 (s), 759 (m), 839 (m), 1208 (s, C-O-C), 1248 (m), 1485(s), 1501 (s), 1589 (m), 1871 (w), 2417 (w, PH), 3042 (w, CH). MS (EI, m/z): 202.05 (M+). tris(4-vinylphenyl)phosphine (P20)
t NaPH2 x 2 NaO Bu (298 mg, 1.20 mmol, 1 eq.) was
P dissolved in thf (5 mL) in a 50 mL Schlenk flask in the glovebox. Under cooling with ice water, 1-fluoro-4- vinylbenzene (439 mg, 3.60 mmol, 3 eq.) was added t dropwise to the NaPH2 x 2 NaO Bu solution via a syringe through a septum. The reaction mixture was stirred for 3 h at room temperature. The reaction was quenched by adding degassed brine (15 mL). The product was extracted with diethyl ether (15 mL) and the aqueous phase was removed. The organic phase was then washed with degassed, aqueous ammonium chloride solution (5 %) (15 mL) and dried over sodium sulfate. The dried organic phase was filtered and the filtrate concentrated under high vacuum to yield a viscous colourless liquid (Yield: 78 %, 0.94 mmol, 318.3 mg).
31P NMR (101.3 MHz, C6D6): δ = -7.8 (J = 6.7 Hz). 1 H NMR (250 MHz, C6D6): δ = 6.91-7.04 (br., 12 H, ArH), 6.63 (br., 3 H, =CH),
5.18-5.38 (m, 6 H, =CH2). 13 3 1 C NMR (62.9 MHz, C6D6): δ = 115.3 (=CH2), 129.1 (PhC ), 129.6 (PhC ), 135.2 (=CH), 136.3 (PhC2), 138.4 (PhC4). IR (goldengate, [cm-1]): 791 (s), 1014 (s), 1089 (br.), 1220 (s), 1507 (s), 1601 (m), 2925 (w). Experimental Part 216
(S)-2,2'-diphosphino-1,1'-binaphthyl (P21)
t NaPH2 x 2 NaO Bu (500 mg, 2.00 mmol, 2 eq.) was dissolved in toluene (5 mL). A solution (S)-binaphthyl-2,2'-ditosylat (595 mg, PH2 PH2 1.00 mmol, 1 eq.) in toluene (5 mL) was added dropwise under vigorous stirring. After the aryl fluoride is added three drops of thf were added with a syringe. The colourless solution becomes pale yellow within 5 minutes. After 2 hours the reaction was finished. To quench the reaction degassed ammonium chloride solution (5 %) was added. The phosphane was extracted with diethylether. The organic ether phase was washed with brine and dried with sodium sulfate. After evaporation of the solvent, the pure product remains as a pale yellow oil (Yield: 285 mg, 0.9 mmol, 90%). It can be purified by recrystallisation from thf/ hexane (20:80). A pale yellow powder can be obtained in this way.
31P NMR (101.3 MHz, C6D6): δ = -136.4 (t, J = 193 Hz). 1 8,8' H NMR (250 MHz, C6D6): δ = 7.97 (d, J = 9.2 Hz, 2 H, ArC H), 7.85 (m, 4 H, ArC4,4',5,5'H), 7.46 (m, 2 H, ArC7,7'H), 7.33–7.19 (m, 2 H, ArC6,6',7,7'H), 7.10 (d, J = 3 8.2 Hz, 2 H, ArC H), 4.22 (d, J = 201 Hz, PH2, 4 H). 13 1 10 9 5 C NMR (62.9 MHz, C6D6): δ = 138.0 (C ), 134.0 (C ), 131.1 (C ), 129.8 (C ), 129.4 (C8), 128.2 (C4), 124.6 (C3), 124.2 (d, J = 11.4 Hz, C2P), 123.8 (C4), 121.7 (C5). MS (EI, m/z): 318.24 (M+). tris(4-iodophenyl)phosphine (P18)
t NaPH2 x 2 NaO Bu (522 mg, 2.10 mmol, 1 eq.) was dissolved I in thf (5 mL) in a 50 mL Schlenk flask. Under cooling with ice water 1-fluoro-4-iodobenzene (1.39 g, 6.30 mmol, 3 eq.),
P which was dissolved in thf (5 mL) was added dropwise to the t NaPH2 x 2NaO Bu solution via a syringe. The reaction I I Experimental Part 217 mixture was then stirred for 2 h at room temperature. Afterwards, the reaction was quenched by addition of degassed and deionised water (5 mL). The product was extracted with diethylether (25 mL). After removal of the aqueous phase, the organic phase was washed twice with an aqueous degassed ammonium chloride solution (5 %) (10 mL) and dried over NaSO4. The dried organic phase was filtered and the filtrate concentrated under high vacuum to yield a pale yellow oil (Yield: 80%, 1.68 mmol, 1.08 g).
31 P NMR (101.3 MHz, C6D6): δ = -132.3 (J =195 Hz). 1 2 H NMR (250 MHz, C6D6): δ = 7.34 (d, J = 8.3 Hz, 6 H, C H), 8.16 (d, J = 8.3 Hz, 6 H, C3H). 13 3 1 C NMR (62.9 MHz, C6D6): δ = 124.1(PhC ), 125.2 (PhC P) (d, J = 9.8 Hz), 138.6 (PhC2), 143.4 (PhC4). MS (EI, m/z): 638.78 (M+).
(4-bromophenyl)phosphine (P13)
t Br NaPH2 x 2 NaO Bu (500 mg (2.00 mmol, 1 eq.) was dissolved in toluene (5 mL). A solution of 1-bromo-4-fluorobenzene (350 mg, 2.00 mmol, 1 eq.) in toluene (5 mL) was added dropwise under vigorous stirring. After the aryl PH2 fluoride was added, three drops of thf were added with a syringe. The colourless solution becomes pale yellow within 5 minutes. After 2 hours the reaction was finished. To quench the reaction degassed ammonium chloride solution (5 %) was added. The phosphane was extracted with diethylether. The organic ether phase was washed with brine and dried with sodium sulfate. After evaporation of the solvent, the pure product remains as a pale yellow oil (Yield: 285 mg, 0.9 mmol, 90%).
31 P NMR (101.3 MHz, C6D6): δ = -122.9 (t, J = 187 Hz) 1 3 H NMR (250 MHz, C6D6): δ = 8.34 (d, J = 11.3 Hz, 6 H, C H), 7.98 (d, J =11.3 Hz, 2 6 H, C H), 4.53 (d, J = 196.3 Hz, PH2). Experimental Part 218
13 3 1 C NMR (62.9 MHz, C6D6): δ = 124.7 (PhC ), 125.3 (PhC P) (d, J = 10.2 Hz), 135.6 (PhC2), 144.5 (PhC4). MS (EI, m/z): 188.93 (M+).
(4-vinylphenyl)phosphine (P14)
t PH2 NaPH2 x 2 NaO Bu (500 mg, 2.00 mmol, 1 eq.) was dissolved in toluene (5 mL). A solution of 1-vinyl-4-fluorobenzene in toluene (5 mL) was added dropwise under vigorous stirring. After the aryl fluoride is added three drops of thf were added with a syringe. The colourless solution becomes pale yellow within 5 minutes. After 2 hours, the reaction was finished. To quench the reaction degassed ammonium chloride solution (5 %) was added. The phosphane was extracted with diethylether. The organic ether phase was washed with brine and dried with sodium sulfate. After evaporation of the solvent, the pure product remains as a pale yellow oil (Yield: 304 mg, 0.9 mmol, 90%).
31 P NMR (101.3 MHz, C6D6): δ = -115 (d, J = 161 Hz). 1 3 4 H NMR (250 MHz, C6D6): δ = 7.34 (m, 8 H, C H + C H), 6.44 (br., 2 H, =CH),
4.98-5.12 (br., 4 H, =CH2), 4.53 (d, 2 H, J = 196.3 Hz, PH2). 13 2 1 C NMR (62.9 MHz, C6D6): δ = 114.3 (=CH2), 126.7 (PhC ), 127.3 (PhC P), 129.6 (PhC3), 136.3 (=CH), 138.5 (PhC4). EI-MS: 338.11 (M+). Experimental Part 219
Chapter 3
Sodium bis(mesitoyl)phosphide (P4)
In a 100 mL thick-walled Schlenk flask equipped with a teflon screw cap, sodium (1.73 g, 0.075 mmol, 3 eq.) and red phosphorus (0.78 g, 0.025 mmol, 1 eq.) were put together under inert conditions. A glass covered magnetic stirrer was added and 20 mL of ammonia were condensed into the flask, by cooling with dry ice/ acetone to -78°C. Subsequently dme (20 mL) was added and the flask was closed and warmed up to room temperature (explosive shield!). After 90 min, stirring at room temperature a change in colour from blue to dark yellow was observed and after another 30 min, the colour became intensively yellow. The pressure in the reaction vessel was 7-8 bar. The reaction mixture was cooled down to -40°C. The Schlenk flask, which had now a pressure of 1 bar, was opened and tert-butanol (3.71 g, 0.05 mol, 2 eq.) was added. The reaction mixture was warmed up to room temperature over a period of two hours. Finally, the solvent was completely removed in vacuo at room temperature. The remaining oil was dissolved in dme (40 mL). Mesitoyl chloride (9.15 g, 0.05 mol, 2 eq.) was added dropwise.
a) Isolation of the product under dry conditions: The reaction mixture was stirred for one hour at room temperature, the precipitate of sodium chloride was removed by filtration and the solvent was evaporated in vacuo. The pure microcrystalline product can be obtained by dissolving the sodium bis(mesitoyl)phosphide in dme and precipitation with n-hexane (Yield: 5.89 g, 67.7 %). b) Working up with degassed water: The reaction mixture was mixed with 100 mL degassed, distilled water. After stirring the solution until the sodium chloride was completely dissolved, the reaction mixture was extracted three times with 50 mL of toluene. After removing the toluene in vacuo, the pure product remains. It can contain small amounts of water, which can be Experimental Part 220
completely removed by azeotropic distillation with toluene. The product is dissolved in toluene and the solvent is removed in vacuo afterwards again. This procedure has to be repeated two or three times. The yield is the same as for procedure a).
MP.: 208°C (Decomposition). 1 H NMR (250.13 MHz, C6D6): = 6.60 (s, 4 H, Mes CH), 2.94 (s, 4 H, dme CH2),
2.87 (s, 6 H, dme CH3), 2.61 (s, 12 H, Mes o-CH3), 2.08 ppm (s, 6 H, Mes p-CH3). 13 1 2 C NMR (75.47 MHz, C6D6): = 236.2 (d, JCP = 94.0 Hz, CO), 145.5 (d, JCP = 1 5 4 3 38.3 Hz, Mes C ), 136.3 (d, JCP = 0.9 Hz, Mes C ), 133.9 (d, JCP = 2.7 Hz, Mes 2,6 3,5 C ), 128.3 (s, Mes C ), 71.0 (s, dme CH2), 58.4 (s, dme CH3), 21.1 (s, Mes p- 4 CH3), 20.1 ppm (d, JCP = 2.5 Hz, Mes o-CH3). 31P NMR (101.25 MHz): = 84.1 ppm (br.). IR (goldengate [cm-1]): 2916 (m, CH str.), 1610 (m), 1559 (s, C=O str.), 1521 (s), 1472 (s), 1456 (s), 1417 (s), 1375 (w), 1296 (w), 1260 (w), 1205 (s) 1139 (s), 1112 (s), 1028 (m), 983 (w), 956 (m), 883 (ss), 843 (ss), 743 (m), 719 (s), 679 (m), 629 (m), 586 (w). UV/vis (thf): 243 nm (shoulder), 285 nm (shoulder), 370 nm (max.). sodium bis(2,6-dimethoxybenzoyl)phosphide (P31)
t NaPH2 x 2 NaO Bu (0.846 g, 3.41 mmol, 1 eq.) was O O dissolved in dme (6 mL) and cooled in an ice water bath to P 0°C. 2,6-dimethoxybenzoyl chloride (1.37 g, 6.82 mmol, OOO O2 eq.) dissolved in dme (8 mL) was added dropwise to the Na solution. After 1 hour of stirring at room temperature the solvent was removed in vacuo to yield a yellow powder of sodium bis(2,6- dimethoxy-benzoyl)phosphide (Yield: 87 %, 1.14 g, 2.97 mmol).
1 8 3 H NMR (300.1 MHz, d -thf): δ = 3.38 (s, 12 H, O-CH3), 6.29 (d, 4 H, Ar-H, J = 8.4 Hz), 7.06 (t, 2 H, Ar-H, 3J = 8.4 Hz). Experimental Part 221
31P{1H}-NMR (121.5 MHz, d8-thf): δ = 91.0 (s). 13C NMR (75.5 MHz, d8-thf): δ = 55.2 (O-Me), 103.7 (Ar-C3), 103.8 (Ar-C1), 129.6 4 2 (Ar-C ), 157.2 (Ar-C ), 212.3 (C=Oacyl). sodium bis(2,6-bis(trifluoromethyl)benzoyl)phosphide (P32)
t 1.0 g (4.03 mmol, 1 eq.) NaPH2 x 2 NaO Bu were dissolved CF3 F3C in 15 mL thf. The solution was cooled down to -78°C in a P dry ice/ acetone bath. 2.23 g (8.06 mmol, 2 eq.) 2,6- CF O OCF 3 3 (di(trifluoromethyl))-benzoyl chloride were added dropwise Na and the reaction mixture was stirred over night at room temperature. The thf was removed in vacuo at room temperature and the product was dissolved in 10 mL toluene. After the filtration of the sodium chloride an excess of n-hexane was addedin order to precipitate the pure product. After filtration the product was dried in high vacuo (Yield: 67 %, 2.70 mmol, 1.44 g).
31P NMR (101.3 MHz, C6D6): δ = 90.8. sodium bis(perfluorooctanoyl)phosphide (P33)
Perfluorooctanoyl chloride (2.95 g, 6.83 mmol, 2 eq.) was C7F15 P C7F15 dissolved in thf (3 mL) and cooled down to -78°C in an O O t Na acetone / dry ice bath. NaPH2 x 2 NaO Bu (2.15 g, 3.41 mmol, 1 eq.) was suspended in thf (5 mL) and added dropwise to the perfluorooctanoyl chloride solution. After two hours, the reaction mixture had warmed up to room temperature and the reaction was completed. 13C NMR could not be measured, due to the poor solubility of the product.
31 P NMR (121.5 MHz, C6D6): δ = 83.0 (br). 19 F-NMR (188.3 MHz, C6D6): δ = -126.14 (m, 4 F), -122.70 (m, 4 F), -122.37 (m, 4 F), -121.93 (m, 4 F), -121.40 (m, 4 F), -118.08 (tt, 4 F, 3J = 12.1 Hz, 4J = 3.0 Hz), 3 4 -80.96 (tt, 6 F, CF3, J = 10.0 Hz, J = 2.3 Hz). Experimental Part 222 bis(2,6-dimethoxybenzoyl)methylphosphane (MethylMeOBAP) (B4a)
Sodium bis(2,6-dimethoxybenzoyl)phosphide (100 mg, 0.26
O O mmol, 1 eq.) was dissolved in dme (5 mL). To this solution CH3 P methyl triflate (0.03 mL, 0.26 mmol, 1 eq.) was added at 0°C.
OOO OAfter stirring the reaction mixture for 2 hours, the solvent was removed in vacuo. The pure product was obtained in a quantitative yield.
1 H NMR (250.1 MHz, C6D6): δ = 1.72 (br, 3 H, P-CH3), 3.38 (s, 12 H, O-CH3), 6.30 (d, 4 H, Ar-H, 3J = 8.4 Hz), 7.10 (t, 2 H, Ar-H, J = 8.4 Hz). 31 1 P{ H}-NMR (121.5 MHz, C6D6): δ = 40.5 (s). 13 3 C NMR (62.9 MHz, C6D6): δ = 31.8 (P-Me), 55.3 (O-Me), 103.8 (Ar-C ), 104.0 1 4 2 (Ar-C ), 129.8 (Ar-C ), 157.4 (Ar-C ), 210.7 (C=Oacyl). bis(2,6-dimethoxybenzoyl)methylphosphane oxide (MethylMeOBAPO) (B4)
To a solution of Methyl-MeOBAP (98 mg, 0.26 mmol, 1eq.) O hydrogen peroxide (30 %) (0.03 mL, 0.26 mmol, 1 eq.) was O O O added slowly. The solution was stirred for 30 minutes. Then P O the solvent was removed in vacuo at room temperature and H3C O O the MethylMeOBAPO was again dissolved in ethanol. The solution was filtrated in order to get rid of the sodium bromide. The filtrate was dried by vacuum (Yield: 78 %, 88 mg, 0.20 mmol).
1 H NMR (300.1 MHz, C6D6): δ = 1.72 (br, 3H, P-CH3), 3.38 (s, 12H, O-CH3), 6.30 (d, 4H, Ar-H, 3J = 7.5 Hz), 7.10 (t, 2H, Ar-H, 3J = 7.5 Hz). 31 1 P{ H}-NMR (101.3 MHz, C6D6): δ = 25.2 (s). 13 3 C NMR (75.5 MHz, C6D6): δ = 30.3 (P-Me), 55.8 (O-Me), 104.1 (Ar-C ), 104.4 1 4 2 (Ar-C ), 131.0 (Ar-C ), 157.1 (Ar-C ), 204.4 (C=Oacyl). Experimental Part 223
1,3-di(bis(mesitoyl)phosphane oxide)propane (B5)
Sodium bis(mesitoyl)phosphide (P4) (1.00 g, O 2.88 mmol, 1 eq.) was dissolved in a mixture O O P P of 5 mL thf and 5 mL toluene. Afterwards 1,3- O O O dibromopropane (0.30 g, 1.44 mmol, 0.5 eq.) was added. Then the reaction mixture was stirred for 24 hours at 50°C. A white precipitate of sodium bromide was formed. After removing the sodium bromide by filtration, the solvent was evaporated in vacuo. The remaining yellow oil was dissolved in diethyl ether and washed with an aqueous and degassed ammonium chloride solution (5%) and brine. After drying the etheral phase with sodium sulfate, it was evaporated in vacuo at room temperature and dried in high vacuo for 4 hours. The remaining pale yellow oil was dissolved in 5 mL ethanol and 0.326 mL (2.88 mmol, 1 eq.) hydrogen peroxide were added and the solution was stirred for 3 hours. The ethanol was removed to yield the pure product as a yellow oil (Yield: 0.749 g, 1.79 mmol, 62%).
1 H NMR (250.1 MHz, C6D6): = 1.66 (quint., J = 6.53 Hz, CH2 ), 2.08 (t, J = 6.53,
4 H, CH2), 2.22 (s, 12 H, p-MesCH3), 2.36 (s, 24 H, o-MesCH3), 6.69 (s, 4 H, MesCH). 13 C NMR (62.9 MHz, C6D6): = 19.7 (p-MesCH3), 27.6 (CH2), 31.6 (o-MesCH3), 2 3 1 4 35.8 (CH2), 129.7 (MesC ), 131.3 (MesC ), 134.8 (MesC ), 143.5 (MesC ), 219.8 (d, J = 88.3 Hz, CO). 31 P NMR (121.5 MHz, C6D6): = 25.2 (t, J = 11.3 Hz).
Experimental Part 224 cyclohexylphosphorylbis(mesitylmethanone) (B6)
Sodium bis(mesitoyl)phosphide (P4) (250 mg, 0.72 mmol, 1 eq.) was dissolved in toluene (5 mL). Cyclohexyl iodide (122.4 mg, 0.72 mmol, 1 eq.) was added and the solution was stirred for 24 h. The solution was found to contain the O 31 O P colourless BAP ( P NMR (C6D6) 101.3 MHz: 74.5 ppm). The white precipitate of sodium iodide was filtered off over O celite, hydrogen peroxide (10%) (0.244 mL, 0.72 mol, 1 eq.) was added and the solution was stirred over night. Diethyl ether (5 mL) was added and the solution was washed with sodium hydrogen carbonate solution (2%) and brine. After drying with sodium sulfate, the solvent was evaporated. A pale yellow product was obtained (Yield: 62 %, 0.45 mmol, 189 mg).
31 P NMR: (121.5 MHz, C6D6): = 32.2. isopropylphosphorylbis(mesitylmethanone) (B7)
Sodium bis(mesitoyl)phosphide (P4) (250 mg,
O 0.72 mmol, 1 eq.) was dissolved in toluene (5 mL). 2- O iodopropane (122.4 mg, 0.72 mmol, 1 eq.) was added P O and the solution was stirred over night. The solution 31 was found to contain the colourless BAP ( P NMR (C6D6) 101.3 MHz: δ = 76.5). The white precipitate of sodium iodide was filtered over celite, hydrogen peroxide (10%) (0.244 mL, 0.72 mol, 1 eq.) was added and the solution was stirred over night. Diethyl ether (5 mL) was added and the solution was washed with sodium hydrogencarbonate solution (2%) and brine. After drying with sodium sulfate, the solvent was evaporated. A pale yellow product was obtained (Yield: 57 %, 0.41 mmol, 150 mg).
31 P NMR (121.5 MHz, C6D6): = 30.8. Experimental Part 225
Allylphosphorylbis(mesitylmethanone) (B8)
Sodium bis(mesitoyl)phosphide (P4) (250 mg, O O 0.72 mmol, 1 eq.) was dissolved in toluene (5 mL). Allyl P bromide (87.1 mg (0.72 mmol, 1 eq.) was added and the O solution was stirred for 12 hours at room temperature. The white precipitate of sodium bromide was removed by filtration and the solvent was evaporated under reduced pressure at room temperature. The remaining 31 phosphane ( P NMR (C6D6) 101.3 MHz: δ = 45.7) was a pale yellow oil. It was dissolved in toluene (10 mL) and hydrogen peroxide (10%) (0.20 mL, 0.72 mmol, 1 eq.) was added. The oxidation was finished sfter stirring for 12 hours at 40°C. Diethyl ether (50 mL) were added and the solution was washed twice with a sodium hydrogen carbonate solution (2%), once with brine and finally with distilled water. After drying the diethyl ether solution with sodium sulfate and filtration, the solution was concentrated in vacuo. A yellow oil was obtained (Yield: 209 mg, 0.55 mmol, 76%).
1 H NMR (300.1 MHz, C6D6): = 2.08 (s, 6 H, p-MesCH3), 2.43 (s, 12 H, o-
MesCH3), 3.10 (d, J = 7.5, 2 H, P-CH2), 5.13 (m, 1 H, =CH), 5.87 (m, 2 H, =CH2), 6.63 (s, 2 H, MesCH). 13 C NMR (62.9 MHz, C6D6): = 20.0 (p-MesCH3), 22.4 (o-MesCH3), 8.4 (CH2), 2 3 1 125.7 (=CH), 128.9 (=CH2), 129.4 (MesC ), 138.7(MesC ), 139.8 (MesC ), 142.3 (MesC4), 215.8 (d, J = 56.61 Hz, CO). 31 P NMR (121.5 MHz, C6D6): = 23.7 (t, J = 9.3 Hz).
Experimental Part 226
(5-Norbornen-2-butyl)-4-bis(mesitoyl)phosphane oxide (B9)
Sodium bis(mesitoyl)phosphide (P4) (1.12 g, 3.21 mmol, O O 1 eq.) and (4-bromobutyl)bicyclo[2.2.1]hept-2-ene4- P O bromobutyl (0,79 g, 3.45 mmol, 1.07 eq.) were dissolved in dme (20 mL) and stirred for two days. Subsequnetly, the solvent was evaporated and the yellow residue was dissolved in toluene (20 mL). Hydrogen peroxide solution (10%) (3 mL) was added and the mixture was stirred for 24 hours at 40°C. After adding diethylether, the solution was washed both with sodium hydrogencarbonate solution (2%) and brine. The organic layer was dried with sodium sulfate and after evaporating the solvent the pure product was obtained as a yellow oil (Yield: 1.142 g, 2.33 mmol, 75%).
1 4 H NMR (300 MHz, CDCl3): = 6.86 (s, 4 H, Mes-CH), 6.10 (m, 1 H, CH ), 5,91 (m, 1 H, CH5), 2.73 (m, 1 H, CH3), 2.73 (m, 1 H, CH6), 1.98 (m, 1 H, CH1), 2.27 (s, 11 1 2 18 H, Mes-CH3), 2.16 (m, 2 H, CH2 ), 1.91 (m, 1 H, CH ), 1.81 (m, 1 H, CH exo), 10 7’ 9 7’’ 1.58 (m, 2 H, CH2 ), 1,36 (m, 1 H, CH ), 1,36 (m, 2 H, CH2 ), 1.04 (m, 1 H, CH ), 8 2 1.04 (m, 2 H, CH2 ), 0.46 ppm (m, 1 H, CH endo). 13 4 C NMR (75 MHz, CDCl3): = 216.4 (d, J = 53.2 Hz, Mes-CO), 141.1 (s, Mes C ), 137.0 (s, C4), 136.4 (s, Mes C1), 135.6 (s, Mes C2,6), 132.2 (s, C5), 129.2 (s, Mes C3,5), 49.5 (s, C7), 45.3 (s, C6), 42.5 (s, C3), 38.4 (s, C1), 34,1 (s, C8), 32.6 (s, C2), 3 9 1 11 2 10 30.1 (d, JCP = 13.4 Hz, C ), 26.4 (d, J = 53.2 Hz, C ), 21.4 (d, JCP = 4.6 Hz, C ),
21.2 (s, Mes p-CH3), 19.8 ppm (s, Mes o-CH3). 31 1 P{ H}-NMR (101 MHz, CDCl3): = 28.1 ppm. IR (goldengate, [cm-1]): 2931 (m, C-H str.), 2864 (m, C-H str.), 1673 (s, C=O str.), 1608 (s), 1448 (m), 1379 (w), 1337 (w), 1296 (w), 1213 (s), 1195 (s), 1147 (m), 1035 (m), 959 (w), 891 (m), 850 (s), 757 (m), 716 (s), 619 (m).
UV/vis (CH2Cl2): 294 nm (max), 366 nm (max), 396 nm (max). Experimental Part 227 ethyl 2-((bis(2,4,6-trimethylbenzoyl)phosphoryl)methyl)acrylate (B10)
O Sodium bis(mesitoyl)phosphide (P4) (250 mg, O 0.72 mmol, 1 eq.) was dissolved in thf (5 mL). Ethyl-2- P (bromomethyl)acrylate (138.9 mg, 0.72 mmol, 1 eq.) O was added and the solution was stirred over night. The O O white precipitate was filtered off and the solvent was removed. Ethanol (5 mL) as well as hydrogen peroxide (10%) (0.244 mL, 0,72 mmol, 1 eq.) were added and the solution was stirred over night. After evaporating the solvent, a pale yellow product was obtained (Yield: 61 %, 0.43 mmol, 195.4 mg).
1 H NMR (250 MHz, C6D6): δ = 6.71 (s, 4H, Mes), 6.34 (s, 1H, C(CH2)(COOEt)),
5.82 (s, 1H, C(CH2)(COOEt)), 4.03 (q, J = 8.2 Hz, 2H, OCH2CH3), 3.39 (m, J =
12.0 Hz, 2 H, PCH2), 2.41 (s, 12H, Mes-ο-CH3), 2.10 (s, 6H, Mes-p-CH3), 1.12 (t, J
= 8.0 Hz, 3H, OCH2CH3). 13 C NMR (62.9 MHz, C6D6): δ = 173.0 (COOEt), 138.3 (C(CH2)(COOEt)), 135.2
(Mes), 134.8 (Mes), 129.3 (Mes), 61.3 (OCH2CH3), 20.8 (Mes-p-CH3), 20.1
(PCH2), 19.7 (Mes-o-CH3), 13.9 (OCH2CH3). 31 P NMR (101.3 MHz, C6D6): δ = 21.7 (t, J = 15.2 Hz). IR (goldengate [cm-1]): 2911.1 (m, CH), 1644.5 (m, C=O), 1556.2 (w, C=C), 1389.2
(w, CH3), 1258.1 (s, C-O), 1045.3 (s, C-O), 1012.0 (s, C-O). UV/vis (acetonitrile): 247 nm (max.).
(prop-2-ynylphosphoryl)bis(mesitylmethanone) (B11)
Sodium bis(mesitoyl)phosphide (P4) (2.17 g, 6.23 mmol, O O 1 eq.) was dissolved in dme (5.00 mL). 3-Bromopropyne P (0.70 mL, 0.77 g, 6.50 mmol, 1.04 eq.) was added and O the solution was stirred for 12 hours at 50°C. A white precipitate of sodium bromide was formed. After removing the sodium bromide by filtration, the solution was evaporated in vacuo. Experimental Part 228
31 The remaining phosphane ( P NMR (C6D6): δ = 46.3) is a pale yellow oil. It was dissolved in ethanol (10 mL) and hydrogen peroxide (10%) (0.36 mL (3.53 mmol, 6.23 mmol, 1 eq.) was added. The solution was stirred for 20 minutes at room temperature. After the reaction was finished, the ethanol was removed in vacuo. The product remains as a pale yellow powder (Yield: 2.04 g, 5.36 mmol, 86%).
