DOCSLIB.ORG

Functionalized Hybrid Silicones – Catalysis, Synthesis and Application

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Functionalized Hybrid Silicones – Catalysis, Synthesis and Application Technische Universität München Fakultät für Chemie Fachgebiet Molekulare Katalyse Functionalized Hybrid Silicones – Catalysis, Synthesis and Application Sophie Luise Miriam Putzien Vollständiger Abdruck der von der Fakultät für Chemie der Technischen Universität München zur Erlangung des akademischen Grades eines Doktors der Naturwissenschaften (Dr. rer. nat.) genehmigten Dissertation. Vorsitzender: Univ.-Prof. Dr. M. Schuster Prüfer der Dissertation: 1. Univ.-Prof. Dr. F. E. Kühn 2. Univ.-Prof. Dr. O.Nuyken (i.R.) Die Dissertation wurde am 16.02.2012 bei der Technischen Universität München eingereicht und durch die Fakultät für Chemie am 08.03.2012 angenommen. The following dissertation was prepared between April 2009 and March 2012 at the Chair of Inorganic Chemistry, Department of Molecular Catalysis of the Technische Universität München. I would like to express my deep gratitude to my academic supervisor Prof. Dr. Fritz E. Kühn for his support and confidence and the freedom of scientific research. This work was supported by a research grant from the BASF Construction Chemicals GmbH, Trostberg, Germany. Acknowledgement I would like to express my sincere gratitude to Prof. Dr. Oskar Nuyken and Dr. Eckhart Louis for their ongoing support and their undamped enthusiasm for my research topic. They supported this work with many inspiring discussions, new ideas and critical questions. I thank the BASF Construction Chemicals GmbH, Trostberg, for giving me the opportunity to work on an industrial cooperation project. Especially, I would like to thank Dr. Simone Klapdohr and Dr. Burkhard Walther, who accompanied this project from the industrial perspectice, for their support and the nice time I had in Trostberg during the application technological tests. I am very grateful to Prof. Dr. James Crivello for his support with the photopolymerization experiments and the very nice and fruitful time at the Rensselaer Polytechnic Institute. I would like to thank all the colleagues at the Technische Universität München for the nice working atmosphere. Especially, I thank my lab mate Simone Hauser for the very comfortable lab climate, for her friendly and polite nature, for various inspiring conversations, also besides chemistry, and for solving small computer problems. I also thank the lab neighbors from the east-west corridor, Jenny Ziriakus, Christina Müller, Philipp Altmann and Stefan Huber, for the nice time we spent together, especially during the coffee breaks, and for their generosity concerning chemicals. Many thanks also to the colleagues from the Si-Institute, Dr. Peter Gigler, Dr. Stefanie Riederer and Dr. Daniel Canella for many inspiring discussions concerning silicon chemistry and to Dr. Manuel Högerl and Dr. Magnus Buchner for the maintainance of the NMR spectrometer. All technicians at the TUM, especially Georgeta Krutsch for NMR experiments and Thomas Schröferl for GC-MS, are gratefully acknowledged. Furthermore, I am grateful to Dr. Marianne Hanzlik for performing several TEM measurements. I also thank the technicians at the BASF in Trostberg, especially Andrea Schneider and Andreas Brey for their support during the application technological tests. Many thanks go to Prof. Dr. Peter Härter, Tobias Kubo and Peter Richter who made the supervision of the practical courses in Weihenstephan almost a pleasure. Furthermore, I am very grateful to the secretaries of the Chair of Inorganic Chemistry for their excellent support with respect to all bureaucratic issues. Additionally, I thank the TUM graduate school for unbureaucratic financial support. My bachelor students Simone Keller and Hannah Weinzierl are gratefully achnowledged for their enthusiastic and energetic contribution to my research. Finally and most of all, I would like to thank my mother and my boyfriend for their perpetual support, patience and trust! Contents Contents 1. Introduction .......................................................................................................... 1 1.1 Hydrosilylation ......................................................................................................... 1 1.2 Polysilalkylene Siloxanes as Hybrid Silicones ......................................................... 2 1.3 Objectives of this Work ............................................................................................ 5 2. Catalysis ............................................................................................................... 6 2.1 Platinum Catalysts and Reaction Mechanism ......................................................... 6 2.2 Test and Comparison of Different Hydrosilylation Catalysts .................................... 8 2.3 PtO2 as Heterogeneous Hydrosilylation Catalyst ................................................... 