The cool-flame oxidation of 3-methylpentane

Abstract

Kinetic and analytical studies of the gaseous oxidation of 3-methylpentane have been carried out both under slow combustion conditions and more especially in the cool-flame region. Analysis of the complex mixtures of in termediate products provides strong evidence for the occurrence of 3-methylpentylperoxy radical isomerization, which leads initially to the formation mainly of the corresponding β- and γ-hydroperoxyalkyl radicals. Detailed comparison of the yields of partial combustion products with those obtained from 3-ethylpentane under similar experimental conditions shows that formation of γ-hydro-peroxyalkyl radicals takes place less readily during the oxidation of 3-methylpentane due to the restricted number of modes of 1:6 hydrogen transfer. In consequence, this branched C₆ alkane gives smaller yields of the corresponding O-heterocycles but larger amounts of β-scission products. During the isomerization of 3-methylpentylperoxy radicals there is evidence for the occurrence of some alkyl group shifts. The results show that there is a somewhat greater tendency for m ethyl groups to migrate than there is for ethyl groups, the difference becoming more marked with increasing temperature.