1 H NMR (250.13 MHz, C6D6): δ = 6.63 (s, 4 H, MesCH), 2.63 (s, 2 H, CCH), 2.42
(s, 12 H, o-MesCH3), 2.06 (s, 6 H, p-MesCH3), 1.57 (s, 2 H, PCH2). 13 4 C NMR (62.90 MHz, C6D6):δ = (d, J = 51.8 Hz, PCO), 141.2 (MesC ), 136.2 1 3 2 (MesC ), 135.8 (MesC ), 129.3 (MesC ), 81.4 (CH2CC), 73.9 (CH2CC), 20.8 (p-
MesCH3), 19.8 (o-MesCH3), 5.8 (CH2CC). 31P NMR (101.25 MHz, C6D6): δ = 18.9 (m). IR (goldengate [cm-1]): 3284 (w), 2970 (w), 2923 (w), 2360 (w), 1954 (w), 1926 (w), 1718 (m), 1675 (s), 1607 (s), 1451 (m), 1424 (m), 1381 (m), 1282 (w), 1210 (s), 1147 (s), 1089 (m), 1035 (m), 959 (w), 887 (m), 850 (s), 806 (m), 741 (w), 664 (w), 620 (m). UV/vis (toluene): 364 nm (max), 392 nm (shoulder).
((4-bromobenzyl)phosphoryl)bis(mesitylmethanone) (B12)
Sodium bis(mesitoyl)phosphide (P4) (250 mg, 0.72 mmol,
O 1 eq.) was dissolved in toluene (5 mL). 1-Bromo-4-
O P (bromomethyl)benzene (180.0 mg, 0.72 mmol, 1 eq.) was O added and the solution was stirred over night. The solution 31 Br was found to contain the colourless BAP ( P NMR (C6D6): δ = 55.2 ppm). The white precipitate was filtered off, hydrogen peroxide (10%) (0.244 mL, 0.72 mmol, 1 eq.) was added and the solution was stirred over night. 5 mL diethyl ether was added and the solution was washed with sodium hydrogencarbonate solution (2%) and brine. After drying with sodium sulfate, the solvent was evaporated. A pale yellow product was obtained (Yield: 84%, 0.60 mmol, 306.8 mg).
Experimental Part 229
1 H NMR (300.1 MHz, C6D6): = 2.13 (s, 6 H, p-MesCH3), 2.40 (s, 12 H, o-
MesCH3), 3.23 (s, 2 H, PCH2), 6.59 (s, MesCH), 7.16-7.26 (m, 2 H, Ar-H), 7.82- 7.84 (m, 2 H, Ar-H). 13 C NMR (62.9 MHz, C6D6): = 14.6 (P-CH2), 18.7 (o-MesCH3), 21.9 (p-MesCH3), 122.9 (ArC4), 127.6 (MesC2), 128.6 (MesC3), 128.9 (ArC2), 12.8 (ArC3) 129.3 (ArC1), 135.7 (MesC1), 139.2 (MesC4), 166.8 (CO), 218.4 (MesCO). 31 P NMR (121.5 MHz, C6D6): = 29.1 (t, J = 16.8 Hz).
((3-bromopropyl)phosphinediyl)bis(mesitylmethanone) (B13a)
Sodium bis(mesitoyl)phosphide (P4) (1.00 g, 2.88 mmol, 1 eq.) was dissolved in toluene (5.00 mL). This solution was added dropwise in a cooled (ice bath) solution of 1,3- dibromopropane (0.028 mL, 0.056 g, 28.8 mmol, 10 eq.) in O O P thf (5.00 mL). Then the reaction mixture was stirred for 24
Br hours at 50°C to complete the reaction. A white precipitate of sodium bromide was formed. After removing the sodium bromide by filtration, the solution was evaporated in vacuo. The remaining yellow oil was dissolved in diethyl ether and washed with an aqueous and degassed ammonium chloride solution (5%). After the ether solution had been dried with sodium sulfate it was evaporated in vacuum at room temperature and dried in high vacuum for 4 hours to remove the excess of 1,3-dibromopropane. (Yield: 1.16 g, 2.59 mmol, 90%).
1 H NMR: (250.1 MHz, C6D6): = 0.98 (t, J = 6.33 Hz), 1.93 (quint., ), 2.14 (s, 6 H,
Ar-CH3), 2.32 (s, 12 H, Ar-CH3), 3.02 (t, J = 6.33 Hz), 6.60 (s, J = 6.33 Hz). 13 C NMR: (62.9 MHz, C6D6): = 20.15 (o-Ar-CH3), 20.8 (p-Ar-CH3), 30.35 (P-CH2), 2 3 1 43.3 (CH2), 65.7 (CH2-Br), 128.2 (MesC ), 129.2 (MesC ), 132.5 (MesC ), 142.7 (MesC4), 216.9 (d, J = 47.8 Hz, CO). 31 P NMR: (121.5 MHz, C6D6): = 50.8 (t, J = 9.6 Hz). Experimental Part 230
((3-bromopropyl)phosphoryl)bis(mesitylmethanone) (B13)
3-BromopropylBAPO (1.16 g, 2.59 mmol, 1 eq.) was dissolved in toluene (5 mL) and hydrogen peroxide (10%) (8.88 mL, 2.59 mmol, 1 eq.) was added. The reaction O O mixture was stirred at 40°C for 12 hours. Afterwards P Br O diethylether (50 mL) were added and the solution was washed with twice sodium hydrogencarbonate (2%) solution, once with brine and finally dried with magnesium sulfate. After removing the solvent in vacuo at room temperature, the pure product was obtained as a yellow oil (Yield: 0.97 g, 2.10 mmol).
1 H NMR (250.1 MHz, C6D6): = 1.73 (quint., J = 6.32 Hz, CH2 ), 2.12 (s, 6 H, p-
MesCH3), 2.30 (s, 12 H, o-MesCH3), 2.88 (t, J = 6.32, 2 H, CH2), 3.41 (t, J =, 2 H,
CH2Br), 6.69 (s, 2 H, MesCH). 13 C NMR (62.9 MHz, C6D6): = 21.0 (p-MesCH3), 28.1 (CH2), 30.9 (o-MesCH3), 2 3 1 33.4 (CH2), 53.7 (CH2-Br), 129.3 (MesC ), 130.2 (MesC ), 135.6 (MesC ), 141.1 (MesC4), 215.8 (d, J = 88.1 Hz, CO). 31 P NMR (121.5 MHz, C6D6): = 25.83 (t, J = 9.7 Hz). + MS (EI, m/z): 446.9 (M ), 416.9 (-2xCH3), 355.0, 339.5 (-C2H4Br), 325.4 (-C3H6Br), 296.3, 295.4, 281.8, 248.4, 221.2, 202.1, 166.2, 147.2 (MesCO), 119.2 (Mes), 91.2, 84.3, 73.3, 65.3.
((3-chloropropyl)phosphoryl)bis(mesitylmethanone) (B14)
Sodium bis(mesitoyl)phosphide (P4) (1.00 g, 2.88 mmol, 1 eq.) was dissolved in toluene (5.00 mL). This solution
O was added dropwise in a cooled (ice bath) solution of 1- O bromo-3-chloropropane (0.028 mL, 4.54 g, 28.8 mmol, P Cl O 10 eq.) in thf (5.00 mL). Then the reaction mixture was stirred for 24 hours at 50°C to complete the reaction. A white precipitate of sodium bromide was formed. After removing the sodium bromide by filtration, the solution Experimental Part 231 was evaporated in vacuo. The remaining yellow oil was dissolved in diethyl ether and washed with an aqueous and degassed ammonium chloride solution (5%). After having dried the ether solution with sodium sulfate, it was evaporated in vacuo at room temperature and dried in high vacuum for 4 hours to remove the excess of 1-bromo-3-chloropropane. The remaining pale yellow oil was dissolved in ethanol (5 mL) and hydrogen peroxide (10%) (0.1 mL, 2.88 mmol, 1 eq.) were added. After stirring the solution for 3 h, the ethanol was removed to yield the pure product as a yellow oil (Yield: 0.749 g, 1.79 mmol, 62%).
1 H NMR (250.1 MHz, C6D6): = 1.76 (quint., J = 6.42 Hz, CH2 ), 2.16 (s, 6 H, p-
MesCH3), 2.34 (s, 12 H, o-MesCH3), 2.98 (t, J = 6.42, 2 H, CH2), 3.49 (t, J =
6.42 Hz, 2 H, CH2Cl), 6.69 (s, 2 H, MesCH). 13 C NMR (62.9 MHz, C6D6): = 19.8 (p-MesCH3), 28.4 (CH2), 31.2 (o-MesCH3), 2 3 1 33.6 (CH2), 57.4 (CH2-Br), 129.5 (MesC ), 130.7 (MesC ), 135.5 (MesC ), 141.2 (MesC4), 216.8 (d, J = 84.8 Hz, CO). 31 P NMR (121.5 MHz, C6D6): = 24.6 (t, J = 9.3 Hz).
((3-aminopropyl)phosphoryl)bis(mesitylmethanone) (B15)
Sodium bis(mesitoyl)phosphide (P4) (22.8 mg, 0.065 mmol, 1 eq.) was dissolved in dme (2 mL). 3- Bromopropylammonium bromide (14 mg, 0.065 mmol, 1 eq.) was added at room temperature. After 15 minutes O O of stirring, the solvent was removed in vacuo at room P O temperature and replaced by 2 mL ethanol. With a HN2 microlitre syringe hydrogen peroxide (30 %) (0.008 ml, 0.065 mmol, 1 eq.) was added slowly. The solution was stirred for 30 minutes. Subsequently, the solvent was removed in vacuo. The product was dissolved in diethylether (2 mL), washed with brine and dried with sodium sulfate. After filtration and evaporation of the diethylether, the pure product was obtained (Yield not determined). Experimental Part 232
1 3 H NMR (300.1 MHz, C6D6): δ = 2.46 (quint., 2 H, P-CH2-CH2, J = 6.9 Hz), 3.22 (t,
2 H, N-CH2, J = 7.4 Hz), 3.68 (t, 2 H, P-CH2, J = 7.4 Hz), 2.18 (s, 6 H, p-MesCH3),
2.42 (s, 12 H, o-MesCH3), 6.69 (s, 2 H, MesCH). 13 C NMR (75.5 MHz, C6D6): δ = 18.4 (p-MesCH3), 28.40 (P-CH2), 31.2 (o- 2 3 MesCH3), 31.9 (P-CH2-CH2), 38.4 (CH2-N), 129.3 (MesC ), 130.9 (MesC ), 135.2 (MesC1), 141.5 (MesC4), 218.8 (d, J = 90.3 Hz, CO). 31 1 P{ H}-NMR (121.5 MHz, C6D6): δ = 23.1 (s).
3-(bis(2,6-dimethoxybenzoyl)phosphino)propylamine (B16)
Sodium bis(2,6-dimethoxybenzoyl)phosphide (25 mg (0.065 mmol, 1 eq.) was dissolved in dme (2 mL). 3-
O O O Bromopropylamine hydrobromide (14 mg, 0.065 mmol, 1 O eq.) was added at room temperature. After stirring the O P O reaction mixture for 15 minutes, the solvent was removed O H2N in vacuo at room temperature and replaced by ethanol (2 mL). With a microlitre syringe hydrogen peroxide (30 %) (0.008 ml, 0.065 mmol, 1 eq.) was added slowly and the solution was stirred for 30 minutes. Subsequently, the solvent was removed in vacuo. The residue was dissolved in diethylether (2 mL) and washed with brine and dried with sodium sulfate. After filtration and evaporation of the diethylether the pure product was obtained.
1 8 3 H NMR (300.1 MHz, d -thf): δ = 2.43 (quint., 2 H, P-CH2-CH2, J = 6.9 Hz), 3.20 (t, 3 3 2 H, N-CH2, J = 7.2 Hz), 3.68 (t, 2 H, P-CH2, J = 6.6 Hz), 3.79 (s, 12 H, O-CH3), 6.60 (d, 4 H, Ar-H, 3J = 8.4 Hz), 7.25 (t, 2 H, Ar-H, 3J = 8.4 Hz). 31P{1H} NMR (121.5 MHz, d8-thf): δ = 24.1 (s). 13 8 C NMR (75.5 MHz, d -thf): δ = 30.31 (P-CH2), 30.5 (P-CH2-CH2), 38.4 (C-N), 55.2 (O-Me), 103.8 (Ar-C3), 104.0 (Ar-C1), 129.6 (Ar-C4), 157.1 (s, Ar-C2), 204.0
(C=Oacyl). Experimental Part 233
(E)-((4-(benzylideneamino)phenyl)phosphoryl)bis(mesitylmethanone) (B17)
In a 20 mL Schlenk flask sodium bis(mesitoyl)phosphide (P4) (100 mg, 0.26 mmol, O 1 eq.) was dissolved in toluene (5.00 mL). N- P N O Benzyliden-4-iodoanilin (79.9 mg, 0.26 mmol, O 1 eq.), which can easily be synthesised from p- 260 iodo aniline and benzaldehyde and [Pd(dba)2] (4.86 mg, 0.014 mmol, 5 mol%) were added. The reaction mixture was stirred for 12 hours at 40°C. After termination of the reaction, the black precipitate was filtered off and the yellow filtrate was evaporated in vacuo at room temperature. The remaining oil was dissolved in ethanol and hydrogen peroxide (0.0029 mL, 0.26 mmol, 1 eq.) was added with a micro litre syringe. After 4 hours the phosphane was completely oxidised. Having added diethyl ether (25 mL) the solution was washed twice with an aqueous sodium hydrogencarbonate solution (2%), twice with brine and finally dried over sodium sulfate. The solvent was removed and the product dried in high vacuum for two hours. (Yield: 123.3 mg, 0.236 mmol, 91%).
1 H NMR (300.1 MHz, C6D6): = 2.24 (s, 6 H, p-MesCH3), 2.52 (s, 12 H, o- 4 MesCH3), 6.64 (s, 4 H, MesC H), 7.28 (m, 2 H, Ar-H), 7.58 (m, 3 H, Ar-H), 7.72- 7.80 (m, 4 H, Ar-H), 8.14 (s, 1 H, =NH-). 13 C NMR (62.9 MHz, C6D6): = 17.3 (p-Mes-CH3), 20.9 (o-Mes-CH3), 121.3 (Ar- CH), 128.4 (Ar-CH), 129.1 (Ar-CH), 129.6 (Ar-CH), 130.7 (Ar-CH), 132.4 (Ar-CH), 135.3 (Ar-CH), 136.8 (Ar-CH), 137.2 (Ar-CH), 138.7 (Ar-CH), 153.5 (Ar-CH), 161.2 (-HC=N), 217 (MesCO-P). 31 1 P{ H}-NMR (121.5 MHz, C6D6): = 9.47 (s).
Experimental Part 234
3-(bis(2,4,6-trimethylbenzoyl)phosphoryl)propanenitrile (B18)
Sodium bis(mesitoyl)phosphide (P4) (2.58 g, 6.48 mmol, O O 1 eq.) was dissolved in dme (5.00 mL). 4-Bromobutyro P O nitrile (0.35 mL, 0.52 g, 3.51 mmol, 1 eq.) was added and the solution was stirred for 12 hours at 50°C. A white precipitate of sodium bromide was formed. After N removing the sodium bromide by filtration, the solution was evaporated in vacuo. The obtained phosphane was a yellow oil. It was dissolved in 10 mL ethanol and 0.36 mL (3.53 mmol, 1 eq.) hydrogen peroxide were added. The solution was stirred for 3 hours at 40°C. After the reaction was finished the ethanol was removed in vacuo. The product remains as a yellow oil. It was dissolved in diethyl ether (20 mL) and washed with sodium hydrogen carbonate solution (2%) (5 mL), brine (5 mL) and dried over sodium sulfate (Yield: 2.05 g, 5.18 mmol, 80.0%,).
1 H NMR (300.13 MHz, C6D6): δ = 6.66 (s, 4 H, Mes), 2.73 (t, J = 6.30 Hz, 2 H,
CH2CN), 2.39 (s, 12 H, o-MesCH3), 2.07 (s, 6 H, p-MesCH3), 1.61–1.54 (m, 2 H,-
CH2-), 1.23 (t, J = 6.75 Hz, PCH2). 13 1 C NMR (75.48 MHz, C6D6): δ = 216.2 (d, J = 52.8 Hz, PCO), 141.2 (MesC ), 4 2 3 136.6 (MesC ), 135.9 (MesC ), 129.3 (MesC ), 118.1 (CN), 20.8 (p-MesCH3), 19.7
(o-MesCH3), 18.3 (CH2CN), 17.2 (CH2CH2CN), 15.1 (PCH2). 31 P{1H}-NMR (121.49 MHz, C6D6): δ = 25.5 (t, J = 9.78 Hz). IR (goldengate [cm-1]): 2925 (w), 2360 (w), 2245 (w), 1715 (m), 1675 (s), 1608 (s), 1425 (m), 1378 (w), 1279 (m), 1250 (m), 1213 (s), 1194 (s), 1165 (m), 1145 (s), 1088 (m), 1033 (m), 956 (w), 888 (m), 851 (s), 800 (w), 751 (m), 617 (m). UV/vis (toluene): 364 nm (max), 394 nm (shoulder).
Experimental Part 235
((2-isocyanatoethyl)phosphinediyl)bis(mesitylmethanone) (B19a)
Sodium bis(mesitoyl)phosphide (P4) (100 mg, 0.28 mmol, 1 eq.) was dissolved in 5.00 mL toluene. 29.54 mg (0.28 mmol, 1 eq.) 2-chloro-ethylisonitril were added and the O O solution was stirred at 40°C for 12 h. After cooling down to P room temperature the white precipitate of sodium chloride N=C=O was removed by filtration over Celite. The filtrate was concentrated and dried in high vacuum. The product was a pale yellow oil (Yield: 79.1 mg, 0.20 mmol, 73%). An oxidation with hydrogen peroxide is not possible because decomposition takes place.
31 P NMR (121.5 MHz, C6D6): = 54.4 (t, J = 9.4 Hz).
((3-azidopropyl)phosphoryl)bis(mesitylmethanone) (B20)
3-BromopropylBAPO (100 mg, 0.22 mmol, 1 eq.) was dissolved in dmso (5.0 mL). Sodium azide (14.3 mg, 0.22 mmol, 1 eq.) was added and the solution was stirred O O for 12 h at 70°C. A white precipitate of sodium bromide P N3 O was formed, which was filtered off and the dmso was removed in vacuo at 50°C. 5 mL of diethylether was added to the residue and the solution was washed twice with brine and dried with magnesium sulfate. After evaporation of the solvent a yellow product was obtained (Yield: 35%, 0.08 mmol, 32.7 mg).
1 H NMR (250.1 MHz, C6D6): = 1.60 (br., CH2 ), 1.68 (br., 2 H, CH2N3), 2.10 (s,
6 H, p-MesCH3), 2.11 (s, 12 H, o-MesCH3), 2.64 (br., 2 H, P(=O)CH2), 6.64 (s, 2 H, MesCH). 31 1 P{ H} NMR (101.3 MHz, C6D6): = 24.6. Experimental Part 236
((2-hydroxyethyl)phosphoryl)bis(mesitylmethanone) (B21)
a) Sodium bis(mesitoyl)phosphide (P4) O O (2.08 g, 5.89 mmol, 1 eq.) was dissolved in dme P (5.00 mL). 2-bromethanol (0.41 mL, 0.78 g, 5.78 mmol, O 1 eq.) were added and the solution was stirred for 24 OH hours at room temperature. The colourless BAP is formed and white sodium bromide precipitates. After removing the sodium bromide by filtration, the solution was evaporated in vacuo.
The remaining yellow oil was dissolved in 10 mL ethanol and 0.65 mL (6.36 mmol, 1.08 eq.) hydrogen peroxide (10%) were added. The solution was stirred for 3 hours at 40°C. After the reaction was completed, the ethanol was removed in vacuo. The product was obtained as a pale yellow crystalline powder (Yield: 1.76 g, 4.55 mmol, 76%). b) Instead of 2-bromoethanol one equivalent of oxirane can be used as electrophile as well. The reaction was performed analogue to a), but the solvent was a mixture of toluene / dme (95:5). The reaction time was 10 days at 60°C. After the reaction was finished, the oxidation was performed in a mixture of water/ ethanol (1:4), which contained one equivalent of sodium hydrogen carbonate.
1 4 1 2 H NMR (250.13 MHz, C6D6): δ = 6.65 (s, 4 H, MesC ), 3.73 (dt, J = 6.00 Hz, J =
18.51 Hz, 2 H, CH2OH), 2.48 (s, 12 H, o-MesCH3), 2.07 (s, 6 H, p-MesCH3), 1.59
(s, 2 H, PCH2). 31 P NMR (121.49 MHz, C6D6): δ = 27.2 (t, J = 9.11 Hz) IR (goldengate, [cm-1]): 3296 (w), 2970 (w), 2919 (w), 2154 (w), 2017 (w), 1971 (w), 1720 (m), 1678 (w), 1609 (m), 1450 (w), 1378 (w), 1261 (s), 1166 (s), 1084 (s), 988 (m), 899 (w), 849 (m), 805 (w), 785 (w), 737 (w). UV/vis (toluene): 320 nm (max), 360 nm (max), 372 nm (shoulder), 390 nm (shoulder). Experimental Part 237 bis(2,6-dimethoxybenzoyl)hydroxyethylphosphanoxide (B22)
Sodium bis(2,6-dimethoxybenzoyl)phosphide (25 mg, 0.065 mmol, 1 eq.) was dissolved in dme (2 mL). With a O O O O microlitre syringe 2-bromoethanol (0.005 ml, 0.065 mmol, O P 1 eq.) was added at room temperature. After stirring the O O reaction mixture for 15 minutes, the solvent was removed HO in vacuo at room temperature and replaced by ethanol (2 mL). To this solution hydrogen peroxide (30 %) (0.008 ml, 0.065 mmol, 1 eq.) was added slowly with a microlitre syringe. The solution was stirred for 5 minutes. Subsequently, the solvent was removed in vacuo (Yield: 76 %, 0.05 mmol, 20.85 mg).
1 8 H NMR (300.1 MHz, d -thf): δ = 3.39 (br., 2 H, P-CH2), 3.42 (s, 12 H, O-CH3), 6.30 (d, 4 H, Ar-H, 3J = 8.4 Hz), 7.07 (t, 2 H, Ar-H, 3J = 8.4 Hz). 31P NMR (101.3 MHz, d8-thf): δ = 26.47 (br.). 13 8 C NMR (75.5 MHz, d -thf): δ = 28.5 (P-CH2), 56.1 (C-OH), 56.2 (O-Me), 104.6 3 1 4 2 (Ar-C ), 104.7 (Ar-C ), 130.5 (Ar-C ), 158.1 (Ar-C ), 206.5 (C=Oacyl).
((oxirane- 2-ylmethyl)phosphoryl)bis(mesitylmethanone) (B23)
Sodium bis(mesitoyl)phosphide (P4) (2.05 g, 5.89 mmol, 1 eq.) was dissolved in dme (5.00 mL). O O Epibromohydrine (1.23 mL, 1.82 g, 13.3 mmol, 1 eq.) P O was added and the solution was stirre d f or 24 hours at
O room temperature. A white precipitate of sodium bromide was formed. After removing the sodium bromide by filtration, the solution was evaporated in vacuo. The remaining yellow oil was dissolved in ethanol (10 mL) and hydrogen peroxide (10%) (0.65 mL, 6.36 mmol, 1.08 eq.) was added. The solution was stirred for 3 hours at 40°C. After the reaction was finished, the ethanol was removed in vacuo. The product was obtained as a yellow oil (Yield: 2.58 g, 6.48 mmol, 49%).
Experimental Part 238
1H NMR (250.13 MHz, C6D6): δ = 6.50 (s, 4 H, MesC4), 3.07 (d, J = 1.75 Hz, 1 H,
CHCH2O), 3.05 (d, J = 2.00 Hz, 1 H, CHCH2O), 2.80–2.70 (m, 1 H, CHCH2O), 2.47
(s, 12 H, o-MesCH3), 2.12 (s, 6 H, p-MesCH3), 1.58 (s, 2 H, PCH2). 31P NMR (121.49 MHz, C6D6): δ = 23.0 (t, J = 12.6 Hz). IR (goldengate, [cm-1]): 2965 (m), 2919 (m), 2645 (w), 2554 (w), 1718 (m), 1678 (s), 1610 (s), 1435 (s), 1376 (m), 1282 (s), 1167 (s), 1088 (s), 1033 (m), 936 (m), 854 (s), 776 (m), 711 (w). UV/vis (toluene): 361 nm (max), 395 nm (Shoulder).
((2,3-dihydroxypropyl)phosphoryl)bis(mesitylmethanone) (B24)
Sodium bis(mesitoyl)phosphide (P4) (250 mg, O O 0.72 mmol, 1 eq.) was dissolved in thf (5 mL). 1-Bromo- P 2,3-propanediol (111.6 mg, 0.063 mL, 0.72 mmol, 1 eq.) O was added and the solution was stirred over night. The HO OH white precipitate was filtered off. The thf was removed in vacuo and the phosphane was dissolved in ethanol (5 mL). Hydrogen peroxide (10%) (0.244 mL, 0.72 mmol, 1 eq.) was added and the solution was stirred over night. Diethyl ether (5 mL) was added and the solution was washed with sodium hydrogen carbonate solution (2%) and brine. After drying with sodium sulfate, the solvent was evaporated. A pale yellow product was obtained (Yield: 64 %, 0.46 mmol, 191.5 mg).
1 H NMR (300.1 MHz, C6D6): = 1.67 (d, J = 7.6 Hz, 2 H, PCH2), 2.11 (s, 6 H, p-
MesCH3), 2.51 (s, 12 H, o-MesCH3), 3.43 (quint., J = 7.4 Hz, 1 H CHOH), 3.82 (d,
J = 7.4 Hz, 1 H CH2OH), 6.41 (s, MesCH). 13 C NMR (62.9 MHz, C6D6): = 10.2 (P-CH2), 18.7 (o-MesCH3), 21.9 (p-MesCH3), 2 3 1 59.2 (CHOH), 73.4 (CH2OH) 127.6 (MesC ), 128.6 (MesC ), 135.7 (MesC ), 139.2 (MesC4), 219.3 (MesCO). 31 P NMR (121.5 MHz, C6D6): = 26.4 (t, J = 16.8 Hz). Experimental Part 239
Acetyl protected BAPO-glucose (B25)
Tetra-O-acetyl-α-D-glucopyranosyl bromide O O (0.26 g, 0.65 mmol, 1 eq.) was dissolved in P acetonitrile (40 mL). BAPO-ethanol (0.5 g, O 1.2 mmol, 2 eq.), calcium sulfate (100 mg) and O H O H silver carbonate (0.27 g, 0.97 mmol, 1.5 eq.) O CH H3C O 3 H H were added. The reaction mixture was refluxed O O O O O H for 6 hours. After cooling down the calcium O CH3 CH3 sulfate and the silver salts were filtered over celite. The solvent was evaporated in vacuo at room temperature. After purification of the product by column chromatogarphy (ethyl acetate/ hexane (90:10), the solvent was evaporated and a yellow oil was obteined.
1 H NMR (300.1 MHz, C6D6): δ = 2.04 (s, 3 H), 2.06 (s, 3 H), 2.09 (s, 3 H), 2.19 (s,
6 H, p-MesCH3), 2.22 (s, 12 H, o-MesCH3), 3.19 (t, 2 H, P-CH2, J = 7.5 Hz), 4.10
(t, 2 H, P-CH2, J = 7.5 Hz), 4.09 (m, 1 H), 4.29 (m, 2 H), 4.78 (br.), 5.02 (t, 1 H, J = 10.3 Hz), 5.45 (t, 1 H, J = 10.3 Hz), 6.46 (s, 2 H, MesCH). 13 C NMR (75.5 MHz, C6D6): δ = 17.9 (p-MesCH3), 19.8, 20.4, 20.9, 21.2, 28.40 (P-
CH2), 30.2 (o-MesCH3), 37.9 (P-CH2-CH2), 63.4, 66.3, 69.7, 70.9, 71.5, 129.8 (MesC2), 131.3 (MesC3), 134.9 (MesC1), 142.5 (MesC4), 169.1, 169.3, 169.7, 169.9, 216.2 (d, J = 82.6 Hz, CO). 31 1 P{ H}-NMR (121.5 MHz, C6D6): δ = 19.73 (br.).
((2-mercaptoethyl)phosphoryl)bis(mesitylmethanone) (B26)
Sodium bis(mesitoyl)phosphide (P4) (250 mg, 0.72 mmol, 1 eq.) was dissolved in a mixture of dme (5 mL) and toluene (5 mL). Thiirane (43.2 mg, 0.72 mmol, 1 eq.) was added O O and the solution was stirred for two days. The solution was P SH 31 O found to contain the colourless BAP ( P NMR (C6D6, 121 MHz): = 41.5 ppm). The solution was cooled down to 0°C in an ice bath and Experimental Part 240 hydrogen peroxide (10%) (0.244 mL, 0.72 mmol ,1 eq.) was added dropwise. Subsequently, the solution was stirred over night at room temperature. 5 mL diethyl ether was added and the solution was washed with sodium hydrogencarbonate solution (2%) and brine. After drying with sodium sulfate, the solvent was evaporated and the product recrystallised from toluene / n-hexane (5:95). A pale yellow product was obtained (Yield: 29%, 0.22 mmol, 83.6 mg).
31 P NMR: (121.5 MHz, C6D6): = 24.3 (t, J = 10.8 Hz).
(((1,3-dioxolan-2-yl)methyl)phosphinediyl)bis(mesitylmethanone) (B27)
Sodium bis(mesitoyl)phosphide (P4) (370 mg, 1.07 mmol, 1 eq.) was dissolved in dme (10.0 mL). 2- O (Bromomethyl)-1,3-dioxolan (0.30mL, 2.93 mmol, P 2.74 eq.) and a catalytic amount of sodium iodide were O O added and the yellow solution was stirred for 48h at O 50°C. A white precipitate which contains sodium bromide and polymerised 2-methylene-1,3-dioxolane was formed. After removing the precipitate by filtration, the solution was evaporated in vacuo. The remaining yellow oil was dried in high vacuum for 4 hours (Yield: 40 mg, 0.10 mmol, 10%).
