The gas‐phase decomposition of methylsilane. Part III. Kinetics

The homogeneous gas‐phase decomposition kinetics of methylsilane and methylsilane‐ d 3 have been investigated by the comparative‐rate‐single‐pulse shock‐tube technique at total pressures of 4700 torr in the 1125–1250 K temperature range. Three primary processes occur: CH 3 SiH 3 → CH 3 SiH + H 2 (1), CH 3 SiH 3 → CH 4 + SiH 2 (2), and CH 3 SiH 3 → CH 2 = SiH 2 + H 2 (3). The high‐pressure rate constants for the primary processes in CH 3 SiH 3 obtained by RRKM calculations are log ( k 1 + k 3 ) (s −1 ) = 15.2 ‐ 64,780 Cal/θ and log k 2 (s − ) = 14.50 ‐ 67,600 → 2800 Cal/θ. For CH 3 SiD 3 these same rate constants are log k 1 (s − ) = 14.99 ‐ 64,700 cal/θ log k 2 (s − ) = 14.68 – 66,700 → 2000 cal/θ, and log k 3 (s − ) = 14.3 ‒ 64,700 cal/θ.