11 2.4 Hydrosilylation of Isopropenyl Compounds ........................................................... 21 2.4.1 Mechanistic Models for the Hydrosilylation of Allyl Compounds ..................... 22 2.4.2 General Observations ..................................................................................... 24 2.4.3 Kinetic Considerations .................................................................................... 25 2.4.4 Scope and Limits of the Reaction ................................................................... 27 2.4.5 Deuteration Experiments and Mechanistic Proposal....................................... 30 3. Synthesis and Functionalization of Hybrid Silicones ...................................... 36 3.1 State of the Art ....................................................................................................... 36 3.2 Synthesis of Si-H-terminated Hybrid Silicones ...................................................... 41 3.3 Functionalization of Hybrid Silicones ..................................................................... 52 3.3.1 Functionalization with Alcohols ....................................................................... 52 3.3.2 Functionalization with Epoxides ...................................................................... 55 3.3.3 Functionalization with Amines ......................................................................... 56 3.3.4 Functionalization with (Meth)acrylates ............................................................ 58 3.3.5 Functionalization with Anhydrides ................................................................... 59 3.3.6 Functionalization with Trialkoxysilanes ........................................................... 60 3.3.7 Functionalization with Acetates ....................................................................... 61 3.3.8 Functionalization with Ether Groups ............................................................... 63 3.3.9 Functionalization with Aliphatic, Cycloaliphatic or Aromatic Groups ............... 65 3.3.10 Further Functionalizations ............................................................................. 66 Contents 4. Stability of Differently-substituted Silicon-containing Model Compounds .... 68 5. Synthesis and Application of Functionalized Hybrid Silicones ...................... 71 5.1 Epoxy-functional Hybrid Silicones ......................................................................... 72 5.1.1 Photochemical Curing of Epoxy-functional Hybrid Silicones ........................... 72 5.1.2 Thermal Curing of Epoxy-functional Hybrid Silicones ..................................... 88 5.2 Preparation and Thermal Curing of Amino-functional Hybrid Silicones ................. 94 5.3 Preparation and Curing of Trimethoxysilyl-functional Hybrid Silicones................ 107 6. Summary and Conclusion ............................................................................... 119 7. Experimental ..................................................................................................... 123 7.1 General ................................................................................................................ 123 7.2 Comparison of Different Hydrosilylation Catalysts ............................................... 123 7.3 Hydrosilylation of Isopropenyl Compounds ......................................................... 126 7.4 Synthesis of Different SiH-terminated Hybrid Silicones ....................................... 131 7.5 Test Reactions for the Functionalization of SiH-terminated Hybrid Silicones ...... 136 7.6 Determination of the Stability of Different Model Compounds ............................. 148 7.7 Synthesis and Photochemical Curing of Epoxy-functional Hybrid Silicones ........ 148 7.8 Thermal Curing of Epoxy-functional Hybrid Silicones .......................................... 154 7.9 Synthesis and Curing of Amino-terminated Hybrid Silicones .............................. 156 7.10 Synthesis and Curing of Trimethoxysilyl-terminated Hybrid Silicones ............... 161 References ............................................................................................................ 165 Abbreviations Abbreviations and Trade Names Å Ångstroem AAS atomic absorption spectroscopy Ac acetate Aerosil® 812S fumed silica AGE allyl glycidyl ether Ancamine® K54 2,4,6-tris-dimethylaminomethylphenol Anti-terra® U80 wetting and dispersing additive Ar Aryl Araldite® 2047-1 cold curing two-part methacrylate adhesive Barytmehl N barite flour BDDVE 1,4-butandiol divinyl ether BHT butylated hydroxytoluene (2,6-di-tert-butyl-p-cresol) BNT-CAT® 440 dibutyltin diketonate br broad Bu butyl t-bu tertiary butyl Byk® 057 defoamer Byk® 354 leveling
Load more

Recommended publications
  • Chapter 21 the Chemistry of Carboxylic Acid Derivatives
