DOCSLIB.ORG

Efficient Cyclization of the Norbornadiene‐Quadricyclane

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Efficient Cyclization of the Norbornadiene‐Quadricyclane DOI: 10.1002/cptc.201900194 Articles 1 2 3 Efficient Cyclization of the Norbornadiene-Quadricyclane 4 5 Interconversion Mediated by a Magnetic 6 7 [Fe3O4À CoSalphen] Nanoparticle Catalyst 8 + [a] + [a] [a] 9 Tobias Luchs , Patrick Lorenz , and Andreas Hirsch* 10 11 12 We report a novel, inexpensive and effective process for the nanoparticles [Fe3O4À CoSalphen] combine a high surface area 13 repeatable photoisomerization of norbornadiene (NBD) to its of catalytically active molecules with straightforward separation 14 metastable isomer quadricyclane (QC), followed by catalytically by the action of an external magnetic field. In combination with 15 induced strain energy release via back-conversion of QC to the promising interconversion couple NBD1-QC1, which fea- 16 NBD. By utilization of a quasi-homogeneous catalyst based on tures outstanding stability (t1/2 =450 days at room temperature) 17 magnetic core-shell nanoparticles, tedious purification steps are and a high energy storage potential (88.34 kJ/mol), the nano- 18 avoided. The core of this material is comprised of Fe3O4 and a particle catalyst [Fe3O4À CoSalphen] shows great potential for 19 catalytically active cobalt(II) complex is anchored on the particle technical applications in molecular solar thermal (MOST) 20 surface as a self-assembled monolayer (SAM). These core-shell energy-storage systems. 21 22 23 1. Introduction by about 89 kJ/mol more stable than QC in case of the parent 24 unfunctionalized, liquid molecule.[7] This together with the low 25 Within one hour, the sun provides more energy to the Earth‘s molecular weight enables high storage capacities. 26 surface than humans consume in a whole year.[1] However, Due to the low quantum yield and lack of absorbance in 27 scooping this enormous potential is not trivial, therefore, highly the visible region of the solar spectrum a triplet photo- 28 efficient technologies are mandatory. Next to common photo- sensitizer, such as acetophenone, is needed to bring about the 29 voltaic devices, molecular solar thermal (MOST) energy storage photoisomerization from neat NBD to QC.[8] This can be 30 and release systems such as organometallic (fulvalene)diruthe- circumvented by designing so called “push-pull” NBD deriva- 31 nium compounds,[2] azobenzenes[3] or dihydroazulene/vinylhepta- tives (Figure 1), they show much higher quantum yields and 32 fulvene couples[4] recently attracted increasing attention.[5] In these provide a better overlap with the solar spectrum. Recently, 33 devices the energy is harvested and transformed into a storable considerable progress has been made in this field.[9] 34 form on a molecular level. Afterwards, the stored energy can be As stated above the main advantage of MOST systems is that 35 released as thermal energy on demand.[2] The big advantage of the stored energy can be released on demand. Therefore, an 36 these systems is that they circumvent the problems associated efficient pathway to isomerize QC back to NBD is needed. 37 with the discontinuous energy production of solar based devices. Although, thermal initiation is possible it is unfavorable due to 38 While the energy produced by common photovoltaics is only energetic reasons. From a practical point of view a catalytically 39 available while the sun is shining, MOST systems are not restricted induced back-reaction is desirable. Various methods have been 40 to this limitation. The valence isomerization of norbornadiene investigated in the past; most approaches employ the catalysis of 41 (NBD) to the metastable and energy rich quadricyclane (QC) unsaturated coordination transition metal complexes,[6] but also [10] 42 (Figure 1) is regarded a very promising concept candidate for this the use of Ag(I) or metal oxides such as MoO3, WO3 or V2O5 has 43 purpose.[6] been reported.[11] In many cases the back-reaction proceeds via an 44 In QC the energy is stored as strain energy due to the oxidized form of QC. It has been shown that this intermediate can 45 introduction of three- and four-membered rings. Overall NBD is also be generated directly via electrochemistry.