Kinetics of Gas-Phase Addition Reactions of Trichlorosilyl Radicals. 5. Cis-Trans Isomerization of 2-Butene Induced by .SiCl3 Radicals

Article abstract of DOI:10.1021/j100220a014

Photolytic reactions of mixtures of HSiCl3 and cis-C4H8 have been investigated between 425 and 525 K in the gas phase.It was found that .SiCl3 radicals induced cis-trans isomerization of cis-C4H8 above 425 K.The rates of the isomerization and of the simultaneous formation of sec-C4H9SiCl3 have been measured at varying HSiCl3 concentrations.The kinetic treatment of these results leads to log-1/k₂ (mol cm^-3)> = 3.15 +/- 0.09 - (16.7 +/- 0.2) kcal/mol/(2.303RT) where the reactions involved are .SiCl3 + cis-C4H8 <*> CH3.CHCH(CH3)SiCl3 (1, -1) and CH3.CHCH(CH3)SiCl3 + HSiCl3 -> sec-C4H9SiCl3 + .SiCl3 (2).The value of log-1/k₂ (mol cm^-3)> at 475 K is -4.5 which agrees quite well with -4.4 obtained at 475 K by previous kinetic method.From this activation energy a bond dissociation energy of D^deg(Cl3Si-C_sec) = 78.3 +/- 2 kcal/mol is obtained.