    Instructor Supplemental Solutions to Problems © 2010 Roberts and Company Publishers Chapter 21 The Chemistry of Carboxylic Acid Derivatives Solutions to In-Text Problems 21.1 (b) (d) (e) (h) 21.2 (a) butanenitrile (common: butyronitrile) (c) isopentyl 3-methylbutanoate (common: isoamyl isovalerate) The isoamyl group is the same as an isopentyl or 3-methylbutyl group: (d) N,N-dimethylbenzamide 21.3 The E and Z conformations of N-acetylproline: 21.5 As shown by the data above the problem, a carboxylic acid has a higher boiling point than an ester because it can both donate and accept hydrogen bonds within its liquid state; hydrogen bonding does not occur in the ester. Consequently, pentanoic acid (valeric acid) has a higher boiling point than methyl butanoate. Here are the actual data: INSTRUCTOR SUPPLEMENTAL SOLUTIONS TO PROBLEMS • CHAPTER 21 2 21.7 (a) The carbonyl absorption of the ester occurs at higher frequency, and only the carboxylic acid has the characteristic strong, broad O—H stretching absorption in 2400–3600 cm–1 region. (d) In N-methylpropanamide, the N-methyl group is a doublet at about d 3. N-Ethylacetamide has no doublet resonances. In N-methylpropanamide, the a-protons are a quartet near d 2.5. In N-ethylacetamide, the a- protons are a singlet at d 2. The NMR spectrum of N-methylpropanamide has no singlets. 21.9 (a) The first ester is more basic because its conjugate acid is stabilized not only by resonance interaction with the ester oxygen, but also by resonance interaction with the double bond; that is, the conjugate acid of the first ester has one more important resonance structure than the conjugate acid of the second.
    [Show full text]
  • The Unique Properties of Siloxanes
    THE UNIQUE PROPERTIES OF SILOXANES This factsheet explains what makes siloxanes unique. Want to know how siloxanes are different from carbon-based materials? Or why they behave differently in the environment? Read on to find out more, including why the current PBT assessment criteria might not be suitable for them. WHAT ARE SILOXANES? Siloxanes are a group of substances characterized by a chain of alternating silicon (Si) and oxygen (O) atoms. Within the group, individual siloxane substances differ in size, weight and shape. They form the backbone of silicone polymers that are used in a variety of applications such as sealants, adhesives, coatings, plastics, cosmetics, medical devices, hygiene products, food contact materials, and many other industrial applications. Siloxane functional group Octamethylcyclotetrasiloxane (D4) WHAT ARE SILICONE POLYMERS? The structure and functionality of these chemical compounds drive the specific Silicones are specialty products that are used in small amounts in hundreds combination of properties of siloxanes of applications where their special performance is needed. They are used as including: adhesives, they create flow, they insulate, and they have excellent mechanical/ optical/thermal resistance among many other properties. Silicone polymers can • High propensity to repel water have very different forms depending on how they are built, for example: • Low water solubility • Volatility USED AS LUBRICANTS AND LIQUIDS/OIL IN HYDRAULIC FLUIDS Silicone materials offer a host of useful characteristics including:
    [Show full text]
  • United States Patent 15) 3,669,956 Borck Et Al
    United States Patent 15) 3,669,956 Borck et al. (45) June 13, 1972 54) 4-SUBSTITUTEDAMNO 260/472, 260/516, 260/518 R, 260/518 A, 260/519, PHENYACETIC ACDS AND 260/556 AR, 260/556 B, 260/558 S, 260/558 A, DERVATIVES THEREOF 260/559 T, 260/559 A, 260/.571, 260/574, 260/.575, (72 Inventors: Joachim Borck; Johann Dahin; Volker 424/244, 424/246, 424/248, 424/250, 424/267, Koppe; Josef Kramer; Gustav Shorre; J. 424/270, 424/272, 424/273, 424/274, 424/304, W. Hermann Hovy; Ernst Schorscher, all 424/309, 424/32 i, 424/324, 424/330 of Darmstadt, Germany 51) int. Cl. ........................................................ C07d 41/04 58) Field of Search........ 260/294X,293.4, 293.47, 239 BF, 73) Assignee: E. Merck A. G., Darmstadt, Germany 260/326.3, 294.3 E (22) Filed: July 22, 1968 56) References Cited (21) Appl. No.: 746,326 UNITED STATES PATENTS (30) Foreign Application Priority Data 3,252,970 5/1966 Huebner................................ 260/239 July 22, 1967 Germany.............................. M 74881 3,385,852 5/1968 Casadio................................. 260/246 Jan. 8, 1968 Germany... ....M 76850 OTHER PUBLICATIONS Feb. 23, 1968 Germany...... ...M 77363 March 1, 1968 Germany.............................. M 77429 Norman et al., J. Chen. Soc. 1963, (Nov.), 5431-6. (52) U.S. Cl................... 260/239 BF, 260/239 A, 260/239 E, Primary Examiner-Henry R. Jiles 260/243 B, 260/246, 260/247. 1, 260/247.2 R, Assistant Examiner-G. Thomas Todd 260/247.2 A, 260/247.2 B, 260/247.5 R, 260/247.7 Attorney-Millen, Raptes & White A, 260/247.7 H,
    [Show full text]
  • Environmental Risk Assessment Report: Decamethylcyclopentasiloxane