[12] Only a few of 46 the known catalysts fulfil the crucial requirements such as absence 47 of side reactions, high turnover frequency and long-term stability. [a] T. Luchs,+ P. Lorenz,+ Prof. Dr. A. Hirsch 48 Department of Chemistry and Pharmacy Very promising results were obtained with square planar 49 Friedrich-Alexander-Universität Erlangen-Nürnberg complexes of Co(II).[13–15] For more detailed information we refer to 50 Nikolaus-Fiebiger-Straße 10, 91058 Erlangen (Germany) a review from Chernoivanov and co-workers.[6] A drawback of E-mail: [email protected] 51 homogeneous catalysts is the tedious removal of the catalyst after [+] These authors contributed equally to this work. 52 Supporting information for this article is available on the WWW under the reaction. In most cases a purification step must be 53 https://doi.org/10.1002/cptc.201900194 implemented which hampers cyclability of the energy storage 54 © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. and release process. Recently, it has been shown that it is possible 55 This is an open access article under the terms of the Creative Commons to deposit catalytically active cobalt phthalocyanine on charcoal Attribution Non-Commercial License, which permits use, distribution and 56 reproduction in any medium, provided the original work is properly cited to avoid this problem, but significant leaching of the catalyst was 57 and is not used for commercial purposes. also detected.[16] However, beside the purification aspect, also the ChemPhotoChem 2020, 4, 52–58 52 © 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA Wiley VCH Donnerstag, 30.01.2020 2001 - closed* / 145760 [S. 52/58] 1 Articles 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Figure 1. Left: The parent NBD-QC MOST energy storage and release system. The energy is stored as strain energy by the photochemical conversion of NBD to QC and can be released on demand with a suitable catalyst. Right: “Push–pull” substituted NBD derivative. By introducing electron-donating and electron- 16 withdrawing groups into one of the double bonds of NBD, the photochemical properties can be significantly improved. 17 18 À 1 19 activity of the immobilized catalyst has to be considered. Depend- energy storage capacity (ΔHstorage =88.34 kJmol ). NBD1 was 20 ing on the solid support material, the accessibility of the active quantitatively converted to its high energy isomer QC1 upon 21 catalyst sites can be hindered. For a technical application of a irradiation at 310 nm, followed by treatment with the magnetic 22 MOST system, the development of simple, robust, inexpensive core-shell nanoparticles [Fe3O4À CoSalphen]. This led to quanti- 23 and effective methods for each step in the reversible isomer- tative back-conversion to the stable NBD1 derivative. After the 24 ization of the NBD-QC system along with facile purification is catalytic back-conversion the catalyst could easily be removed 25 required. Due to their high surface to volume ratio in comparison by the action of an outside magnet and further cycles of 26 to the bulk material,[17] the tunability of their surface properties[18] photochemical isomerization to QC1 and catalytic back-con- 27 and their facile synthesis, metal oxide nanoparticles are an version to NBD1 could be performed without deterioration of 28 excellent platform for this task. the nanoparticle catalyst or the energy storage material NBD1- 29 The core of these nanoparticles provides intrinsic properties QC1. We further investigated the catalytic potential of [19] [20] 30 such as paramagnetism and photocatalytic activity, while [Fe3O4À CoSalphen] together with a triplet photosensitizer and 31 the interaction with the environment can be modified by the parent NBD to show the promising potential of this 32 depositing self-assembled monolayers (SAMs) of active mole- magnetic core-shell nanoparticle catalyst in MOST applications, 33 cules on the oxide surface. The resulting core-shell materials due to the facile separation by the action of an external 34 combine the intrinsic properties of the core with the tunable magnetic field. 35 properties of the shell. These include dispersibility,[21] 36 biocompatibility[22] or supramolecular aggregation towards 37 defined superstructures.