- SELECTIVE PREPARATION OF VINYL- AND ETHYL-FUNCTIONALIZED CHLOROSILANES
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A method of preparing an organosilicon compound via selective silylation of ethylene is disclosed. The method comprises reacting via silylation (A) a hydridochlorosilane compound and (B) ethylene in the presence of (C) a catalyst, thereby preparing the organosilicon compound. The silylation may be selectively conducted as a dehydrogenative coupling to prepare the organosilicon compound as a vinylchlorosilane compound, or as a hydrosilylation to prepare the organosilicon compound as an ethylchlorosilane compound. The catalyst (C) comprises a Ru(0) complex, and may be recycled for use in subsequent silylation reactions without purification. The organosilicon compound prepared according to the method is also disclosed.
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Paragraph 0097-00107; 00108-00110
(2021/06/26)
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- Silyl and σ-silane ruthenium complexes: Chloride substituent effects on the catalysed silylation of ethylene
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Silylation of ethylene by the chlorosilanes HSiMe2Cl and HSiMeCl2 was catalysed by the bis(dihydrogen) complex RuH 2(η2-H2)2(PCy3) 2 (1). Dehydrogenative silylation leading to the formation of the corresponding vinylsilanes was in competition with hydrosilylation. The rate and selectivity of the reactions were influenced by the number of chloro substituents and the ethylene pressure. A comparative mechanistic study was performed in toluene-d8 with the two chlorosilanes. Reaction of 1 with an excess of HSiMe2Cl (10 equiv.) produced the σ-silane complexes RuH2(η2-H2)(η2- HSiMe2Cl)(PCy3)2 (2Me2Cl), RuH 2(η2-HSiMe2Cl)2(PCy 3)2 (3Me2Cl) and the silyl complex RuCl(SiMe2Cl)(η2-H2)(PCy3) 2 (4Me2Cl), all characterised by multinuclear NMR spectroscopy. Complexes 2Me2Cl and 3Me2Cl adopt a cis configuration for the two bulky phosphine ligands as a result of stabilising SISHA (Secondary Interactions between Silicon and Hydrogen Atoms) interactions. Complex 4Me2Cl resulted from the stoichiometric reaction of HSiMe2Cl with 1 producing RuHCl(η2-H 2)(PCy3)2in situ which further reacted with evolution of H2 and formation of 4Me2Cl. When reacting 1 with 10 equiv. of HSiMeCl2, the corresponding complexes 3MeCl 2 and 4MeCl2 were detected as well as traces of 2MeCl 2. The reactivity toward ethylene was then examined. Under catalytic conditions (excess silane in toluene-d8, ethylene atmosphere) only two compounds could be characterised: free PCy3 and the new (η6-aryl)(disilyl) complexes of the general formula Ru(η6-C6D5CD3)(SiMe 3-nCln)2(PCy3) (6Me 3-nCln-d8, n = 1,2). The X-ray structure of 6MeCl2 was obtained on a single-crystal at 160 K. When only 2 equiv. of HSiMe2Cl were added, the ethylene(silyl) complex RuH(SiMe 2Cl)(C2H4)(PCy3)2 (7Me2Cl) was obtained in addition to the organic products resulting from catalytic hydrogenation, hydrosilylation and dehydrogenative silylation, i.e. C2H6 (major one), C2H3SiMe 2Cl and C2H5SiMe2Cl. In the case of 2 equiv. of HSiMeCl2, upon ethylene addition, 7MeCl2 was formed in minority compared to a new disilyl complex Ru(SiMeCl2) 2(PCy3)2 (8MeCl2) characterised by NMR spectroscopy and X-ray diffraction on a single crystal at 160 K. In 8MeCl2, a formal 14-electron species, stabilisation through two agostic C-H bonds of the cyclohexyl groups was ascertained by DFT calculations.
- Lachaize, Sebastien,Vendier, Laure,Sabo-Etienne, Sylviane
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experimental part
p. 8492 - 8500
(2011/01/08)
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- Mechanistic studies on ethylene silylation with chlorosilanes catalysed by ruthenium complexes
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Silylation of ethylene by chlorosilanes is catalysed by ruthenium complexes. Mechanistic investigations reveal the presence of a complicated network of reactions leading to new σ-silane, ethylene and silyl complexes.
- Lachaize, Sebastien,Sabo-Etienne, Sylviane,Donnadieu, Bruno,Chaudret, Bruno
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p. 214 - 215
(2007/10/03)
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- Continuous single-stage organomagnesium synthesis of a mixture of ethylethoxysilanes and dimethylethylethoxysilane
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Simultaneous synthesis of ethylethoxysilanes and dimethylethylethoxysilane from a mixture of ethyl chloride, tetraethoxysilane, and dimethyldichlorosilane with magnesium (supply rate 75-100 g h-1) was studied. Schemes of intermediate processes are proposed. Reactivity of dimethyldichlorosilane and diethyldichlorosilane relative to each other is evaluated. Various grades of magnesium are tested. To reduce the amount of regenerated solvent (toluene) its mixtures with oligodiethylsiloxanes are used. The mixture of ethyl-substituted silanes can be used in subsequent preparation of oligo-ethylsiloxane liquids modified with the terminal dimethylethylsiloxy groups, which are characterised by improved lubricating properties.
- Klokov, Boris A.
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p. 122 - 128
(2013/09/07)
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- Selectivite de la scission Si-C dans des composes du type Me3SiCH2Σ; une synthese originale et sure de l'iodoacetate d'ethyle
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The regiochemistry of the electrophilic cleavage of the SiCsp3 bond in compounds Me3SiCH2Σ (Σ = Me, Pr, Cl, COOEt) and Me3SiCHΣ2 (Σ = Cl) has been investigated using ICl, Me3SiOSO2Cl and HO3SCl as the electrophiles.When Σ = Pr or Cl a regioselective cleavage of the Si-CH3 bond was observed, producing silylated chlorosulfonates or sulfates which often were new compounds.With Σ = COOEt a regiospecific splitting of the Si-CH2COOEt bond was observed.This confirms the synthetic potential of ethyl trimethylsilylacetate.
- Bordeau, M.,Djamei, S. M.,Dunogues, J.
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p. 413 - 417
(2007/10/02)
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- NOUVELLES UTILISATIONS DU TETRAMETHYLSILANE COMME AGENT DE METHYLATION DES CHLOROSILANES; VALORISATION DU METHYLTRICHLOROSILANE
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In the presence of catalytic amounts of AlCl3, the chlorosilanes MeSiCl3, ClMe2SiCH2Cl and PhSiCl3 convert Me4Si into Me3SiCl.In the first case, at 130 deg C, two by-products from the industrial synthesis of Me2SiCl2 provide the useful Me3SiCl as the unique product with a 44percent conversion ratio from Me4Si.From ClMe2SiCH2CL, the only products formed are Me3SiCl and Me3SiCH2Cl, which is a useful reagent for organic syntheses (formation ratio: 32percent), if the reaction is performed under atmospheric pressure, but if an autoclave is used EtMe2SiCl (88percent maximal yield) is obtained.
- Bordeau, M.,Djamei, S. M.,Calas, R.,Dunogues, J.
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p. 131 - 138
(2007/10/02)
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