Acetylenic silanes

Fine, submicrometer and quasispherical SiC powders have been synthesized in a vertical tubular flow reactor by using the silane-acetylene-argon system [88]. 

Silylacetylenes are intermediates in the preparation of PhCHOHC CH from benzaldehyde, and a mixture of allene-acetylene isomers results from Me3SiC= CCHjOPh using Bu Li-Base-Bu sB. MegNH adds to the double bond of trimethylsilyl vinylacetylenes, and the conductivity assessed for the (phthalo-cyaninato)silane-acetylene linear polymer. ... 

Protection of an acetylenic hydrogen is often necessary because of its acidity. The bulk of a silane can protect an acetylene against catalytic hydrogenation because of rate differences between an olefin (primary or secondary) vs. the more hindered protected alkyne. Trialkylsilylacetylenes are often used as a convenient method for introducing an acetylenic unit because they tend to be easily handled liquids or solids, as opposed to gaseous acetylene. 

The length of the axial bond would be expected on all theories to be important. The barrier height does decline from ethane to methyl silane to methyl germane, but of course the bonded atoms are different. Unfortunately reliable values are not available for dimethyl mercury, dimethyl acetylene, and similar molecules with still longer bonds. An apparent exception is provided by methyl mercaptan and methyl alcohol. The latter, with the shorter axial bond, has the lower barrier. 

Organo-silane werden durch Elektrolyse an der C-Metall-Bindung gespalten. So erhalt man z. B. aus Trimethyl-phenylathinyl-silan in Methylamin/Lithiumchlorid (s. a. S. 577) an Platin-Elektroden Phenyl-acetylen (38% d.Th.). Als Nebenprodukte fallen infolge Hydrierung Trimethyl-(2-phenyl-athyl)-silan (10% d.Th.) und A thy T benzol (30% d.Th.)... 

Beta SiC powder from the decomposition of methyl-trichlorosilane (MTS) in the presence of hydrogen in an argon plasma. Also from the gaseous thermal decomposition of tetramethylsilane, Si(CH3)4, in a flowthrough reactor between 850 and 1500°CP 1 and by the reaction of acetylene and silane. 

Submicron pSiC powder by reacting silane and acetylene in a 10-50 W continuous-wave CO2 laser beam.P" l... 

Nowadays silenes are well-known intermediates. A number of studies have been carried out to obtain more complex molecules having Si=C double bonds. Thus, an attempt has been made to generate and stabilize in a matrix 1,1-dimethyl-l-silabuta-l,3-diene [125], which can be formed as a primary product of pyrolysis of diallyldimethylsilane [126] (Korolev et al., 1985). However, when thermolysis was carried out at 750-800°C the absorptions of only two stable molecules, propene and 1,1-dimethylsilacyclobut-2-ene [127], were observed in the matrix IR spectra of the reaction products. At temperatures above 800°C both silane [126] and silacyclobutene [127] gave low-molecular hydrocarbons, methane, acetylene, ethylene and methylacetylene. A comparison of relative intensities of the IR... 

The limits of the original BIRD-FIMBC sequence and the excellent /ci 1 filter quality of the double tuned G-BIRD element is exemplified in the spectra obtained with the molecule 1,3-butadiynyl (ferf-butyl) diphenyl-silane (Figure 6). This molecule provides a stringent test, since it contains all together aliphatic, aromatic and acetylenic protons, and the corresponding ch coupling constant values vary from 125 to 260 Flz. 

A new type of asymmetric hydrosilylation which produces axially chiral allenylsilanes has been reported by use of a palladium catalyst coordinated with the bisPPFOMe ligand 51b.64 The hydrosilylation of l-buten-3-ynes substituted with bulky groups such as tert-butyl at the acetylene terminus took place in a 1,4-fashion to give allenyl(trichloro)-silanes with high selectivity. The highest enantioselectivity (90% ee) was observed in the reaction of 5,5-dimethyl-T hexen-3-yne with trichlorosilane catalyzed by the bisPPFOMe-palladium complex (Scheme 13). 

The unexpected formation of the first bis(triorganosilyl)silyl dianions has been reported by Sekiguchi et al. in 1999. Thus, the reaction of l,l-bis(triorganosilyl)-2,3-bis(trimethylsilyl)silacyclopropenes 128 and 129 with lithium provided the dilithiosilanes Li2[Si(R2R Si)2] (130 R = R1 =/-Pr 131, R = Me, R1 =/-Bu) with the only byproduct being bis(trimethylsilyl) acetylene Me3SiCCSiMe3 132 (Scheme 21 ).281>282 For reactions of silyl dianions at preparing unsaturated silanes, see Section 5.2. 

Finally, it has been reported that the titanium-catalyzed (TiCl4/Et2AlCl) cyclotrimerization of l-phenyl-2-(trimethylsilyl)acetylene affords the ter-phenyl silane l,3,5-triphenyl-2,4,6-tris(trimethylsilyl)benzene in trace amounts.101... 

Silicones can be prepared in such a way that they contain only one percent or less of vinyl groups and silicon hydrides, which undergo a catalytic hydrosilylation reaction to give the desired cross-linking (Figure 18.3). Vinyl silanes are made by Si-H addition to acetylene, and thus two hydrosilylations are involved. 

The addition reaction of alkyl and/or phenyl substituted silicon hydrides to acetylenes has limitations mainly due to the hydrogen donation step (cf. Scheme 5.1). Reaction (5.17) shows that the replacement of Ph by MesSi group in silanes made the reaction easier, the effect being cumulative. Indeed, the reaction time decreased from 88 h for PhsSiH to 3h for (TMS)3SiH [39], together with the amelioration of yields, and a slightly better cis stereoselectivity. 

ACETONE TRIMETHYLS ILVL ENOL ETHER SILANE, (ISOPROPE NYLOXY )TR IMETHYL SILANE, TRIMETHYL[(1-METHYLETHENYL)0XY]- (1833-53-0), 65, 1 Acetonitrile, purification, 66, 101 Acetophenone Ethanone, 1-phenyl- (98-86-2), 65, 6, 119 Acetophenone silyl enol ether Silane, trimethyl[(1-phenylvinyl)oxy] Silane, tririethyl[(l-phenylethenyl )oxy]- (13735-81-4), 65, 12 4-ACET OXYAZET ID IN-2-ONE 2-AZET IDINONE, 4-HYDROXY-ACETATE (ESTER) 2-AZET ID1N0NE, 4-(ACETYL0XY)- (2 8562 - 53-0), 65, 135 Acetylene Ethyne (74-86-2), 65, 61... 

In a similar manner, dimethyl-bis(phenylethynyl)silane forms a derivative in which both acetylenic groups act as bridging ligands (79, 80) ... 

Finally, atomic and molecular proton affinities (PAs) have also been evaluated for various functionals for ammonia, water, acetylene, silane, phosphine, silylene, hydrochloric acid, and molecular hydrogen. For G2 and G3 theories, the mean unsigned error in PAs is 1.1 and... 

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