1 H NMR (250.1 MHz, CDCl3): = 1.61 (s, 2 H, PCH2), 2.29 (s, 18 H, Ar-CH3), 3.41
(t, 4 H, OCH2), 5.14 (t, 1 H, OCH), 6.73 (s, 4 H, CarH). 31 P NMR (101.3 MHz, C6D6): = 46.3.
((3-(diphenylphosphino)propyl)phosphoryl)bis(mesitylmethanone) (B28)
3-BromopropylBAPO (100 mg, 0.22 mmol, 1 eq.) was dissolved in thf (5.0 mL). The solution was
O cooled down to -78°C with dry ice / acetone and a O P P O Experimental Part 241 potassium diphenylphosphide solution (0.5 M in thf) (0.44 mL, 0.22 mmol, 1 eq.) was added very slowly. It was taken care to wait that the red colour of the potassium diphenylphosphide disappeared after the addition of each drop. The precipitate of potassium bromide was filtered off and the filtrate was concentrated under vacuum at room temperature. The product was recrystallised from toluene / hexane (Yield: 45 mg, 0.08 mmol, 37%).
1 H NMR (250.1 MHz, C6D6): = 1.60 (br., CH2 ), 1.78 (br., 2 H, CH2PPh2), 2.11 (s,
6 H, p-MesCH3), 2.12 (s, 12 H, o-MesCH3), 2.64 (br., 2 H, P(=O)CH2, 6.64 (s, 2 H, MesCH), 7.05 (t, J = 8.7 Hz, 2 H, PhC2H) , 7.10 (m, 2 H, PhC2H) 7.19 (m, 1 H, PhC3H). 31 1 P{ H} NMR (101.3 MHz, C6D6): = 21.6 (P=O), 10.7 (PPh2). diethyl 2-(bis(2,6-dimethoxybenzoyl)phosphoryl)ethylphosphonate (B29)
Sodium bis(2,6-dimethoxybenzoyl)phosphide (100 mg, 0.26 mmol, 1 eq.) was dissolved in dme (5 mL) and O OO O bromoethylphosphonic diethylester (63.7 mg, 0.26 mmol,
P 1 eq.) was added at room temperature. A white precipitate O O O of sodium bromide is formed and after 2 hours of stirring the
P solvent was removed in vacuo at room temperature. EtO OEt O Subsequently, the pale yellow residue was dissolved in ethanol (5 mL) and hydrogen peroxide (0.3 mL, 0.26 mmol, 1 eq.) was added. The solution was stirred for 2 hours at 40°C. After filtration the solution was evaporated to obtain the pure product as a yellow oil (Yield: 97.35 mg, 0.19 mmol, 74%).
1 H NMR (250.13 MHz, CDCl3): δ = 1.19 ppm (m, 6 H, OCH2CH3), 1.83 (m, 2 H,
PCH2), 2.24 (m, 2 H, PCH2), 3.40 (s, 12 H, O-CH3), 3.95 (m, 4 H, OCH2CH3), 6.31 (d, 4 H, Ar-H, 3J = 7.9 Hz), 7.07 (t, 2 H, Ar-H, 3J = 7.9 Hz). Experimental Part 242
13 1 2 C NMR (62.9 MHz, CDCl3): δ = 205.2 (d, JCP = 51.9 Hz, ArCO), 157.1 (Ar-C ), 4 1 3 2 131.0 (Ar-C ), 104.4 (Ar-C ), 104.1 (Ar-C ), 62.1 (d, J = 6.6 Hz, OCH2CH3), 55.8
(O-CH3), 19.9 (PCH2), 19.0 (PCH2), 16.4 ppm (OCH2CH3). 31 P NMR (101.3 MHz, CDCl3): δ = 29.3 (P(OEt)3), 21.3 ppm ((ArCO)2P).
((thiophene-3-ylmethyl)phosphinediyl)bis(mesitylmethanone) (thiophene-BAP) (B30a)
Sodium bis(mesitoyl)phosphide (P4) (250 mg, 0.72 mmol, 1 eq.) and 3-chloromethylthiophene (95.4 mg, 0.72 mmol, 1 eq.) were dissolved in toluene (5 mL) and stirred for 12
O P S hours at 50°C. The white precipitate of sodium chloride was
O removed by filtration and the solvent was evaporated under reduced pressure at room temperature. The remaining phosphane was a pale yellow oil (Yield: 297.8 mg, 0.68 mmol, 95%).
1 8 H NMR: (300.1 MHz, d -thf): = 1.72 (s, 6 H, p-MesCH3), 2.24 (s, 2 H, CH2), 2.63 2 4 3 (s, 12 H, p-MesCH3), 5.23 (br., 1 H, C H), 5.47 (m, 1 H, C H), 5.50 (m, 1 H, C H), 6.41 (MesCH). 13 8 C NMR: (62.9 MHz, d -thf): = 18.9 (CH2), 22.3 (p-MesCH3), 26.3 (o-MesCH3), 119.4 (thiophene-C2H), 121.0 (thiophene-C5H), 123.8 (thiophene-C4H), 124.4 (MesC3), 126.2 (thiophene-C3), 126.9 (MesC1), 137.7 (MesC2), 142.2 (MesC4), 227.0 (MesCO). 31P{1H}-NMR: (121.5 MHz, d8-thf): = 49.46 (s).
Experimental Part 243
((thiophene-3-ylmethyl)phosphoryl)bis(mesitylmethanone) (B30)
ThiopheneBAP (297.8 mg, 0.68 mmol, 1 eq.) was dissolved in toluene (10 mL). Hydrogen peroxide (10%) (0.19 mL, O 0.72 mmol, 1 eq.) was added. After stirring for 12 hours at O P 40°C, the oxidation was finished. Diethyl ether (25 mL) was O S added and the solution was washed twice with an aqueous sodium hydrogen carbonate solution (2%), once with brine and finally with distilled water. After drying the diethyl ether solution with sodium sulfate and filtration, the solution was concentrated in vacuo. A yellow oil was obtained (Yield: 247 mg, 0.56 mmol, 83%).
1 H NMR (300.1 MHz, C6D6): = 1.95 (s, 6 H, p-MesCH3), 2.28 (s, 12 H, p- 2 MesCH3), 2.45 (s, 2 H, CH2), 6.61 (MesCH), 6.85 (br., 1 H, C H), 6.88 (m, 1 H, C4H), 7.06 (m, 1 H, C3H). 13 C NMR (75.5 MHz, C6D6): = 8.1 (CH2), 19.4 (p-MesCH3), 21.2 (o-MesCH3), 124.6 (thiophene-C2H), 125.4 (thiophene-C5H), 126.9 (MesC1), 128.4 (thiophene- C4H), 129.4 (MesC3), 129.9 (thiophene-C3), 136.6 (MesC2), 140.9 (MesC4), 215.5 (d, J = 51.53 Hz, MesCO). 31 P NMR (121.5 MHz, C6D6): = 22.8 (t, J = 11.3 Hz).
3-(3-(bis(2,4,6-trimethylbenzoyl)phosphoryl)propyl)-1-methyl-1H- imidazol-3-ium bromide (B31)
((2-Bromopropyl)-phosphoryl) bis(mesitylmethanone) O O (B13) (825 mg, 1.78 mmol, 1 eq.) and methylimidazol P O (0.15 mL, 155 mg, 1.89 mmol, 1.06 eq.) were dissolved in toluene (2 mL). The solution was stirred for 24 h at N 50°C. A yellow precipitate was formed. The solution was Br N decanted and the yellow solid was washed three times with 2 mL toluene. The microcrystalline product was dried for two hours in vacuo.
Experimental Part 244
1 H NMR (300.13 MHz, D2O): δ = 8.71 (s, 1 H, ImH), 7.40 (d, J = 10.3 Hz, 2 H, Im),
6.78 (s, 4 H, MesCH), 3.82 (s, 3 H, NCH3), 3.04 (br., 2 H, NCH2), 2.43 (s, 12 H, o-
MesCH3) , 2.09 (s, 6 H, p-MesCH3), 1.67–1.64 (m, 2 H, PCH2CH2), 0.55 (m, 2 H,
PCH2). 31 P NMR (101.25 MHz, D2O): δ = 23.1 (br.)
((2-oxopropyl)phosphinediyl)bis(mesitylmethanone) (BAP-acetone) (B32a)
Sodium bis(mesitoyl)phosphide (P4) (250 mg, 0.72 mmol, 1 eq.) was dissolved in toluene (5 mL). Bromoacetone (98.6 mg, 0.72 mmol, 1 eq.) (caution!, glassware can be cleaned with an
O O aqueous ammonia solution), which was prepared according to P O literature261 were added dropwise and the solution was stirred for 12 hours at room temperature. The white precipitate of sodium bromide was removed by filtration and the solvent was evaporated under reduced pressure at room temperature. The obtained phosphane was a pale yellow oil (Yield: 299.5 mg, 0.67 mmol, 93%).
1 H NMR (300.1 MHz, C6D6): = 1.61 (s, 3 H, CH3), 2.13 (s, 6 H, p-MesCH3), 2.58
(s, 12 H, p-MesCH3), 2.64 (s, 2 H, CH2), 6.61 (MesCH). 13 C NMR (62.9 MHz, C6D6): = 20.7 (o-MesCH3), 27.9 (p-MesCH3), 58.4 (P-CH2), 2 3 1 4 71.9 (COCH3), 129.3 (MesC ), 134.4 (MesC ), 135.5 (MesC ), 139.2 (MesC ),
191.8 (CH2CO), 219.3 (MesCO). 31 P NMR (121.5 MHz, C6D6): = 47.5 (t, J = 10.3 Hz).
Experimental Part 245
((2-oxopropyl)phosphoryl)bis(mesitylmethanone) (BAPO-acetone) (B32)
BAPacetone (299.5 mL, 0.67 mmol, 1 eq.) was dissolved in toluene (10 mL). Hydrogen peroxide (10%) (0.19 mL, 0.72 mmol, 1 eq.) was added. The oxidation was completed O O after stirring for 12 hours at 40°C. Diethyl ether (25 mL) was P O added and the solution was washed twice with a sodium O hydrogen carbonate solution (2%), once with brine and finally with distilled water. After drying the diethyl ether solution with sodium sulfate and filtration, the solution was concentrated in vacuo. A yellow oil was obtained (Yield: 242 mg, 0.53 mmol, 78%).
1 H NMR (300.1 MHz, C6D6): = 1.57 (s, 3 H, CH3), 2.15 (s, 6 H, p-MesCH3), 2.38
(s, 2 H, CH2), 2.44 (s, 2 H, CH2), 6.71 (MesCH). 13 C NMR (62.9 MHz, C6D6): = 18.7 (o-MesCH3), 21.1 (p-MesCH3), 27.4 (P-CH2), 2 3 1 4 35.9 (COCH3), 132.3 (MesC ), 134.4 (MesC ), 136.7 (MesC ), 142.4 (MesC ),
194.0 (CH2CO), 216.1 (MesCO). 31 P NMR: (121.5 MHz, C6D6): = 24.3 (t, J = 9.4 Hz).
((4-acetylphenyl)phosphinediyl)bis(mesitylmethanone) (B33a)
Sodium bis(mesitoyl)phosphide (P4) (100 mg, 0.28 mmol, 1 eq.) was dissolved in toluene (5.00 mL). p- Iodobenzophenone (70.3 mg, 0.28 mmol, 1 eq.) was added O O and the solution was stirred until the white powder was P dissolved. Afterwards [Pd(dba)2] (4.86 mg, 0.014 mmol, 5 mol%) was added. This mixture was stirred for 12 hours at 40°C. After cooling down to room temperature, the black O precipitate was removed by filtration over Celite. The filtrate was concentrated and dried in high vacuum. The product is a pale yellow oil (Yield: 105.7 mg, 0.238 mmol, 85%). Experimental Part 246
1 H NMR (200. MHz, C6D 6): = 2.45 (s, 3 H, CH3CO), 2.32 (s, 6 H, o-Mes-CH3), 3 2.43 (s, 12 H, p-Mes-CH3), 6.79 (s, 4 H, MesC H), 7.90-7.94 (m, 4 H, Ar-CH). 31 P NMR (80.1 MHz, C6D6): = 54.3 (t, J = 18.7 Hz).
((4-acetylphenyl)phosphoryl)bis(mesitylmethanone) (B33)
((4-Acetylphenyl)phosphinediyl)-bis(mesitylmethanone) (P4) (105.7 mL, 0.238 mmol) was dissolved in toluene (2.5 ml). Hydrogen peroxide (30%) (0.13 mL, 0.43 mmol, 1.5 eq.) was O added and the emulsion was stirred for 2 hours at 40°C. O P O Diethyl ether (25 ml) was added and the ether solution was washed twice with brine and once with a aqueous sodium hydrogencarbonate solution (2%). The ether layer was dried O with MgSO4 and the diethyl ether was removed in vacuo. The product remains as a yellow oil (Yield: 85.4 mg, 0.186 mmol, 78%).
1 H NMR (300.1 MHz, C6D6): = 2.68 (s, 3 H, CH3CO), 2.33 (s, 6 H, p-MesCH3), 4 2.43 (s, 12 H, o-MesCH3), 6.79 (s, 4 H, Mes-C H), 7.6 (m, 4 H, ArCH). 13 C NMR (62.9 MHz, C6D6): = 19.3 (p-MesCH3) , 21.4 (p-MesCH3), 28.2 (CO- 3 2 2 3 4 CH3), 128.1 (PhC ), 129.5 (MesC ), 132.5 (PhC ), 134.3 (MesC ) 138.9 (PhC ), 1 1 4 139.1 (PhC ), 140.2 (MesC ), 144.7 (MesC ), 194.3 (COCH3), 216 (d, J =, CO-P). 31 P NMR (121.5 MHz, C6D6): = 5.47 (t, J = Hz, ) IR (goldengate, [cm-1]): 2924 (w), 2353.9 (vw), 1721 (s), 1690.7 (s), 1607 (m), 1494 (m), 1455 (w), 1391 (w), 1259.3 (s), 1217 (w), 1121 (w), 1087 (m), 1029 (m), 958 (w), 851 (w), 695 (vs), 628 (s).
2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)acetaldehyde (BAPO- acetaldehyde) (B34) Experimental Part 247
In a 20 mL Schlenk flask sodium bis(mesitoyl)phosphide O O (P4) (100 mg, 0.26 mmol, 1 eq.) was dissolved in thf P O (5.00 mL). Chloro-acetaldehyde (0.02 mL, 0.26 mmol, H O 1 eq.) was added with a micro litre syringe. The reaction mixture was stirred for 12 hours at 40°C. After the reaction was completed, the precipitate of sodium chloride was filtered off and the yellow filtrate was evaporated in vacuo at room temperature. The remaining oil was dissolved in ethanol and 0.0029 mL (0.26 mmol, 1 eq.) hydrogen peroxide were added with a micro litre syringe. After 4 hours, the phosphane was completely oxidised. The solvent was removed and the product dried in high vaccum for two hours. (Yield: 75.9 mg, 0.20 mmol, 76%).
1 H NMR (300.1 MHz, C6D6): = 0.42 (s, 2 H, PCH2), 2.14 (s, 6 H, p-CH3), 2.51 (s,
12 H, p-CH3), 6.72 (s, 4 H, Mes-CH). 31 P NMR (121.5 MHz, C6D6): = 18.67 (t, J = 9.8 Hz). IR (goldengate, [cm-1]): 2960 (w), 2920 (w), 1656 (C=O, m), 1609 (m), 1441 (w), 1260 (m), 1159 (m), 1999 (m), 951 (m). UV/ vis (acetonitrile): 372 nm (max.)
2-(bis(2,6-dimethoxybenzoyl)phosphino)acetaldehyde (MeOBAP acetaldehyde) (B35a)
Sodium bis(2,6-dimethoxybenzoyl)phosphide (200 mg, O O 0.52 mmol, 1 eq.) was dissolved in dme (5 mL). To this O solution chloroacetaldehyde (45 %) (0.08 mL, 0.52 mmol, O P 1 eq.) was added at room temperature. After stirring the O O O reaction mixture for 2 hours at 60°C, the solvent was H removed in vacuo at room temperature (Yield: not determined).
Experimental Part 248
1 H NMR (300.1 MHz, C6D6): δ = 3.35 (s, 2 H, P-CH2), 3.38 (s, 12 H, O-CH3), 6.29 (d, 4 H, Ar-H, 3J = 8.4 Hz), 7.06 (t, 2 H, Ar-H, 3J = 8.4 Hz). 31 1 P{ H}-NMR (121.5 MHz, C6D6): δ = 44.8 (s). 13 1 C NMR (62.9 MHz, C6D6): δ = 31.9 (d, P-CH2, J = 14.4 Hz), 55.4 (s, O-Me), 104.0 (s, Ar-C3), 104.1 (s, Ar-C1), 130.0 (s, Ar-C4), 157.3 (s, Ar-C2), 189.3 (s, 1C,
C=Oaldehyde), 210.57 (s, C=Oacyl).
2-(bis(2,6-dimethoxybenzoyl)phosphoryl)acetaldehyde (MeOBAPO acetaldehyde) (B35)
To a solution of MeOBAP acetaldehyde (210 mg, 0.52 mmol, O OO O 1eq.) in ethanol (8 mL), hydrogen peroxide (30%) (0.06 mL,
P 0.52 mmol, 1 eq.) was added slowly with a microlitre syringe. O O The reaction mixture was stirred for 30 minutes. O O H Subsequently, the solvent was removed in vacuo at room temperature and the MeOBAPO acetaldehyde was once again dissolved in ethanol. After filtration of the sodium bromide the solvent was removed in vacuo to yield a yellow oil (Yield: 82 %, 179 mg, 0.43 mmol).
1 H-NMR (300.1 MHz, C6D6): δ = 3.34 (s, 2 H, P-CH2), 3.37 (s, 12 H, O-CH3), 6.29 (d, 4 H, Ar-H, 3J = 8.4 Hz), 7.06 (t, 2 H, Ar-H, 3J = 8.4 Hz). 31 1 P{ H}-NMR (101.3 MHz, C6D6): δ = 24.9 (s). 13 3 C-NMR (75.5 MHz, C6D6): δ = 31.9 (P-CH2), 55.3 (O-Me), 103.1 (Ar-C ), 103.8 1 4 2 (Ar-C ), 129.61 (Ar-C ), 157.2 (Ar-C ), 198.7 (C=Oaldehyde), 203.5 (C=Oacyl). -1 IR (cm ): 2961 (s), 2917 (s), 2848.6 (m), 1719 (s, C=Oaldehyde), 1595 (s, C=Oacyl st.), 1474 (m), 1433 (m), 1392 (s), 1367 (s), 1299 (m), 1254 (m), 1171 (m), 1108 (m), 1074 (m), 1028 (w). UV/vis (acetonitrile) in nm: 264 (max). Experimental Part 249
((2-(1,3-dioxolan-2-yl)ethyl)phosphinediyl)bis(mesitylmethanone) (B36a)
Sodium bis(mesitoyl)phosphide (P4) (2.00 g, 5.74 mmol, O 1 eq.) was dissolved in thf (20.0 mL). 2-(2-B rom ethyl)-
P 1,3-dioxolan (0.80mL, 6.80 mmol, 2.74 eq.) and a O catalytic amount of sodium iodide were added and the O yellow solution was stirred for 48h at 50°C. A white O precipitate of sodium bromide was formed. After removing the sodium bromide by filtration, the solution was evaporated in vacuo. The remaining yellow oil was dried in high vacuum for 4 hours. (Yield: 1.64 g, 3.85 mmol, 67%)
1 H NMR (250.1 MHz, C6D6): = 1.51 (t, J = 3 Hz, 2 H, PCH2), 1.58 (s, 2 H, CH2),
2.33 (s, 9 H, Ar-CH3), 2.42 (s, 9 H, Ar-CH3), 3.63 (t, J = 6 Hz, 4 H, OCH2), 4.91 (t, J
= 4.5 Hz, 1 H, OCH), 6.60 (s, 2 H, CarH), 6.75 (s, 2 H, CarH). 13 C NMR (62.9 MHz, C6D6): = 1.1 (PCH2), 19.7 (o-Ar-CH3), 25.5 (p-Ar-CH3), 37.4
(CH2), 64.6 (OCH2), 102.4 (CH), 127.4-128.9 (m-CarH), 133.6 (CCO), 135.1 (o-
CarCH3), 138.9 (p-CarCH3), 216.8 (CO), 217.4 (CO). 31 P NMR (101.3 MHz, C6D6): = 51.0 (t, J = 10.0 Hz).
(((1,3-dioxolan-2-yl)methyl)phosphoryl)bis(mesitylmethanone) (B36)
((2-(1,3-dioxolan-2-yl)ethyl)- phosphinediyl)bis
O O (mesitylmethanone) (B36a) (1.64 g, 3.85 mmol, 1 eq.)
P was dissolved in degassed toluene (15 mL). Degassed O distilled water (9.00 mL), potassium carbonate O (100 mg) and hydrogen peroxide (30%) (0.50 mL, O 3.85 mmol, 1 eq.) were added. The mixture was stirred for 10 h at 50°C. Afterwards diethyl ether (50 mL) was added and the ether layer was washed with an aqueous sodium carbonate solution (2%) and a saturated sodium chloride solution. The ether solution was dried with sodium sulfate. After the filtration of the Experimental Part 250 sodium sulfate the filtrate was concentrated under vacuum. The remaining yellow oil was dried under high vacuum for two hours (Yield: 1.60 g, 3.62 mmol, 94%).
1 H NMR (250.1 MHz, C6D6): = 1.59 (s, 2 H, PCH2), 2.26 (s, 2 H, CH2), 2.44 (s, 6
H, Ar-CH3), 2.47 (s, 12 H, Ar-CH3), 3.63 (t, J = 6 Hz, 4 H, OCH2), 4.82 (t, J =
4.5 Hz, 1 H, OCH), 6.63 (s, 2 H, CarH), 6.75 (s, 2 H, CarH). 13 C NMR (62.9 MHz, C6D 6): = 1.2 (PCH2), 19.5 (o-Ar-CH3), 27.5 (p-Ar-CH3), 37.5 2 3 (CH2), 64.5 (OCH2), 64.7 (OCH2), 103.2 (CH), 134.5 (MesC ), 135.9 (MesC ), 136.5 (MesC1), 137.6 (MesC4), 216.4 (d, J = 50.3 Hz, CO). 31 P NMR (101.3 MHz, C6D6): = 27.4 (t., J = 9.5 Hz). IR: (goldengate, [cm-1]): 2389 (w), 2280 (s), 2157 (m), 2020 (m), 1965 (m), 1720 (m), 1617 (m), 1550 (w), 1454 (m), 1330 (s), 1283 (w), 1161 (m), 1013 (m), 812 (s), 774 (m), 759 (w), 743 (w), 709 (w), 662 (w). UV/ vis (acetonitrile): 361 nm (max.), 392 nm (shoulder).
3-(bis(2,4,6-trimethylbenzoyl)phosphoryl)propanal (B37)
In a 50 mL Schlenk flask (((1,3-dioxolan-2-yl)methyl)- O O phosphoryl)-bis(mesitylmethanone) (50 mg, 0.11 mmol, P 1 eq.) was dissolved in diethylether (1 mL) and a O H mixture of trifluoroacetic acid (4.5 mL) and distilled O water (0.5 mL) was added. The mixture was stirred at 0°C for 3 hours. 5 mL diethylether were added afterwards and the ether layer was separated and washed with 10 mL of sodium hydrogencarbonate solution (2%) and 10 L of brine. In the last step, the ether layer was dried with sodium sulfate and the solvent was evaporated. The pale yellow product remains (Yield: 23%).
1 H NMR (300.1 MHz, C6D6): = 8.85 (s, 1 H, CHO). 31 P NMR: (101.3 MHz, C6D6): = 22.6. Experimental Part 251
2-(bis(2,4,6-trimethylbenzoyl)phosphino)acetic acid (B38a)
Sodium bis(mesitoyl)phosphide (P4) (1.00 g, 2.88 mmol, 1 eq.) was dissolved in thf (5.00 mL). Bromoacetic acid O (0.40 g, 2.88 mmol, 1 eq.) was dissolved in thf (5.00 mL). P The solutions were put together and stirred for 24 hours O HO at room temperature. A white precipitate of sodium O bromide was formed. After removing the sodium bromide by filtration, the solution wa s evaporated in vacuo. The remaining yellow oil was dissolved in diethyl ether and washed with an aqueous and degassed ammonium chloride solution (5%). After the ether solution was dried with sodium sulfate, the solvent was evaporated in vacuum at room temperature and dried in high vacuum for 4 hours. (Yield: 0.96 g, 2.51 mmol, 87%)
1 H NMR (250.1 MHz, C6D6): = 1.57 (s, 2 H, PCH2), 2.22-2.42 (m, 18 H, Ar-CH3),
6.55 (s, 2 H, CarH), 6.45 (s, 2 H, CarH), 11.08 (s, 1 H, OH). 31 P NMR (101.3 MHz, C6D6): = 46.7.
2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)acetic acid (BAPO-acetic acid) (B38)
2-(Bis(2,4,6-trimethylbenzoyl)phosphino)-acetic acid O O (B38a) (1.00 g, 2.60 mmol, 1 eq.) was dissolved in P O degassed ethanol (5.00 mL) and hydrogen peroxide HO O (30%) (0.29 mL, 2.60 mmol, 1 eq.) was added. The solution was stirred at 40°C for one hour. The ethanol was removed in vacuo at room temperature. A white crystalline powder was obtained, which can be easily recrystallised from 40°C warm water (Yield: Quantitative).
MP.: 118.9 °C (decomposition). 1 H NMR (300.1 MHz, C6D6): = 1.66 (s, 1 H, PCH2), 2.40 (s, 6 H, p-CH3), 2.47 (s, 3 12 H, o-CH3), 6.63 (s, 4 H, Mes-C ). Experimental Part 252
13 C NMR (62.9 MHz, C6D6): = 1.2 (d, JCP = 10.9, PCH2), 19.8 (o-Ar-CH3), 28.0 (p- 2 3 1 4 Ar-CH3), 129.5 (MesC ), 132.4 (MesC ), 138.2 (MesC ), 142.2 (MesC ), 169.1
(COOH), 212.2 (d, JCP = 56.61 Hz, CO). 31 P NMR (121.5 MHz, C6D6): = 19.6 (t, J = 10.9 Hz). IR (goldengate, [cm-1]): 2389 (w), 2280 (s), 1720 (m), 1610 (m), 1453 (m), 1330 (s), 1260 (m), 1161 (m), 1089 (m), 1012 (m), 812 (s), 774 (w), 759 (w), 742 (w), 695 (w), 664 (w). UV/vis (acetonitrile):270 nm (max.), Shoulder: 335, 370 nm (shoulder).
2-(bis(2,6-dimethoxybenzoyl)phosphino)acetic acid (MeOBAP acetic acid) (B39a)
Sodium bis(2,6-dimethoxybenzoyl)phosphide (100 mg, 0.26 mmol, 1 eq.) was dissolved in dme (5 mL), O O O bromoacetic acid (36 mg, 0.26 mmol, 1 eq.) was dissolved
P in dme (2 mL) and added to this solution at room O O O temperature. After stirring the reaction mixture for 2 hours, O HO the solvent was removed in vacuo at room temperature (Yield: not determined).
1 2 H NMR (300.1 MHz, C6D6): δ = 3.37 (d, 2 H, P-CH2, J = 0.9 Hz), 3.40 (s, 12 H, O- 3 3 CH3), 6.31 (d, 4 H, Ar-H, J = 8.4 Hz), 7.07 (t, 2 H, Ar-H, J = 8.4 Hz). 31 1 P{ H}-NMR (101.3 MHz, C6D6): δ = 49.2 (s) 13 C NMR (75.5 MHz, C6D6): δ = 29.4 (s, 1C, P-CH2), 55.4 (s, 4C, O-Me), 103.8 (s. 4C, Ar-C3), 104.1 (s, 2C, Ar-C1), 129.8 (s, 2C, Ar-C4), 157.4 (s, 4C, Ar-C2), 165.0
(s, 1C, C=Oacid), 211.9 (s, 2C, C=Oacyl).
2-(bis(2,6-dimethoxybenzoyl)phosphoryl)acetic acid (MeOBAPO-acetic acid) (B39) Experimental Part 253
To a solution of MeOBAP-acetic acid (109 mg, 0.26 mmol, O 1eq.) in ethanol (4 mL), hydrogen peroxide (30 %) (0.03 ml, OO O 0.26 mmol, 1 eq.) was added slowly. The reaction mixture P O O was stirred for 30 minutes. Subsequently, the solvent was O OH removed in vacuo and the MeOBAPO-acetic acid was once O again dissolved in ethanol. After filtration of the sodium bromide the solvent was evaporated in vacuo to yield crystalline MeOBAPO-acetic acid (Yield: 78 %, 88 mg, 0.20 mmol).
1 8 2 H NMR (300.1 MHz, d -thf): δ = 3.34 (d, 2 H, P-CH2, J = 3.9 Hz), 3.37 (s, 12 H, 3 3 O-CH3), 6.29 (d, 4 H, Ar-H, J = 8.4 Hz), 7.06 (t, 2 H, Ar-H, J = 8.4 Hz). 31P{1H}-NMR (121.5 MHz, d8-thf): δ = 22.2 (s). 13 8 3 C NMR (75.5 MHz, d -thf): δ = 29.4 (P-CH2), 55.3 (O-Me), 103.8 (Ar-C ), 104.3 1 4 2 (Ar-C ), 129.7 (Ar-C ), 157.1 (Ar-C ), 164.2 (C=Oacid), 203.6 (C=Oacyl). IR (cm-1): 3104 (s), 3003 (s), 2972 (s), 2939 (s), 2840 (s), 2528 (br.), 1719 (s,
C=Oacid), 1595 (s, C=Oacyl), 1473 (m), 1449 (m), 1433 (s), 1391 (m), 1367 (m), 1293 (s), 1277 (s), 1252 (s), 1168 (m), 1105.7 (s), 1075.0 (s), 1027.4 (m). UV/vis (acetonitrile): 264 nm (max).
