Rate constants for abstraction of hydrogen from benzene, toluene, and cyclopentane by methyl and ethyl radicals over the temperature range 650–770 K

Abstract

Rate constants for the abstraction of hydrogen from benzene, toluene, and cyclopentane by methyl and ethyl radicals have been measured relative to the corresponding abstraction reaction from ethylene. The method is based on the effect on the rates of formation of methane and ethane of the addition of small quantities of the reactants to the thermal chain reactions of ethylene in the temperature range 650–770 K. Taking the following values of the rate constants for the reference reactions (R = 8.314 J mol−1 K−1):[Formula: see text]the following rate constants were measured:[Formula: see text]The values of the activation energies are discussed in relation to the dissociation energies of the C—H bonds in the reactants. Keywords: kinetics, abstraction, methyl, ethyl, benzene, toluene.