1
|
Normand AT, Wu Y, Régnier T, Fleurat-Lessard P, Rousselin Y, Théron B, Le Gendre P, Carta M. Poly(vinyl chloride) Dechlorination Catalyzed by Zirconium. Chemistry 2024; 30:e202304005. [PMID: 38314958 DOI: 10.1002/chem.202304005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 02/02/2024] [Accepted: 02/05/2024] [Indexed: 02/07/2024]
Abstract
Poly(vinyl chloride) undergoes dechlorination in the presence of triethylsilane (Et3SiH) and a catalytic amount of [Cp2Zr(NPh2)][CH3B(C6F5)3] (1 b) at 40-80 °C, with up to 91 % efficiency. Stoichiometric reactivity studies conducted on cyclohexyl chloride as a model suggest that 1 b dechlorinates PVC by initial chloride abstraction, followed by hydride transfer to the cationic PVC chain from Et3SiH. Consumer items such as pipe fitting, vinyl disc or electric cable insulation undergo either dechlorination or hydrosilylation of the carbonyl-containing copolymer (polyvinyl acetate) or plasticizer (phthalate).
Collapse
Affiliation(s)
- Adrien T Normand
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), 9 avenue Alain Savary, 21078, Dijon Cedex, France
| | - Yue Wu
- Department of Chemistry, Faculty of Science and Engineering, Swansea University, Singleton Park, SA2 8 PP, Swansea, Wales
| | - Tiffanie Régnier
- Plateforme d'Analyse de l'Institut de Chimie Moléculaire de l'Université de Bourgogne (PACSMUB), 9 avenue Alain Savary, 21078, Dijon Cedex, France
| | - Paul Fleurat-Lessard
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), 9 avenue Alain Savary, 21078, Dijon Cedex, France
| | - Yoann Rousselin
- Plateforme d'Analyse de l'Institut de Chimie Moléculaire de l'Université de Bourgogne (PACSMUB), 9 avenue Alain Savary, 21078, Dijon Cedex, France
| | - Benjamin Théron
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), 9 avenue Alain Savary, 21078, Dijon Cedex, France
| | - Pierre Le Gendre
- Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB), 9 avenue Alain Savary, 21078, Dijon Cedex, France
| | - Mariolino Carta
- Department of Chemistry, Faculty of Science and Engineering, Swansea University, Singleton Park, SA2 8 PP, Swansea, Wales
| |
Collapse
|
2
|
Varga V, Pokorná K, Lamač M, Horáček M, Pinkas J. Preparation of silyl-terminated branched polyethylenes catalyzed by Brookhart's nickel diimine complex activated with hydrosilane/B(C 6F 5) 3. Dalton Trans 2024; 53:5249-5257. [PMID: 38406967 DOI: 10.1039/d3dt04200f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Brookhart's nickel α-diimine complex [(κ2-N,N-BIAN)NiCl2] (1) (where BIAN = {Ar-NAceN-Ar}, Ace = acenaphthen-1,2-diyl, and Ar = 2,6-(iPr)2-C6H3) activated with a hydrosilane/B(C6F5)3 (SiHB) adduct forms a highly active catalytic system for ethylene polymerization. Under optimal conditions, the activity of the system depends on the nature of hydrosilane and decreases in the order R3SiH > Ph2SiH2 > PhSiH3. The decrease in system activity within the hydrosilane series is correlated with increasing formation of Ni(I) species. In addition to their activation effect, hydrosilanes act as efficient chain termination/chain transfer agents, with the Si/Ni ratio controlling the molecular weight of the resulting polyethylene (PE). The use of Et3SiH generated elastomeric, highly branched polymers with a saturated chain-end, while systems using Ph2SiH2 and PhSiH3 led to branched end-functionalized PEs terminated with the hydrosilyl functionality (i.e. br-PE-SiPh2H or br-PE-SiPhH2).
Collapse
Affiliation(s)
- Vojtech Varga
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic.
| | - Kristýna Pokorná
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic.
| | - Martin Lamač
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic.
| | - Michal Horáček
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic.
| | - Jiří Pinkas
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic.
| |
Collapse
|
3
|
Dumon AS, Rzepa HS, Alamillo-Ferrer C, Bures J, Procter R, Sheppard TD, Whiting A. A computational tool to accurately and quickly predict 19F NMR chemical shifts of molecules with fluorine-carbon and fluorine-boron bonds. Phys Chem Chem Phys 2022; 24:20409-20425. [PMID: 35983846 DOI: 10.1039/d2cp02317b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the evaluation of density-functional-theory (DFT) based procedures for predicting 19F NMR chemical shifts at modest computational cost for a range of molecules with fluorine bonds, to be used as a tool for assisting the characterisation of reaction intermediates and products and as an aid to identifying mechanistic pathways. The results for a balanced learning set of molecules were then checked using two further testing sets, resulting in the recommendation of the ωB97XD/aug-cc-pvdz DFT method and basis set as having the best combination of accuracy and computational time, with a RMS error of 3.57 ppm. Cationic molecules calculated without counter-anion showed normal errors, whilst anionic molecules showed somewhat larger errors. The method was applied to the prediction of the conformationally averaged 19F chemical shifts of 2,2,3,3,4,4,5,5-octafluoropentan-1-ol, in which gauche stereoelectronic effects involving fluorine dominate and to determining the position of coordination equilibria of fluorinated boranes as an aid to verifying the relative energies of intermediate species involved in catalytic amidation reactions involving boron catalysts.