[23] In recent years magnetic core-shell 2. Results and Discussion 38 nanoparticles have attracted a lot of interest as a solid support 39 for a series of applications including water remediation,[24] 2.1. Synthesis and Characterization of a CoSalphen Catalyst [25] 40 biosensing and catalytic processes. In contrast to conven- ([Fe3O4À CoSalphen]) Immobilized on Magnetic Iron Oxide NPs 41 tional solid support materials, magnetic core-shell nanoparticles 42 combine a high surface area with facile separation by For the preparation of [Fe3O4À CoSalphen], commercially available 2 43 application of a magnetic field, thus rendering filtration or Fe3O4 nanoparticles with a specific surface area of 100 m /g 44 centrifugation as separation methods unnecessary. (determined by BET analysis) were treated with the carboxylic acid 45 Herein we report an inexpensive, effective and repeatable bearing cobalt Salphen complex (CoSalphen) in isopropanol 46 process for the light induced photoisomerization of NBD to QC (Figure 2). To ensure a high degree of surface functionalization 47 and the catalytic back-conversion of QC to NBD without the the nanoparticles were stirred with an
Load more

Recommended publications
  • United States Patent Office Paiented Sept
    3,151,173 United States Patent Office Paiented Sept. 29, 1964 i 2 p-toluene sulfonic acid (which is the preferred catalyst 3,151,173 of the present invention). Weaker acids, having first EPOCESS FOR PRGEJCNG SALKY DENE pixa values above 2.5, are less effective. The second class NGREORNENE - Sasks. Tyce, RAS Creek H.Rindred, e., assignor to E. E. of catalysts includes compounds Sugh as boron trifluoride, di Post de NextGE's and Copany, Wisnington, Dei, boron trichloride, aluminum chloride, aluminum bromide, a corporation of Delaware Zinc chloride, titanium tetrachloride, ferric chloride, ferric Na Drawing. Fied Jay 8, 1961, Ser. No. 24,783 bromide, stannic chloride, antimony pentachloride, ni f6 (Cairns. (C. 268-666) obium tetrachloride, tellurium dichloride, bismuth tri chloride, mercuric chioride, and tantulum tetrachloride. This invention relates to a new method for the prepara O The Friedel-Crafts catalysts tend to induce polymeriza tion of Substituted norbornene compounds. More par tion which is evidenced by a darkening of the reaction ticularly this invention relates to a new method of pre mixture. It is preferred to stop the reaction when this paring 5-alkylidene-noirborneine compounds. discoloration occurs. Certain norbornene compounds have been found to The catalyst concentration may range from about be very useful for the preparation of ethylene copolymers. 0.0025 mole to 2.5 mole per mole of the 2-alkylnorborna Jinfortunately, the present methods for the preparation diene compound. The preferred concentration often. f these norbornene compounds, such as 5-methylene ranges from about 0.02 mole to 0.04 mole. However, norbornere, are rather costly and thereby restrict the use When catalysts are used, such as hydrogen chloride, fulness of such compounds in commercial production.
    [Show full text]
  • High-Level Studies of the Ionic States of Norbornadiene and Quadricyclane
    High-level studies of the ionic states of norbornadiene and quadricyclane, including analysis of new experimental photoelectron spectra by configuration interaction and coupled cluster calculations. Michael H. Palmer,1,a Marcello Coreno,2,b Monica de Simone,3,b Cesare Grazioli,3,b R. Alan Aitken,4 Søren Vrønning Hoffmann,5,b Nykola C. Jones5,b and Coralyse Peureux.4 1 School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, Scotland, UK 2 ISM-CNR, Istituto di Struttura della Materia, LD2 Unit 34149 Trieste, Italy, 3 IOM-CNR Laboratorio TASC, Trieste, Italy 4 School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, Scotland, UK. 5 ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000, Aarhus C, Denmark a) Email: [email protected]: b) Electronic addresses: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected] ABSTRACT Synchrotron-based photoelectron spectra (PES) of norbornadiene (NBD) and quadricyclane (QC) differ significantly from previous studies. The adiabatic ionization energy (AIE1) for 2 NBD, assigned to the B1 state at 8.279 eV, shows a progression of 18 members, with decreasing vibration frequency from 390 to 340 cm-1; our calculated frequency is 381 cm-1. 2 Similarly, the AIE1 for QC at 7.671 eV, assigned to the B2 state, discloses a vibrational progression of 9 or more members, with vibration frequency decreasing from 703 to 660 cm-1; Our calculated vibration frequency is 663 cm-1.
