Abstraction of chlorine atoms from chloroalkanes. III. The kinetics of liquid phase reactions of trichlorosilyl radicals with chloromethanes

The kinetics of chlorine atom abstraction from the chloromethanes (ClM), CCl₄, CHCl₃, CH₂Cl₂, and CH₃Cl by radiolytically generated trichlorosilyl radicals was studied in the liquid phase by a competitive method. Arrhenius parameters of chlorine atom abstraction from chloromethanes relative to that of bromine atom abstraction from cyclohexyl bromide (RBr) were as follows: The error limits are two standard deviations (2σ) from least mean square Arrhenius plots. From the linear correlation between E_cl values derived from the reactions of SiCl₃ and cyclohexyl radicals with the ClM series it is estimated that E_cl (R + CH₃Cl) ? 16 kcal/mole. In addition the relative Arrhenius parameters for the hydrogen atom abstraction from SiHCl₃ and chlorine atom abstraction from CCl₄ by cyclohexyl radicals were obtained log A_H/A_cl = 0.12 ± 0.15 and E_H ? E_cl = 0.24 ± 0.26. The E_H ? E_cl value was combined with existing data on E(R + CCl₄) to yield the E_H(R + SiHCl₃) value.