11-(bis(2,4,6-trimethylbenzoyl)phosphoryl)undecanoic acid (BAPO- undecanoic acid) (B40)
In a 20 mL Schlenk flask sodium bis(mesitoyl)phosphide (P4) (251.9 mg, 0.724 mmol,
O 1 eq.) was dissolved in thf (5.00 mL). 11-bromo- O O P undecanoic acid (197.8 mg, 0.72 mmol, 1 eq.) was OH O 8 added and the solution was stirred for two days at 40°C. The white precipitate of sodium bromide was filtered off and the solvent of the yellow filtrate was removed in vacuo at room temperature. The phosphane 31 remains as a yellow oil ( P NMR (C6D6, 81.0 MHz): δ = 51.5). After solving the phosphane in ethanol, hydrogen peroxide (10%) (0.24 g, 0.72 mmol, 1 eq.) was added and the solution was stirred for 40 minutes at 40°C. The ethanol was Experimental Part 254 evaporated in vacuo at room temperature and the solid pale yellow product was dried in high vacuum (Yield: 312.3 mg, 0.594 mmol, 82%).
1 H NMR (300.1 MHz, C6D6): = (300.1 MHz, C6D6): = 1.26-1.31 (m, 12H, -CH2-),
1.48-1.50 (m, 4 H, -CH2-), 2.38 (t, 2 H, J = 5.7 Hz, -CH2-COOH), 2.42 (s, 6 H, p- 3 CH3), 2.53 (s, 12 H, o-CH3), 6.74 (s, 4 H, Mes-C ). 13 C NMR (62.9 MHz, C6D6): = 19.9 (d, JCP = 52.8 Hz, P-CH2), 20.1 (s, p-CH3),
25.3 (CH2), 28.0 (o-CH3), 28.2 (CH2), 29.2 (CH2), 29.5 (CH2), 32.9 (CH2-COOH), 133.5 (MesC2), 138.4 (MesC3), 139.2 (MesC1), 142.2 (MesC4), 180.2 (COOH),
218.3 (d, JCP = 52.8 Hz, CO-P) 31 P NMR (121.5 MHz, C6D6): = 18.12 (t, JCP = 9.8 Hz). UV/Vis (acetonitrile): 284 nm (max.), 311 nm (max.), 384 nm (max.) sodium 2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)acetate (B42)
BAPO-acetic acid (0.1 g, 0.25 mmol, 1 eq.) was O O suspended in distilled water (2 mL) and sodium P O hydrogencarbonate (21.0 mg, 0.25 mmol, 1 eq.) were NaO O added. A clear pale yellow solution was obtained. After removing the water in vacuo at room temperature, a pale yellow crystalline powder was isolated (Yield: quantitative). The same procedure can be performed to synthesise other alkali salts of BAPO-acetic acid from carbonates or hydrogencarbonates. (e.g. with potassium hydrogen carbonate, or lithium carbonate).
1 H NMR (300.1 MHz, D2O): = 1.66 (s, 1 H, PCH2), 2.43 (s, 6 H, p-MesCH3), 2.47 3 (s, 12 H, o-MesCH3), 6.64 (s, 4 H, Mes-C ). 13 C NMR (62.9 MHz, D2O): = 1.2 (d, JCP = 10.9, PCH2), 19.8 (o-Ar-CH3), 28.0 (p- 2 3 1 4 Ar-CH3), 129.5 (MesC ), 132.4 (MesC ), 138.2 (MesC ), 142.2 (MesC ), 169.1
(COO), 213.4 (d, JCP = 56.86 Hz, CO). 31 P NMR (121.5 MHz, D2O): = 23.6 (t, J = 10.8 Hz). Experimental Part 255 methyl 2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)acetate (B43)
Sodium bis(mesitoyl)phosphide (P4) (250 mg, 0.72 mmol, 1 eq.) was dissolved in toluene (5 mL). Bromoacetic acid methylester (109.8 mg, 0.72 mmol, 1 eq.) was added and O O the solution was stirred for 12 hours at room temperature. P O The white precipitate of sodium bromide was removed by O OMe filtration and the solvent was evaporated under reduced 31 pressure at room temperature. The remaining phosphane ( P NMR (C6D6, 81.0 MHz): δ = 46.7) was a pale yellow oil. It was dissolved in toluene (10 mL). Hydrogen peroxide (10%) (0.20 mL, 0.72 mmol, 1 eq.) was added. After stirring for 12 hours at 40°C the oxidation was finished. Diethyl ether (50 mL) was added and the solution was washed twice with a sodium hydrogen carbonate solution (2%), once with brine and finally with distilled water. After drying the diethyl ether solution with sodium sulfate and filtration, the solution was concentrated in vacuo. A yellow oil was obtained (Yield: 227 mg, 0.55 mmol, 77%).
1 H NMR (250 MHz, C6D6, 25 °C): = 6.43 (s, 4 H, MesCH), 3.88 (t, 3 H, J =
7.2 Hz, OCH3), 3.23 (s, 2 H, PCH2), 2.23 (s, 12 H, o-MesCH3), 1.97 (s, 6 H, p-
MesCH3). 31 1 P{ H} NMR (101.3 MHz, C6D6): = 26.2 (t, J = 9.8 Hz). UV/vis (acetonitrile): 240 (shoulder), 310 (max), 360 (max), 389 (max).
4-nitrophenyl 2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)acetate (B44)
Sodium bis(mesitoyl)phosphide (P4) (321 mg, 0.92 mmol, 1 eq.) was dissolved in dme (2.00 mL). 4- O O Nitrophenylbromoacetate (242 mg, 0.93 mmol, 1 eq.) was P O O added and the solution was stirred for one hour at 0°C (ice O bath). A white precipitate of sodium bromide was formed. After removing the sodium bromide by filtration, the
NO2 Experimental Part 256 solution was evaporated in vacuo. 31 The remaining phosphane ( P NMR (C6D6, 81.0 MHz): δ = 43.8) was a yellow oil. It was dissolved in dme (5 mL) and hydrogen peroxide (0.1 mL, 0.93 mmol, 1 eq.) was added. The solution was stirred for 20 minutes at room temperature. After the reaction was finished, the dme was removed in vacuo. The remaining dark yellow oil was dissolved in diethyl ether (10 mL) and the solution was washed twice with an aqueous sodium hydrogen carbonate solution (2%) (5 mL), with brine (5 mL) and it was dried over magnesium sulfate (1.0 g), which was filtered off afterwards. After evaporation of the diethyl ether, a dark yellow oil was obtained. It is important to complete the reaction within one day because the not oxidised phosphane is unstable and auto-oxidation takes place (Yield: 273 mg, 0.52 mmol, 57%).
1 H NMR (250.13 MHz, C6D6): δ = 7.92 (d, J = 9.25 Hz, 2 H, O2NCCH), 6.61 (s, 4 3 H, MesC ), 6.47 (d, J = 9.25 Hz, 2 H, O2NCCH2CH2), 2.40 (s, 12 H, p-MesCH3),
2.11 (s, 2 H, PCH2), 2.00 (s, 6 H, o-MesCH3). 13 C NMR (62.90 MHz, C6D6): δ = 120.2 (d, J = 52.4 Hz, PCO), 163.2 (-CH2COO-), 1 4 4 1 3 154.4 (ArC -O), 145.5 (ArC -NO2), 142.0 (MesC ), 136.5 (MesC ), 135.6 (MesC ), 2 2 3 129.5 (MesC ), 123.8 (ArC ), 121.2 (ArC ), 20.8 (p-MesCH3), 19.8 (p-MesCH3),
19.4 (PCH2). 31 P NMR (101.25 MHz, C6D6): δ = 18.0 (t, J = 11.75 Hz). IR (goldengate [cm-1]): 2965 (w), 2923 (w), 2362 (w), 1765 (m), 1718 (w), 1678 (w), 1609 (m), 1592 (m), 1522 (s), 1489 (m), 1450 (w), 1378 (w), 1345 (s), 1285 (m), 1201 (s), 1161 (s), 1110 (s), 1035 (w), 1013 (w), 957 (w), 929 (w), 852 (s), 752 (m), 721 (w), 619 (w). UV/vis (toluene): 360 nm (max.), 395 nm (shoulder).
Experimental Part 257
2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)acetamide (B45)
Sodium bis(mesitoyl)phosphide (P4) (250 mg, 0.72 mmol, 1 eq.) was dissolved in toluene (5 mL). Bromoacetic amide
O (99.0 mg, 0.72 mmol, 1 eq.) was added and the solution was O 31 P stirred over night. The colourless BAP ( P NMR (101.3 MHz, O C6D6): δ = 47.7) was formed. The white precipitate was filtered H N O 2 off, hydrogen peroxide (10%) (0.244 mL, 0.72 mmol, 1 eq.) was added and the solution was stirred over night. Diethyl ether (5 mL) was added and the solution was washed with sodium hydrogen carbonate solution (2%) and brine. After drying with sodium sulfate, the solvent was evaporated. A pale yellow product was obtained (Yield: 87 %, 0.63 mmol, 251.4 mg).
1 H NMR (300.1 MHz, C6D6): = 1.64 (s, 6 H, p-MesCH3), 2.34 (s, 12 H, o-
MesCH3), 2.43 (s, 2 H, CH2), 5.21 (br., 2 H, NH2), 6.83 (MesCH). 13 C NMR (62.9 MHz, C6D6): = 19.5 (o-MesCH3), 22.8 (p-MesCH3), 58.4 (P-CH2), 2 3 1 4 127.4 (MesC ), 128.7 (MesC ), 135.7 (MesC ), 139.2 (MesC ), 174.1 (CONH2), 217.3 (MesCO). 31 P NMR (121.5 MHz, C6D6): = 20.6 (t, J = 4.7 Hz).
2-(2-(bis(2,4,6-trimethylbenzoyl)phosphoryl)ethyl)isoindoline-1,3-dione (B46)
Sodium bis(mesitoyl)phosphide (P4) (250 mg O O (0.72 mmol, 1 eq.) was dissolved in toluene (5 mL). N- P O O (2-Bromoethyl)phthalimide was added and the solution N was stirred over night. The solution was found to 31 O contain the colourless BAP ( P NMR (C6D6, 80.0 MHz): δ = 46.4). The white precipitate was filtered off, hydrogen peroxide (10%) (0.244 mL, 0.72 mmol, 1 eq.) was added and the solution was stirred over night. Diethyl ether (5 mL) was added and the solution was washed with sodium hydrogencarbonate solution (2%) and brine. After drying with sodium sulfate, the Experimental Part 258 solvent was evaporated. A pale yellow product was obtained (Yield: 76 %, 0.55 mmol, 283.5 mg).
1 H NMR (300.1 MHz, C6D6): = 2.18 (s, 6 H, p-MesCH3), 2.46 (s, 12 H, o-
MesCH3), 2.53 (br., 2 H, CH2), 3.77 (br., 2 H, NCH2), 6.68 (s, MesCH), 7.26-7.51 (m, 4 H, Ar-H). 13 C NMR (62.9 MHz, C6D6): = 19.7 (o-MesCH3), 22.2 (p-MesCH3), 28.2 (N-CH2), 2 3 2 3 39.1 (P-CH2), 127.3 (MesC ), 128.3 (MesC ), 128.8 (ArC ), 128.8 (ArC ) 129.3 (ArC1), 133.4 (ArC4), 135.7 (MesC1), 139.2 (MesC4), 166.8 (CO), 218.4 (MesCO). 31 P NMR (121.5 MHz, C6D 6): = 22.8.
((3-(triethoxysilyl)propyl)phosphoryl)bis(mesitylmethanone) (B47)
Sodium bis(mesitoyl)phosphide (P4) (4.28 g, 12.3 mmol,
O O 1 eq.) was dissolved in thf (10 mL). 3-Iodopropyl-
P triethoxysilane (1.85 g, 8.78 mmol, 1 eq.), which was O prepared corresponding to literature,262 were added and OEt the solution was stirred for 3 hours at 50°C. The thf was Si EtO OEt evaporated in vacuo and the remaining oil was dissolved in toluene. A white precipitate of sodium iodide was formed. After removing the sodium iodide by filtration over celite, the solution was evaporated in vacuo. 31 The remaining phosphane ( P NMR (C6D6, 80.0 MHz): δ = 51.39) was a pale yellow oil. It was dissolved in 10 mL toluene. 50 mg potassium hydrogen carbonate were dissolved in 3.80 mL (12.3 mmol, 1 eq.) hydrogen peroxide (10%). This solution was added to the toluene solution of the phosphane. The oxidation was completed after stirring for 4 hours at 40°C. Diethyl ether (50 mL) was added and the solution was washed twice with a sodium hydrogen carbonate solution (2%), once with brine and finally with distilled water. After drying with magnesium sulfate and filtration the solution was concentrated in vacuo. A yellow oil was obtained (Yield: 6.19 g, 11.3 mmol, 92%).
Experimental Part 259
1H NMR (300.13 MHz, C6D6): δ = 6.66 (s, 4 H, MesC4), 3.83 (q, J = 7.00, 6 H,
OCH2CH3), 2.49 (s, 12 H, o-MesCH3), 2.07 (s, 6 H, p-MesCH3), 1.45–1.37 (br.,
2 H, PCH2CH2), 1.24 (t, J = 7.00 Hz, 9 H, OCH2CH3), 1.15–0.93 (br., 2 H, PCH2),
0.81 (t, J = 7.80 Hz, 2 H, SiCH2). 13C NMR (75.48 MHz, C6D6): δ = 217.2 (d, J = 60.38 Hz, CO), 140.6 (MesC4), 1 3 2 135.9 (MesC ), 129.2 (MesC ), 127.6 (MesC ), 58.3 (OCH2CH3), 20.8 (p-MesCH3),
19.8 (o-MesCH3), 18.3 (OCH2CH3), 15.9 (PCH2), 12.6 (SiCH2), 1.2 (PCH2CH2). 31P NMR (121.49 MHz, C6D6): δ = 27.7 (t, J = 9.60 Hz). IR (goldengate [cm-1]): 2974 (w), 2926 (w), 1721 (w), 1675 (w), 1609 (w), 1444 (w), 1390 (w), 1261 (w), 1211 (w), 1195 (w), 1165 (m), 1078 (s), 958 (m), 889 (w), 850 (w), 788 (m), 750 (m), 619 (w). UV/VIS (toluene): 364 nm (max), 397 nm (shoulder).
((3-(diethoxy(methyl)silyl)propyl)phosphoryl)bis(mesitylmethanone) (B48)
Sodium bis(mesitoyl)phosphide (P4) (3.05 g, 8.76 mmol,
O O 1 eq.) wase dissolved in thf (10 mL). 3-Chloropropyl-
P diethoxymethylsilane (1.85 g, 8.78 mmol, 1 eq.) and O sodium iodide (0.48 g, 3.20 mmol, 0.37 eq.) was added OEt Si and the solution was stirred for 18 hours at 50°C. The EtO Me thf was evaporated in vacuo and the remaining oil was dissolved in toluene. A white precipitate of sodium iodide was formed. After removing the sodium iodide by filtration over celite, the solution was evaporated in vacuo. 31 The remaining phosphane ( P NMR (121.49 MHz, C6D6): δ = 44.3) was a pale yellow oil, which was dissolved in toluene (10 mL). Potassium hydrogen carbonate (50 mg) was dissolved in hydrogen peroxide (10%) (1.08 mL, 3.53 mmol, 1 eq.) and this solution was added to the toluene solution of the phosphane. After stirring for 4 hours at 40°C, the oxidation was completed. 50 mL diethyl ether were added and the solution was washed twice with a sodium hydrogen carbonate solution (2%), once each with brine and distilled water. After drying with magnesium Experimental Part 260 sulfate and filtration the solution was concentrated in vacuo. (Yield: 3.98 g, 7.71 mmol, 88%).
1 H NMR (300.13 MHz, C6D6): δ = 6.69 (s, 4 H, MesCH), 3.75 (q, J = 6.93, 4 H,
OCH2), 2.44 (s, 12 H, o-MesCH3), 2.10 (s, 6 H, p-MesCH3), 1.24 (t, J = 6.93, 6 H,
OCH2CH3), 1.08–0.96 (m, 4 H, PCH2 + PCH2CH2), 0.76–0.72 (br., 2 H, SiCH2),
0.39 (s, 3 H, SiCH3). 13 4 C NMR (75.48 MHz, C6D6): δ = 216.3 (d, J = 45.3 Hz, MesCO), 141.0 (MesC ), 1 3 2 135.9 (MesC ), 129.3 (MesC ), 127.2 (MesC ), 57.9 (OCH2CH3), 28.0 (SiCH2CH2),
20.8 (p-MesCH3), 19.8 (o-MesCH3), 18.4 (OCH2CH3), 15.8 (PCH2), -1.1 (SiCH3). 31 P NMR (121.49 MHz, C6D6): δ = 27.7 (br.) IR (goldengate [cm-1]): 2959 (w), 2925 (w), 1718 (w), 1672 (w), 1608 (w), 1450 (w), 1260 (m), 1210 (w), 1193 (m), 1162 (w), 1147 (w), 1076 (s), 1012 (s), 888 (w), 848 (m), 795 (m), 731(m), 694 (w), 617 (w). UV/vis (toluene): 364 nm (max), 394 nm (shoulder).
((3-(diethoxy(phenyl)silyl)propyl)phosphoryl)bis(mesitylmethanone) (B49)
Sodium bis(mesitoyl)phosphide (P4) (250 mg, 0.72 mmol, 1 eq.) was dissolved in a mixture thf (5 mL) O O and dme (3 mL). 3-Chloropropyldiethoxyphenylsilane P O (200 mg, 0.72 mmol, 1 eq.) was added and the solution was stirred for 20 days at 50°C. The white precipitate of EtO Si OEt sodium chloride was removed by filtration and the solvent was evaporated under reduced pressure at room temperature. The 31 remaining phosphane ( P NMR (121.49 MHz, C6D6): δ = 45.2) was a pale yellow oil. It was dissolved in toluene (10 mL). Potassium hydrogen carbonate (50 mg) was dissolved in hydrogen peroxide (10%) (0.20 mL, 0.72 mmol, 1 eq.). This solution was added to the toluene solution of the phosphane. After stirring for 17 hours at Experimental Part 261
40°C the oxidation was completed. Diethyl ether (50 mL) was added and the solution was washed twice with a sodium hydrogen carbonate solution (2%), once with brine and finally with distilled water. After drying the diethyl ether solution with sodium sulfate and filtration, the solution was concentrated in vacuo. A yellow oil was obtained (Yield: 369 mg, 0.64 mmol, 89%).
1 H NMR (300.13 MHz, C6D6): δ = 7.82-7.81 (m, 2 H, o-PhCH), 7.33-7.27 (m, 2 H, p-PhCH), 6.65 (s, 4 H, MesCH), 3.82-3.75 (br., 4 H, OCH2CH3), 2.45 (s, 12 H,o-
MesCH3), 2.07 (s, 6 H, p-MesCH3), 1.91-1.83 (m, 2 H,PCH2CH2), 1.25-1.20 (m,
6 H, OCH2CH3), 1.00-0.88 (m, 2 H, SiCH2), 0.59-0.50 (m, 2 H, PCH2). 31 P NMR (121.49 MHz, C6D6): δ = 27.8 (t, J = 9.48 Hz) IR (goldengate [cm-1]): 2963 (w), 2360 (w), 2159 (w), 1724 (w), 1609 (w), 1413 (w), 1259 (m), 1081 (m), 1012 (s), 863 (w), 791 (s), 738 (w), 701 (w). UV/vis (Chloroform): 285 nm (max.), 361 nm (max), 388 nm (shoulder).
((perfluorooctyl)phosphoryl)bis(mesitylmethanone) (B50)
Sodium bis(mesitoyl)phosphide (P4) (66 mg, 0.178 mmol, 1 eq.) was dissolved in thf (2.00 mL). The yellow solution was heated up to 40°C and perfluoro-1-bromooctan (0.46 mL, O O 0.178 mmol, 1 eq.) was added with a microlitre syringe. After P two days the reaction was finished and the white precipitate O CF8 17 of sodium bromide was removed by filtration. The pale yellow filtrate was concentrated in vacuo at room temperature and the remaining yellow 31 oil was dried in high vacuum. The isolated phosphane ( P NMR (81.0 MHz, C6D6) = 46.4 MHz) was dissolved in ethanol (5 mL) and oxidised by adding hydrogen peroxide (30%) (0.02 mL, 0.178 mmol, 1 eq.) and stirring the solution for one hour at 40°C (Yield: 110.2 mg, 0.145 mmol, 82%).
1 H NMR: (200.0 MHz, C6D6): = 2.12 (s, 3H, o-CH3), 2.53 (s, 3H, p-CH3), 6.62 (s, MesC4H). Experimental Part 262
13 C NMR: (50.3 MHz, C6D6): = 20.2 (s, CH3, o-CH3), 28.0 (s, CH3, p-CH3), 81.3
(br., CF2), 93.2 (br., CF2), 105.8 (d., JCP = 35.3 Hz), CF2, P-CF 2 ), 107.2 (br., CF2), 3 114.2 (br., CF2), 115.4 (br., CF2), 116.8 (br., CF2), 117.1 (br., CF3), 129.1 (Mes-C ), 1 2 4 139.4 (Mes-C ), 140.1 (Mes-C ), 140.9 (Mes-C ), 226.0 (d, JCP = 51.8 Hz, MesCO- P). 31 P NMR: (81.0 MHz, C6D6): = 21.5 (br). UV/vis (acetonitrile): 289 nm (max.), 385 (max.).
((perfluorophenyl)phosphoryl)bis(mesitylmethanone) (B51)
Sodium bis(mesitoylphosphide) (P4) (250 mg,
F 0.72 mmol, 1 eq.) was dissolved in thf (5 mL). O F F Hexafluorobenzene (133.9 mg, 0.72 mmol, 1 eq.) was P O added and the solution was stirred for 12 h at 60°C. The F O F solvent was evaporated and the residual phosphane was dissolved in ethanol (5 mL). Hydrogen peroxide (10%) (0.244 mL, 0.72 mmol, 1 eq.) was added. Subsequently, the solution was stirred over night at room temperature. 5 mL diethyl ether was added and the solution was washed with sodium hydrogencarbonate solution (2%) and brine. After drying with sodium sulfate, the solvent was evaporated. The pale yellow product was obtained (Yield: 63 %, 0.45 mmol, 228.6 mg).
31 P NMR (121.5 MHz, C6D6): = 2.4. bis(perfluorooctanoyl)perfluorooctanylphosphane (B52a)
The solution of sodium bis(perfluorooctanoyl)phosphide O O (2.60 g, 3.07 mmol, 1 eq.) in thf (8 mL) was cooled down to C7F15 P C7F15 0°C in an ice water bath. Subsequently, 1- C8F17 bromoperfluorooctane (0.79 mL, 3.07 mmol, 1 eq.) was dissolved in thf (4.2 mL) and added dropwise to the solution. After stirring the solution for 16 hours, the solvent was removed in vacuo at room temperature. 13C Experimental Part 263
NMR could not be measured, due to the bad solubility of the product in deuterated solvents.
31 2 3 P NMR (121.5 MHz, C6D6): δ = 71.55 (tt, J = 66.9 Hz, J = 13.1 Hz). 19 F-NMR (188.3 MHz, C6D6): δ = -126.16 (m, 4 F), -122.68 (m, 4 F), -122.34 (m, 4 F), -121.91 (m, 4 F), -121.39 (m, 4 F), -121.02 (m, 4 F), -118.08 (tt, 4 F, 3J = 4 3 4 12.1 Hz, J = 3.0 Hz), -117.29 (m, 4 F), -80.98 (tt, 6 F, CF3, J = 10.0 Hz, J = 2.3 3 4 Hz), -64.24 (tt, 3F, CF3, J = 14.1 Hz, J = 2.6 Hz). bis(perfluorooctanoyl)perfluorooctanyphosphanoxide (B52)
O O Bis(perfluorooctanoyl)-perfluorooctanylphosphane (3.78 g, O 3.04 mmol, 1 eq.) was dissolved in ethanol (20 mL). To this C7F15 P C7F15 C8F17 solution hydrogen peroxide (30 %) (0.3 mL, 3.04 mmol, 1 eq.) was added slowly. The reaction mixture was stirred for 30 minutes. The sodium bromide precipitate was removed by filtration. The filtrate was concentrated in vacuo at room temperature to yield bis(perfluorooctanoyl)- perfluorooctanylphosphanoxide (Yield: 95 %, 2.88 mmol, 3.64 g).
31 P NMR (121.5 MHz, C6D6): δ = 7.8 (m). 13 C NMR (75.5 MHz, C6D6): δ = 103.7 (m), 107.0 (m), 110.0 (m), 113.7 (m), 203.3 (s, C=O). 19 F-NMR (188.3 MHz, C6D6): δ = -126.23 (m, 4 F), -122.73 (m, 4 F), -122.36 (m, 4 F), -121.99 (m, 4 F), -121.39 (m, 4 F), -121.06 (m, 4 F), -118.12 (tt, 4 F, 3J = 4 3 4 12.1 Hz, J = 3.0 Hz), -117.33 (m, 4 F), -81.02 (tt, 6 F, CF3, J = 10.0 Hz, J = 2.3 3 4 Hz), -64.27 (tt, 3 F, CF3, J = 14.1 Hz, J = 2.6 Hz). -1 IR (goldengate, [cm ]): 2445.9 (m), 2360.4 (m), 1697.4 (s, C=Oacyl st.), 1421 (s), 1363 (m), 1323.7 (m), 1233.2 (m), 1200.0 (m), 1143.1 (m), 1105.7 (w), 1018.2 (m). UV/vis (acetonitrile): 257 nm (max.). Experimental Part 264 bis(2,4,6-trimethylbenzoyl)phosphinecarbonitrile (B56a)
O O Sodium bis(mesitoyl)phosphide (P4) (370 mg, 1.07 mmol, 1 eq.) was dissolved in thf (10.0 mL). P CN Bromocyan (113 mg, 1.07 mmol, 1 eq.) was added. The reaction takes place immediately. A white precipitate of sodium bromide was observed. After removing the precipitate by filtration the solution was evaporated in vacuo. The remaining yellow oil was dried in high vacuum for 4 hours (Yield: 259 mg, 0.07 mmol, 69%).
1 H NMR: (250.1 MHz, CDCl3): = 2.23 (s, 12 H, o-Mes-CH3), 2.26 (s, 6 H, p-Mes- 4 CH3), 6.42 (s, 2 H, MesC H). 31 P NMR: (101.3 MHz, C6D6): = 0.13. bis(2,6-dimethoxybenzoyl)-N-piperidinylphosphanoxide (B58)
Sodium bis(2,6-dimethoxybenzoyl)phosphide (200 mg, 0.52 mmol, 1 eq.) was dissolved in thf (5 mL). Acetic acid O O O (0.03 mL, 0.52 mmol, 1 eq.) was added at room O temperature. After stirring the reaction mixture for 2 hours, O P O NO the solvent was removed in vacuo at room temperature. 2- Propanol (10 mL) was added and the solution was stirred at 70°C under atmospheric conditions for 80 hours according to Lit263. The solvent was replaced with dichloromethane (5 mL). To this solution triethylamine (0.07 mL, 0.52 mmol, 1 eq.) and piperidine (0.05 mL, 0.52 mmol, 1 eq.) were added. Finally, the reaction mixture was cooled down to 0°C with an ice-bath and a solution of hexachloroethane (107 mg, 0.52 mmol, 1 eq.) in dichloromethane (5 mL) was added dropwise. The solution was stirred for 2 hours at 0°C. Subsequently, the solvent was removed in vavcuo (Yield: 41%, 0.21 mmol, 96.9 mg).
31 P NMR (101.3 MHz, C6D6): δ = -4.7 (s). MS (MALDI, m/z): 461.16 (M+). Experimental Part 265 mesityl(mesityl(phenyl)phosphino)methanone (B59a)
In a three neck round bottom flask, equipped with a dropping funnel and a magnetic stirrer, thf (500 mL) and P magnesium turnings (5.0 g, 0.2 mol, 1 eq.) were
O suspended. Using a dropping funnel, bromomesitylen (39.81 g, 0.2 mol, 1 eq.) was added dropwise in the flask. After a while, the exothermic reaction starts and it can be necessary to cool the reaction mixture with an ice bath. After adding the complete amount of bromomesitylene, the reaction mixture was stirred for another 2 hours in order to complete the reaction. Subsequently, the non reacted magnesium turnings were filtered off. The brownish solution was added dropwise to a solution of PCl3 (9.17 g, 0.06 mol, 1/3 eq.) in thf (20 mL), which was cooled down with an ice bath to 0°C. A suspension was obtained of dissolved MesPCl2 and a precipitate of
MgClBr, which was filtered off. The thf was removed and the pale yellow MesPCl2 was dissolved in toluene (500 mL). Sodium sand (20.3 g, 0.88 mol, 4.4 eq.) and 1,1,2,2-N,N,N,N-tetramethylethylendiamine (TMEDA) (1.0 mL) was added. The reaction mixture was refluxed for 12 h. The colour became pale yellow and a precipitate of sodium chloride was observed. After cooling down to room temperature tBuOH (29.6 g, 0.4 mol, 2 eq.) was added dropwise within one hour. After adding mesitoyl chloride (36.5 g, 0.2 mol, 1 eq.), the pH-value of the solution was controlled and neutralized by adding small amounts of sulphuric acid dropwise
(pH should be 7). Iodobenzene (45.5 g, 0.22 mol, 1.1 eq.) and [Pd(PPh3)] (1 mol%, 2.3 g, 4 mmol) were added. After stirring over night at 70°C the reaction is finished. The solvent was removed in vacuo and the remaining brown oil was diluted in diethyl ether. After filtration over aluminium oxide, the ether solution was washed twice with brine and dried with magnesium sulfate. The product was obtained by removing the solvent under vacuum at room temperature (Yield: 54% yellow oil, 38.9 g, 0.11 mol).