    [Show full text]
  • The Photochemistry of Some Substituted 2-Cyclohexenones and the Excited States Involved
    PHOTOCHEMISTRY OF SUBSTITUTi':D 2... CYCLOHE:XE;NONES THE PHOTOCHEMISTRY OF S0~1E SUBSTITUTED 2~CYCLOHEXENONES AND THE EXCITED STATES INVOLVED By FLOlTI FP~ERICK SNYDER, B.Sce .A Thesis Submitted to the Faculty of Graduate Studies in Partial Fulfilment of the Requirements for the Degree Master of Science McMaster University October 1969 To MOM and DAD on Your 25th Anniversary MASTER OF SCIENCE (1969) McMASTER UNIVERSITY (Ghemi stry) Hamilton, Ontario. TITLE: The Photochemistry of some Substituted 2-Cyclohexenones and the Excited States Involved AUTHOR: Floyd Frederick Snyder, B.Sc. '(University of Alberta) SUPERVISOR: Dr. J. J. McCullough NUMBER OF PAGES: viii, 87 SCOPE AND CONTENTS: The photoadditions of 3~phenyl-2-cyclohexenone to bicyclo [2.2.1] ­ hepta-2,5-diene, bicyclo [2.2.1] hept-2mene and cyclopentene have been studied. In all cases £.!1! fused cyclobutane products were obtained. Quenching and sensitization experiments indicated a singlet excited state to be active in photocycloaddition. Phosphorescence and fluorescence emission were observed from 3-phenyl-2-cyclohexenoneo Energy transfer to the lo~.rest triplet of 3-phenyl-2-cyclohexenone was evident from the quenching of Michler's ketone phosphorescence. Two norbornene dimers were detected in the photolysis of 3-phenyl-2-cyclo­ hexenone and norbornene giving evidence for a higher triplet excited state of the enone. The photoaddition of 3-methyl-2-cyclohexenone to cyclopentene l.ras studied for comparison and both .£!..! and !.r..!.U! fused adducts l-Tere obtained. In photolyses with bicyclo [2e2el] hepta-2,5­ diene or cyclopentene, 2-phenyl... 2-cyclohexenone lvas unreactive. iii ACKNOWLEDGEMENTS It is a pleasure to express my gratitude to Dr.
    [Show full text]
  • Specialty Silicones Norbornadiene Technical Data
    SiVance® Specialty Silicones Norbornadiene Technical Data Description Typical Properties SiVance Norbornadiene Product Code 3000064155 (bicyclo[2.2.1]hepta-2,5- diene) is an unsaturated, CAS Number 121-46-0 bicyclic hydrocarbon. Molecular Weight (g/mol) 92.14 Recommended Use Specific Gravity, at 25°C 0.91 Norbornadiene is used in the synthesis of complex Boiling Point 89°C polycyclic hydrocarbons. Flash Point, TCC -21°C This hydrocarbon is the most stable diolefin derived from the norbornane and norbornene. Purity 99.5% Norbornadiene is primarily of interest as a ligand Appearance Clear Faint Yellow Liquid in homogeneous catalysis, but it has been heavily studied due to its high reactivity and distinctive Values shown are not intended for specification preparation structural property of being a diene that cannot isomerize. Handling and Storage Precautions If stored for longer than one year, the material should be reevaluated prior to use. Store the container in a cool, dry area. Keep the container tightly closed when not in use. Additional safety, environmental and regulatory issues are addressed in the Safety Data Sheet. Please contact your SiVance Representative for additional information. PLEASE NOTE: As each customer’s use of our product may be different, information we provide, including without limitation, recommendations, test results, samples, care/labeling/processing instructions or marketing advice, is provided in good faith but without warranty and without accepting any responsibility/liability. Each customer must test and be responsible for its own specific use, further processing, labeling, marketing, etc. All sales are exclusively subject to our standard terms of sale posted at www.milliken.com/terms (all additional/different terms are rejected) unless explicitly agreed otherwise in a signed writing.
