Point of Attack in Hydrocarbon Oxidation

Abstract

A CONFLICT apparently exists between the aldehyde degradation mechanism indicated by the recent findings of Bailey and Norrish¹ and of Knox and Norrish², on one hand, and the preferential attack at the tertiary and secondary carbon atoms deduced, indirectly, by Walsh³, Boord⁴ and Badin and Pease⁵. A possible solution is provided by some recent studies, by gas-phase chromatography, of the products of slow oxidation of n-heptane, in a flow system. Although no tests for formaldehyde were made, aldehydes from C₂ to C₆ were detected at 300° C.; at 280° C., however, the extent of reaction was very small, and the only products condensed at − 80° C., apart from traces of peroxides, consisted of propionaldehyde and n-butyraldehyde. This suggests that the initial attack is at one of the secondary carbon atoms, with subsequent fission of one of the central C—C bonds. The more reactive chain carriers formed during this process can then attack the primary carbon also, and lead to the formation of higher aldehydes.