Collapse
Affiliation(s)
- Alexandre S Dumon
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, Wood Lane, London W12 OBZ, UK.
| | - Henry S Rzepa
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, Wood Lane, London W12 OBZ, UK.
| | | | - Jordi Bures
- Department of Chemistry, The University of Manchester, Manchester M13 9PL, UK
| | - Richard Procter
- Department of Chemistry, Christopher Ingold Laboratories, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - Tom D Sheppard
- Department of Chemistry, Christopher Ingold Laboratories, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - Andrew Whiting
- Centre for Sustainable Chemical Processes, Department of Chemistry, Science Laboratories, Durham University, South Road, Durham, DH1 3LE, UK
| |
Collapse
|
4
|
Zhang X, Zhang X, Song Q, Sivaguru P, Wang Z, Zanoni G, Bi X. A Carbene Strategy for Progressive (Deutero)Hydrodefluorination of Fluoroalkyl Ketones. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202116190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Xiaolong Zhang
- Department of Chemistry Northeast Normal University Changchun 130024 China
| | - Xinyu Zhang
- Department of Chemistry Northeast Normal University Changchun 130024 China
| | - Qingmin Song
- Department of Chemistry Northeast Normal University Changchun 130024 China
| | | | - Zikun Wang
- Department of Chemistry Northeast Normal University Changchun 130024 China
| | - Giuseppe Zanoni
- Department of Chemistry University of Pavia Viale Taramelli 12 27100 Pavia Italy
| | - Xihe Bi
- Department of Chemistry Northeast Normal University Changchun 130024 China
- State Key Laboratory of Elemento-Organic Chemistry Nankai University Tianjin 300071 China
| |
Collapse
|
5
|
Wang T, Xu M, Jupp AR, Chen SM, Qu ZW, Grimme S, Stephan DW. Frustrated Lewis pair catalyzed hydrodehalogenation of benzyl-halides. Chem Commun (Camb) 2022; 58:1175-1178. [PMID: 34981087 DOI: 10.1039/d1cc05943b] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
10 mol% B(2,6-C6F2H3)3 in the presence of excess tetramethylpiperidine (TMP) and H2 (or D2) is shown to catalyze the hydrogenative dehalogenation of benzyl-halides to give corresponding toluene derivatives. These reactions proceed via an initial FLP activation of H2 yielding the ammonium hydridoborate [TMPH][HB(2,6-C6F2H3)3]. This species acts in analogy to a FLP to cooperatively activate C-X bond (X = Cl, Br, I) of benzyl-halides delivering hydride and generating the corresponding ammonium halide salts.
Collapse
Affiliation(s)
- Tongtong Wang
- Department of Chemistry, University of Toronto, 80 St. George St, Toronto, ON, M5S3H6, Canada. .,College of Chemistry, Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116023, China
| | - Maotong Xu
- Department of Chemistry, University of Toronto, 80 St. George St, Toronto, ON, M5S3H6, Canada.
| | - Andrew R Jupp
- Department of Chemistry, University of Toronto, 80 St. George St, Toronto, ON, M5S3H6, Canada.
| | - Shi-Ming Chen
- Department of Chemistry, University of Toronto, 80 St. George St, Toronto, ON, M5S3H6, Canada.
| | - Zheng-Wang Qu
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstrasse 4, Bonn 53115, Germany.
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstrasse 4, Bonn 53115, Germany.
| | - Douglas W Stephan
- Department of Chemistry, University of Toronto, 80 St. George St, Toronto, ON, M5S3H6, Canada.
| |
Collapse
|
6
|
Zhang X, Zhang X, Song Q, Sivaguru P, Wang Z, Zanoni G, Bi X. A Carbene Strategy for Progressive (Deutero)Hydrodefluorination of Fluoroalkyl Ketones. Angew Chem Int Ed Engl 2021; 61:e202116190. [PMID: 34889004 DOI: 10.1002/anie.202116190] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Indexed: 12/29/2022]
Abstract
Hydrodefluorination is one of the most promising chemical strategies to degrade perfluorochemicals into partially fluorinated compounds. However, controlled progressive hydrodefluorination remains a significant challenge, owing to the decrease in the strength of C-F bonds along with the defluorination. Here we describe a carbene strategy for the sequential (deutero)hydrodefluorination of perfluoroalkyl ketones under rhodium catalysis, allowing for the controllable preparation of difluoroalkyl- and monofluoroalkyl ketones from aryl- and even alkyl-substituted perfluoro-alkyl ketones in high yield with excellent functional group tolerance. The reaction mechanism and the origin of the intriguing chemoselectivity of the reaction were rationalized by density functional theory (DFT) calculations.