    [Show full text]
  • Effect of Solvent on 1,3-Dipolar Cycloaddition Transition States
    Loyola University Chicago Loyola eCommons Dissertations Theses and Dissertations 1993 Effect of solvent on 1,3-dipolar cycloaddition transition states Sheila Louise Celsor Loyola University Chicago Follow this and additional works at: https://ecommons.luc.edu/luc_diss Part of the Chemistry Commons Recommended Citation Celsor, Sheila Louise, "Effect of solvent on 1,3-dipolar cycloaddition transition states" (1993). Dissertations. 3013. https://ecommons.luc.edu/luc_diss/3013 This Dissertation is brought to you for free and open access by the Theses and Dissertations at Loyola eCommons. It has been accepted for inclusion in Dissertations by an authorized administrator of Loyola eCommons. For more information, please contact [email protected]. This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License. Copyright © 1993 Sheila Louise Celsor LOYOLA UNIVERSITY OF ClllCAGO EFFECT OF SOLVENT ON 1,3-DIPOLAR CYCWADDITION TRANSmON STATES A DISSERTATION SUBMITTED TO THE FACULTY OF THE GRADUATE SCHOOL IN CANDIDACY FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF CHEMISTRY BY SHEILA LOUISE CELSOR CHICAGO, ILLINOIS MAY 1993 Copyright by Sheila L. Celsor, 1993 All rights reserved TABLE OF CONTENTS LIST OF ILLUSTRATIONS . iv LIST OF TABLES . vi LIST OF ABBREVIATIONS ..................................... ix CHAPTER I . 1 INTRODUCTION . 1 CHAPTER II . 7 HISTORY . 7 CHAPTER III 37 RESULTS . 37 1. Overall yields of mono-pyrazoline adducts. 37 2. Relative yields of mono-pyrazoline adducts and product ratios. 37 3. Rate of formation of monoadducts in n-hexane. 42 4. Rate of formation of monoadducts in acetonitrile. 53 5. Rate of disappearance of diphenyldiazomethane in hexane. 58 6.
    [Show full text]
  • The Photochemical Dimerization of Norbornadiene Using Chromium
    The photochemical dimerization of norbornadiene using chromium carbonyls by Brian Kellog Hill A thesis submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in Chemistry Montana State University © Copyright by Brian Kellog Hill (1969) Abstract: Norbornadiene has previously been shown to undergo dimerization photochemically with Group VI and VIII and thermally with Group VIII unsubstituted metal carbonyls. Furthermore, diene-iron-tricarbonyls cause the reaction to be more stereospecific and give only two products instead of the usual eleven obtained using the unsubstituted metal carbonyls. To learn if this change in products was generally characteristic of unsubstituted and substituted metal carbonyls a series of chromium carbonyls were investigated. The products of the chromium metal carbonyls were three trans dimers, a saturated cage dimer and one ketone insertion product. A possible mechanism for the photochemical dimerization of norbornadiene using chromium hexacarbonyl and substituted chromium carbonyl as sensitizers was determined. A common intermediate for the reactions has been proposed. THE PHOTOCHEMICAL DIMERIZATION OF NORBORNADIENE USING CHROMIUM CARBONYLS' by BRIAN KELLOGG HILL A thesis submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in , C h em istry Approved: Head, Major Department CHairmanT ExaumhingC om m ittee MONTANA STATE UNIVERSITY Bozeman,' Montana August, 1969 ill ACKNOWLEDGEMENT The author would like to acknowledge Dr..E. W. Jennings for his encouragement and advice, without which this research would not have been completed. Special recognition is due the author's wife, Gayle, for her confi­ dence and sacrifices. Appreciation is expressed to the National Defense Education Act for the financial assistance of a fellowship.