    Environmental Risk Assessment Report: Decamethylcyclopentasiloxane Science Report Environmental Risk Assessment: Decamethylcyclopentasiloxane 1 The Environment Agency is the leading public body protecting and improving the environment in England and Wales. It’s our job to make sure that air, land and water are looked after by everyone in today’s society, so that tomorrow’s generations inherit a cleaner, healthier world. Our work includes tackling flooding and pollution incidents, reducing industry’s impacts on the environment, cleaning up rivers, coastal waters and contaminated land, and improving wildlife habitats. Published by: Author(s): Environment Agency, Rio House, Waterside Drive, Aztec West, Brooke D N, Crookes M J , Gray D and Robertson S Almondsbury, Bristol, BS32 4UD Tel: 01454 624400 Fax: 01454 624409 Dissemination Status: www.environment-agency.gov.uk Publicly available / released to all regions ISBN: 978-1-84911-029-7 Keywords: © Environment Agency April 2009 Decamethylcyclosiloxane, siloxane All rights reserved. This document may be reproduced with prior Research Contractor: permission of the Environment Agency. Building Research Establishment Ltd, Bucknalls Lane, Garston, Watford, WD25 9XX. Tel. 01923 664000 The views expressed in this document are not necessarily those of the Environment Agency. Environment Agency’s Project Manager: Steve Robertson, Chemicals Assessment Unit, Red Kite House, This report is printed on Cyclus Print, a 100 per cent recycled Howbery Park, Wallingford OX10 8BD. Tel 01491 828555 stock, which is 100 per cent post consumer waste and is totally chlorine free. Water used is treated and in most cases returned Collaborator(s): to source in better condition than removed. D Gray, Health and Safety Executive Further copies of this report are available from: Product code: The Environment Agency’s National Customer Contact Centre SCHO0309BPQX-E-P by emailing [email protected] or by telephoning 08708 506506.
    [Show full text]
  • Understanding the Thermochemical Conversion of Biomass to Overcome Biomass Recalcitrance Kwang Ho Kim Iowa State University
    Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2015 Understanding the thermochemical conversion of biomass to overcome biomass recalcitrance Kwang Ho Kim Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Agriculture Commons, and the Bioresource and Agricultural Engineering Commons Recommended Citation Kim, Kwang Ho, "Understanding the thermochemical conversion of biomass to overcome biomass recalcitrance" (2015). Graduate Theses and Dissertations. 14382. https://lib.dr.iastate.edu/etd/14382 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Understanding the thermochemical conversion of biomass to overcome biomass recalcitrance by Kwang Ho Kim A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Agricultural and Biosystems Engineering Program of Study Committee: Robert C. Brown, Co-Major Professor Xianglan Bai, Co-Major Professor Kurt Rosentrater Matthew Darr Brent Shanks Young Jin Lee Iowa State University Ames, Iowa 2015 Copyright © Kwang Ho Kim, 2015. All rights reserved. ii DEDICATION Dedicated to my family for their unwavering support
    [Show full text]
  • Silicone Elastomers with Exceptional Elongation ACS Rubber
    Silicone Elastomers with Exceptional Elongation Barry Arkles*, Jonathan Goff, Santy Sulaiman Gelest Inc. 11 East Steel Rd. Morrisville, PA 19067 Presented at the 188th Technical Meeting of Rubber Division, ACS / International Elastomer Conference Paper # 124 October 12-15, 2015 Cleveland, OH *Speaker 1 ABSTRACT Polysiloxanes elastomers formed by the step-growth of heterobifunctional macromers achieve high molecular weights and show elastomeric behavior. There is no apparent mechanism for crosslinking and advanced NMR and DSC techniques as well as rheological studies support the fact that, within the limits of detection, the step-growth elastomers are linear. When formed into nanocomposites by the incorporation of surface passivated fumed silica, they exhibit elongations exceeding 5000%. At extensions comparable to conventional silicone elastomers, they show similar elastic recovery. At greater extensions, recovery is reduced marginally. These materials are readily manufacturable and can be compounded and processed similar to conventional two-component platinum cure silicone RTVs. We have adopted the designation of xPDMS for these materials, a modified acronym for “high eXtension PolyDiMethylSiloxanes”. The synthesis, characterization, and mechanical properties of the first example of of an xPDMS suitable for commercial production is presented. INTRODUCTION In most commercial applications, single component silicone elastomers are conventionally prepared by either the crosslinking of a polysiloxane component in a silica reinforced base by a peroxide (HCR, high consistency rubber) or by a moisture-cure mechanism (condensation RTVs, room temperature vulcanizates)1. Another more flexible approach for commercial fabrication of silicone elastomers is to use two polysiloxane components in which 2 one polysiloxane component is generally of higher molecular weight and can be thought of the matrix polymer, and the second polysiloxane component, which is generally of lower molecular weight and can be thought of as a crosslinker.
