Abstraction of chlorine atoms from polychloroalkanes. II. Neighboring group effect on the rates of chlorine abstraction by cyclohexyl radicals

The kinetics of chlorine atom abstraction from trichloromethyl groups of the haloethanes (XCCl₃), CF₃CCl₃, CH₃CCl₃, C₂Cl₆, C₂Cl₅H, and CH₂ClCCl₃, by radiolytically generated cyclohexyl radicals was studied in the liquid phase by a competitive method. The chlorine atom abstraction data were put on an absolute basis by comparing the rates of the metathetical reactions with the known rate of addition of cyclohexyl radicals to C₂Cl₄. The following Arrhenius parameters were obtained: The error limits are the standard deviations from least mean square Arrhenius plots. It is shown that the neighboring group effect on the rate of chlorine atom abstraction from the trichloromethyl groups can be correlated with Taft polar substituent constants.