    [Show full text]
  • Diels-‐Alder Reactions of Dienophiles and Cyclopentadiene Using A
    Diels-Alder Reactions of Dienophiles and Cyclopentadiene Using a Sealed Tube Protocol Richard T. Taylor*, Christopher M. Goins and Katherine R. Taylor Department of Chemistry and Biochemistry Miami University Oxford, OH 45056 USA [email protected]; [email protected]; [email protected] Abstract: The Diels-Alder reaction of various reactive dienophiles with cyclopentadiene is reported. Rather than cracking dicyclopentadiene in a separate step, the reagents were mixed in a sealed tube and the reactions carried out at 185C. Conversion to the adducts is dependent on the nature of the dienophile and the reaction time. In those cases where stereochemistry is relevant, the endo/exo ratios are reported and compared to those reported at lower temperatures. Introduction: The Diels-Alder reaction is one of the most powerful tools for the construction of complex structures in few steps with control of stereochemistry and regiochemistry.1 The array of diene-dienophile couplings is well-understood. Within the range of materials available to the synthetic chemist, 1,3-cyclopentadiene is one of the most reactive dienes. The diene is only available as its dimer, the product of the [4 +2] cycloaddition with itself.2 The traditional method for utilizing cyclopentadiene in a reaction involves thermal cracking of the dimer at extremely high temperature, trapping the distilled monomer at a low temperature and using it in a reaction before it reverts back to the dimer3. The dimer is in a slow equilibrium with the monomer so that reactions of cyclopentadiene are reported using the diene and allowing reaction of the monomer to drive the equilibrium to the product.4 There are reports of conducting this reaction in the dimer as solvent at its reflux temperature with some success.5 We report a herein a related strategy wherein we place the two reactants in a sealed tube and raise the temperature to above 180C.
    [Show full text]
  • INTRAMOLECULAR L&DIPOLAR CYCLOADDITIONS OF
    INTRAMOLECULAR l&DIPOLAR CYCLOADDITIONS OF NORBORNADIENE-TETEIERED NITRILE OXIDES A Thesis Presented to The Faculty of Graduate Studies of The University of Guelph In partial fulfillment of requirements for the degree of Masters of Science August, 2000 O Carol Yip, 2000 National Library Bibliothèque nationale I*I of Canada du Canada Acquisitions and Acquisitions et Bibliographie Services services bibliographiques 395 Wellington Street 395. rue Wellington Ottawa ON K1A ON4 Otbwa ON K1A ON4 Canada Canada Your fi& votre refence Our lile Notre reférence The author has granted a non- L'auteur a accordé une licence non exclusive licence allowing the exclusive permettant à la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or sell reproduire, prêter, distribuer ou copies of this thesis in microform7 vendre des copies de cette these sous paper or electronic formats. la forme de microfiche/fïIm7de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thése. thesis nor substantial extracts fiom it Ni la thèse ni des extraits substantiels may be printed or othenvise de celle-ci ne doivent êeimprimés reproduced without the author's ou aueement reproduits sans son permission. autorisation. ABSTRACT INTRA.MOLECULAR 13-DIPOLAR CYCLOADDITIONS OP NORBORNADIENE-TETHERED NITRILE OXIDES Carol Yip Advisor: University of Guelph Dr, William Tarn Although the intermolecular reactions of 1,3-dipoles with norbornadiene and its derivatives have been subjected to considerable investigation, the intramolecular variants have not been shidied- In this thesis, a novel strategy to a highly regio- and stereocontrolled assembly of anguiar fused-tricyclic frameworks via intramolecular cycloaddition reactions of norbomadiene-tethered nitrile oxides is presented.