    [Show full text]
  • Hydrosilylation Reactions Catalyzed by Rhenium
    molecules ReviewReview HydrosilylationHydrosilylation ReactionsReactions CatalyzedCatalyzed byby RheniumRhenium DuoDuo WeiWei1,2 1,2,, Ruqaya Ruqaya Buhaibeh Buhaibeh 22, ,Yves Yves Canac Canac 22 andand Jean-Baptiste Jean-Baptiste Sortais Sortais 2,3,*2,3, * 11 Univ.University Rennes, Rennes, CNRS, CNRS, ISCR - ISCR-UMR UMR 6226, 6226, F-35000 35000 Rennes, Rennes, France; France; [email protected] [email protected] 22 LCC-CNRS,LCC-CNRS, Université Université dede Toulouse, Toulouse, UPS, UPS, 31400 31400 Toulouse, Toulouse, France; [email protected] (R.B.); [email protected]@lcc-toulouse.fr (Y.C.) (Y.C.) 33 InstitutInstitut Universitaire Universitaire de de France France 1 1 rue rue Descartes, Descartes, 75231 CEDEX Paris 05, Cedex 75231 Paris,05, France France ** Correspondence:Correspondence: [email protected] [email protected] Abstract:Abstract: Hydrosilylation isis anan important process,process, notnot onlyonly inin thethe siliconsilicon industryindustry toto produceproduce siliconsilicon polymers,polymers, butbut alsoalso in finefine chemistry. InIn this review,review, thethe developmentdevelopment ofof rhenium-basedrhenium-based catalystscatalysts forfor thethe hydrosilylationhydrosilylation of of unsaturated unsaturated bonds bonds in in carbonyl-, carbonyl-, cyano-, cyano-, nitro-, nitro-, carboxylic carboxylic acid acid derivatives derivatives and alkenesand alkenes is summarized. is summarized. Mechanisms Mechanisms of rhenium-catalyzed of rhenium-catalyzed
    [Show full text]
  • Chapter 18 Ethers and Epoxides; Thiols and Sulfides Ethers
    Chapter 18 Ethers and Epoxides; Thiols and Sulfides Ethers • Ethers (R–O–R’): – Organic derivatives of water, having two organic groups bonded to the same oxygen atom © 2016 Cengage Learning 2 NAMES AND PROPERTIES OF ETHERS 3 Nomenclature: Common Names • Simple ethers are named by identifying two organic substituents and adding the word ether – Name the groups in alphabetical order – Symmetrical: Use dialkyl or just alkyl © 2016 Cengage Learning 4 Nomenclature: IUPAC Names • The more complex alkyl group is the parent name • The group with the oxygen becomes an alkoxy group © 2016 Cengage Learning 5 Nomenclature: Cyclic Ethers (Heterocycles) • Heterocyclic: Oxygen is part of the ring. O • Epoxides (oxiranes) H2C CH2 O • Oxetanes • Furans (Oxolanes) O O • Pyrans (Oxanes) O O O • Dioxanes O © 2013 Pearson Education, Inc. 6 Epoxide Nomenclature • Name the starting alkene and add “oxide” © 2013 Pearson Education, Inc. 7 Epoxide Nomenclature • The oxygen can be treated as a substituent (epoxy) on the compound • Use numbers to specify position • Oxygen is 1, the carbons are 2 and 3 • Substituents are named in alphabetical order © 2013 Pearson Education, Inc. 8 Properties of Ethers • Possess nearly the same geometry as water – Oxygen atom is sp3-hybridized – Bond angles of R–O–R bonds are approximately tetrahedral • Polar C—O bonds © 2013 Pearson Education, Inc. 9 Properties of Ethers: Hydrogen Bond • Hydrogen bond is a attractive interaction between an electronegative atom and a hydrogen atom bonded to another electronegative atom • Ethers cannot hydrogen bond with other ether molecules, so they have a lower boiling point than alcohols • Ether molecules can hydrogen bond with water and alcohol molecules • They are hydrogen bond acceptors © 2013 Pearson Education, Inc.