Experimental Part 266
1 4 H NMR (C6D6): = 7.56 (m, 2 H, PhCH), 7.11 (m, 3 H, PhCH), 6.86 (d, JHP = 2.8 3 Hz, 2 H, Mes-CH), 6.68 (s, 2 H, Mes-C H), 2.50 (s, 6 H, o-MesCH3), 2.33 (s, 6H, 4 para-CH3 mesityl und mesitoyl), 2.13 (d, JHP= 5.3 Hz, 6H, ortho-CH3 mesityl) 13 1 C NMR (C6D6): = 220.8 (d, JCP= 47.5 Hz, C=O), 146.1 (d, JCP= 15.6 Hz), 140.8
(d, JCP= 17.7 Hz), 140.5 (d, JCP= 15.4 Hz), 138.5 (s), 134.2 (d, JCP= 9.4 Hz), 134.1
(s), 130.3 (d, JCP= 14.5 Hz), 129.8 (d, JCP= 5.4 Hz), 128.8 (s), 128.3 (d, JCP= 5.2
Hz), 127.9 (d, JCP= 22.4 Hz), 126.7 (br), 123.8 (d, JCP= 5.9 Hz), 24.2 (s, para-CH3), 4 3 24.0 (s, para-CH3), 20.8 (d, JCP= 3.5 Hz, ortho-CH3 mesitoyl), 19.7 (d, JCP= 7.0
Hz, ortho-CH3 mesityl), 31 P NMR (C6D6): = 8.6 (s) MS (EI, m/z) = 374.4 (M+, 1%), 147.2 (MesCO+. , 100%), IR (golengate, [cm-1]): 3052 / 2915 (m, CH str.), 1649 (ss, C=O str.), 1606 (m), 1447 (s), 1433 (s), 1380 (m), 1293 (w), 1262 (w), 1201 (m), 1141 (m), 1099 (w), 1029 (s), 863 (s), 845 (s), 743 (s), 730 (s), 691 (s), mesityl(mesityl(phenyl)phosphoryl)methanone (B59)
Mesityl(mesityl(phen yl)phosphino) methanone (P4) (38.9 g, 0.11 mol, 1 eq.) was disso lved in toluene O P (250 mL), water (50 mL) and hydrogen peroxide (30%) O (22.7 g, 0.2 mol, 1 eq.) was added. After stirring for 12 hours at 40°C the MAPO (B59) was formed. The solution was washed twice with an aqueous sodium hydrogencarbonate solution (2%), once with brine and finally dried over sodium sulfate. 50% of the toluene was removed under reduced pressure and an excess of pentane was added (~200 mL).The product is obtained as an pale yellow powder, which is very light sensitive (Yield: 76%, 82.5 mmol). To get absolute pure product column chromatography with n-heptane / ethyl acetate
(4:1, Rf = 0.19) can be performed. But up to 50% can decompose. Therefore, it must be performed under light exclusion (Yield: 37.5%, 41.0 mmol).
Experimental Part 267
1 H NMR (C6D6): = 7.99 (m, 2H, Hphenyl), 7.13 (m, 3H, Hphenyl), 6.71 (s, 4H, meta-H mesityl und mesitoyl), 2.58 (s, 6H, ortho-CH3 mesitoyl), 2.33 (s, 6H, ortho-CH3 mesityl), 2.13 (s, 3H, para-CH3 mesitoyl), 2.07 (s, 3H, para-CH3 mesitoyl) 13 1 C NMR (C6D6): = 218.1 (d, JCP= 70.8 Hz, C=O), 144.9 (d, JCP= 10.2 Hz), 142.2
(d, JCP= 2.7 Hz), 139.6 (s), 137.7 (d, JCP= 41.5 Hz), 135.8 (s), 134.8 (d, JCP= 94.35
Hz), 131.3 (d, JCP= 2.1 Hz), 131.2 (d, JCP= 4.1 Hz), 128.9 (s), 128.6 (d, JCP= 11.6 3 Hz), 127.8 (d, JCP= 23.8 Hz),123.4 (d, JCP= 86.3 Hz), 23.7 (d, JCP= 3.4 Hz, ortho- 3 CH3 mesityl), 20.8 (s, para-CH3), 20.6 (d, JCP= 1.2 Hz, ortho-CH3 mesitoyl), 19.8
(s, para-CH3), 31 P NMR (C6D6): = 24.6 (s) IR (goldengate, [cm-1]): 3024 / 2964 / 2923 / 2866 (w, CH), 1665 (vs, C=O), 1606 (s), 1436 (s), 1259 (m), 1192 (s), 1106 (s), 1029 (s), 888 (m), 849 (s), 799 (m), 750 (m), 737 (m), 708 (m), 694 (s), 612 (m)
UV/Vis (CH2Cl2): 255 nm (abs. max.), 376 nm (shoulder: 363, 390)
Chapter 4
Rearrangement of bis(2,6-dimethoxybenzoyl)hydroxyethyl- phosp hanoxide to P34
Bis(2,6-dimethoxybenzoyl)hydroxyethylphosphane oxide O O O P OH was dissolved in a small amount of thf. A pale yellow solution was obtained, which became colourless after the O O O O addition of a few drops hydrochloric acid.
1 8 H NMR (300.1 MHz, d -thf): δ = 3.37 (br, 2 H, P-CH2), 3.41 (s, 12 H, O-CH3), 3.78 3 3 (br., 2 H, O-CH2), 6.30 (d, 4 H, Ar-H, J = 8.4 Hz), 7.07 (t, 2 H, Ar-H, J = 8.4 Hz). 31 2 P NMR (101.3 MHz, C6D6): δ = -227.9 (t, J = 16.6 Hz). 13 C NMR (75.5 MHz, thf): δ = 28.5 (s, P-CH2), 56.12 (s, C-OH), 56.20 (s, O-Me), 104.62 (s, Ar-C3), 104.72 (s, Ar-C1), 130.57 (s, Ar-C4), 158.12 (s, Ar-C2), 206.54 (s,
C=Oacyl). Experimental Part 268
Decomposition of Ph-BAPO in benzene:
Bis(mesitoyl)phenylphosphanoxide (80.0 mg, 1.02 mmol) was dissolved in benzene (0.4 mL) and irradiated for 30 minutes. Crystals of D1 were obtained by concentrating the pale yellow benzene solution. In the NMR spectrum the signals of diphenylphosphonic acid can be detected that corresponds to the signals given in Ref264. In addition, signals of phenylmesitoylphosphinic acid were obtained.
1 D1: H NMR (250.0 MHz, C6D6 25°C): δ = 6.80 (s, 2H, Ar-H), 6.99 (s, 2H, Ar-H),
2.88 (s, 12H, Ar-CH3), 2.71 (s, 12H, Ar-CH3), 2.45 (s, 6H, Ar-CH3), 2.48 (s, 6H, Ar-
CH3). 13 C NMR (62.9 MHz, C6D6, 25°C): δ = 168.6 (s, 2C, -CO2-), 142.9 (s, 2C, C=C),
21.1-21.3 (br, 4C, p-CH3), 20.8 (s 2C, o-CH3), 19.8 (s, 2C, o-CH3), 138.8 (s, 2C, Ar4-C), 137.6 (s, 2C, Ar4-C-C=C), 135.2 (s, 4C, Ar1-C), 134.6 (s, 4C, Ar1-C-COO), 130.7 (s, 4C, Ar2-C C=C), 129.1 (s, 4C, Ar2-C), 125.4 (s, 4C, Ar3-C), 127.5 (s, 4C, Ar3-C). MS (EI, m/z): 588 (M+), 546, 462, 442, 425, 408, 393, 385, 366, 352, 343, 332, 262, 238, 147(100%), 119, 91, 80, 65.
D3: Phenylmesitoylphosphinic acid: MP.: 148°C 1 H NMR (C6D6): 13.82 (s, 1H, OH), 7.73 (m, 2H, Hphenyl), 7.57 (m, 1H, para-Hphenyl),
7.42 (m, 2H, Hphenyl), 6.74 (s, 2H, meta-Hmesitoyl), 2.25 (s, 3H, para-CH3), 2.03 (s,
6H, ortho-CH3), 13 1 C NMR (C6D6): 215.7 (d, JCP= 117.0 Hz, C=O), 139.6 (s, para-Cmesitoyl), 136.2 (d,
JCP= 46.6 Hz, ipso-Cmesitoyl), 134.4 (s, para-Cphenyl), 133.1 (d, JCP= 2.9 Hz, ortho-
Cmesitoyl), 132.5 (d, JCP= 10.3 Hz, meta-Cmesitoyl), 128.5 (d, JCP= 7.0 Hz, ortho-
Cphenyl), 128.4 (d, JCP= 6.1 Hz, meta-Cphenyl), 127.6 (d, JCP= 129.9 Hz, ipso-Cphenyl), 4 21.1 (d, JCP= 6.7 Hz, ortho-CH3), 14.3 (s, para-CH3). 31 1 3 P{ H}-NMR (C6D6): δ = 17.7 (t, JPH= 10.7 Hz) Experimental Part 269
IR (goldengate [cm-1]): 3321 (br, OH), 2976 / 2923 (m, CH), 1671 (s, C=O), 1609 (m), 1589 (m), 1440 (m), 1298 (w), 1217 (w), 1165 (w), 1118 (m), 1030 (m), 988 (s), 1005 (s), 975 (s), 952 (s), 929 (m), 895 (s), 889 (s), 850 (s), 753 (m), 726 (s), 690 (s), 572 (s).
Decomposition of Ph-BAPO in toluene
Bis(mesitoyl)phenylphosphane oxide (80.0 mg, 1.92 mmol) was dissolved in toluene (0.4 mL). The yellow solution was irradiated for 30 minutes with a UV lamp. Colourless crystals of the tetramer D1 were formed during one day out of the toluene solution. The 1H NMR-Spectrum of the pale yellow solution shows the signals of mesitoyl aldehyde.
Decomposition of Ph-BAPO in CCl4
Bis(mesitoyl)phenylphosphane oxide (80 mg, 1.92 mmol) was dissolved in carbon tetrachloride (0.4 mL). This yellow solution was irradiated for 30 seconds with a UV lamp. PhP(O)Cl2 is obtained in 40% Yield. Analytical data of PhP(O)Cl2 corresponds to values given in Ref265. The mesitoyl radicals recombine to D1.
Decomposition of Ph-BAPO in benzene in the presence of Diphenyldisulfide as scavengers
Bis(mesitoyl)phenylphosphane oxide (40.0 mg, 0.96 mmol, 1 eq.) was dissolved in benzene (0.4 mL) and diphenyldisulfide (209.3 mg, 2 eq., 1.92 mmol) was added. The yellow solution was irradiated for 30 minutes with a UV lamp. According to the NMR-spectrum the reaction is quantitative. A colourless crystalline powder of D8 was obtained by cooling down the solution to -30 °C for three days.
D4: The NMR data corresponds to Ref266. 1 D8: H NMR (250.0 MHz, C6D6): δ = 6.98 (m, 2 H, CHS-Ar), 7.01 (m, 4 H, CHS-Ar),
7.62 (m, 4 H, , CHS-Ar), 7.66 (m, 1 H, CHP-Ar), 7.64 (m, 2 H, CHP-Ar), 8.01 (m, 2 H,
CHP-Ar). Experimental Part 270
31 1 31 P{ H} NMR (121.5 MHz, C6D6): δ = 46.9; P NMR (121.5 MHz, C6D6): δ = 46.9 (t, J = 13.2 Hz). MS (ESI, m/z): 343.40 (MH+).
Decomposition of Ph-BAPO in benzene in the presence of methylphenyldisulfide as scavengers
Bis(mesitoyl)phenylphosphane oxide (400 mg, 9.60 mmol) was dissolved in benzene (4 mL) and two equivalents of methylphenyldisulfide (299.5 mg, 19.2 mmol) were added. The yellow solution was irradiated for 30 minutes with a UV lamp. Directly from this solution NMR spectroscopy and ESI-mass spectroscopy was performed.
1 D8: see above. 4: H NMR (250.0 MHz, C6D6): 6.70 (s, 2 H, Ar-H), 2.37 (s, 6 H, Ar- CH3), 2.24 (s, 3 H, Ar-CH3), 2.14 (s, 3 H, S-CH3). 13 C NMR (62.9 MHz, C6D 6): δ = 196.8 (C(O)S), 11.5 (CH3), 18.8 (o-Mes-CH3), 20.8 3 1 2 4 (p-Me s-CH3), 129.1 (Ar-C ), 133.6 (Ar-C ), 134.4 (Ar-C ), 138.9 (Ar-C ). MS (ESI, m/z): 194.07 (M+).
1 D10: H NMR (250.0 MHz, C6D 6): 2.12 (s, 3 H. CH3), 7.01 (m, 1 H, S-Ar-H), 7.12 (m, 2 H, S-Ar-H), 7.21 (m, 2 H, s-Ar-H), 7.55 (m, 1 H, S-Ar-H), 7.60 (m, 2 H, S-Ar- H), 7.95 (m, 2 H, S-Ar-H). 31 P NMR (121.5 MHz, C6D 6): 47.4 (q, J = 12.8 Hz). MS (ESI, m/z): 281.0512 (M+).
1 D7: H NMR (250.0 MHz, C6D 6): δ = 2.24 (s, 3 H, p-MesCH3), 2.37 (s, 6 H, o-Mes-
CH3), 6.70 (s, 2 H, Mes-H), 7.22 (m, 3 H, m- und p- Ph-H), 7.61 (m, 2 H, o-Ph-H); MS (ESI, m/z): 255.08 (M+).
1 D11: H NMR (250.0 MHz, C6D6): 8.00-8.05 (br., 5 H, Ar-H), 2.15 (s, 6 H, CH3). 31 P NMR (121.5 MHz, C6D6): δ = 54.7 (sept., J = 13.4 Hz). MS (ESI, m/z): 218.02 (M+). Experimental Part 271
Decomposition of Ph-BAPO in benzene in the presence of TEMPO as scavenger
Bis(mesitoyl)phenylphos p h ane oxide (40.0 mg, 0.96 mmol) was dissolved in benzene (0.4 mL) and two equivalents of TEMPO (299.5 g, 1.92 mmol, 2 eq.) was added. The yellow solution was irradiated for 30 minutes with a UV lamp.
D12: 1H NMR (250.0 MHz, C6D6, 25°C): 1.42 (s, 24 H, CH3), 2.33 (q, 4, CH2), 2.56 (t, 8 H, CH2), 8.15 (br., 5 H, Ar-H). 31P NMR (121.5 MHz, C6D6, 25°C): δ = 25.6 (t, J = 12.8 Hz). MS (ESI, m/z): 437.3 (MH+). D13: MS (ESI, m/z): 304 (MH+).
Decomposition in the presence of [Cu(acac)2]:
Bis(mesitoyl)phenylphosphane oxide (40.0 mg, 0.96 mmol, 1 eq.) and Cu(acac)2 (632.5 mg, 2.40 mmol, 5 eq.) were dissolved in thf (1.5 mL). This solution was irradiated for 15 minutes with a UV lamp. After 24 h, green crystals of D15 were obtained (41%, 173 mg, 0.19 mmol).
Decomposition in the presence of Ni(CF3COO)2:
Bis(mesitoyl)phenylphosphane oxide (40.0 mg, 0.96 mmol) and Ni(CF3COO)2 (620.2 mg, 2.40 mmol, 5 eq.) were dissolved in thf (1.5 mL). This solution was irradiated for 15 minutes with a UV lamp. Green crystals of D17 were obtained by layering the solution with n-hexane after two days (40%, 0.38 mmol).
Dimesityl diketone (A9):
Dimethyl oxalate (59.0 g, 0.5 mol, 1 eq.) was dissolved in thf (200 mL). During 1 h, this solution was added dropwise to a solution of mesityl magnesium bromide that was prepared by mesityl bromide (153 mL, 1 mol, 1 eq.), magnesium turnings (24.3 g, 1 mol, 1 eq.) and thf (200 mL) according to the standard procedure for the Experimental Part 272 preparation of Grignard reagents267. After 1 h of stirring, the solvent was removed and the residue was recrystallised in n-hexane. Yield: (119.1 g, 80 %). The analytical data corresponds to Ref268.BAPO* decomposition in benzene solution
BAPO* (0.5 g, 1.41 mmol, 1 eq.) was dissolved in benzene (5 mL) and irradiated for 10 minutes with a UV lamp. Then the benzene was evaporated in vacuo. Hexane (10 mL) was added to the yellow oil and stirred for one hour. Afterwards the insoluble pale yellow powder was filtered off. A mixture of different unidentified phosphorus compounds was obtained as well as di(phenylphosphonic) acid, which was characterised by NMR spectroscopy. The signals correspond to literature264. The n-hexane solution was evaporated and analysed by NMR and EI-mass spectroscopy.
13 D19: C NMR (C6D6, 25°C, selected signals): δ = 169.1 (MesCOO), 138.4 t ( BuC=C), 20.8 ((H3C)3C), 80.3 ((H3C)3C). MS (EI, m/z): M+ = 464.3 g/mol
* BAPO decomposition in CCl4 solution
BAPO* (0.1 g, 0.27 mmol) was dissolved in tetrachloromethane (1 mL) and irradiated for 10 min with a UV lamp. After evaporating the solvent in vacuo, the remaining oil was dissolved in deuterated benzene. The NMR shows the signals of dichlorophenylphosphane and mesitoyl chloride, which correspond to literature265, 269.
Decomposition of BAPO* in benzene in the presence of diphenyldisulfide as scavenger
BAPO* (50 mg, 0.13 mmol) was solubilized in benzene (0.4 mL) and an excess of diphenyldisulfide was added. The yellow solution was irradiated for 30 minutes with a UV lamp. According to the NMR-spectrum the reaction is quantitative. The Experimental Part 273 phenyl dithiophosphonic acid was detected with NMR spectroscopy. The measured signals correspond to literature266. Furthermore, the phenyl thioester of mesitoylic acid and pivaloylic acid were obtained by NMR spectroscopy. Their signals correspond to literature269.
Decomposition of BAPO* in benzene in the presence of TEMPO as scavenger
BAPO* (40 mg, 0.11 mmol) was dissolved in benzene (0.4 mL) and an excess of TEMPO was added. The orange solution was irradiated for 30 minutes with a UV lamp. The bis(TEMPO)phenylphosphane oxide (D12) was obtained. The analytical data is in accordance with the data obtained from the decomposition reaction with Ph-BAPO.
Decomposition of Me-BAPO in benzene:
Me-BAPO (72.0 mg, 2.0 mmol) was dissolved in benzene (0.4 mL) and irradiated for 30 minutes with a middle pressure mercury lamp. Crystals of D1 were obtained by concentrating the pale yellow benzene solution. In the 31P NMR spectrum the signals of dimethylphosphonic acid can be detected that corresponds to the signals given in Ref270. In the EI-MS spectrum of the reaction mixture signals of methylmesitoylphosphinic acid were obtained (m/z = 225.08).
Decomposition of Me-BAPO in benzene in the presence of Diphenyldisulfide as scavengers
Me-BAPO (50 mg, 0.14 mmol) was dissolved in benzene (0.4 mL) and an excess of diphenyldisulfide was added. The yellow solution was irradiated for 30 minutes with a UV lamp. In the NMR-spectrum the reaction is quantitative. The methylphosphonic thiophenylester and mesitoyl thiophenylester were obtained by NMR spectroscopy. Their signals correspond to literature. 31 MeP(=O)(SPh)(SPh) D10: P NMR (121.5 MHz, C6D6): 52.93 (q, J = 12.8 Hz). Experimental Part 274
Decomposition of Me-BAPO in benzene in the presence of TEMPO as scavenger
Me-BAPO (40 mg, 0.11 mmol) was dissolved in benzene (0.4 mL) and an excess of TEMPO was added. The orange solution was irradiated for 30 minutes with a UV lamp. The bis(TEMPO)phenylphosphane oxide was obtained. 31 MeP(=O)(TEMPO)(MesCO): P NMR (121.5 MHz, C6D6): 367 (br.). 31 MeP(=O)(TEMPO)2, D30: P NMR (121.5 MHz, C6D6): 42.6 (q, J = 8.8 Hz).
Decomposition of Me-BAPO in the presence of Cu(acac)2,
Me-BAPO (40.0 mg (0.96 mmol, 1 eq.) and Cu(acac)2 (632.5 mg, 2.40 mmol, 5 eq.) were dissolved in thf (1.5 mL). This solution was irradiated for 15 minutes with a UV lamp. After 24 h pale blue crystals of D16 were formed (32%, 173 mg, 0.19 mmol).
Decomposition of Me-BAPO in the presence of methylphenyldisulfide as scavengers
Me-BAPO (400 mg, 9.60 mmol, 1 eq.) was dissolved in benzene (4 mL) and methylphenyldisulfide (299.5 mg, 19.2 mmol, 2 eq.) was added. The yellow solution was irradiated for 30 minutes with a UV lamp. Directly from this solution NMR spectroscopy and ESI-mass spectroscopy was performed. 31 MeP(=O)(SMe)(SPh), D28: P NMR (121.5 MHz, C6D6): 53.63 (q, J = 10.6 Hz). 31 MeP(=O)(SMe)(SMe), D29: P NMR (121.5 MHz, C6D6): 59.85 (q, J = 14.7 Hz).
Thermal decomposition of Ph-BAPO in substance
In a closed 50 mL round bottom flask Ph-BAPO (B2) (1.00 g, 2.4 mmol) was heated up to 140°C in an oil bath under argon atmosphere for 12 hours. The Ph- BAPO melted. The pale yellow colour of the starting material does not change. After 12 hours everywhere in the flask colourless needles crystallised. On the bottom of the flask a yellow solidified melt remains. Experimental Part 275
The colourless needles are mesitoyl anhydride. The analytical data corresponds to literature271. 272 The pale yellow melt is Ph5P5. The analytical data corresponds to literature . 31 P5Ph5 (D32): P NMR: δ = -0.3 (m).
Thermal decomposition of a Ph-BAPO solution in p-Xylene
In a 50 mL round bottom flask Ph-BAPO (1.00 g, 2.4 mmol) was dissolved in p- xylene (10 mL). This solution was heated up to 140°C in the closed flask. The pale yellow colour of the solution did not change in this period of time. After evaporating the solvent a pale yellow powder remains. The analysis shows that the product is pure D34. The analytical data corresponds to literature273. (MesCO)P(Ph)–O–(COMes) (D34): 31P{1H} NMR: δ = 98.78.
Thermal decomposition of MAPO, B3
In meltery: In a closed 50 mL round bottom flask MAPO (1.0 g, 2.8 mmol) was heated up to 140°C with an oil bath under argon atmosphere for 12 hours. The MAPO melts and the pale yellow colour of the starting material did not change. After cooling down to room temperature a yellow solidified melt of D35 was obtained (Yield: quantitative).
In solution: In a 50 mL round bottom flask MAPO (1.0 g, 2.8 mmol) was dissolved in p-Xylene (10 mL). This solution was heated up to 140°C in the closed flask under argon atmosphere. The pale yellow colour of the solution did not change in this time. After evaporating the solvent, a yellow powder remains. The analysis shows that the product is pure D35 (Yield: quantitative). In both cases, the analytical data corresponds to literature274. 31 1 Ph2P–O–(MesCO) (D35): P{ H} NMR: δ = 101.9. Experimental Part 276
Lithium diphenylphosphinite
In a 50 mL round bottom flask MesCO-O-PPh2 (0.50 g, 1.44 mmol, 1 eq.) was dissolved in diethyl ether (10 mL). The solution was cooled down to 0°C with ice- water and phenyl lithium (2 M in dibutylether) (0.72 mL, 1.44 mmol, 1 eq.) was added dropwise. The reaction mixture was extracted twice with 5 mL distilled water. The 1,3,5-trimethylbenzil remains in the ether solution. The lithium diphenylphosphite dissolves in the aqueous phase and can be isolated by evaporating the water. Crystals can be obtained from a concentrated thf solution by evaporation. The analytical data corresponds to literature275, 276, 277.
General procedure for light induced condensation reactions
One equivalent Ph-BAPO is irradiated with a UV lamp in a solution of thf or toluene with two equivalent of the reagent. After 5 minutes, the reaction was completed and a colourless solution is obtained. The reaction did not depend on the concentration of the solution.
Diethylamine, HNEt2: After two minutes the reaction was finished. Mesitylaldehyde 31 and phenylphosphonic diethylamide ( P NMR (101.3 MHz, C6D6): δ = 16.64 (quint., J = 10.9 Hz)) was obtained in a quantitative yield.
Ethanol: After 5 minutes, the reaction was finished. The colourless solution 31 contained 85% PhP(=O)(OEt)2 ( P NMR (101.3 MHz, C6D6): 16.2), 15% 31 PhPH(=O)(OEt) ( P NMR (101.3 MHz, C6D6): δ = 36.8) and the corresponding amounts of mesitoyl ethylester and mesitylaldehyde.
2-Bromoethanol, Br-CH2-CH2-OH: After 5 minutes the reaction was finished. The 31 colourless solution contained (80% PhP(=O)(OC2H4Br)2 ( P NMR (101.3 MHz, 31 C6D6): 17.3), 20% PhPH(=O)(OC2H4Br) ( P NMR (101.3 MHz, C6D6): δ = 36.4) and the corresponding amounts of mesitoyl ethylester and mesitylaldehyde.
Experimental Part 277
Phenol: After three minutes, the reaction is finished. The reaction was quantitative 31 and the solution contained pure PhP(=O)(OPh)2 ( P NMR (101.3 MHz, C6D6): δ = 11.5) and mesityl aldehyde. p-Methoxyphenol: After three minutes the reaction was finished. The reaction is 31 quantitative and the solution conatined pure (MesO-Ph)P(=O)(OPh)2 ( P NMR
(101.3 MHz, C6D6): δ = 12.8) and the corresponding mesitylaldehyde.
Chapter 5
Poly(ethyl 2-((bis(2,4,6-trimethylbenzoyl)phosphoryl)methyl)acrylate (PM6)
ethyl2-((bis(2,4,6-trimethylbenzoyl)phosphoryl)methyl) acrylate BAPO (250 mg) was dissolved in toluene (5 mL). AIBN (3 mol%) was added and the solution was stirred for two days at 60°C. After O O removing the solvent, a pale yellow solid was obtained (Yield:
n quantitative).
1 H NMR (250 MHz, C6D6): δ = 6.69 (s, 4H, Mes), 4.08 (m, 2H, OCH2CH3), 3.64 (m,
2 H, PCH2), 2.41 (m, 12H, Mes-ο-CH3), 2.15 (m, 6H, Mes-p-CH3), 1.15 (m, 3H,
OCH2CH3). 31 P NMR (101.3 MHz, C6D6): δ = 26.9 (br.). IR (goldengate, [cm-1]): 2279.5 (s, C≡N), 2159.4 (m, C≡N), 1617.8 (m, C=O),
1453.4 (m, CH3), 1393.0 (w, CH3), 1260.9 (s, C-O), 1231.6 (s, C-O), 1161.6 (s, C- O), 1095.0 (s, C-O), 1041.1 (s, C-O). UV/vis (acetonitrile): 238 nm (max.). MS (MALDI-TOF, m/z): 1361.7 (Trimer), 1199.9 (Trimer - C=O - O - Mes), 1123.6 (Trimer – 2 Mes), 1003.6 (Trimer – 3 Mes), 907.5 (Dimer), 637.3 (Dimer – 2 Mes – 2 O). Experimental Part 278
BAPO-cellulose (PM2)
Mes 6-Azido-6-deoxy cellulose (DS 0.60) (0.3 g, 1.64 mmol, O 1 eq.) and propargylBAPO (B11) (0.62 g, 1.64 mmol, O P O N 1 eq.) were dissolved in dmso (30 mL). A solution of Mes N HN copper(II) sulfate pentahydrate (0.012 g, 0.049 mmol, H O O 3 mol%) in water (5 mL) and a solution of sodium HO O H OH ascorbate (0.019 g, 0.098 mmol) dissolved in water H H (5 mL) were added. After stirring the mixture at 70 °C for 24 h, the product was precipitated by adding methanol (75 mL). The polymer was collected by filtration. The product was washed three times with methanol (200 mL) and dried in vacuo to yield BAPO-cellulose. Degree of substitution (DS): 0.52 (calculated from N, C and H content, determined by elemental analysis).
31P NMR (DMSO-d6): 21.9 (br.). 1H NMR (DMSO-d6): 7.25 (s, =CH-N, triazole) 6.87 (br., MesCH), 3.3–4.5 (br.,
ROH), 2.44 (br., o-MesCH3), 2.21 (br., p-MesCH3), 2.07 (P-CH2). EA: Determined: [C]: 48.27 %, [H]: 5.87 %, [N]: 9.98 %. -1 IR (goldengate [cm ]): 3340 (m, OH), 2921 (w, C-H), 2110 (w, N3), 1659 (w, MesC=O), 1608 (w), 1448 (w), 1377 (w), 1296 (vw), 1296 (vw), 1153 (m, P=O), 1021 (s, C-O), 888 (w), 852 (w), 813 (w), 663 (vw), 618 (vw).
