Evaluation of the Activation Energies of Radical Substitution Reactions in the Gaseous Phase. I. An Empirical Method Employing the Morse Function

Abstract

Abstract An empirical evaluation of the activation energy has been carried out for the radical substitution reaction involving polyatomic molecules. The potential energy along the reaction path is assumed to be expressed for the initial and the final systems by the two Morse functions with the coefficient “a′,” which is different from the “a” in the usual Morse function of the bond. The difference between the a′Δr* values in the Morse functions of the initial and the final systems in the transition state is empirically determined as a function, af′Δrf*–ai′Δri*=βQ, of the reaction heat, Q. From the Morse function with “a′” and the above relation, the activation energy is calculated by using the bond dissociation energies of the initial and the final molecules. The treatment proposed is useful for the evaluation of the activation energies of many types of radical substitution reactions.