    [Show full text]
  • Synthesis of Pendant Epoxy Functional Polydimethyl Siloxane for Modification of Diglycidyl Ether of Bis-Phenol A
    Available online at http://www.urpjournals.com Advances in Polymer Science and Technology: An International Journal Universal Research Publications. All rights reserved Original Article Synthesis of pendant epoxy functional polydimethyl siloxane for modification of Diglycidyl Ether of Bis-phenol A Jenish Paul1, 2, A. Benny Cherian2, K.P.Unnikrishnan2 and Eby Thomas Thachil1 1- Polymer Science &Rubber Technology, Cochin university of science & Technology,Kochi- 22 2- Chemistry Department, Union Christian College, Aluva-5 Received 22 December 2011; accepted 30 December 2011 Abstract In this study, pendant epoxy functional poly dimethyl siloxanes were synthesized by the hydrosilylation reaction of pendant silyl hydride functional polydimethyl siloxane with allyl glycidyl ether. The hydrosilylation reaction was characterized by spectroscopic techniques. Samples of pendant epoxy functional poly dimethyl siloxanes and pendant silyl hydride functional polydimethyl siloxane were blended with commercial epoxy resin, diglycidyl ether of bis-phenol A, at various ratios using a polyamine as curing agent. The results show that the addition of functionalised poly dimethyl siloxanes increases the flexibility of the cross linked network and also the thermal stability and water resistance. © 2011 Universal Research Publications. All rights reserved Key words: DGEBA; resin; polysiloxanes; hydrosilylation; blending. 1. Introduction functionalise them. One of the major processes used to Epoxy resin exhibits many desirable properties, such as functionalize polysiloxanes is hydrosilylation of high strength and modulus, excellent chemical and solvent polyhydridosiloxanes [12]. resistance, good thermal and electrical properties and 1.2. Hydrosilylation outstanding adhesion to various substrates, and easy process Hydrosilanes react with compound containing carbon- ability under various conditions [1-5]. Epoxy resins are also carbon multiple bonds when catalyzed by transition metal widely used as molding compounds and encapsulation of complexes.
    [Show full text]
  • Hydrosilylation of Alkynes Catalysed by Platinum on Titania.Pdf
    Journal of Organometallic Chemistry xxx (2010) 1e5 Contents lists available at ScienceDirect Journal of Organometallic Chemistry journal homepage: www.elsevier.com/locate/jorganchem Hydrosilylation of alkynes catalysed by platinum on titania Francisco Alonso a,*, Robinson Buitrago b, Yanina Moglie a, Javier Ruiz-Martínez b, Antonio Sepúlveda-Escribano b,*, Miguel Yus a a Departamento de Química Orgánica, Facultad de Ciencias, and Instituto de Síntesis Orgánica (ISO), Universidad de Alicante, Apdo. 99, E-03080 Alicante, Spain b Departamento de Química Inorgánica, Facultad de Ciencias, and Instituto Universitario de Materiales (IUMA), Universidad de Alicante, Apdo. 99, E-03080 Alicante, Spain article info abstract Article history: The heterogeneous hydrosilylation of alkynes catalysed by platinum on titania is reported. A variety of Received 2 August 2010 hydrosilanes react with both terminal and internal alkynes to furnish the corresponding vinyl silanes in Received in revised form high yields and short reaction times as well as in a regio- and stereoselective manner. The catalyst can be 29 September 2010 easily recovered and reused in several consecutive cycles. Accepted 29 September 2010 Ó 2010 Elsevier B.V. All rights reserved. Keywords: Hydrosilylation Alkynes Platinum Titania Heterogeneous catalysis 1. Introduction (e.g. with platinumephosphine complexes) while the heteroge- neous version of this reaction has been somewhat neglected. Vinyl silanes are very versatile organosilicon compounds with Heterogeneous catalysts offer several advantages over the homo- manifold applications in organic synthesis [1]. There is a general geneous counterparts, such as easy recovery, easy recycling, and upsurge of interest in these organometalloids due to their partic- enhanced stability [13,14]. To the best of our knowledge, only three ular non-toxicity, high chemical stability and low molecular weight reports describe the heterogeneous platinum-catalysed hydro- when compared with other organometallic reagents.