Collapse
Affiliation(s)
- Xiaolong Zhang
- Department of Chemistry, Northeast Normal University, Changchun, 130024, China
| | - Xinyu Zhang
- Department of Chemistry, Northeast Normal University, Changchun, 130024, China
| | - Qingmin Song
- Department of Chemistry, Northeast Normal University, Changchun, 130024, China
| | | | - Zikun Wang
- Department of Chemistry, Northeast Normal University, Changchun, 130024, China
| | - Giuseppe Zanoni
- Department of Chemistry, University of Pavia, Viale Taramelli 12, 27100, Pavia, Italy
| | - Xihe Bi
- Department of Chemistry, Northeast Normal University, Changchun, 130024, China.,State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin, 300071, China
| |
Collapse
|
7
|
Arora V, Narjinari H, Nandi PG, Kumar A. Recent advances in pincer-nickel catalyzed reactions. Dalton Trans 2021; 50:3394-3428. [PMID: 33595564 DOI: 10.1039/d0dt03593a] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Organometallic catalysts have played a key role in accomplishing numerous synthetically valuable organic transformations that are either otherwise not possible or inefficient. The use of precious, sparse and toxic 4d and 5d metals are an apparent downside of several such catalytic systems despite their immense success over the last several decades. The use of complexes containing Earth-abundant, inexpensive and less hazardous 3d metals, such as nickel, as catalysts for organic transformations has been an emerging field in recent times. In particular, the versatile nature of the corresponding pincer-metal complexes, which offers great control of their reactivity via countless variations, has garnered great interest among organometallic chemists who are looking for greener and cheaper alternatives. In this context, the current review attempts to provide a glimpse of recent developments in the chemistry of pincer-nickel catalyzed reactions. Notably, there have been examples of pincer-nickel catalyzed reactions involving two electron changes via purely organometallic mechanisms that are strikingly similar to those observed with heavier Pd and Pt analogues. On the other hand, there have been distinct differences where the pincer-nickel complexes catalyze single-electron radical reactions. The applicability of pincer-nickel complexes in catalyzing cross-coupling reactions, oxidation reactions, (de)hydrogenation reactions, dehydrogenative coupling, hydrosilylation, hydroboration, C-H activation and carbon dioxide functionalization has been reviewed here from synthesis and mechanistic points of view. The flurry of global pincer-nickel related activities offer promising avenues in catalyzing synthetically valuable organic transformations.
Collapse
Affiliation(s)
- Vinay Arora
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati-781039, Assam, India.
| | - Himani Narjinari
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati-781039, Assam, India.
| | - Pran Gobinda Nandi
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati-781039, Assam, India.
| | - Akshai Kumar
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati-781039, Assam, India. and Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati-781039, Assam, India
| |
Collapse
|
8
|
Fang H, Oestreich M. Defunctionalisation catalysed by boron Lewis acids. Chem Sci 2020; 11:12604-12615. [PMID: 34094457 PMCID: PMC8163203 DOI: 10.1039/d0sc03712e] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 07/22/2020] [Indexed: 12/22/2022] Open
Abstract
Selective defunctionalisation of organic molecules to valuable intermediates is a fundamentally important transformation in organic synthesis. Despite the advances made in efficient and selective defunctionalisation using transition-metal catalysis, the cost, toxicity, and non-renewable properties limit its application in industrial manufacturing processes. In this regard, boron Lewis acid catalysis has emerged as a powerful tool for the cleavage of carbon-heteroatom bonds. The ground-breaking finding is that the strong boron Lewis acid B(C6F5)3 can activate Si-H bonds through η1 coordination, and this Lewis adduct is a key intermediate that enables various reduction processes. This system can be tuned by variation of the electronic and structural properties of the borane catalyst, and together with different hydride sources high chemoselectivity can be achieved. This Perspective provides a comprehensive summary of various defunctionalisation reactions such as deoxygenation, decarbonylation, desulfurisation, deamination, and dehalogenation, all of which catalysed by boron Lewis acids.
Collapse
Affiliation(s)
- Huaquan Fang
- Institut für Chemie, Technische Universität Berlin Strasse des 17. Juni 115 10623 Berlin Germany
| | - Martin Oestreich
- Institut für Chemie, Technische Universität Berlin Strasse des 17. Juni 115 10623 Berlin Germany
| |
Collapse
|