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The kinetics and mechanism of the shock induced gas phase decomposition of ethylsilane
Author(s) -
Rickborn S. F.,
Ring M. A.,
O'Neal H. E.
Publication year - 1984
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550161109
Subject(s) - chemistry , silylene , dissociation (chemistry) , acetylene , decomposition , arrhenius equation , kinetics , bond dissociation energy , activation energy , organic chemistry , silicon , physics , quantum mechanics
The decomposition kinetics of ethylsilane under shock tube conditions ( P T ca. 3100 torr, T ≃ 1080–1245 K), both in the absence and presence of silylene trapping agents (butadiene and acetylene) are reported. Arrhenius parameters under maximum butadiene inhibition are: log k (C 2 H 5 SiH 3 ) = 15.14‐64,769 ± 1433 cal/2.303 RT ; log k (C 2 H 5 SiD 3 ) = 15.29‐66,206 ± 1414/2.303 RT. The uninhibited reaction is subject to silylene induced decomposition (63% lowest T ‐‐ 24% highest T ). Major reaction products are ethylene and hydrogen, consistent with two dominant primary dissociation reactions: C 2 H 5 SiD 3 → C 2 H 5 SiD + D 2 , ϕ ≃ 0.66; C 2 H 5 SiD 3 → CH 3 CH = SiD 2 + HD, ϕ ≃ 0.30. Minor products suggest several other less important primary processes: alkane elimination, ϕ ≃0.02, and free‐radical production via simple bond fission, ϕ ≃0.02. An upper limit for the activation energy of the decomposition, C 2 H 5 SiH → C 2 H 4 + SiH 2 , of E < 30 ± 4 kcal is established, and speculations on the mechanism of this decomposition (concerted or stepwise) with conclusions in favor of the stepwise path are made. Computer modeling studies for the reaction both in the absence and presence of butadiene are shown to be in good agreement with the experimental observations.