Mechanism of the Thermal Decomposition of Ethylsilane

Article abstract of DOI:10.1021/j100033a022

Products and kinetics of the thermal decomposition of ethylsilane, under static system conditions, are reported.Both neat and propylene-inhibited reactions follow silylene chain mechanisms.Modeling fits to product yield and reactant loss data establish approximate values for the rate constants of the ethylsilylene decomposition to ethylene and silylene (k₂ ca. 2 x 10⁶ s^-1) and the ethylsilylene isomerization to vinylsilane (k₈ ca 5 x 10² s^-1), both at 723 K.RRKM and thermochemical analyses of these results yield values for the high-pressure activation energy of the ethylsilylene decomposition (EtSiH <*> C2H4 + SiH2) of E₂ = 25.0 kcal/mol and a heat of formation for ethylsilylene of ΔH_f(EtSiH) = 47.7 +/- 2.5 kcal/mol.An enthalpy group additivity for the methylene group in organosilanes and organosilylenes of ΔH_f = -1.3 +/- 2 kcal/mol is deduced as well as the activation energy of the isomerization of ethylsilylene to vinylsilane (EtSiH <*> CH2=CHSiH3) of E₈ = 35.6 +/- 2 kcal/mol.