The oxidation of neopentane

Abstract

The gas phase oxidation of neopentane has been studied in a static system at 280 °C. It is shown that the main course of the reaction is best understood as a degenerately branched chain reaction propagated by the hydroxyl radical. Two simultaneous radical chain mechanisms arise from the decomposition of the transient unstable species neopentylperoxy to give on the one hand either isobutyraldehyde and carbon monoxide, or isobutene and acetone, and on the other hand isobutene and formaldehyde possibly via oxetane. Isobutene and isobutyraldehyde do not accumulate as end products of the reaction, but are further oxidized to acetone and carbon monoxide. Pivalaldehyde and isobutene are the first detectable intermediate products, and the former is primarily responsible for the degenerate branching mechanism. It is concluded that the accumulation of formaldehyde in the system can account for an apparent change from homogeneous to heterogeneous chain termination as the reaction proceeds.