Reactions of the ethyl radical I. Metathesis with unsaturated hydrocarbons

Abstract

The kinetic study of the abstraction of the hydrogen atom from selected hydrocarbons by the ethyl radical reveals a natural correspondence between molecular structure and molecular reactivity. Values of the energy of activation of the series n -heptane, 1-heptene and 1-heptyne are distinct at 10·6 ± 0·4, 8·3 ± 0·5 and 7·6 ± 0·2 kcal mole -1 , respectively, and illustrate the activating influence of bond multiplicity. The group of olefines: 1-heptene, 1-octene, cyclo hexene and trans -4-octene appear to share a common value of 8·3 kcal mole -1 for the energy of activation, within the limits of experimental error. Values of the frequency factor correspond closely to the numbers of equivalent hydrogen atoms in the molecule of the hydrocarbons.