- Remarkable activity, selectivity and stability of polymer-supported Pt catalysts in room temperature, solvent-less, alkene hydrosilylations
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A polystyrene-resin supported Pt catalyst displays higher conversion, remarkably improved selectivity and excellent recyclability relative to Speier's catalyst in the room temperature solvent-less hydrosilylation of oct-1-ene using trichlorosilane.
- Drake,Dunn,Sherrington,Thomson
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- The Addition Rates of Dichloro- and Trichlorosilane to 2-Pentene and 1-Octene
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When mixtures of dichloro- and trichlorosilane were added to 2-pentene and 1-octene in the presence of a solution of chloroplatinic acid, dichloro-silane added much more rapidly than trichlorosilane.But when each silane was added separately under identical conditions, trichlorosilane added much more rapidly than dichlorosilane to the same olefins.
- Benkeser, Robert A.,Muench, Wayne C.
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- PROCESS FOR THE STEPWISE SYNTHESIS OF SILAHYDROCARBONS
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The invention relates to a process for the stepwise synthesis of silahydrocarbons bearing up to four different organyl substituents at the silicon atom, wherein the process includes at least one step a) of producing a bifunctional hydridochlorosilane by a redistribution reaction, selective chlorination of hydridosilanes with an ether/HCI reagent, or by selective chlorination of hydridosilanes with SiCI4, at least one step b) of submitting a bifunctional hydridochloromonosilane to a hydrosilylation reaction, at least one step c) of hydrogenation of a chloromonosilane, and a step d) in which a silahydrocarbon compound is obtained in a hydrosilylation reaction.
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Page/Page column 65; 66; 85
(2021/12/08)
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- Contra-thermodynamic Olefin Isomerization by Chain-Walking Hydrofunctionalization and Formal Retro-hydrofunctionalization
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We report a contra-thermodynamic isomerization of internal olefins to terminal olefins driven by redox reactions and formation of Si-F bonds. This process involves chain-walking hydrosilylation of internal olefins and subsequent formal retro-hydrosilylation. The process rests upon the high activities of platinum hydrosilylation catalysts for isomerization of metal alkyl intermediates and a new, metal-free process for the conversion of alkylsilanes to alkenes. By this approach, 1,2-disubstituted and trisubstituted olefins are converted to terminal olefins.
- Hanna, Steven,Butcher, Trevor W.,Hartwig, John F.
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supporting information
p. 7129 - 7133
(2019/09/12)
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- Hydrosilylation of alkenes catalyzed by Fe powder
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A novel iron-catalyzed hydrosilylation of alkenes process under solvent-free conditions has been reported. The influence of the amount of Fe catalyst, reaction temperature and various alkenes and silanes on the hydrosilylation were investigated. High yields of adduct were obtained in the hydrosilylation of octene with MeCl2H, Me2ClSiH and Ph2SiH2 by using 10 mol% iron powder as a signal catalyst.
- Yang, Xiaoling,Bai, Ying,Li, Jiayun,Dai, Zinan,Peng, Jiajian
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- Platinum Catalysis Revisited-Unraveling Principles of Catalytic Olefin Hydrosilylation
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Hydrosilylation of C-C multiple bonds is one of the most important applications of homogeneous catalysis in industry. The reaction is characterized by its atom-efficiency, broad substrate scope, and widespread application. To date, industry still relies on highly active platinum-based systems that were developed over half a century ago. Despite the rapid evolution of vast synthetic applications, the development of a fundamental understanding of the catalytic reaction pathway has been difficult and slow, particularly for the industrially highly relevant Karstedt's catalyst. A detailed mechanistic study unraveling several new aspects of platinum-catalyzed hydrosilylation using Karstedt's catalyst as platinum source is presented in this work. A combination of 2H-labeling experiments, 195Pt NMR studies, and an in-depth kinetic study provides the basis for a further development of the well-established Chalk-Harrod mechanism. It is concluded that the coordination strength of the olefin exerts a decisive effect on the kinetics of the reaction. In addition, it is demonstrated how distinct structural features of the active catalyst species can be derived from kinetic data. A primary kinetic isotope effect as well as a characteristic product distribution in deuterium-labeling experiments lead to the conclusion that the rate-limiting step of platinum-catalyzed hydrosilylation is in fact the insertion of the olefin into the Pt-H bond rather than reductive elimination of the product in the olefin/silane combinations studied.
- Meister, Teresa K.,Riener, Korbinian,Gigler, Peter,Stohrer, Jürgen,Herrmann, Wolfgang A.,Kühn, Fritz E.