    [Show full text]
  • Norbornadiene As a Universal Substrate for Organic and Petrochemical Synthesis V.R
    Eurasian ChemTech Journal 3 (2001) 73-90 Norbornadiene as a Universal Substrate for Organic and Petrochemical Synthesis V.R. Flid*, O.S. Manulik, D.V. Dmitriev, V.B. Kouznetsov, E.M. Evstigneeva, A.P. Belov, and A.A. Grigor’ev Lomonosov State Academy of Fine Chemical Technology, pr. Vernadskogo 86, Moscow, 117571 Russia Abstract A wide range of rare polycyclic hydrocarbons can be obtained through catalytic processes involving norbornadiene (NBD). The problem of selectivity is crucial for such reactions. The feasibility of controlling selectivity and reaction rate has been shown for cyclic dimerization, co-dimerization, isomerization and allylation of NBD. Kinetic rules have been scrutinized. Consistent mechanisms have been proposed. Fac- tors affecting directions of the reactions and allowing us to obtain individual stereoisomers quantitatively, have been established. A series of novel unsaturated compounds has been synthesized; they incorporate a set of double bonds with different reactivity and can find an extremely wide range of applications. Introduction possibilities, its utilization as a universal substrate is rather limited, since NBD-derivatives can form all The importance of NBD and its derivatives in vari- kinds of isomers: skeleton, regio, stereo, enantio ones. ous fields of human activity is growing. More and A resultant mixture of isomeric products is often dif- more new applications are being discovered for these ficult to separate and analyze, and the consumption compounds. Since they were first obtained less than of reagents may become excessive. All this restricts 50 years ago, these substances have been success- widespread use of NBD. fully utilized in medicine, agriculture, rocketry, syn- Metal-complex catalysis is very interesting and theses of polymers with unique properties, microelec- attractive for solving various problems connected with tronics, and as solar energy converters.
    [Show full text]
  • [3+2] Cycloaddition Reactions Within Molecular Electron Density Theory
    Article Unveiling the Unexpected Reactivity of Electrophilic Diazoalkanes in [3+2] Cycloaddition Reactions within Molecular Electron Density Theory Luis R. Domingo 1,* , Mar Ríos-Gutiérrez 1 and Nivedita Acharjee 2 1 Department of Organic Chemistry, University of Valencia, Dr. Moliner 50, Burjassot, 46100 Valencia, Spain; [email protected] 2 Department of Chemistry, Durgapur Government College, J. N. Avenue, Durgapur, West Bengal 713214, India; [email protected] * Correspondence: [email protected] Abstract: The [3+2] cycloaddition (32CA) reactions of strongly nucleophilic norbornadiene (NBD), with simplest diazoalkane (DAA) and three DAAs of increased electrophilicity, have been studied within the Molecular Electron Density Theory (MEDT) at the MPWB1K/6-311G (d,p) computational level. These pmr-type 32CA reactions follow an asynchronous one-step mechanism with activation enthalpies ranging from 17.7 to 27.9 kcal·mol−1 in acetonitrile. The high exergonic character of these reactions makes them irreversible. The presence of electron-withdrawing (EW) substituents in the DAA increases the activation enthalpies, in complete agreement with the experimental slowing- down of the reactions, but contrary to the Conceptual DFT prediction. Despite the nucleophilic and electrophilic character of the reagents, the global electron density transfer at the TSs indicates rather non-polar 32CA reactions. The present MEDT study establishes the depopulation of the N–N–C core in this series of DAAs with the increase of the EW character of the substituents present at the carbon Citation: Domingo, L.R.; center is responsible for the experimentally found deceleration. Ríos-Gutiérrez, M.; Acharjee, N. Unveiling the Unexpected Reactivity Keywords: molecular electron density theory; norbornadiene; diazoalkanes; conceptual DFT; electron of Electrophilic Diazoalkanes in [3+2] localization function Cycloaddition Reactions within Molecular Electron Density Theory.
