Kinetics and mechanism of the shock induced thermal decomposition of n-propylsilane

The kinetics and mechanism of the thermal decomposition of n-propylsilane have been studied by the single pulse shock tube-comparative rate technique at pressures around 4700 torr between 1095–1240 K. The primary dissociation processes are 1,1 and 1,2 H₂ elimination with ø_1,1 ? 0.75 and ø_1,2 ? 0.25, respectively. Subsequent decompositions of the primary process product, n-propylsilylene, to propylene and ethylene is complete even in the presence of excess butadiene. Possible mechanistic paths for these decompositions are discussed and an activation energy range of 30 ± 4 kcal is established for both processes. Induced decomposition via silylene chains accounts for 36–46% of the overall reaction in the uninhibited decomposition of n-propylsilane. The silylene chains are quenched in excess butadiene, and studies under maximum inhibition give overall decomposition kinetics of, log k(nPrSiD₃, s^?1) = 15.26–65,300 ± 1950 cal/2.303. Computer modeling results of the overall reaction both in the absence and presence of butadiene are also presented and shown to be in acceptable agreement with the experimental observations.