Study of the methyl–isobutane reaction in the range 478 ⩽T/K ⩽ 560

Abstract

The reactor design in an existing molecular modulation spectrometer (m.m.s.) has been modified to extend its operating temperature into a regime where methyl reactions of current interest may be conveniently studied. In this paper we present the first direct measurements on the reaction of methyl radicals with isobutane in the range 478 ⩽T/K ⩽ 560.

The m.m.s. information has been complemented by product studies using gas chromatography. Conditions have been chosen so as to facilitate the use of a simple analysis of the m.m.s. data to extract the kinetic information. The rate constant is satisfied by the expression k₅=(6.2 ± 1.1)× 10^–13 exp (–36.6 ± 0.7 kJ mol^–1/RT)cm³ molecule^–1 s^–1. The results have been used to discuss the possibility of curved Arrhenius behaviour for this reaction.