Methylsilane, decomposition

An example of an alcohol that can undergo rapid skeletal rearrangement is 3,3-dimethyl-2-phenyl-2-butanol (Eq. 29). Attempts to reduce this alcohol in dichloromethane solution with l-naphthyl(phenyl)methylsilane yield only a mixture of the rearranged elimination products 3,3-dimethyl-2-phenyl-l-butene and 2,3-dimethy 1-3-phenyl-1 -butene when trifluoroacetic acid or methanesulfonic acid is used. Use of a 1 1 triflic acid/triflic anhydride mixture with a 50 mol% excess of the silane gives good yields of the unrearranged reduction product 3,3-dimethyl-2-phenylbutane, but also causes extensive decomposition of the silane.126 In contrast, introduction of boron trifluoride gas into a dichloromethane solution of the alcohol and a 10 mol% excess of the silane... 

The decrease of thermal stability of (fluoromethyl)silanes in comparison to the non-fluorinated methylsilanes is evident from their decomposition temperature under static conditions. This drops significantly in the series H3CSiH3 (> 340 °C), F3CSiH3, and F2HCSiH3 (> 180 °C) to FH2CSiH3... 

The colorless product darkened upon standing for several days (even when stored in a dark bottle) but no decomposition products could be detected in the proton NMR spectrum. [The following peaks were observed for the completely enolized neat sample 1.23 [C(0113)3, rel. area-9.00], 6.09 (CH, rel. area-0.96), 14.76 (OH, rel. area-0.93) (peak positions are given in p.p.m. downfield from the internal standard tetra-methylsilane).] The physical properties were identical with those of an analyzed sample synthesized by a dijfferent method (24). The yield of this reaction was found to be fairly insensitive to the order of adding pinacolone and ethyl heptafluorobutyrate. 

Similarly, methylbromosilane only yields decomposition products including methylsilane by reaction with Na-Hg. Dimethylbromosilane reacts with Na-Hg to give (Me2HSi)2Hg, which is thermally unstable. Its thermolysis proceeds by two routes, one of which produces dimethylsilylenemercury ... 

The decomposition of chemically activated dimethylsilane and ethylsilane produced by the reaction of singlet methylene with methylsilane has been... 

Other negative groups on the silicon atom also stabilise the Si—C bond. Methyltrichlorosilane (H3C—SiCl3), for example, is thermally more stable than methylsilane (H3C—SiH3). Chlorotriphenylsilane can be distilled at 378 °C without decomposition. 

It was ascertained from these observations that very complicated subsequent reactions result from the thermal decomposition of SiMc4 and of the methylsilanes in the gas phase, in which compounds are formed containing a molecular skeleton of alternating Si and C atoms. Because a kinetic investigation into the complexities of these reactions would have little chance of success without previous knowledge of how these compounds are formed, and secondly, the influence of reaction conditions, the investigations were directed towards the preparation and identification of reaction products. 

The primary reaction involving the thermal decomposition of methylsilanes in the gas phase. 

The Formation of Carbosilanes by Thermal Decomposition of Methylsilanes 37 Table 15. Thermal behavior of l,l,3,3-tetramethyl-l,3-disilapentene... 

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