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p. 1274 - 1284
(2016/02/18)
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- Radical addition of silanes to alkenes followed by oxidation
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Phenyldimethylsilane and trichlorosilane are shown to undergo efficient radical hydrosilylation reactions, on reaction with various alkenes, using triethylborane as the initiator. Adducts from the trichlorosilane reactions can be oxidised to afford alcohols in good yields. This two-step process leads to the anti-Markovnikov hydration of alkenes. Georg Thieme Verlag Stuttgart · New York.
- Palframan, Matthew J.,Parsons, Andrew F.,Johnson, Paul
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experimental part
p. 2811 - 2814
(2012/01/06)
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- Effect of catalysts on the reaction of allyl esters with hydrosilanes
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The reaction of hydrosilylation of allyl esters XOCH 2CH=CH 2 (X = MeCO, CF 3CO, C 3F 7CO) and PhOCH 2CH=CH 2 with hydrosilanes HSiY 3 (Y = Cl, OEt) in the presence of the Speier catalyst, the Speier catalyst with additives, and of various nickel complexes was studied. The catalytic hydrosilylation reaction in the presence of the Speier catalyst is accompanied by the reduction. Additives to the Speier catalyst (vinyltriethoxysilane and some ethers) allow to suppress considerably the reduction reaction. In the presence of the studied nickel complexes mainly reduction and isomerization reactions occurred. The best nickel catalysts of hydrosilylation were the mixtures of NiCl 2 or Ni(acac) 2 with phosphine oxides. In contrast to allyl esters, the hydrosilylation of simple olefins proceeds easier, the content of the product of hydrosilylation in the reaction mixture reaches 94.3%. Pleiades Publishing, Ltd., 2010.
- Belyakova,Pomerantseva,Efimova,Chernyshev,Storozhenko
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experimental part
p. 728 - 733
(2011/01/05)
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- Novel optically active biaryl phosphorus compound and production process thereof
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The invention provides a novel optically active biaryl phosphorus compound that can be produced easily without the step of optical resolution, which is almost indispensable step in a conventional method. A phosphorus compound defined by the following general formula (1): in the formula (1), R1 denotes a hydrogen atom or a hydroxy protective group; R2 denotes a group defined by the following formula (R2-1) or (R2-2); R3, R4, R5, and R6 may be the same or different and independently denote a hydrogen atom, an alkyl group, an alkoxy group, an acyloxy group, a halogen atom, a haloalkyl group, or a dialkylamino group; two among R3, R4, R5, and R6 may form an aromatic ring optionally having a substituent group, and two among R3, R4, R5, and R6 may form a methylene chain optionally having a substituent group or a (poly)methylenedioxy group optionally having a substituent group: in the formula (R2-1) and (R2-2), R7 denotes an alkyl group, a cycloalkyl group, an aryl group, an alkoxy group, or an aryloxy group; R8 and R9 independently denote a hydrogen atom, an alkyl group, or an aryl group; z denotes a divalent group; and a denotes an integer of 0 or 1.
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Page/Page column 17
(2008/12/06)
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- PROCESS FOR PREPARING ORGANOCHLOROSILANES BY DEHYDROHALOGENATIVE COUPLING REACTION OF ALKYL HALIDES WITH CHLOROSILANES
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The present invention relates to a process for preparing organochlorosilanes and more particularly, to the process for preparing organochlorosilanes of formula I by a dehydrohalogenative coupling of hydrochlorosilanes of formula II with organic halides of formula III in the presence of quaternary phosphonium salt as a catalyst to provide better economical matter and yield compared with conventional methods, because only catalytic amount of phosphonium chloride is required and the catalyst can be separated from the reaction mixture and recycled easily, wherein R1 represents hydrogen, chloro, or methyl; X represents chloro or bromo; R2 is selected from the group consisting of C1-17 alkyl, C1-10 fluorinated alkyl with partial or full fluorination, C2-5 alkenyl, silyl containing alkyl group represented by (CH2)nSiMe3-mClm wherein n is an integer of 0 to 2 and m is an integer of 0 to 3, aromatic group represented by Ar(R′)q wherein Ar is C6-14 aromatic hydrocarbon, R′ is C1-4 alkyl, halogen, alkoxy, or vinyl, and q is an integer of 0 to 5, haloalkyl group represented by (CH2)pX wherein p is an integer of 1 to 9 and X is chloro or bromo, and aromatic hydrocarbon represented by ArCH2X wherein Ar is C6-14 aromatic hydrocarbons and X is a chloro or bromo; R3 is hydrogen, C1-6 alkyl, aromatic group represented by Ar(R′)q wherein Ar is C6-14 aromatic hydrocarbon, R′ is C1-4 alkyl, halogen, alkoxy, or vinyl, and q is an integer of 0 to 5; and R4 in formula I is the same as R2 in formula III and further, R4 can also be (CH2)pSiR1Cl2 or ArCH2SiR1Cl2, when R2 in formula III is (CH2)pX or ArCH2X, which is formed from the coupling reaction of X—(CH2)p+1—X or XCH2ArCH2X with the compounds of formula II; or when R2 and R3 are covalently bonded to each other to form a cyclic compounds of cyclopentyl or cyclohexyl group, R3 and R4 are also covalently bonded to each other in the same fashion.
