Kinetic and product studies of the thermal decomposition of dimethylsilane in a single-pulse shock tube and in a stirred flow reactor

Abstract

Kinetic and product studies of the pyrolyses of dimethylsilane in a single-pulse shock tube (1135-1290 K) and in a stirred flow reactor (890-1000 K) are reported. The shock-induced reaction is accelerated by free-radical and silylene chains which cannot be quenched by trapping agents. The mechanisms of the pyrolyses in various temperature ranges are discussed and modeling results for the stirred flow and shock tube reactions are shown to be in reasonable agreement with experimental observations. Mechanisms for the decomposition of dimethylsilylene to ethylene and acetylene via silacyclopropane and silacyclopropene intermediates, respectively, are proposed. Arrhenius parameters for molecular elimination of methane from dimethylsilane are deduced (log k/sub CH/sub 4// = 14.8 - 73.000/2.3 RT), establishing an activation energy for CH/sub 3/SiH insertion into the (C-H) bond of methane of E similarly ordered 24.5 kcal (pressure standard state). 32 references, 1 figure, 6 tables.