THE INHIBITED AUTOXIDATION OF STYRENE: PART V. THE KINETICS AND DEUTERIUM ISOTOPE EFFECT FOR INHIBITION BY DIPHENYLAMINE, PHENYL-α-NAPHTHYLAMINE, AND PHENYL-β-NAPHTHYLAMINE

Abstract

The thermal oxidation of styrene inhibited by diphenylamine, phenyl-α-naphthylamine, and phenyl-β-naphthylamine has been examined. It has been shown that the autocatalysis of the diphenylamine- and phenyl-β-naphthylamine-inhibited oxidations is probably due to a reaction between the inhibitor radical and the hydroperoxide formed in the primary step of inhibition. This reaction is too slow to produce significant autocatalysis with phenyl-α:-naphthylamine under the present experimental conditions.The primary inhibition reaction involves abstraction of the amino hydrogen since its replacement by deuterium leads to a fairly large kinetic isotope effect (kH/kD ~ 3–4).