General procedure for the synthesis of BAPO-functionalised silicones (PM7)
A diluted solution of BAPO-functionalised di- or tri-alkoxysilane and the comonomers in toluene were stirred together with an excess of hydrochloric acid (1%) for two hours at 40°C. The organic layer was separated and washed once with sodium hydrogencarbonate solution (2%) and twice with brine. After drying with sodium sulfate, the toluene was removed at room temperature in vacuo. The pale yellow product was obtained in almost quantitative yields. Experimental Part 279
(3-(Diethoxymethylsilyl)propyl)bis(mesitoyl)phosphane oxide, Diethoxydimethylsilan copolymer ratio (BAPO-monomer/ comonomer): 5:95
1 H NMR (400.13 MHz, C6D6): δ = 6.68 (s, 4 H, MesCH), 3.83 (q, J = 7.00 Hz, 4 H,
OCH2CH3), 2.45 (s, 12 H, o-MesCH3), 2.09 (s, 6 H, p-MesCH3), 1.91–1.73 (m, 2 H,
PCH2CH2), 1.29 (t, J = 7.00, 6 H, OCH2CH3), 1.18–1.12 (br., 4 H, SiCH2 + PCH2),
0.30 (s, 6 H, SiCH3). 13 4 1 C NMR (100.62 MHz, C6D6): δ = 136.2 (MesC ), 129.6 (MesC ), 58.1
(OCH2CH3), 21.2 (p-MesCH3), 20.2 (o-MesCH3), 18.8 (OCH2CH3), 16.0 (PCH2),
1.5–0.8 (br., SiCH3). 31 P NMR (101.25 MHz, C6D6): δ = 28.6–27.2 (br.). IR (goldengate [cm-1]): 2962 (w), 2363 (w), 1675 (m), 1609 (w), 1413 (w), 1269 (m), 1063 (s), 1018(s), 849 (w), 796 (s), 699 (w), 619 (w). UV/vis (toluene): 363 nm (max), 395 nm (Shoulder).
GPC: Mn = 1544 g / mol, Mw = 2139 g / mol, Q = 1.38.
Poly(3-(Triethoxysilyl)propyl)bis(mesitoyl)phosphane oxide
1 H NMR (300.13 MHz, C6D6): δ = 6.74 (s, 4 H, MesCH), 3.80 (q, J = 7.05 Hz, 4 H,
OCH2CH3), 2.43 (s, 12 H, o-MesCH3), 2.16 (s, 6 H, p-MesCH3), 1.52–1.37 (br.,
2 H, PCH2CH2) ,1.15 (t, J = 7.05, 6 H, OCH2CH3), 1.11–1.00 (br., 4 H, PCH2 +
SiCH2). 31 P NMR (121.49 MHz, C6D6): δ = 27.7 (br.). IR (goldengate [cm-1]): 2963 (w), 1723 (w), 1672 (w), 1609 (w), 1414 (w), 1259 (m), 1084 (m), 1013 (s), 851 (w), 792 (s), 695 (w), 618 (w). UV/VIS (toluene): 288 nm (max.), 361 nm (max), 388 nm (shoulder).
GPC: Mn = 256’278 g / mol, Mw = 468’595 g / mol, Q = 1.828. Experimental Part 280
Poly(3-(Diethoxyphenylsilyl)propyl)bis(mesitoyl)phosphane oxide
1 H NMR (300.13 MHz, C6D6): δ = 7.82–7.80 (m, 2H, Ph-o-H), 7.33–7.27 (m, 3H, Ph-m-H, Ph-p-H), 6.65 (s, 4H, Mes), 3.82–3.63 (m, 4H, OCH2CH3), 2.45 (s, 12H, Mes-o-CH3), 2.07 (s, 6H, Mes-p-CH3), 1.95–1.83 (m, 2H, SiCH2CH2CH2P), 1.25– 1.21 (m, 6H, OCH2CH3), 1.09– 0.92 (m, 4H, PCH2, SiCH2). 31 P NMR (121.49 MHz, C6D6): δ = 27.8 (t, J = 8.08 Hz). IR (goldengate, [cm-1]): 2963 (w), 2360 (w), 2342 (w), 1724 (w), 1610 (w), 1413 (w), 1259 (m), 1082 (m), 1012 (s), 863 (w), 790 (s), 739 (w), 700 (w), 661 (w). UV/VIS (chloroform): 281 nm (max.), 360 nm (max.), 384 nm (Shoulder).
GPC: Mn = 155’675 g/mol, Mw = 294’401 g/mol, Q = 1.891
Poly(3-(Diethoxymethylsilyl)propyl)bis(mesitoyl)phosphane oxide
1 H NMR (300.13 MHz, C6D6): δ = 6.70 (s, 4 H, Mes), 2.43 (s, 12 H, Mes-o-CH3),
2.22 (s, 6 H, Mes-p-CH3), 1.90–1.78 (m, 2 H, SiCH2CH2CH2P), 0.40 (s, 3 H,
SiCH3), not visible in the spectrum: OCH2CH3, SiCH2, PCH2. 31 P{1H} NMR (121.49 MHz, C6D6): δ = 27.7 (m). IR (goldengate [cm-1]): 2963 (w), 2360 (w), 2342 (w), 1720 (w), 1675 (w), 1609 (w), 1413 (w), 1259 (m), 1083 (m), 1012 (m), 861 (w), 790 (s), 760 (m), 699 (w), 668 (w). UV/vis (chloroform): 285 nm (max.), 360 nm (max.), 387 nm (shoulder).
GPC: Mn = 245’079 g / mol, Mw = 407’489 g / mol, Q = 1.663.
(3-(Diethoxyphenylsilyl)propyl)bis(mesitoyl)phosphan oxide, diethoxydimethylsilane copolymer ratio (BAPO-monomer/ comonomer): 1:20
1 H NMR (250.13 MHz, C6D6): δ = 7.83–7.81 (m, 2 H, o-PhCH), 7.34–7.27 (m, 3 H, m-PhCH + p-PhCH), 6.65 (s, 4 H, MesCH), 3.86–3.75 (br., 4 H, OCH2CH3), 2.41
(s, 12 H, o-MesCH3), 2.08 (s, 6 H, p-MesCH3), 1.95–1.83 (m, 2 H, SiCH2CH2), Experimental Part 281
1.33–1.21 (br., 6 H, OCH2CH3), 1.08–0.94 (m, 2 H, SiCH2), 0.41 (s, 6 H, SiCH3)
(not visible in the spectrum: PCH2) 31 P NMR (101.25 MHz, C6D6): δ = 28.6 (Br.). IR (goldengate, [cm-1]): 2962 (w), 2360 (w), 2343 (w), 1724 (w), 1724 (w), 1610 (w), 1412 (w), 1258 (m), 1072 (m), 1016 (m), 842 (w), 792 (s), 739 (w), 701 (w). UV/VIS (Chloroform): 277 nm (max.), 362 nm (max.), 388 nm (shoulder). GPC: Mn = 165’588 g/mol, Mw = 315’434 g/mol, Q = 1.905.
(3-(Diethoxyphenylsilyl)propyl)bis(mesitoyl)phosphane oxide, Dimethoxydimethylsilane copolymer ratio (BAPO-monomer/ comonomer): 1:20
1 H NMR (250.13 MHz, C6D6): δ = 7.93–7.81 (m, 6 H, o-PhCH), 7.32–7.28 (br., 4 H, m-PhCH + p-PhCH), 6.65 (s, 4 H, MesCH), 3.83–3.75 (br., 4 H,
OCH2CH3), 3.57 (s, 6 H, OCH3), 2.44 (s, 12 H, o-MesCH3), 2.08 (s, 6 H, p-
MesCH3), 1.95–1.84 (br., 2 H, PCH2CH 2), 1.27–1.21 (br., 6 H, OCH2CH 3), 1.12–
0.89 (br., 4 H, SiCH2 + PCH2), 0.41 (s, 6 H, SiCH3). 31 P NMR (101.25 MHz, C6D6): δ = 27.8 (t, J = 9.06 Hz). IR (goldengate, [cm-1]): 3070 (w), 3050 (w), 2939 (w), 2837 (w), 2360 (w), 2343 (w), 1591 (w), 1429 (w), 1262 (w), 1187 (w), 1125 (m), 1116 (m), 1073 (s), 1029 (w), 998 (w), 806 (m), 760 (w), 737 (m), 718 (m), 698 (m), 663 (w). UV/vis (chloroform): 277 nm (max.), 360 nm (max.), 387 nm (shoulder).
(3-(Diethoxymethylsilyl)propyl)bis(mesitoyl)phosphane oxide, Diethoxydimethylsilane copolymer ratio (BAPO-monomer/ comonomer): 1:20
1 H NMR (250.13 MHz, C6D6): δ = 6.69 (s, 4 H, MesCH), 3.05 (br., 9 H,
OCH2CH3), 2.43 (s, 12 H, o-MesCH3), 2.09 (s, 6 H, p-MesCH3), 1.95–1.83 (m, 2 H,
PCH2CH2), 1.47–1.33 (br., 6 H, OCH2CH3), 1.07–0.93 Experimental Part 282
(br., 2 H, SiCH2), 0.40 (s, 6 H, SiCH3) (not visible in the spectrum: PCH2). 31 P NMR (101.25 MHz, C6D6): δ = 27.8 (br.). IR (goldengate [cm-1]): 2962 (w), 2360 (w), 1724 (w), 1674 (w), 1610 (w), 1413 (w), 1258 (m), 1011 (s), 862 (w), 790 (s), 701 (w). UV/vis (chloroform): 281 nm (max.), 361 nm (max.), 389 nm (Shoulder). GPC: Mn = 298’369 g / mol, Mw = 886’298 g / mol, Q = 2.970.
(3-(Diethoxymethylsilyl)propyl)bis(mesitoyl)phosphane oxid, dimethoxydimethylsilan copolymer ratio (BAPO-monomer/ comonomer): 1:20
1 H NMR (250 MHz, C6D6): δ = 7.95–7.88 (m, 2 H , o-PhCH), 7.32–7.28 (m,
4 H, m-PhCH + p-PhCH), 6.68 (s, 4 H, MesCH), 4.05–3.96 (br., 4 H, OCH2CH3),
3.57 (s, 6 H, 2 x SiOCH3), 2.44 (s, 12 H, o-MesCH3), 2.09 (s, 6 H, p-MesCH3),
1.29-1.23 (br., 6 H, OCH2CH3), 1.06–0.90 (br., 2 H, SiCH2), 0.87–0.66 (br., 2 H,
PCH2), 0.41 (s, 6 H, 2xSiCH3).
31P NMR (101.25 MHz, C6D6): δ = 28.3-27.6 (br.). IR (goldengate, [cm-1]): 3071 (w), 3050 (w), 2939 (w), 2837 (w), 2361 (w), 2343 (w), 2120 (w), 1591 (w), 1429 (w), 1261 (w), 1187 (w), 1125 (m), 1116 (m), 1074 (m), 1029 (w), 998 (w), 806 (m), 760 (w), 737 (m), 718 (m), 698 (m), 663 (w). UV/vis (toluene): 281 nm (max.), 360 nm (max.), 387 nm (shoulder).
(3-(Triethoxysilyl)propyl)bis(mesitoyl)phosphane oxide Triethoxy(vinyl)silane copolymer ratio (BAPO-monomer/ comonomer): 1:1
1 H NMR (300 MHz, C6D6): δ = 6.74 (s, 4 H, Mes), 6.08 (m, 3 H, CH=CH2), 3.64 (m,
2 H, OCH2CH3), 2.43 (s, 12 H, Mes-ο-CH3), 2.15 (s, 6 H, Mes-p-CH3), 1.47 (m,
2 H, SiCH2CH2CH2P), 1.15 (t, J = 7.0 Hz, 3 H, OCH2CH3). Experimental Part 283
13 C NMR (75.5 MHz, C6D6): δ = 218.9 (C=O), 143.3 (Mes), 131.4 (Mes), 126.2
(Mes), 21.0 (Mes-p-CH3), 18.8 (Mes-o-CH3). 31 P NMR (101.3 MHz, C6D6): δ = 28.1 (br.). 31 1 P{ H} NMR (101.3 MHz, C6D6): δ = 28.6 (br.). IR (goldengate [cm-1]): 2959.2 (w, CH st.), 1721.2 (m, C=O st.), 1672.3 (m, C=O st.), 1608.8 (m, C=C st.), 1408.4 (m, CH3 def.), 1260.9 (s, C-O st.), 1084.4.0 (s, C- O st.). UV/vis (acetonitrile): 233 nm (max.).
(3-(Triethoxysilyl)propyl)bis(mesitoyl)phosphane oxide Triethoxy(vinyl)silane copolymer ratio (BAPO-monomer/ comonomer): 1:3
1 H NMR (300 MHz, C6D6): δ = 6.75 (s, 4 H, Mes), 6.22 (m, 3 H, CH=CH2), 3.74 (q,
J = 7.0 Hz, 2 H, OCH2CH3), 2.47 (s, 12 H, Mes-ο-CH3), 2.15 (s, 6 H, Mes-p-CH3),
1.47 (m, 2 H, SiCH2CH2CH2P), 1.18 (m, 3 H, OCH2CH3). 13 C NMR (75.5 MHz, C6D6): δ = 136.0 (Mes), 129.3 (Mes), 20.8 (Mes-p-CH3), 19.9
(Mes-o-CH3). 31 P NMR (101.3 MHz, C6D6): δ = 27.7 (m). 31 1 P{ H} NMR (101.3 MHz, C6D6): δ = 27.9 (m). IR (goldengate, [cm-1]): 2961.3 (w, CH), 1725.4 (w, C=O), 1672.6 (m, C=O),
1608.3 (s, C=C), 1408.3 (s, CH3), 1261.6 (s, C-O), 1213.0 (m, C-O), 1076.8 (s, C- O). UV/vis (acetonitrile): 239 nm (max.).
(3-(Triethoxysilyl)propyl)bis(mesitoyl)phosphane oxide Triethoxy(vinyl)silane copolymer ratio (BAPO-monomer/ comonomer): 1:20
Experimental Part 284
1 H NMR (300 MHz, C6D6): δ = 6.71 (s, 4 H, Mes), 6.08 (m, 3 H, CH=CH2), 3.63 (m,
2 H, OCH2CH3), 2.44 (s, 12 H, Mes-ο-CH3), 2.16 (s, 6 H, Mes-p-CH3), 1.58 (m,
2 H, SiCH2CH2CH2P), 1.18 (m, 3 H, OCH2CH3). 13 C NMR (75.5 MHz, C6D6): δ = 135.7 (Mes), 129.3 (Mes), 60.4 (OCH2CH3), 21.4
(Mes-p-CH3), 19.8 (Mes-o-CH3), 17.3 (OCH2CH3). 31 P NMR (101.3 MHz, C6D6): δ = 27.8 (br.). 31 1 P{ H} NMR (101.3 MHz, C6D6): δ = 28.0 (br.). IR (goldengate, [cm-1]): 3063.2 (w, CH), 2959.1 (w, CH), 1702.1 (w, C=O), 1602.3
(m, C=C), 1408.7 (s, CH3), 1275.7 (s, C-O),1068.5 (s, C-O). UV/vis (acetonitrile): 239 nm (max.).
(3-(Diethoxymethylsilyl)propyl)bis(mesitoyl)phosphane oxide Diethoxy(methyl)(vinyl)silane copolymer ratio (BAPO-monomer/ comonomer): 1:1
1 H NMR (200 MHz, C6D6): δ = 6.70 (s, 4 H, Mes), 6.08 (m, 3 H, CH=CH2), 3.40 (m,
2 H, OCH2CH3), 2.45 (s, 12 H, Mes-ο-CH3), 2.10 (s, 6 H, Mes-p-CH3), 1.60 (m,
2H, SiCH2CH2CH2P), 0.43 (s, 6 H, SiCH3). 13 C NMR (62.9 MHz, C6D6): δ = 203.6 (C=O), 140.8 (Mes), 135.9 (Mes), 129.3
(Mes), 20.8 (Mes-p-CH3), 19.5 (Mes-o-CH3), 15.8 (OCH2CH3), 1.2 (SiCH3). 31 P NMR (80 MHz, C6D6): δ = 27.7 (br.). 31 1 P{ H} NMR (80 MHz, C6D6): δ = 27.7 (br.). IR (goldengate, [cm-1]): 2955.0 (w, CH), 1720.0 (w, C=O), 1674.5 (m, C=O),
1608.4 (m, C=C), 1407.3 (s, CH3), 1259.4 (s, C-O), 1193.8 (m, C-O), 1068.1 (s, C- O), 1013.9 (s, C-O). UV/vis (acetonitrile): 239 nm (max.).
(3-(Diethoxymethylsilyl)propyl)bis(mesitoyl)phosphane oxide Diethoxy(methyl)(vinyl)silane copolymer ratio (BAPO-monomer/ comonomer): 1:3 Experimental Part 285
1 H NMR (250 MHz, C6D6): δ = 6.75 (s, 4 H, Mes), 6.06 (m, 3 H, CH=CH2), 3.43 (m,
2 H, OCH2CH3), 2.49 (s, 12 H, Mes-ο-CH3), 2.14 (s, 6 H, Mes-p-CH3), 1.58 (m,
2 H, SiCH2CH2CH2P), 0.40 (s, 6 H, SiCH3). 13 C NMR (62.9 MHz, C6D6): δ = 140.8 (Mes), 135.9 (Mes), 129.3 (Mes), 20.8 (Mes- p-CH3), 19.9 (Mes-o-CH3), 15.8 (OCH2CH3), 1.2 (SiCH3). 31 P NMR (121.5 MHz, C6D6): δ = 27.7 (br.). 31 1 P{ H} NMR (121.5 MHz, C6D6): δ = 27.7 (br.). IR (goldengate, [cm-1]): 2956.6 (w, CH), 1719.1 (w, C=O), 1673.6 (m, C=O),
1608.5 (m, C=C), 1407.4 (s, CH3), 1259.7 (s, C-O), 1193.9 (m, C-O), 1064.1 (s, C-O). UV/vis (acetonitrile): 239 nm (max.).
(3-(Diethoxymethylsilyl)propyl)bis(mesitoyl)phosphane oxide Diethoxy(methyl)(vinyl)silane copolymer ratio (BAPO-monomer/ comonomer): 1:20
1 H NMR (300 MHz, C6D6): δ = 6.74 (s, 4H, Mes), 6.07 (m, 3H, CH=CH2), 3.41 (m,
2H, OCH2CH3), 2.48 (s, 12H, Mes-ο-CH3), 2.16 (s, 6H, Mes-p-CH3), 1.58 (m, 2H,
SiCH2CH2CH2P), 0.48 (s, 6H, SiCH3). 13 C NMR (62.9 MHz, C6D6): δ = 136.2 (Mes), 133.5 (Mes), 129.3 (Mes), 59.8
(OCH2CH3), 20.8 (Mes-p-CH3), 19.9 (Mes-o-CH3), 15.2 (OCH2CH3), 1.6 (SiCH3). 31 P NMR (121.5 MHz, C6D6): δ = 27.6 (br.). 31 1 P{ H} NMR (121.5 MHz, C6D6): δ = 27.7 (br.). IR (goldengate [cm-1]): 3055.3 (w, CH), 2963.1 (m, CH), 1676.0 (w, C=O), 1597.5
(m, C=C), 1407.1 (m, CH3), 1259.2 (s, C-O), 1062.4 (s, C-O), 1007.0 (s, C-O). UV/vis (acetonitrile): 240 nm (max.). Experimental Part 286
General procedure for light induced gelation of vinyl substituted BAPO-functionalised silicones
The vinyl- and BAPO-functionalised copolymer was dissolved in benzene and the solution was irradiated with a middle pressure mercury lamp for 5 minutes. It results a pale yellow gel.
BAPO-functionalised polynorbornene (PM5)
(5-Norbornen-2-butyl)-4-bis(mesitoyl)phosphane oxide (0.5 g, 1.01 mmol, 1 eq.) and norbornene (1.89 g (20.2 mmol, 20 eq.) were dissolved in dichloromethane (50 mL). Grubbs catalyst first generation (3 mol%, 509 mg) was added and the solution was refluxed for 2 hours. Subsequently, vinylethylether (1 mL) was added to abort the reaction. The reaction mixture was filtrated over celite. The filtrate was added to methanol (100 mL). The polymer precipitated immediately.
31 1 P{ H} NMR (121.5 MHz, C6D6): δ = 24.7 (br.).
GPC: Mn = 235677, Mw = 452.363 g/mol.
BAPO-functionalised polystyrenes (PM3, PM4) a) In a 20 mL Schlenk flask sodium bis(mesitoyl)phosphide (P4) (100 mg, 0.26 mmol, 1 eq.) was dissolved in a mixture of toluene (5.00 mL) and thf (5 mL). Poly (bromomethylstyrene) (51.9 mg, 0.26 mmol, 1 eq.) was added and the solution was stirred for 72 hours at 60°C. The white precipitate was filtered off and the filtrate was concentrated in vacuo. The remaining oil was dissolved in toluene and hydrogen peroxide (10%) (0.01 mL, 0.26 mmol, 1 eq.) was added. The oxidation of the phosphane was completed after 4 hours. After adding toluene (15 mL), the solution was washed twice with an aqueous sodium hydrogencarbonate solution (2%), twice with brine and finally dried over sodium sulfate. The solvent was removed and the product dried in high vacuum for two hours. (Yield: 87.02 mg, 0.19 mmol, 74%). Experimental Part 287
31 P NMR (121.3 MHz, C6D6): δ = 26.3 (br.) b) In a 20 mL Schlenk flask sodium bis(mesitoyl)phosphide (P4) (100 mg, 0.26 mmol, 1 eq.) was dissolved in toluene (10.0 mL). poly(p-iodostyrene)
(51.9 mg, 0.26 mmol, 1 eq.) and [Pd(dba)2] (4.86 mg, 0.014 mmol, 5 mol%) were added. The solution was stirred for 72 hours at 85°C. Subsequently, the white precipitate was filtered off over celite and the filtrate was concentrated in vacuo. It was important to remove all the sodium iodide before the oxidation of the phosphane. The remaining oil was dissolved in toluene and hydrogen peroxide (0.01 mL, 0.26 mmol, 1 eq.) was added with a micro litre syringe. The oxidation of the phosphane was completed after 4 hours. After adding toluene (15 mL), the solution was washed twice with an aqueous sodium hydrogencarbonate solution (2%), twice with brine and finally dried over sodium sulfate. The solvent was removed and the product dried in high vacuo for two hours (Yield: 123.3 mg, 0.236 mmol, 91%).
31 P NMR (121.3 MHz, C6D6): δ = 9.3 (br.)
Functionalisation of cotton with BAPO-acetic acid
A piece of cotton (10x10 cm) was warmed up to 40°C for one hour in 30 mL of a solution of BAPO-acetic acid (200 mg) and DCC (200 mg) in dichloromethane. Subsequently, the cotton was soaked in pure dichloromethane twice for 2 hours each time and air dried. The functionalosed cotton was obtained.
General procedure for the functionalisation of cotton with BAPOsiloxanes and -silicones
A solution (1%) of the siloxane (silicone) in dichloromethane was used to impregnate the cotton by immersing it into the solution for 15 minutes. Experimental Part 288
Subsequently, the cotton was soaked in pure dichloromethane twice for 2 hours each time and air dried. The functionalosed cotton was obtained.
General procedure to perform a radical polymerisation on BAPO- functionalised cotton
A piece of BAPO-functionalised cotton was immersed into a solution of the monomer in n-hexane (3%).Subsequently, it was irradiated in the solution for 10 minutes. Next, the cotton was extracted several times with a soxhlet extractor with dichloromethane as solvent.
Chemisorption of phenolphthaleine on BAPO-functionalised cotton during irradiation with ultraviolet light
BAPO-functionalised cotton was immersed into a concentrated solution of phenolphthaleine in thf and irradiated with a middle pressure mercury lamp. Afterwards the cotton was washed three times with thf. After soaking the cotton in water and adding a drop of sodium hydroxide solution (1%) the cotton became red.
Synthesis of silver, copper and nickel (nano)particles
A solution (5%) of one equivalent silver triflate, copper(I)tetrafluoroborate or nickel trifluoroacetate in thf was irradiated with a middle pressure mercury lamp for 30 minutes in the presence of one equivalent Ph-BAPO.
AgOTf: An orange solution of silver nanoparticles was obtained. After a few days elemental silver precipitated.
AgOTf/ PPh3: A yellow solution of silver nanoparticles was obtained. Elemental silver does not precipitation, even after one week no precipitate was observed.
Experimental Part 289
Cu(BF4)2: A pale green solution of copper nanoparticles is obtained. After one day elemental copper precipitations.
Ni(CF3COO)2: A blue-green solution of nickel nanoparticles was obtained. After a few hours elemental nickel precipitated.
The same experiment with AgOTf was performed under hydrogen atmosphere with only 0.1 equivalents of Ph-BAPO. The result was the same as the one described above under argon atmosphere.
Chapter 6
General emulsion polymerisation procedure
In a cylindrical 100 mL Schlenk flask, degassed distilled water (33.5 mL), a degassed sodium dodecylsulfate solution (1.00 mL), freshly distillated styrene (10.0 g) and photoinitiator (BAPO-acetic acid sodium salt) (30.0 mg) were mixed under argon atmosphere. The reaction mixture was vigorously stirred with a large, magnetic, teflon-coated, stirring bar. The reaction mixture was irradiated with a middle pressure mercury UV lamp for 30 minutes. After switching off the UV lamp, the solution was stirred for 72 h, in order to complete the reaction. One drop of an aqueous hydroquinone solution (1%) was added to quench the reaction. The white latex was filtered over cotton wool into a glass flask with a screwing cap (Yield: 96%). For the analysis the polymer samples were prepared as described below.
GPC: The solvent was removed in vacuo completely. The remaining white powder was diluted in chloroform.
Light scattering: One drop of the latex was diluted with 5 mL water. The cell was filled with this diluted emulsion. Experimental Part 290
Yield analysis: A petri dish (7 cm diameter) was filled with 3 mm dried sand (12 h, 110°C, in vacuo for several days) and balanced. Subsequently, 1 mL latex was added. Afterwards it was put in the oven for 12 h at 110°C under vacuum. The petri dish was balanced again. The weight difference is the yield of the solid component of the latex.
NMR and other methods of analysis: sodium chloride solution (2% in water) was added to the latex to precipitation the polystyrene. The white precipitate was filtered off and washed three times with water. Subsequently, the polystyrene was dried in vacuo. Alternatively, the polystyrene particles can be isolated by centrifugation.
