Primary reaction channels and kinetics of the thermal decomposition of phenylsilane

Abstract

The thermally induced decomposition of phenylsilane has been investigated by three different experimental methods: a static method, a comparative rate-single pulse shock tube (CR-SPST) method, and a very low-pressure pyrolysis (VLPP) method. Decomposition is mainly heterogeneous under static conditions but appears homogeneous in the other two systems. Homogeneous dissociations occur by two channels with yields, PhSiH3 →1 H2 + PhSiH, φ1 ∼ 0.84 ± 0.04; PhSiH3 →2 PhH + SiH2, φ2 ∼ 0.16 ± 0.04. Coupling of CR-SPST and homogeneous static reactor data spanning temperatures from 693 to 1236 K for the benzene formation channel and adjusting for falloff by RRKM methods gives high-pressure Arrhenius parameters of A1 = 1014.0±0.4, E1= 59.3 ± 2.1 and A2 = 1013.9±0.2, E2 = 62.0 ± 0.9 (A in s-1 and E in kcal/mol) for the two primary dissociation channels. These parameters yield RRKM calculated rate constants under VLPP conditions which agree within the errors with experimental rate constants. © 1995 American Chemical Society.