The addition of neopentane to slowly reacting mixtures of hydrogen and oxygen at 480°C—I: Formation of primary products from neopentane

Abstract

When small amounts of neopentane are added to slowly reacting mixtures of H 2 + O 2 + N 2 at 480°C, the major primary products are isobutene, 3,3-dimethyloxetan, CH 3COCH 3, CH 4, and HCHO. In the initial stages of the reaction, the product ratios [CH 3COCH 3] [3,3,- dimethyloxetan] and ([CH 3COCH 3] + [3,3-dimethyloxetan]) [isobutene] are almost linearly dependent on the pressure of O 2 used. An oxidative mechanism involving the formation of (CH 3) 2C(CH 2OOH)CH 2 and (CH 3) 2C(CH 2OOH)CH 2O 2 radicals is proposed, and rate constants for a number of the elementary steps have been determined. The rate constant obtained for the reaction ( CH 3) 3 CCH 2O 2 → (rm>CH 3) 2 C(CH 2 OOH)CH 2 is a factor of about 10 2 lower than previously suggested. Mechanisms for the formation of the minor primary products, 2-methylprop-2-en-1-al, 2-methylprop-2-en-1-ol, and isobutyraldehyde are also discussed. A maximum value of 1.6 × 10 3 sec −1 is obtained for the rate constant of the methyl-group transfer reaction ( CH 3) 3 CCH 2O 2 → (rm>CH 3) 2 CCH 2 OOCH 3