Appendix
Appendix 292
Abbreviations
A1 Compound number 1 AC8 acrylate of perluoroctanol acac Acetylacetonate/ o Ar Aryl B1 BAPO number 1 B1a BAP of BAPO number 1 BAP Bis(acyl)phosphane or Bis(mesitoyl)phosphane MeOBAP Bis(2,6-dimethoxybenzoyl)phosphane MesBAP Bis(mesitoyl)phosphane BAPO Bis(acyl)phosphane oxide or Bis(mesitoyl)phosphane oxide MeOBAPO Bis(2,6-dimethoxybenzoyl)phosphane oxide MesBAPO Bis(mesitoyl)phosphane oxide tBu tert-Butyl Bz Benzyl cmc Critical micelle concentration COD 1,5-Cyclooctadiene d douplett D1 Decomposition Product number 1 DBP Dibenzoylperoxide DCC Dicyclohexyl carbodiamide dma Dimethylacetamide dme 1,2-Dimethoxyethane dmf Dimethylformamide dmso dimethylsulfoxide EA Elemental Analysis EI Electron Impact EP Emulsion polymerisation EPR Electon Paramagnetiv Resonance Appendix 293
ESI Electro Spray Ionisation Et Ethyl Ether Diethylether Eq. Equation Fig. Figure HV High Vacuum IR Infra red isc Inter System Crossing KPS Potassium peroxodisulfate L Ligand M Metal (in general) MAPO mono(acyl)phosphane oxide, mesitoyldiphenylphosphane oxide (Lucirin TPO) Me Methyl MeCN Acetonitril Mes Mesityl MMA Methylmethacrylate MO Molecular orbital M.p. Melting point MS Mass Specroscopy m/z mass/charge-ratio NB Norbonene NBD Norbornadien NMP nitroxide mediated polymerisation NMR Nuclear Magnetic Resonance Nr. Number P1 Phosphane number 1 PD Polydispersity PM1 Polymer number 1 PMMA Poly(methylmethacrylate) Ph Phenyl Appendix 294
Ph-BAPO Bis(mesitoyl)phenylphosphane oxide (Irgacure 819) iPr isoPropyl quart. Quartet quint. Quintet
Q Polydispersity (Mw / Mn) R aliphatic moiety R1 Radical number 1 Ref. Reference RT Room Temperature Red. Reduction s singulet, solid solv. Solvent SP Suspension polymerisation t triplet thf Tetrahydrofurane TMEDA 1,1,2,2-N,N,N,N, tetramethylethylenediamine X Halide Appendix 295
Compounds
i i t A1 [Mg( Pr2)2] + P 4 A2 2 [Mg( Pr2)2] + P4 A3 NaO Bu + P4 NN t A4 A5 [Na10(Se)(O Bu)12] A6 Na2Se Cl Cl
O I N A7 A8 MesMgBr A9 O
O O
A10 Ph2P–OLi A11 B1a P O O
O O O O B2 [(MesCO) P(=O)Ph] B3 [(MesCO)PPh ] B4 2 2 P O H3C O O
O O O O CH3 O P P O B4a P B5 O O B6 O O P OOOO O
O O
P O O O O O B7 B8 P B9 P O O
O O P O O O
B10 O B11 P B12 O P O O O O Br Appendix 296
B13 B13a O O B14 O O O O P P Cl P Br O O Br
O O O O O P N B15 O B16 B17 O O O O P O P O O H2 N H2N
O O
P O B18 O B19a O O B20 O P P N3 O N=C=O N
O O O O O OO O P B21 P B22 B23 O O O P O OH O O HO
O O O O P O P O B24 B25 H O H B26 O O O CH H3C O 3 O HO H H P O O O SH OH O O H O O CH3 CH3
O O O O O
O P B27 P B28 O B29 O O O P P O O O O P EtO OEt O Appendix 297
O O
O P O B30 B30a O P B31 O P S N O O Br S N
O O O B32 O B32a O B33 O P P O O P O O
O
O O O O O O O O B33a P B34 P B35 P O OO O H O O H O
O O O O O O P P O B35a P B36 B36a O O O O O O O O H O
O O O O O P P B37 B38 P B38a O O O H HO HO O O O
O O O O O O O O O B39 P B39a P B40 O O O P O O OH O O O OH O 8 O HO Appendix 298
O O O O O O O B41 P B42 P B43 O O O O O P ONa NaO O O O O OMe
O O O O P P O O O B44 O O B45 O B46 O N P O O
H2N O NO2
O O O O O O P P P O B47 O B48 O B49 EtO Si OEt OEt Si Si OEt EtO OEt EtO Me
F O F F O O O P O B50 O B51 F B52 C7F15 P C7F15 O O F C8F17 P O C8F17
O O O O O O B52a B53 B54 P C7F15 P C7F15 P Me O O C8F17 O O
O O O O O O O B55 O B56 B57 P P P CN H O O O O
O O O O O P B58 B59 P B59a O P O O N O O
Appendix 299
O O O HO OH P P O O O D1 O D2 D3 P O O OH
D4 MesCHO D5 PhP(=O)Cl2 D6 MesCOCl
O S S O O P CH 3 D7 S D8 D9 S
O O S S S S N N P CH3 H3C P CH3 O D10 D11 D12 O P O
O O P [Cu(Ph(MesCO) D13 N D14 D15 O O PO2)(acac)]2 O 2
[Ni4((MesCO)P(O)O)2 O O [(Me(MesCO) (CF3COO)2 D16 D17 D18 P O P O O P(=O)O)2Cu]x (OP(=O)(Ph)-O- P(=O)PhO) (thf) ] x thf 2 4
O O O D19 O D20 PivCHO D21 Mes Mes O O O O D22 PivCOCl D23 D24 O N S
O O HO O O OH S S D25 P P D26 CH3 D27 P O P H3CCH3 CH3 O OH
O O S S S S N N D28 P CH3 D29 H3C P CH3 D30 O CH3 Me O P O Me Appendix 300
O O O P P P O D31 O CH3 D32 P D33 P P O 2
FG FG O O P O P O D34 O D35 D36 O P O
O
FG FG NR2 O O R2N P O D37 FG D38 O P O D39 O
P1 [Li2P16(thf)8] P2 Na2P16 P3 Na3P7
Na O O t t P4 P5 [Na3P7(NaO Bu)6] P6 [Na13(PH2)(O Bu)12] P
NN [Na(dme)3][Na12 P7 t P8 [NaPH2(solv.)]x P9 P (PH2)(O Bu)12] Na+ O t P10 NaPH2 x 2 NaO Bu P11 P12 HO3S PH2 PH2
O
O P13 Br PH2 P14 PH P15 P H
I
H H HOOC P COOH P P16 P17 P18 P
I I Appendix 301
NO2
P19 P20 P21 PH 2 PH 2 P P
O2N NO2 CF F 3 COOH
P22 P23 P24 P P P
F3C CF HOOC COOH 3 F F
F F F
P25 F P F P26 F P27 P P
F F F
MeSO2 SO2Me SiM e3 H P P P28 P29 P30 P Me3Si SiMe 3
SO Me 2 Me3Si SiMe 3
Na Na O O O O Na CF3 O O CF3 P31 P32 P33 O O P P C7F15 P C7F15 O O CF3 F3C
O O PCl2 O OH P [MesCO)2P- P34 P35 P36 O P(MesCO)2] O O O
PH2 BAPO- Na P37 P38 P PM1 functionalised O polythiophene
BAPO BAPO BAPO-functionalised PM2 PM3 PM4 cellulose PS PS PS PS BAPO- BAPO-functionalised BAPO-functionalised PM5 PM6 PM7 functionalised polynorbornene polymethacrylate silicones in general Appendix 302
cross linked BAPO- BAPO- BAPO-functionalised PM8- PM15- functionalised PM18- functionalised silicones for water PM14 PM17 vinylsilicones for PM20 vinylsilicones for repellent application gelation gelation
O R1 R2 O
Appendix 303
Crystallography data
Ph2P(O)(MesCO) (B3)
Empirical formula C22H21O2P1 Temperature 298(2) K Wavelength 0.71073 Å Crystal system Monoclinic Space group P2(1)/c Unit cell dimensions a = 15.3120(6) Å α = 90° b = 12.2044(4) Å β = 93.9993(3)° c = 20.2996(6) Å γ = 90° Volume 3784.23 Å3 Z 4 Absorption coefficient 0.45 mm–1 F(000) 2472 Crystal size 0.16 × 0.26 × 0.25 mm3 Data collection Oxford XCalibur, with CCD area detector Mo Kα, graphite monochromator Detector distance 50 mm Exposure time/frame 5 s Solution by direct methods, SHELXTL 97 Refinement method full matrix least-squares on F2 Theta range for data collection 2.13° to 29.13° Index range –18 ≤ h ≤ 20, –16 ≤ k ≤ 15, –27 ≤ l ≤ 25 Reflections collected 36209 Independent reflections 9100 [R(int) = 0.0797] Absorption correction none Data / restraints / parameters 9100 / 0 / 457 Goodness-of-fit on F2 0.732
Final R indices [I > 2σ(I)] R1 = 0.0510, wR2 = 0.1013
R indices (all data) R1 = 0.2039, wR2 = 01013 Largest diff. peak and hole 0.25 and –0.22 eÅ-3
Appendix 304
(MesCO)2P(O)CH2COOH (B38)
Empirical formula C22H25O5P1 Temperature 298(2) K Wavelength 0.71073 Å Crystal system Trinclinic Space group P-1 Unit cell dimensions a = 8.6245(2) Å α = 68.139(3)° b = 11.0500(3) Å β = 79.296(2)° c = 11.7088(3) Å γ = 87.501(2)° Volume 1017.20 Å3 Z 2 Absorption coefficient 0.16 mm–1 F(000) 428 Crystal size 0.13 × 0.18 × 0.21 mm3 Data collection Oxford XCalibur, with CCD area detector Mo Kα, graphite monochromator Detector distance 50 mm Exposure time/frame 5 s Solution by direct methods, SHELXTL 97 Refinement method full matrix least-squares on F2 Theta range for data collection 2.13° to 29.13° Index range –9 ≤ h ≤ 8, –12 ≤ k ≤ 12, –13 ≤ l ≤ 13 Reflections collected 5587 Independent reflections 2529 [R(int) = 0.0797] Absorption correction none Data / restraints / parameters 2529 / 0 / 260 Goodness-of-fit on F2 0.993
Final R indices [I > 2σ(I)] R1 = 0.0490, wR2 = 0.1516
R indices (all data) R1 = 0.0705, wR2 = 0.1516 Largest diff. peak and hole 0.48 and –0.47 eÅ-3 Appendix 305
(MesCO)2PCH2COOH (B38a)
Empirical formula C22H25O4P1 Temperature 298(2) K Wavelength 0.71073 Å Crystal system Monoclinic Space group P2(1)/c Unit cell dimensions a = 10.3965(1) Å α = 90° b = 11.8467(6) Å β = 100.594(10)° c = 16.8998(2) Å γ = 90° Volume 2045.97 Å3 Z 4 Absorption coefficient 0.11 mm–1 F(000) 762 Crystal size 0.33 × 0.19 × 0.25 mm3 Data collection Oxford XCalibur, with CCD area detector Mo Kα, graphite monochromator Detector distance 50 mm Exposure time/frame 5 s Solution by direct methods, SHELXTL 97 Refinement method full matrix least-squares on F2 Theta range for data collection 2.13° to 34.31° Index range –15 ≤ h ≤ 16, –18 ≤ k ≤ 16, –26 ≤ l ≤ 26 Reflections collected 28083 Independent reflections 8009 [R(int) = 0.0466] Absorption correction none Data / restraints / parameters 28083 / 0 / 245 Goodness-of-fit on F2 0.684
Final R indices [I > 2σ(I)] R1 = 0.0459, wR2 = 0.1324
R indices (all data) R1 = 0.1529, wR2 = 0. 1324 Largest diff. peak and hole 0.30 and –0.23 eÅ-3 Appendix 306
(MesCO)2P(O)CH2CO2Et (B53)
Empirical formula C 24H29O5P1 Temperature 298(2) K Wavelength 0.71073 Å Crystal system Triclinic Space group P-1 Unit cell dimensions a = 11.7740(2) Å α = 90.130(3)° b = 14.3780(3) Å β = 106.380(3)° c = 15.4560(3) Å γ = 90.130(3)° Volume 2510.28 Å3 Z 4 Absorption coefficient 0.17 mm–1 F(000) 1150 Crystal size 0.38 × 0.13 × 0.21 mm3 Data collection Oxford XCalibur, with CCD area detector Mo Kα, graphite monochromator Detector distance 50 mm Exposure time/frame 5 s Solution by direct methods, SHELXTL 97 Refinement method full matrix least-squares on F2 Theta range for data collection 2.13° to 34.31° Index range –18 ≤ h ≤ 17, –22 ≤ k ≤ 21, –23 ≤ l ≤ 23 Reflections collected 46677 Independent reflections 18208 [R(int) = 0.0551] Absorption correction none Data / restraints / parameters 18208 / 0 / 555 Goodness-of-fit on F2 0.763
Final R indices [I > 2σ(I)] R1 = 0.0459, wR2 = 0.1324
R indices (all data) R 1 = 0.2186, wR2 = 0. 1499 Largest diff. peak and hole 0.45 and –0.19 eÅ-3 Appendix 307
t (MesCO)2P(O)O Bu (B1a)
Empirical formula C 24H31O3P1 Temperature 298(2) K Wavelength 0.71073 Å Crystal system Triclinic Space group P1 Unit cell dimensions a = 9.6440(3) Å α = 107.547(3)° b = 11.6045(3) Å β = 105.812(3)° c = 12.0880(3) Å γ = 100.591(3)° Volume 1187.77 Å3 Z 2 Absorption coefficient 0.12 mm–1 F(000) 336.0 Crystal size 0.11× 0.13 × 0.15 mm3 Data collection Oxford XCalibur, with CCD area detector Mo Kα, graphite monochromator Detector distance 50 mm Exposure time/frame 10 s Solution by direct methods, SHELXTL 97 Refinement method full matrix least-squares on F2 Theta range for data collection 2.13° to 34.45° Index range –14 ≤ h ≤ 15, –18 ≤ k ≤ 18, –19 ≤ l ≤ 19 Reflections collected 46211 Independent reflections 18280 [R(int) = 0.0409] Absorption correction none Data / restraints / parameters 18280 / 3 / 505 Goodness-of-fit on F2 0.602
Final R indices [I > 2σ(I)] R1 = 0.0445, wR2 = 0.1358
R indices (all data) R 1 = 0.1978, wR2 = 0.1358 Largest diff. peak and hole 0.40 and –0.16 eÅ-3 Appendix 308
(MesCO)2P(O)C2H4OH (B21)
Empirical formula C 22H27O4P1 Temperature 298(2) K Wavelength 0.71073 Å Crystal system Triclinic Space group P1 Unit cell dimensions a = 8.2318(2) Å α = 104.047(3)° b = 11.0006(2) Å β = 105.964(3)° c = 13.2166(3) Å γ = 102.410(3)° Volume 1064.14 Å3 Z 2 Absorption coefficient 0.17 mm–1 F(000) 554.0 Crystal size 0.19× 0.19 × 0.21 mm3 Data collection Oxford XCalibur, with CCD area detector Mo Kα, graphite monochromator Detector distance 50 mm Exposure time/frame 15 s Solution by direct methods, SHELXTL 97 Refinement method full matrix least-squares on F2 Theta range for data collection 2.13° to 26.045° Index range –9 ≤ h ≤ 10, –13 ≤ k ≤ 12, –16 ≤ l ≤ 16 Reflections collected 15091 Independent reflections 6558 [R(int) = 0.073] Absorption correction none Data / restraints / parameters 6558 / 0 / 502 Goodness-of-fit on F2 0.877
Final R indices [I > 2σ(I)] R1 = 0.0606 , wR2 = 0.1422
R indices (all data) R 1 = 0.1562, wR2 = 0.1422 Largest diff. peak and hole 0.18 and –0.19 eÅ-3 Appendix 309
[Cu2(acac)2((MesCO)P(=O)O)2]*2thf (D15)
Empirical formula Cu2C52H54O12P2 Temperature 200 K Wavelength 0.71073 Å Crystal system Triclinic Space group P1 Unit cell dimensions a = 10.6957(1) Å α = 91.9158(7)° b = 10.9460(1) Å β = 91.556(8)° c = 11.2082(1) Å γ = 100.119(8)° Volume 1290.34 Å3 Z 1 Absorption coefficient 0.93 mm–1 F(000) 580.0 Crystal size 0.35× 0.32 × 0.10 mm3 Data collection Oxford XCalibur, with CCD area detector Mo Kα, graphite monochromator Detector distance 50 mm Exposure time/frame 15 s Solution by direct methods, SHELXTL 97 Refinement method full matrix least-squares on F2 Theta range for data collection 2.13° to 34.315° Index range –16 ≤ h ≤ 16, –17 ≤ k ≤ 16, –17 ≤ l ≤ 17 Reflections collected 26266 Independent reflections 17276 [R(int) = 0.0535] Absorption correction none Data / restraints / parameters 3433 / 3 / 596 Goodness-of-fit on F2 0.641
Final R indices [I > 2σ(I)] R1 = 0.0509 , wR2 = 0.1506
R indices (all data) R 1 = 0.2247, wR2 = 0.1508 Largest diff. peak and hole 0.38 and –0.30 eÅ-3 Appendix 310
[Ni4((MesCO)P(=O)O)2(CF3COO)2(OP(=O)(Ph)OP(=O)PhO)2(thf)4]*thf (D17)
Empirical formula Ni4C80F6O25P6H92 Temperature 200 K Wavelength 0.71073 Å Crystal system Triclinic Space group P-1 Unit cell dimensions a = 16.1030(9) Å α = 87.299(1)° b = 16.3006(9) Å β = 71.257(1)° c = 20.319(11) Å γ = 65.918(1)° Volume 4589.26 Å3 Z 7 Absorption coefficient 0.31 mm–1 F(000) 1688.0 Crystal size 0.25× 0.15 × 0.13 mm3 Data collection Oxford XCalibur, with CCD area detector Mo Kα, graphite monochromator Detector distance 50 mm Exposure time/frame 10 s Solution by Patterson, SHELXTL 97 Refinement method full matrix least-squares on F2 Theta range for data collection 2.13° to 28.355° Index range –21 ≤ h ≤ 21, –21 ≤ k ≤ 21, –27 ≤ l ≤ 27 Reflections collected 47884 Independent reflections 22650 [R(int) = 0.0915] Absorption correction none Data / restraints / parameters 22650 / 0 / 1141 Goodness-of-fit on F2 0.854
Final R indices [I > 2σ(I)] R1 = 0.0613 , wR2 = 0.1506
R indices (all data) R 1 = 0.1511, wR2 = 0.1511 Largest diff. peak and hole 0.98 and –0.77 eÅ-3 Appendix 311
[Cu2((MesCO)MeP(=O)O)2]x (D16)
Empirical formula (Cu1C24H20O10P2)x Temperature 200 K Wavelength 0.71073 Å Crystal system Triclinic Space group P-1 Unit cell dimensions a = 9.8785(2) Å α = 105.830(3)° b = 10.9930(2) Å β = 95.937(3)° c = 12.1016(2) Å γ = 102.066(3)° Volume 1218.28 Å3 Z 2 Absorption coefficient 1.29 mm–1 F(000) 706.0 Crystal size 0.45× 0.32 × 0.30 mm3 Data collection Oxford XCalibur, with CCD area detector Mo Kα, graphite monochromator Detector distance 50 mm Exposure time/frame 15 s Solution by direct methods, SHELXTL 97 Refinement method full matrix least-squares on F2 Theta range for data collection 2.13° to 34.75° Index range –15 ≤ h ≤ 15, –17 ≤ k ≤ 17, –19 ≤ l ≤ 19 Reflections collected 23105 Independent reflections 9777 [R(int) = 0.2505] Absorption correction none Data / restraints / parameters 9777 / 3 / 280 Goodness-of-fit on F2 1.141
Final R indices [I > 2σ(I)] R1 = 0.3161 , wR2 = 0.4506
R indices (all data) R 1 = 0.4063, wR2 = 0.5591 Largest diff. peak and hole 3.57 and –4.26 eÅ-3 Appendix 312
t [Na12(P7)2(O Bu)6(dme)6]*dme (P5)
Empirical formula Na12P14O20C52H124 Temperature 200 K Wavelength 0.71073 Å Crystal system Monoclinic Space group C2/c Unit cell dimensions a = 26.4783(3) Å α = 90° b = 15.0795(2) Å β = 113.404(4)° c = 26.5184(3) Å γ = 90° Volume 9717.12 Å3 Z 6 Absorption coefficient 0.21 mm–1 F(000) 3906.0 Crystal size 0.24× 0.28 × 0.35 mm3 Data collection Oxford XCalibur, with CCD area detector Mo Kα, graphite monochromator Detector distance 50 mm Exposure time/frame 10 s Solution by Patterson, SHELXTL 97 Refinement method full matrix least-squares on F2 Theta range for data collection 2.13° to 40.255° Index range –48 ≤ h ≤ 44, –27 ≤ k ≤ 27, –47 ≤ l ≤ 48 Reflections collected 129125 Independent reflections 30436 [R(int) = 0.0417] Absorption correction none Data / restraints / parameters 30436 / 0 / 466 Goodness-of-fit on F2 0.921
Final R indices [I > 2σ(I)] R1 = 0.0431 , wR2 = 0.1408
R indices (all data) R 1 = 0.0616, wR2 = 0.1410 Largest diff. peak and hole 1.72 and 0.90 eÅ-3 Appendix 313
t [Na(dme)3][Na12(PH2)(O Bu)12] (P7)
Empirical formula Na13P1O18C60H140 Temperature 30 K Wavelength 0.71073 Å Crystal system Cubic Space group F-43c Unit cell dimensions a = 26.0835(3) Å α = 90° b = 26.0835(3) Å β = 90° c = 26.0835(3) Å γ = 90° Volume 17745.88 Å3 Z 4 Absorption coefficient 0.148 mm–1 F(000) 6416.0 Crystal size 0.28 × 0.28 × 0.30 mm3 Data collection Oxford XCalibur, with CCD area detector Mo Kα, graphite monochromator Detector distance 50 mm Exposure time/frame 30 s Solution by Patterson, SHELXTL 97 Refinement method full matrix least-squares on F2 Theta range for data collection 2.71° to 20.81° Index range –26 ≤ h ≤ 25, –26 ≤ k ≤ 26, –25 ≤ l ≤ 26 Reflections collected 19929 Independent reflections 786 [R(int) = 0.0417] Absorption correction none Data / restraints / parameters 786 / 31 / 101 Goodness-of-fit on F2 1.034
Final R indices [I > 2σ(I)] R1 = 0.0889 , wR2 = 0.2373
R indices (all data) R 1 = 0.1158, wR2 = 0.2647 Largest diff. peak and hole 0.235 and 0.054 eÅ-3
Literature 315
Literature
Literature 316
[1] J.P. Fisher, M.D. Timmer, T.A. Holland, D. Dean, P.S. Engel, A.G. Mikos, Biomacromolecules 2003, 4, 1327. [2] J.V. Crivello, K. Dietliker, Photoinitiators for Free Radical Cationic and Anionic Photopolymerization, 2nd Edition 1998, SITA Technology Ltd. London. [3] K. Dietliker, A Compilation of Photoinitiators - Commercially available for UV today, 2002, SITA Technology Ltd., London. [4] K. Dietliker, T. Jung, J. Benkhoff, H. Kura, A. Matsumoto, H. Oka, D. Hristova, G. Gescheidt, G. Rist, Macromol. Symp. 2004, 217, 77. [5] U. Kolczak, G. Rist, K. Dietliker, J. Wirz, J. Am. Chem. Soc. 1996, 118, 6477. [6] S. Jockusch, N. J. Turro, J. Am. Chem. Soc. 1998, 120, 11773. [7] M. Spichty, N.J. Turro, G. Rist, J-L. Birbaum, K. Dietliker, J-P. Wolf, G. Gescheidt, J. Photochem. Photobiol. A: Chemistry 2001, 142, 209. [8] K. Dietliker, T. Jung, J. Benkhoff, H. Kura, A. Matsumoto, H. Oka, D. Hristova, G. Gescheidt, G. Rist, Macromol. Symp. 2004, 217, 77. [9] D.G. Leppard, M. Koehler, Ger. Offen. 1996, 37. [10] G. Ullrich, B. Ganster, U. Salz, N. Moszner, R. Liska, J. Polym. Sci., Part A Polym. Chem. 2006, 44, 1686. [11] T. Majima, W. Schnabel, Makromol. Chem. 1991, 192, 2307. [12] P. Murer, J.P. Wolf, S. Burkhardt, H. Grützmacher, D. Stein, K. Dietliker, WO 2006056541 2006. [13] D. Stein, Kurze Synthesewege zu hochfunktionalisierten Phosphorverbindungen 2006, Dissertation, ETH Zürich, Nr.: 16735. [14] E.D. Günersel, Y. Hepuzer, Y. Yagci, Angew. Makromol. Chem. 1990, 264, 88. [15] T.N. Makarov, A.N. Savitsky, K. Möbius, D. Beckert, H. Paul, J. Phys. Chem. A 2005, 109, 2254. [16] S. Jockusch, N. J. Turro, J. Am. Chem. Soc. 1998, 120, 11773. [17] T. Majima, Y. Konishi, A. Böttcher, K. Kuwata, M. Kamachi, W. Schnabel, J. Photochem. Photobiol. A: Chem. 1991, 58, 239. Literature 317
[18] M. Weber, N. J. Turro, J. Phys. Chem. A 2003, 107, 3326. [19] S. Jockrusch, I.V. Koptyug, P.F. McGarry, G.W. Sluggett, N.J. Turro, D.M. Watkins, J. Am. Chem. Soc. 1997, 119, 11495. [20] J.E. Bax ter, R.S. Davidson, H.J. Hageman, K.A. McLauchlan, D.G. Stevens, J. Chem. Soc., Chem. Commun. 1987, 73. [21] G.W. Sluggett, P.F. McGarry, I.V. Koptyug, N.J. Turro, J. Am. Chem. Soc. 1996, 118, 7367. [22] M. Weber, N.J. Turro, J. Phys. Chem. A 2003, 107, 3326. [23] G.W. Sluggett, P.F. McGarry, I.V. Koptyug, N.J. Turro, J. Am. Chem. Soc. 1996, 118, 7367. [24] I. Gatlik, P. Rzadek, G. Gescheidt, G. Rist, B. Hellrung, J. Wirz, K. Dietliker, G. Hug, M. Kunz, J-P. Wolf, J. Am. Chem. Soc. 1999, 121, 8332. [25] H. Hayashi, Y. Sakaguchi, M. Karachi, W. Schnabel, J. phys. Chem. 1987, 91, 3936. [26] A. Kajiwara, Y. Konishi, Y. Morishima, W. Schnabel, K. Kuwata, M. Kamachi, Macromolecules 1993, 26, 1656. [27] D. Hristova, I. Gatlik, G. Rist, K. Dietliker, J-P. Wolf, J-L. Birbaum, A. Savitsky, K. Möbius, G. Gescheidt, Macromolecules 2005, 38, 7714. [28] U. Kolczak, G. Rist, K. Dietliker, J. Wirz, J. Am. Chem. Soc. 1996, 118, 6477. [29] G.W. Sluggett, C. Turro, M.W. George, I.V. Koptyug, N.J. Turro, J. Am. Chem. Soc. 1995, 117, 5148. [30] T. Sumiyoshi, W. Schnabel, Makromol. Chem. 1985, 186, 1811. [31] T. Sumiyoshi, W. Schnabel, A. Henne, P. Lechtken, Polymer 1985, 26, 141. [32] M.T. Nguyen, T-K. Ha, Chem. Phys. 1989, 131, 245. [33] M. Spichty, N.J. Turro, G. Rist, J-L. Birbaum, K. Dietliker, J-P. Wolf, G. Gescheidt, J. Photochem. Photobiol. A: Chemistry 2001, 142, 209. [34] H.J. Hageman, T. Overeem, Makromol. Chem., Rapid Commun. 1981, 2, 719. [35] J.E. Baxter, R.S. Davidson, Makromol. Chem., Rapad Común. 1987, 2, 311. [36] H.J. Hageman, T. Overeem, Makromol. Chem. 1988, 189, 2769. Literature 318
[37] W. Rutsch, K. Dietliker, D. Leppard, M. Köhler, L. Misev, U. Kolczak, G. Rist, Prog. Org. Coat. 1996, 27, 227. [38] D. Leca, L. Fensterbank, E. Lacote, M. Malacria, Chem. Soc. Rev. 2005, 34, 858. [39] F. Toyokawa, E.I. Fukukawa, Y. Shibasaki, S. Ando, M.Ueda, J. Polym. Sci., Part A Polym. Chem. 2005, 43, 2527. [40] T.A. von Werne, D.S. Germack, E.C. Hagberg, V.V. Sheares, C.J. Hawker, K.R. Carter, J. Am. Chem. Soc. 2003, 125, 3831. [41] A. Nagata, T. Sakaguchi, T. Ichihashi, M. Miya, K. Ohta, Macromol. Rapid Commun. 1997, 18, 191. [42] J. Stumpe, L. Goldenberg, O. Kulikovska, WO 2006061419 A2, 2006. [43] W. Kern, J. Hobisch, K. Hummel, Macromol. Chem. Phys. 1997, 198, 443. [44] X. Coqueret, Macromol. Chem. Phys. 1999, 200, 1567. [45] R. Balaji, D. Grande, S. Nanjundan, Polymer 2004, 1089. [46] G. Sharma, M. Ballauff, Macroml. Rapid Commun. 2004, 25, 543. [47] Y.B. Malysheva, A.V. Gushchin, Y. Mei, Y. Lu, M. Ballauff, S.Proch, R. Kempe, Eur. J. Inorg. Chem. 2008, 379. [48] Y. Mei, G. Sharma, Y. Lu, M. Ballauff, Langmuir 2005, 21, 12229. [49] G. Sharma, Y. Mei, Y. Lu, M. Ballauff, T. Irrgang, S. Proch, R. Kempe, J. Catal. 2007, 246, 10. [50] O.A. Neumüller, Römpps Chemie Lexikon 1985, Achte, Neubearbeitete und erweiterte Auflage, FranckH Fachlexikon, Stuttgart. [51] B. Vollmert, Grundriss der makromolekularen Chemie, 5 Bde, E. Vollmert- Verlag, Karlsruhe, 1988. [52] J.M.G. Cowie, Chemie und Physik der synthetischen Polymeren, 2nd Ed., Vieweg & Sohn Verlagsgesellschaft mbH, Braunschweig/ Wiesbaden, 1997. [53] T.A. von Werne, D.S. Germack, E.C. Hagberg, V.V. Sheares, C.J. Hawker, K.R. Carter, J. Am. Chem. Soc. 2003, 125, 3831. [54] D.E. Smith, R.S. Clair, M.C. Ezenyilimba, J.F. Reber, EP0906931A2 1999. [55] A. Yoshimatsu, A. Kondo, R. Tsushima, EP0308864A2 1988. Literature 319
