- Direct synthesis of organodichlorosilanes by the reaction of metallic silicon, hydrogen chloride and alkene/alkyne and by the reaction of metallic silicon and alkyl chloride
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Dichloroethylsilane was synthesized by the reaction of metallic silicon, hydrogen chloride and ethylene using copper(I) chloride as the catalyst, the silicon conversion and the selectivity for dichloroethylsilane being 36 and 47%, respectively. At a lower reaction temperature or at a higher ratio of ethylene: hydrogen chloride a higher selectivity was obtained, however the silicon conversion was lower. The silicon-carbon bond formation is caused by the reaction of a surface silylene intermediate with ethylene. The reaction with propylene in place of ethylene gave dichloroisopropylsilane (22% selectivity) and dichloro-n-propyl-silane (8% selectivity) together with chlorosilanes. A part of the dichloroisopropylsilane is formed by the reaction of silicon, hydrogen chloride and isopropyl chloride formed by hydrochlorination of propylene. Use of acetylene instead of alkenes resulted in dichlorovinylsilane formation with a 34% selectivity. Alkyldichlorosilanes were also produced directly from silicon with alkyl chlorides, propyl and butyl chlorides. During the reaction the alkyl chloride is dehydrochlorinated over the surface of copper originating from the catalyst to afford hydrogen chloride and alkene. The hydrogen chloride formed participates in the formation of the silicon-hydrogen bond in alkyldichlorosilane, and the reaction of silicon, hydrogen chloride and alkene also causes alkyldichlorosilane formation. The reaction with isopropyl chloride gave a very high selectivity (85%) for dichloroisopropylsilane, the silicon conversion being 86%. The Royal Society of Chemistry 2001.
- Okamoto, Masaki,Onodera, Satoshi,Yamamoto, Yuji,Suzuki, Eiichi,Ono, Yoshio
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- Method for preparing tertiary hydrocarbon-silyl compounds
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A method for preparing a tertiary hydrocarbon-silyl compound comprises the step of reacting a grignard reagent represented by the general formula: R1 MgX1 (wherein R1 represents a tertiary hydrocarbon group and X1 is a halogen atom) with a silicon atom-containing compound represented by the general formula: X2m R2n SiH4-m-n (wherein X2 is a halogen atom and may be identical to or different from X1 ; R2 is a monovalent hydrocarbon group; m is 1, 2 or 3; and n is 0, 1 or 2, provided that m+n is not more than 3 and that if n is 2, R2 's may be identical to or different from one another) in an aprotic inert organic solvent in the presence of a copper compound and/or a quaternary ammonium salt. According to this method, the tertiary hydrocarbon-silyl compounds can industrially efficiently and rapidly produced in high yields.
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- Silaethane XIII. Erzeugung von SiC-Doppelbindungen in der Koordinationssphaere von Eisencarbonylkomplexen
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The suitability of the vinylsilyliron complexes RSi(Cl)CH=CH2 t (3), Fe(CO)2cp (4)> and of MeSi(Cl)CMe=CH2 (14) as precursors for the generation of silaethane derivatives has been investigated.The starting compounds 1 to 4 and 14 can be obtained from Me(Vi)SiCl2, Ph(Vi)SiCl2, HSiCl3 and MeSiCl3, respectively, by judicious combination of published procedures.They have been characterized by analytical and spectroscopic studies as well as by comparison with known data.The generation of the Si=C intermediates was attempted by treating the vinylsilyl iron complexes with LiBut at low temperatures (-10 deg C).Only with 1 was a smooth reaction observed with formation of the Z/Z dimer 1,3-bis(cyclopentadienyl-dicarbonyliron)-1,3-dimethyl-2,4-dineopentyl-1,3-disilacyclobutane (16) of the expected silaethane MeSi=CHCH2But.This intermediate also seems plausible on the basis of trapping experiments, using 2,3-dimethyl-1,3-butadiene, isoprene or 1,3-cyclohexadiene.However, since 16 is formed as the main product even in the presence of an excess of these dienes, the cyclization of the lithiated precursor ClSiMeCH(CH2But)SiMeCH(Li)CH2But must be regarded as an alternative route to 16.The crystal and molecular structure of 16 indicate a Z/Z configuration of the bulky ring substituents.The disilacyclobutane skeleton is nonplanar with a dihedral angle of 18.7 deg.Similar to other 1,3-disilacyclobutane derivatives, 16 shows a fairly short transannular Si(1)...Si(2) distance of 2.641(1) Angstroem.Due to the -I effect of the phenyl substituent reaction of 2 with LiBut yields oligomeric coupling products, whereas in 3, 4 or 14 for steric reasons LiBut clearly attacks the carbonyl ligand instead of the CC double bond to give black, pyrophoric solids of low solubility.
- Auner, Norbert,Grobe, Joseph,Schaefer, Thomas,Krebs, Bernt,Dartmann, Mechtild
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- SILACYCLOHEXADIENYLANIONEN BIS- UND TRIS-(TRIMETHYLSILYL)-SILACYCLOHEXADIENE
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1,1-Dialkyl(1,1-diaryl)-4-R-1-silacyclohexadienyl anions (1) are available by ether cleavage of the corresponding 1,1-dialkyl(1,1-diaryl)-4-methoxy-4-R-1-silacyclohexa-2,5-dienes (4), or by deprotonation of the 1,1-dialkyl(1,1-diaryl)-4-R-1-silacyclohexa-2,4-dienes (3) - which are available from 4 - with n-BuLi or LDA resp.The anions 1 are regioselectively silylated by trimethylchlorosilane to give the 6-trimethylsilyl-1-silacyclohexa-2,4-dienes (7,8), their alkylation or acylation occurs exclusively in 4-position to 16 or 17 resp.Deprotonation of 7, 8 with n-BuLi gives the 2-trimethylsilyl-1-silacyclohexadienyl anions (9), with trimethylchlorosilane they react regioselectively to give the 2,6-bis(trimethylsilyl)-1-silacyclohexa-2,4-dienes (10, 11), with alkyl halides and ketones the anion 9 reacts only in the 4-position.The 1-silacyclohexa-2,5-dienes 22, 25, 28 substituted at the silicon atom by functional groups (O-i-Prop) or by hydrogen can be transformed into 2,6-bis(trimethylsilyl)-1-silacyclohexa-2,4-dienes 24, 27, 33 resp., if LDA is used as base.The easily formed 4-R-2,6-bis(trimethylsilyl)-1-silacyclohexa-2,4-dienyl anions (by deprotonation of 10, 11, 24, 27, 33 with LDA) react with trimethylchlorosilane regioselectively to give 4-R-2,4,6-tris(trimethylsilyl)-1-silacyclohexa-2,5-dienes 37.Accessing 37 succeeds very simply by manifold-silylation of the 1-sila-2,4-cyclohexadienes 38 with excess trimethylchlorosilane in the presence of 3 mol LDA.Owing to trimethylsilyl substitution in the 2,6-position of the 1-silacyclohexa-2,4-dienes, the ring-silicon atom is strongly sterically shielded, therefore reactions of functional groups at the silicon atom are restricted.
- Maerkl, G.,Hoellriegl, H.,Schlosser, W.
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p. 129 - 170
(2007/10/02)
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