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Mechanisms and kinetics of the thermal decompositions of trichlorosilane, dichlorosilane, and monochlorosilane
Author(s) -
Walker K. L.,
Jardine R. E.,
Ring M. A.,
O'Neal H. E.
Publication year - 1998
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/(sici)1097-4601(1998)30:1<69::aid-kin9>3.0.co;2-s
Subject(s) - dichlorosilane , trichlorosilane , chemistry , thermal decomposition , arrhenius equation , decomposition , kinetics , shock tube , silylene , analytical chemistry (journal) , thermodynamics , organic chemistry , activation energy , shock wave , silicon , physics , quantum mechanics
Decomposition studies of trichlorosilane, dichlorosilane, and monochlorosilane at 921 K, 872 K, and 806 K, respectively, are reported. The studies were made at fixed reactant pressures over a range of total pressures in a wall conditioned, quartz reactor connected to a quadrupole mass‐spectrometer. Products were monitored sequentially and continuously in time. The dichlorosilane decomposition was also studied by the comparative‐rate single‐pulse shock‐tube method at temperatures around 1250 K. Two mechanisms of decomposition are considered: a silylene based mechanism initiated by molecular elimination reactions (Scheme I), and a free radical based mechanism initiated by bond fission reactions (Scheme V). Modeling tests of these mechanisms show that only the former is consistent with the experimental data. The decompositions are shown to be essentially nonchain processes initiated by the following pressure dependent reactions: HSiCl 3 (SINGLEBOND)4→ SiCl 2 +HCl, H 2 SiCl 2 (SINGLEBOND)1→ SiCl 2 +H 2 and H 3 SiCl(SINGLEBOND)5→ HSiCl+H 2 . High pressure Arrhenius parameters recommended for these reactions are A 4,∞ =A 1,∞ =A 5,∞ =10 14.5±0.5 s −1 , E 4,∞ =71.9±2.1 kcal/mol, E 1,∞ =69.2±2.0 kcal/mol, and E 5,∞ =60.6±1.8 kcal/mol. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 69–88, 1998.