    [Show full text]
  • Click Chemistry with Cyclopentadiene Brian J
    pubs.acs.org/CR Review Click Chemistry with Cyclopentadiene Brian J. Levandowski and Ronald T. Raines* Cite This: Chem. Rev. 2021, 121, 6777−6801 Read Online ACCESS Metrics & More Article Recommendations ABSTRACT: Cyclopentadiene is one of the most reactive dienes in normal electron- demand Diels−Alder reactions. The high reactivities and yields of cyclopentadiene cycloadditions make them ideal as click reactions. In this review, we discuss the history of the cyclopentadiene cycloaddition as well as applications of cyclopentadiene click reactions. Our emphasis is on experimental and theoretical studies on the reactivity and stability of cyclopentadiene and cyclopentadiene derivatives. CONTENTS Author 6794 Notes 6794 1. Introduction 6777 Biographies 6794 2. History of Cyclopentadiene 6778 − π Acknowledgments 6794 3. Diels Alder Reactivity and -Facial Selectivity of Abbreviations 6794 Cyclopentadiene Cycloadditions 6778 References 6794 3.1. Diels−Alder Reactivity 6778 3.2. Hyperconjugative Aromaticity and Antiaro- maticity 6779 3.3. π-Facial Selectivity of 5-Substituted Cyclo- 1. INTRODUCTION pentadienes 6779 In 2001, Sharpless and co-workers introduced the term “click 4. Stability of Cyclopentadiene 6780 ” 4.1. Dimerization 6780 reaction to describe chemical transformations that are high- 1 − 4.2. 1,5-Sigmatropic Shifts 6781 yielding under mild conditions. The Diels Alder reaction is a 4.3. In Situ Sources of Cyclopentadiene 6785 chemical transformation between a conjugated diene and a dienophile that results in the formation of a 6-membered 5. Polymer Chemistry with Cyclopentadiene 6785 − 5.1. Synthesis of Cyclopentadiene-Functional- cycloadduct. The most reactive Diels Alder dienes are 5- or 6- ized Polymers 6785 membered cyclic dienes such as 1,2,4,5-tetrazine, ortho-quinone, 5.2.
    [Show full text]
  • List of Indirect Additives Used in Food Contact Substances Page 1 of 131
    List of Indirect Additives Used in Food Contact Substances Page 1 of 131 FDA Home3 The List of Indirect Additives Used in Food Contact Substances4 Indirect Additives Used in Food Contact Substances List of Indirect Additives Used in Food Contact Substances Please note that by being listed below, no inference should be made about the legality of using any one of these specific substances as an "indirect" food additive. Their presence on this list only indicates that the names of these substances are found (or, in the case of some of the polymers, are implied) in 21CFR parts 175 - 178. The regulation(s) cited for a substance should always be consulted for the complete context before any conclusion is made as to allowed regulated use. To access the specific regulations listed below, type in the title number, 21, and then the section and part numbers, e.g. 175 and 105 at the Government Printing Office web site. Definitions of the labels that are found in this inventory are: Label Definition DOCNUM The PAFA database number MAINTERM The name of the substance as recognized by CFSAN Chemical Abstract Service (CAS) Registry Number for the substance or a numerical code CAS RN OR assigned by CFSAN to those substances that do not have a CAS Registry Number OTHER CODE (888nnnnnn or 977nnnnnn-series) Regulation numbers in Title 21 of the U.S. Code of Federal Regulations where the substance appears. (Note that if a substance is mentioned in 21CFR parts 175 - 178 and, REGNUM thus, is listed below, any other citations for the same substance in other sections of 21CFR dealing with food additives (parts 1 - 199 inclusive) are also cited.) Search Criteria Show Items Reset No of Records Found: Sort by: Go Reset 3,237 CAS RN Doc or Other No.
    [Show full text]