Absolute rate constants for hydrocarbon oxidation. XI. The reactions of tertiary peroxy radicals

Abstract

Rate constants have been measured for the chain-terminating self-reactions of six tertiary peroxy radicals. The rate constants vary from ~ 1 × 10³ M⁻¹ s⁻¹ for t-butylperoxy to ~ 6 × 10⁴ M⁻¹ s⁻¹ for 1,1-diphenylethylperoxy radicals. It is suggested that the variation in the rate constants may be related to differences in the stability of the alkoxy radical products of tetroxide decomposition.Rate constants for hydrogen atom abstraction from aralkanes by tertiary peroxy radicals do not seem to be significantly affected by the structure of the attacking radical.In solution the triphenylmethylperoxy radical probably exists in equilibrium with the triphenylmethyl radical and oxygen. Chain termination in oxidations involving the triphenylmethylperoxy radical as the chain carrier occurs by the reaction of this radical with a triphenylmethyl radical.