BATTELLE MEMORIAL INST COLUMBUS OH COLUMBUS United States
The thermal-decomposition kinetics of the following arylsilanes have been investigated using both static and flow techniques monophenylsilane, diphenylsilane, triphenylsilane, tetraphenylsilane, diphenyldimethylsilane, and triphenylmethylsilane. The phenylhydrosilanes decompose via a bimolecular second-order redistribution reaction, with no evidence for free-radical formation. On the other hand, the main mode of decomposition of tetraphenylsilane involves elimination of phenyl radicals followed by attack of these radicals on the parent silane. The decomposition of the phenylmethylsilanes also proceeds via free-radical mechanism, but the main reaction path results in intramolecular cyclization, yielding compounds containing the dibenzosilole nucleus. Reasons for these three basically different modes of reaction are discussed in terms of substituent size and degree of p-dpi bonding between the phenyl rings and silicon.