    [Show full text]
  • Pph3-Assisted Esterification of Acyl Fluorides with Ethers Via C
    Article PPh3‐Assisted Esterification of Acyl Fluorides with Ethers via C(sp3)–O Bond Cleavage Accelerated by TBAT Zhenhua Wang 1, Xiu Wang 1 and Yasushi Nishihara 2,* 1 Graduate School of Natural Science and Technology, Okayama University, 3‐1‐1 Tsushimanaka, Kita‐ku, Okayama 700‐8530, Japan; [email protected]‐u.ac.jp (Z.W.); [email protected]‐u.ac.jp (X.W.) 2 Research Institute for Interdisciplinary Science, Okayama University, 3‐1‐1 Tsushimanaka, Kita‐ku, Okayama 700‐8530, Japan * Correspondence: ynishiha@okayama‐u.ac.jp; Tel.: +81‐86‐251‐7855; Fax: +81‐86‐251‐7855 Received: 23 May 2019; Accepted: 26 June 2019; Published: 28 June 2019 Abstract: We describe the (triphenylphosphine (PPh3)‐assisted methoxylation of acyl fluorides with cyclopentyl methyl ether (CPME) accelerated by tetrabutylammonium difluorotriphenysilicate (TBAT) via regiospecific C–OMe bond cleavage. Easily available CPME is utilized not only as the solvent, but a methoxylating agent in this transformation. The present method is featured by C–O and C–F bond cleavage under metal‐free conditions, good functional‐group tolerance, and wide substrate scope. Mechanistic studies revealed that the radical process was not involved. Keywords: Acyl fluorides; cyclopentyl methyl ether (CPME); tetrabutylammonium difluorotriphenysilicate (TBAT); carbon‐oxygen bond cleavage; esterification 1. Introduction The C−O bond cleavage in ethers is one of the most fundamental transformations in organic synthesis and has been widely applied in the manufacturing of fine chemicals as well as the synthesis of polyfunctional molecules [1–5]. Particularly, the preparation and degradation of ethers have often been considered important synthetic strategies for the protection/deprotection of hydroxyl groups.
    [Show full text]
  • Comparing PPG Polysiloxane Coatings and Traditional Coating Systems
    Comparing PPG Polysiloxane Coatings and Traditional Coating Systems INTRODUCTION The last two decades have seen continuous This document examines the chemistry behind AND EXECUTIVE improvement in the performance and aesthetic PSX 700 and PSX 700SG coatings, and explains SUMMARY versatility of polysiloxane coatings. Recently, PPG why they offer superior long-term economic and achieved a significant technological advance with environmental performance compared to traditional the launch of PSX® 700SG, a new semi-gloss (SG) epoxy/urethane and epoxy/silicone-alkyd coating polysiloxane coating developed for applications systems. where the ultra-high solids content, long-term weatherability and performance of standard polysiloxane coatings are desired, but the inherent high gloss of the coating is not. PSX 700 PSX 700SG is the latest advance in the PSX 700 Since their introduction two decades ago, poly- COATINGS line of polysiloxane coatings by PPG. It offers siloxane coatings have continued to grow in both TECHNOLOGY all the performance and aesthetic advantages of development and application. Like urethanes and earlier PSX 700 coatings, but with a new propri- alkyds, they are recognized as a distinct category etary formulation that tempers the high-gloss of products within the coatings industry and, appearance of earlier-generation products. according to listings in a major industry trade magazine, the number of polysiloxane coatings “PSX 700SG is the latest The origins of the PSX 700 product line can be manufacturer tripled between 2000 and 2004. traced to 1994 when Ameron International, which advance in the PSX 700 line of was acquired by PPG in 2006, introduced the Even more importantly, polysiloxanes are now a polysiloxane coatings by PPG.” first polysiloxane coatings to the protective and preferred coating system for numerous industrial, marine coatings market.
    [Show full text]