ESTIMATION OF BOND-DISSOCIATION GIBBS ENERGIES FOR CARBON HALOGEN BONDS IN ANION-RADICALS OF SOME ARYL HALIDES AND SUBSTITUTED BENZYL HALIDES

A thermochemical cycle incorporating the standard potential E(RX/RX.-) -degrees of aryl halides and m- and p-substituted benzyl halides RX, t he standard potential E(X./X-)-degrees of the halide ion X- and the bo nd dissociation Gibbs energy DELTAG(BDE)-degrees(RX) of RX is used to determine the bond dissociation Gibbs energy DELTAG(BDE)-degrees(RX.-) of the carbon-halogen bond in some anion radicals RX.-. The values of E(RX/RX.-)-degrees are not directly measurable for most benzylic subs trates but can be approximated by the standard potentials for the Corr esponding compounds in which the CH2X group is replaced by an H atom. The calculations are compared with experimental results and similar ca lculations published recently.