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- Process for preparing organochlorosilanes by dehydrohalogenative coupling reaction of alkyl halides with chlorosilanes
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The present invention relates to a process for preparing organochlorosilanes and more particularly, to the process for preparing organochlorosilanes of R4R3CHSiR1Cl2(I) by a dehydrohalogenative coupling of hydrochlorosilanes of HSiR1Cl2(II) with organic halides of R2R3CHX (III) in the presence of quaternary phosphonium salt as a catalyst to provide better economical matter and yield compared with conventional methods, because only a catalytic amount of phosphonium chloride is required and the catalyst can be separated from the reaction mixture and recycled easily.
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- Asymmetric Hydrosilylation of 1-Alkenes Catalyzed by Palladium-MOP
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Asymmetric hydrosilylation of simple terminal alkenes (RCH=CH2) with trichlorosilane at 40 deg C in the presence of 1*10-3 or 1*10-4 molar amounts of palladium catalyst prepared in situ from 3-C3H5)>2 and (S)-2-diphenylphosphino-2'-methoxy-1,1'-binaphthyl ((S)-MeO-MOP) proceeded with unusual regioselectivity and with high enantioselectivity to give high yields of 2-(trichlorosilyl)alkanes together with a minor amount of 1-(trichlorosilyl)alkanes.Optically active alcohols, RCH(OH)CH3, were obtained by oxidation of the carbon-silicon bond.Regioselectivities for forming 2-silylalkanes over 1-silylalkanes and enantiomeric purities of alcohols are as follows: R=n-C4H9: 89/11, 94percent ee (R).R=n-C6H13: 93/7, 95percent ee (R).R=n-C10H21: 94/6, 95percentee (R).R=PhCH2CH2: 81/19, 97percentee (S).R=PhCH2CH2CH2: 80/20, 92percent ee (R).R=cyclo-C6H11: 66/34, 96percent ee (R).A similar hydrosilylation of 1-alkenes, 4-pentenyl benzoate and 1,5-heptadiene gave corresponding 2-alkanols of 90percent ee and 87percent ee, respectively, the ester carbonyl and the internal double bond remaining intact.
- Uozumi, Yasuhiro,Kitayama, Kenji,Hayashi, Tamio,Yanagi, Kazunori,Fukuyo, Emiko
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p. 713 - 722
(2007/10/02)
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- Electrophilic cleavage reactions of carbon-silicon bonds in neutral hexacoordinate silicon compounds: diorgano(phtalocyaninato)silicon
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Preparations of diorgano(phtalocyaninato)silicon 1)(R2)> and their reactions with N-bromosuccinimide (NBS), halogens, copper(II) halides, and 3-chloroperbenzoic acid (MCPBA) are reported.The alkyl-silicon bonds are readily cleaved by NBS, halogens, and CuX2 to give the corresponding alkyl halides.The reactivity of aryl-silicon bonds toward NBS and halogen depends greatly on the electronic effect of the substituent on the benzene ring, but these bonds are almost inert to CuX2.The reactivity of the carbon-silicon bond towards NBS cleavage decreases in the order 4-MeOC6H4 > n-C8H17 > 4-MeC6H4 > Ph >> 3-CF3C6H4.Cleavage of alkyl-silicon bonds may involv one-electron transfer from substrate to reagent and alkyl radical intermediates, while the electrophilic aromatic substitution mechanism may operate in the cleavage of aryl-silicon bonds. are stable to MCPBA.
- Tamao, Kohei,Akita, Munetaka,Kato, Hidehito,Kumada, Makoto
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p. 165 - 180
(2007/10/02)
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- Synthesis of Certain Cyclic Silanes
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The chlorotrialkylsilanes 21-24 have been synthesized as precursors to potential steric blocking groups for alkanes and cycloalkanes.Reaction of these chlorosilanes with one of the organometallic reagents methyllithium, methylmagnesium chloride, n-octylmagnesium bromide, or p-chlorobenzylmagnesium chloride formed the silanes 25-34.
- House, Herbert O.,Hrabie, Joseph A.,Narasimhan, S. Lakshmi
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p. 124 - 127
(2007/10/02)
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