[56] D.E. Thomas, DE 2310538A1 1973. [57] J.R. McCracken, A.Datyner, J. Appl. Polym. Sci. 1974, 18, 3565. [58] M. Bardosova, R.H. Tredgold, J. Mater. Chem. 2002, 12, 2835. [59] P.A. Lovell, M.S. El-Aaser, Emulsion Polymerization and Emulsion Polymers, John Wiley and Sons, New York, 1997. [60] M.D. Lechner, K. Gehrke, E.H. Nordmeier, Makromolekulare Chemie, 2. Auflage, Birkhäuser Verlag, Basel 1996. [61] S. Nozari, K. Tauer, A.M. Imroz Ali, Macromolecules 2005, 38, 10449. [62] J. Kim, J. Kwak, Y.C. Kim, D. Kim, Colloid. Polym. Sci. 2006, 284, 771. [63] P.B. Zetterlund, M.N. Alam, H. Minami, M. Okubo, Macromol. Rapid Commun. 2005, 26, 955. [64] T. Nakamura, P.B. Zetterlund, M. Okubo, Macromol. Rapid Commun. 2006, 27, 2004. [65] P.B. Zetterlund, T. Nakamura, M. Okubo, Macromol. 2007, 40, 8663. [66] P. MacLeod, P.G. Odell, F.E. Torres, M.K. Michael, Jpn. Kokai Tokyo Koho 1999, 11. [67] H. Maehata, X. Liu, M. Cunningham, B. Keoshkerian, Macromol. Rapid Commun. 2008, 29, 479. [68] K. Min, K. Matyjaszewski, Macromolecules 2007, 40, 7217. [69] M. Nazimuddin, A.R. Das, B.M. Mandal, S.N. Bhattacharyya, Eur. Polym. J. 1990, 26, 837. [70] T. Ngai, C. Wu, Langmuir 2005, 21, 8520. [71] H.M. Jung, Y. Yoo, Y.S. Kim, J.H. Lee, Macromol. Symp. 2007, 249. [72] W.Y. Chiu, A.M. Lai, L.W. Chen, C.C. Chen, J. Appl. Poly. Sci. 1991, 42, 2787. [73] T.Y. Guo, G.L. Tang, G.J. Hao, M.D. Song, B.H. Zhang, J. Appl. Polym. Sci. 2003, 90, 1290. [74] J. Delgado, M.S. El-Aasser, C.A. Silebi, J.W. Vanderhoff, J. Guillot, J. Polym. Sci. 1950, 20, 225. [75] P.L. Tang, E.D. Sudol, C.A. Silebi, M.S. El-Aaser, J. Appl. Polym. Sci. 1991, 43, 1059. Literature 320
[76] R. Faridi-Majidi, N. Sharifi-Sanjani, J. Appl. Polym. Sci. 2007, 105, 1244. [77] S. Wang, X. Wang, Z. Zhang, Eur. Polym. J. 2007, 43, 178. [78] X. Wang, Z. Zhang, Rad. Phys. Chem. 2006, 75, 1001. [79] K. Dietliker, A Compilation of Photoinitiators, Commercially available for UV today, 2002, SITA Technology Limited, Edinburgh, London UK. [80] C. Fröhlich, G. Goldmann, H. Perrey, DE3219121A1 1983. [81] N.J. Turro, M.F. Chow, C.J. Chung, C.H. Tung, J. Am. Chem. Soc. 1980, 102, 7393. [82] A.L. Barney, GB802853A. [83] S.K. Gosh, B.M. Mandal, Polymer 1993, 34, 4287. [84] W. Uhl, M. Benter, Chem. Commun. 1999, 771. [85] C. Dohmeier, H. Schnöckel, C. Robl, U. Schneider, R. Ahlrichs, Angew. Chem. Int. Ed. Engl. 1994, 33, 199. [86] Y. Peng, H. Fan, H. Zhu, H.W. Roesky, J. Magull, C.E. Hughes, Angew. Chem. Int. Ed. Eng. 2004, 43, 3443. [87] J.D. Masuda, W.W. Schoeller, B. Donnadieu, G. Bertrand, Angew. Chem. 2007, 119, 7182; Angew. Chem. Int. Ed. Engl. 2007, 46, 7052. [88] Y. Xiong, S. Yao, M. Brym, M. Driess, Angew. Chem. Int. Ed. Engl. 2007, 46, 4511. [89] M. Driess, Angew. Chem. Int. Ed. Engl. 1991, 30, 1022. [90] M. Driess, A.D. Fanta, D.R. Powell, R. West, Angew. Chem. Int. Ed. Engl. 1989, 28, 1038. [91] M. Ehses, A. Romerosa, M. Peruzzini, Top. Curr. Chem. 2002, 220, 108. [92] M. Peruzzini, J.A. Ramirez, F. Vizza, Angew. Chem. Int. Ed. Engl. 1998, 37, 2255. [93] M. Peruzzini, L. Gonsalvi, A. Romerosa, Chem. Soc. Rev. 2005, 34, 1038. [94] J.M. Lynam, Angew. Chem. Int. Ed. Engl. 2008, 47, 831. [95] C.C. Cummins, Angew. Chem. 2006, 118, 876; Angew. Chem. int. Ed. Engl. 2006, 45, 862. Literature 321
[96] A. Schmidpeter, G. Burget, F. Zwaschka, W.S. Sheldrick, Z. Anorg. Allg. Chem. 1985, 527, 17. [97] L. Maier, Fortschr. Chem. Forsch. 1984, 118, 1078. [98] H.A. Lehmann, G. Grossmann, Pure Appl. Chem. 1980, 52, 905. [99] J. Staendeke, Chem. Ztg. 1972, 96, 494. [100] C. Brown, R.F. Hudson, G.A. Wartew, H. Coates, Chem. Commun. 1978, 7. [101] C. Brown, R.F. Hudson, G.A. Wartew, Phosphorus Sulfur and Rel. Elem. 1979, 6, 481. [102] C. Brown, R.F. Hudson, G.A. Wartew, Phosphorus Sulfur and Rel. Elem. 1978, 5, 121. [103] C. Brown, R.F. Hudson, G.A. Wartew, J. Chem. Soc., Perkin Trans. 1979, 1799. [104] F. Knoll, G. Bergerhoff, Monatsh. Chem. 1966, 97, 814. [105] M. Baudler, W. Faber, Chem. Ber. 1980, 113, 3394. [106] M. Baudler, O. Exner, Chem. Ber. 1983, 116, 1268. [107] M. Baudler, D. Düster, K. Langerbeins, J. Germeshausen, Angew. Chem. 1984, 96, 309; Angew. Chem. Int. Ed. Engl. 1984, 23, 317. [108] M. Baudler, O. Exner, R. Heumüller, D. Düster, J. Germeshausen, J. Hahn, Z. Anorg. Allg. Chem. 1984, 518, 7. [109] U. Müller, Anorganische Strukturchemie, 4. Auflage 2004, Teubner B.G. GmbH, Wiesbaden. [110] A. Cahour, Liebigs Ann. Chem. 1982, 122, 329. [111] D.J. Peterson, US 3397039 1968. [112] G. Becker, W. Holderich, Chem. Ber. 1959, 92, 1118. [113] E. C. Evers, J. Am. Chem. Soc. 1951, 73, 2038. [114] P. Royen, W. Zschaage, Z.Naturforsch.(B) 1953, 8, 777. [115] E. C. Evers, E. H. Street, S. L. Jung, J. Am. Chem. Soc. 1951, 73, 5088. [116] R. D. Stewart, R. I. Wagner, American Potash & Chem Corporation 1959, Patent US2900416. Literature 322
[117] L. Brandsma, N. Gusarova, S. Arbuzova, B. Trofimov, Phosphorus, Sulfur Silicon Relat. Elem. 1996, 111, 807 [118] L. Brandsma, N. K. Gusarova, A. V. Gusarov, H. D. Verkruijsse, B. A. Trofimov, Synth. Commun. 1994, 24, 3219. [119] L. Brandsma, J. A. Vandoorn, R. J. Delang, N. K. Gusarova, B. A. Trofimov, Mendeleev Commun. 1995, 14. [120] M. C. J. M. Van Hooijdonk, Disertation thesis, Universität Utrecht, 1999. [121] C. L. Liotta, M. L. McLaughlin, B. A. Obrien, Tetrahedron Lett. 1984, 25, 1249. [122] H. Schäfer, G. Fritz, W. Hölderich, Z. Anorg. Allg. Chem. 1977, 428, 222. [123] G. Becker, H.-M. Hartmann, W. Schwarz, Z. Anorg. Allg. Chem. 1989, 577, 9. [124] D. Hoffmann, T. Kottke, R. J. Lagow, R. D. Thomas, Angew. Chem. 1998, 37, 1537; Angew. Chem. Int. Ed. Engl. 1998, 37,1537. [125] F. Glorius, G. Altenhoff, R. Goddard, C. Lehmann, Chem. Commun. 2002, 2704. [126] J. Geier, H. Grützmacher, Chem. Commun. 2003, 2942. [127] R.H. Crabtree, The Organometallic Chemistry of the Transition Metals, 3rd Edition 2001, Wiley-VCH, New York, S. 91pp. [128] A. Köllhofer, H. Plenio, Tet. Let. 2003, 44, 1305. [129] O. Herd, A. Hessler, M. Hingst, M.Tepper, O. Stelzer, J. Organomet. Chem. 1996, 522, 69. [130] M.L. Clarke, D. Ellis, K.L. Mason, A.G. Orpen, P.G. Pringle, R.L. Wingad, D.A. Zaher, R.T. Baker, Dalt. Trans. 2005, 7, 1294. [131] E. Le Gall, K.B. Aissi, I. Lachaise, M. Trouple, Synlett 2006, 6, 954. [132] M.L. Clarke, D. Ellis, K.L. Mason, A.G. Orpen, P.G. Pringle, R.L. Wingad, D.A. Zaher, R.T. Baker, Dalt. Trans. 2005, 7, 1294. [133] E. Le Gall, K.B. Aissi, I. Lachaise, M. Trouple, Synlett 2006, 6, 954. [134] D.J.H. Smith, Comprehensive Organic Chemistry, Vol. 2 1979, (Ed: I.O. Sutherland), Pergamom, Oxford, 1129. Literature 323
[135] K. Issleib, A. Tzschach, H.U. Block, Chem. Ber. 1968, 101, 2931. [136] J.E. Swartz, J.F. Bunnett, J. Org. Chem. 1979, 44, 340. [137] A.M. Aguiar, H.J. Greenberg, K.E. Rubenstein, J. Org. Chem. 1963, 28, 2091. [138] H.C.E. McFarlane, W.McFarlane, Polyhedron 1983, 2, 303. [139] O. Herd, A. Hessler, K.P. Langhans, O. Stelzer, W.S. Sheldrick, N. Weferling, J. Organomet. Chem. 1994, 457, 99. [140] R. Uriarte, T.J. Mazanec, K.D. Tau, D.W. Meek, Inorg. Chem. 1980, 19, 79. [141] O. Herd, D. Hoff, K.W. Kottsieper, C. Liek, K. Wenz, O. Stelzer, W.S. Sheldrick, Inorg. Chem. 2002, 41, 5034. [142] F. Bitterer, O. Herd, A. Hessler, M. Kühnel, K. Rettig, O. Stelzer, W.S. Sheldrick, S. Nagel, N. Rösch, Inorg. Chem. 1996, 35, 4103. [143] O. Herd, A. Hessler, K.P. Langhans, O. Stelzer, W.S. Sheldrick, N. Weferling, J. Organomet. Chem. 1994, 475, 99. [144] O. Stelzer, O. Herd, N. Weferling, DE 4325816 1995. [145] O. Stelzer, O. Herd, N. Weferling, DE 4141299 1993. [146] V.I. Sorokin, M. Nieuwenhuyzen, G.C. Saunders, Mendeleev Commun. 2006, 172. [147] S. Sasaki, Y. Tanabe, M. Yoshifuji, Bull. Chem. Soc. Jpn. 1999, 72, 563. [148] Y.A. Veits, N.B. Karlstedt, A.V. Chuchuryukin, I.P. Beletskaya, Russ. J. Org. Chem. 2000, 36, 750. [149] L.I. Goryunov, J. Grobe, V.D. Shteingarts, B. Krebs, A. Lindemann, E.U. Würthwein, C. Mück-Lichtenfeld, Chem. Eur. J. 2000, 6, 4612. [150] H.G. von Schnering, V. Manriquez, W. Honle, Angew. Chem. Int. Ed. Engl. 1981, 20, 594. [151] V. A. Milyukov, A.V. Kataev, O.G. Sinyashin, E. Hey-Hawkins, Russ. Chem. Bull., Int. Ed. 2006, 55, 1295. [152] M. Baudler, R. Heumüller, J. Hahn, Z. Anorg. Allg. Chem. 1985, 529, 7. [153] I.D. Grice, I.D. Jenkins, W.K. Busfield, K.A.Byriel, C.H.L. Kennard, Acta Cyrstallogr., Sect.E: Struct. Rep. Online 2004, 60, 2384. Literature 324
[154] W. Honle, H.G. von Schnering, A. Schmidpeter, G. Burget, Angew. Chem. Int. Ed. Engl. 1984, 23, 817. [155] M. Driess, R. Mulvey, M. Westerhausen, Molecular Clusters of the Main Group Elements, M. Driess, H. Nöth (Eds.), Wiley-VCH, 2004, 391. [156] M. Driess, Acc. Chem.Res. 1999, 32, 1017. [157] M. Driess, Adv. Inorg. Chem. 2000, 50, 235.
[158] T. Gottschalk, B.Jaun, F. Diederich, Angew. Chem. 2006, 119, 264; Angew. Chem. Int. Ed. 2007, 46, 260. [159] J. Rebek, Angew. Chem. 2005, 117, 2104; Angew. Chem. Int. Ed. Engl. 2005, 44, 2068. [160] D. Fiedler, D. H. Leung, R. Bergman, K. Raymond, Acc. Chem. Res. 2005,
38, 351.
[161] J. Cioslowski, J. Am. Chem. Soc. 1991, 113, 4139. [162] W. Rosch, U. Hees, M. Regitz, Chem. Ber. Recl. 1987, 120, 1645 [163] W. Roesch, M. Regitz, Angew. Chem. 1984, 96, 898. [164] A. Schmidpeter, A. Wilhalm, Angew. Chem. 1984, 96, 901; Angew. Chem.- Int. Edit. Engl. 1984, 23, 903. [165] M. Valentini, H. Ruegger, P.S Pregosin, Helv. Chim. Acta 2001, 84, 2833. [166] P.S Pregosin, Prog. Nucl. Magnet. Res. Spec. 2006, 49, 261. [167] A. Macchioni, Chem. Rev. 2005, 105, 2039. [168] J. van Beek, B. Meier, unpublished results. [169] D. Freude, J. Haase, "Quadrupole Effects in Solid State NMR" in "NMR, Basic Principles and Progress" 1993, Vol. 29, Springer Verlag Berlin. [170] B.Q. Sun, J.H. Baltisberger, Y. Wu, A. Samoson and A. Pines, Solid State NMR 1992, 1, 267-295. [171] A. Samoson, B.Q. Sun and A. Pines, "Pulsed Magnetic Resonance: NMR, ESR and Optics", Oxford Science Publications 1992, Oxford, 80-94. Literature 325
[172] R.R. Ernst, G. Bodenhausen and A. Wokaun, Principles of Nuclear Magnetic Resonance in One and Two Dimensions, Oxford Science Publications 1987, New York. [173] N. Bloembergen, E.M. Purcell, R.V. Pound, Phys. Rev. 1948, 73, 679. [174] M. Podewitz, M. Reiher, unpublished results. [175]((a) M. A. Bennett, R. S. Nyholm, J. D. Saxby, J. Organomet. Chem. 1967, 10, 301–306; b) D. I. Hall, R. S. Nyholm, J. Chem. Soc., A 1971, 1491–1493;. c) L. V. Interrante, G. V. Nelson, J. Organomet. Chem. 1970, 25, 153–160; d) M. A. Bennett, L. V. Interrante, R. S. Nyholm, Z. Naturforsch., B: Chem. Sci. 1965, 20, 633–634; e) H. Luth, M. R. Truter, A. Robson, J. Chem. Soc., A 1969, 28–41; f) I. H. Wang, G. R. Dobson, J. Organomet. Chem. 1988, 356, 77–84; g) L. V. Interrante, G. V. Nelson, Inorg. Chem. 1968, 7, 2059–2063; h) M. A. Bennett, G. B. Robertson, I. B. Tomkins, P. O. Whimp, J. Chem. Soc. D 1971, 341–342. i) M. A. Bennett, E. J. Hann, J. Organomet. Chem. 1971, 29, C15–C16; j) P. R. Brookes, J. Organomet. Chem. 1972, 42, 459–469; k) P. R. Brookes, J. Organomet. Chem. 1972, 43, 415–423; l) D. I. Hall, R. Nyholm, J. Chem. Soc., Dalton Trans. 1972, 804–808. m) M. A. Bennett, W. R. Kneen, R. S. Nyholm, Inorg. Chem. 1968, 7, 556–560. n) M. A. Bennett, R. Bramley, I. B. Tomkins, J. Chem. Soc., Dalton Trans. 1973, 166–168; o) M. A. Bennett, H. K. Chee, J. C. Jeffery, G. B. Robertson, Inorg. Chem. 1979, 18, 1071–1076; p) M. A. Bennett, W. R. Kneen, R. S. Nyholm, J. Organomet. Chem. 1971, 26, 293–303. q) M. A. Bennett, W. R. Kneen, R. S. Nyholm, Inorg. Chem. 1968, 7, 552–556.). [176] W.C. Davis, C.J.O.R. Morris, Bull. Soc. Chim. France 1933, 53, 980. [177] a) D.A. Pears, K.E. Treacher, M. Nisar, WO 2007096592 A1 2007, 47pp; b) S. Matsuoka, M. Amano, Y. Kida, JP 02049009 1990, 9; c) H.E. Ramsden, US 310985119631105 1963, 5pp. [178] a) J. Tong, S. Liu, S. Zhang, L. Shengwan, Z. Shengshi, Spectrochim. Acta, Part: A, Mol. Biomol. Spect. 2007, 67, 837; b) P.C. Nam, P. Garbaux, M.T. Nguyen, Eur. J. Mass Spect. 2003, 9, 257; c) L.R. Frank, K. Evertz, L. Zsolnai, G. Literature 326
Huttner, J. Orgmet. Chem. 1981, 221, 301; d) L. Meier, Phosph. and Rel. Group V Elem. 1974, 4, 41. [179] S.O. Grim, A.W. Yankowsky, J. Org. Chem. 1974, 42, 1236. [180] P.W. Miller, M. Nieuwenhuyzen, X. Xu, S.L. James, Chem. Comm. 2002, 18, 2008. [181] V. Ravindar, H. Schumann, H. Hemling, J. Blum, Inorg. Chim. Acta 1995, 240, 145. [182] E. Le Gall, K. Ben Aissi, I. Lachaise, M. Troupel, Synlett 2006, 6, 954. [183] P.W. Miller, M. Nieuwenhuyzen, J.P.H. Charmant, S.L. James, Inorg. Chem. 2008, 47, 8367. [184] M.T. Reetz, G. Mehler, Tet. Let. 2003, 44, 5493. [185] B. Richter, E. de Wolf, G. van Koten, B.J. Deelman, J. Org. Chem. 2000, 65, 3885. [186] Z. Wu, R.R. Stanley, C.U. Pittman Jr., J. Org. Chem. 1999, 64, 8386. [187] H. Grützmacher, J. Geier, D. Stein, T. Ott, H. Schönberg, R.H. Sommerlade, S. Boulmaaz, J.P. Wolf, P. Murrer, T. Ulrich, Chimia 2008, 62, 18. [188] E.W. Turnblom, T.K. Katz, J. Am. Chem. Soc. 1974, 93, 4065. [189] D.A. Edwards, M.F. Mahon, T.J. Paget, J. Chem. Cryst. 1996, 26, 361. [190] W. Hoggen, W. Ruji, Y. Xinkan, C. Leifeng, C. Ruyu, Jiegou Huyxe (Chin.), Chiese J. Struct. Chem. 1987, 6, 139. [191] C. Hendriksen, Crystal structure of BAPO-acetic acid methylester, unpublished results. [192] W. Dreissig, K. Plieth, Acta Crystalogr., Sect.B: Struct. Crystalogr. Cryst. Chem. 1971, 27, 1146. [193] N. Kise, N. Ueda, Bull. Chem. Soc. Jpn. 2001, 74, 755. [194] S. Kingsley, A. Vij, V. Chandrasekhar, Inorg. Chem. 2001, 40, 6059. [195] T. Majima, W. Schnabel, Macromol. Chem. 1991, 192, 2307. [196] K.W. Oliver, D.J. Rettig, R.C. Thompson, J. Trotter, Can. J. Chem. 1982, 60, 2017. [197] D. Fenske, R. Mattes, J. Lons, K.F. Tebbe, Chem. Ber. 1973, 106, 1139. Literature 327
[198] M.L.C.E. Kouwijzer, B.P. van Eijck, W.J. Muizebelt, Acta Crystalogr., Sect.C: Cryst. Struct. Commun. 1991, 47, 634. [199] M. Kant, S. Bischoff, Z. Anorg. Allg. Chem. 1999, 625, 707. [200] L. Maier, Helv. Chim. Acta 1971, 54, 275. [201] L.F. Tietze, T. Eicher, Namesnreaktionen in der Organischen Chemie, 1. Auflage 2007, Wiley-VCH Verlag, Weinheim. [202] J. Bigeault, L. Giordano, G. Buono, Angew. Chem., Int. Ed. 2005, 44, 4753. [203] Y. Iriyama, T. Yasuda, D. Cho, H. Yasuda, J. Appl. Polym. Sci. 1990, 39, 249. [204] H. Saechtling, Kunststoff-Taschenbuch, 29. Auflage 2004, Hanser Fachbuchverlag, München. [205 ] F. Tourillon, F. Garnier, J. Electroanal. Chem. 1981, 111, 111. [206] B.S. Ong, Y.W. Wu, P. Liu, S. Gardner, J. Am. Chem. Soc. 2003, 126, 3378. [207] F. Garnier, R. Hajlaoui, A. Yassar, P. Srivastava, Science 1994, 265, 1684. [208] H. Sirringhaus, P.J. Brown, R.H. Friend, M.M. Nielen, K. Bechgaard, B.M.W. Langeveld-Voss, A.J.H. Spiering, R.A.J. Janssen, E.W. Meijer, P. Herwig, D.M. de Leeuw, Nature 1999, 401, 685. [209] K. Koseki, T. Yamaoka, T. Tsunoda, Y. Funahashi, Nippon Insatsu Gakkai Ronbunshu 1976, 16, 131. [210] J.H. Malpert, A. Mjiritski, D.C. Perrysburg, S. Rubinsztajn, EP 1136533 A1 2001. [211] R. Mercier, X. Coqueret, A. Lablache-Combier, C. Loucheux, Eur. Polym. J. 1988, 24 639. [212] G.O. Phillips, P.A. Williams, Handbook of Hydrocolloids 2000, Woodhead Publishing Ltd., Abington, Cambridge. [213] L.A. Estroff, A.D. Hamilton, Chem. Rev. 2003, 104, 1201. [214] M. van Hooren, "Oligomere Modellsysteme elektrisch leitfähiger Copolymere auf Basis von Pyrrol und Thiophen" 1999, Dissertation, Universität Hannover. [215] M. Castellano, A. Gandini, P. Fabbri, M.N. Belgacem, J. Coll. Interf. Sci. 2004, 273, 505. Literature 328
[216] A. Huber, Diplomarbeit, ETH Zürich. [217] T. Liebert, C. Hänsch, T. Heinze, Macromol. Rapid Commun. 2006, 27, 208. [218] G. Schmid, Chem. Rev. 1992, 92, 1709. [219] J.A. Widegren, R.G. Finke, J. Mol. Catal. A 2003, 191, 187. [220] D.L. Feldheim, C.A. Foss (Eds.), Metal Nanoparticles 2002, Marcell Dekker, New York. [221] M. Raffi, F. Hussain, T.M. Bhatti, J.I. Akhter, A. Hameed, M.M. Hasan, J. Mater. Sci. Tech. 2008, 24, 192. [222] K. Philippot, B. Chaudret, C. R. Chimie 2003, 6, 1019. [223] J.H. Adair, E. Suvaci, Curr. Opin. Colloid Interface Sci. 2000, 5, 160. [224] S. Eustis, M.A. El-Sayed, Chem. Soc. Rev. 2006, 35, 209. [225] T. Nakamura, P.B. Zetterlund, M. Okubo, Macromol. Rapid Commun. 2006, 27, 2014. [226] P.B. Zetterlund, T. Nakamura, M. Okubo, Macromolecules 2007, 40, 8663. [227] P.J. MacLeod, P.G. Odell, F.E. Torres, M.K. Georges, Jpn. Kokai Tokkyo Koho 1999, 11pp. [228] A. Schmit, A. Boeckmann, Ger. Offen. DE 3012821 A1 1981, 51 pp. [229] W. Zhang, C. Wu, T. Ngai, C. Lou, Wuli Huaxue Xuebao 2000, 16, 116. [230] J. Wang, H. Wu, A. Wang, Y. Cao, Y. Duan, P. Yuan, Hecheng Huaxue 2004, 12, 213. [231] M. Antonietti, Macromol. Chem. Phys. 1995, 196, 441. [232] J.R. McCracken, A. Datyner, J. Appl. Polym. Chem. 1974, 18, 3365. [233] P.L. Tang, E.D. Sudol, C.A. Silebi, M.S. El-Aaser, J. Appl. Polym. Sci. 1991, 43, 1059. [234] T.Y. Guo, G.L. Tang, G.J. Hao, M.D. Song, B.H. Zhang, J. Appl. Polym. Sci. 2003, 90, 1290. [235] X. Du, J. He, J. Appl. Polym. Sci. 2008, 108, 1755. [236] Z. Xu, X. Hu, X. Li, C. Li, Polym. Chem. 2007, 46, 481. [237] T. Ngai, C. Wu, Langmuir 2005, 21, 8520. Literature 329
[238] H. Maehata, X. Liu, M. Cunningham, B. Keoshkerian, Macromol. Rapid. Commun. 2008, 29, 479. [239] H.M. Jung, Y. Yoo, Y.S. Kim, J.H. Lee, Macromol. Symp. 2007, 249, 521. [240] B. Keoshkerian, P.J. MacLeod, P.G. Odell, M.K. Georges, US 6469094 2002. [241] K. Tauer, C. Schellenberg, A. Zimmermann, Macromol. Symp. 2000, 150, 1. [242] P.L. Kuo, N.J. Turro, C.M., Tseng, M.S. El-Aasser, J.W. Vanderhoff, Macromolecul. 1987, 20, 1216. [243] G. Pan, E.D. Sudol, V.L. Dimonie, M.S. El-Aasser, Macromolecul. 2001, 34, 481. [244] C.K. Grätzel, M. Jirousek, M. Grätzel, Langmuir 1986, 2, 292. [245] J.A. Abusleme, P.A. Guarda, R.J. de Pasquale, EP 0650982 A1 1995. [246] J.S. Guo, M.S. El-Aasser, J.W. Vanderhoff, J. Polym. Sci. 1989, 27, 691. [247] J. Bräuer, unpublished results. [248] R. K. Harris, E. D. Becker, S. M. C. De Menezes, R. Goodfellow, P. Granger, Pure Appl. Chem. 2001, 73, 1795-1818. [249] A. D. Bain, G. J. Duns, Can. J. Chem. 1996, 74, 819-824. [250] M. Bak, J. T. Rasmussen, N. C. Nielsen, J. Magn. Reson. 2000, 147, 296- 330. [251] SAINT, Reference manual, Siemens Energy and Automation, Madison, WI, 1994-1996. [252] G. M. Sheldrick, SADABS, Empirical Absorption Correction Program, University of Göttingen, Germany, 1997. [253] G. M. Sheldrick, SHELXS-97, Program for Crystal Structure Solution, University of Göttingen, Germany, 1997. [254] G. M. Sheldrick, SHELXL-97, Program for Crystal Structure Refinement, University of Göttingen, Germany, 1997. [255] S. J. Dolman, K.C. Hultzsch, F. Pezet, X. Teng, A.H. Hoveyda, R.R. Schrock, J. Am. Chem. Soc. 2004, 126, 10945. [256] T. Heinze, K. Rahn, M. Jaspers, H. Berghmans, J. Appl. Polym. Sci. 1996, 60, 1891. Literature 330
[257] W.T. Flowers, J.F. Robinson, D.R. Taylor, A.E. Tipping, J. Chem. Soc., Perkin Trans. 1 1981, 356; R. Stolle, J. Prakt. Chem. 1912, 85, 386. The product could only be synthesised in glacial acetic acid, not in CCl4. [258] E.A. Chernyshev, A.V. Kisin, V.G. Lathkin, V.M. Nosava, M.V. Polyakova, V.C. Ryalkov, Russ. Chem. Bull. 1995, 44, 718. [259] M. Butts, T. Ganicz, A. Kowalewska, S.A. Nye, W.A. Staczuk, S. Rubinsztain, J. Mater. Chem. 2005, 15, 611. [260] P. Nongkunsarn, C. A. Ramdsen, Tetrahedron 1997, 53, 3818. [261] P.A. Levene, Organic Synthesis, Collect. Vol. II 1943, 88, New York. [262] G. Dubois, R. Tripier, S. Brandes, F. Denat, R. Guilard, J. Mat. Chem. 2002, 12, 2255. [263] M. M. Rauhut, H. A. Currier, J. Org. Chem. 1961, 26, 4626. [264] G. Ohms, G. Grossmann, B. Schwab, H. Schiefer, Phosphorus, Sulfur, Silicon Relat. Elem. 1992, 68, 77. [265] Purnanand, P.D. Shakya, S. Saxena, M. Sharma, Basant Lal, Phosphorus, Sulfur, Silicon Relat. Elem. 2002, 177, 1093. [266] T. Imamoto, M. Kodera, M. Yokohama, Synhtesis 1982, 2, 134. [267] K. Schwetlick, Organikum, 20. Auflage, 1999, Wiley VCH, Weinheim. [268] L. Horner, K. Dickerhof, Chem. Ber. 1983, 116, 1603. [269] H.O. Kalinowski, S. Berger, S. Braun, 13C NMR-Spektroskopie 1984, Georg Thieme Verlag, Stuttgart. [270] G. Ohms, G. Grossmann, B. Schwab, H. Schiefer, Phosphorus, Sulfur , Silicon Rel. Elem. 1992, 68, 77. [271] F. Kazemi, H. Sharghi, M.A. Nasseri, Synthesis 2004, 2, 205. [272] J.D. Masuda, A.J. Hoskin, T.W. Graham, C. Beddie, M.C. Fermin, N. Etkin, D.W. Stephan, Chem. Eur. J. 2006, 12, 8696. [273] M. Scherer, D. Stein, F. Breher, J. Geier, H. Schönberg, H. Grützmacher, Z. Anorg. Allg. Chem. 2005, 631, 2770. [274] J. Brierley, J. Dickstein, S. Tripplett, Phosphorus and Sulfur and the Related Elements 1979, 7, 167. Literature 331
[275] K. Issleib, E. Fluck, Zeitschrift für Chemie 1968, 8, 3818. [276] L. Horner, P. Beck, V.G. Toscano, Chem. Ber. 1961, 94, 1317. [277] A.J. Hoskin, D.W. Stephan, Organomet. 1999, 18, 2479.