Review Lecture: Local weather forecasting

Abstract
Studies have been made of the extent and mechanism of formation of ketones during the slow combustion of 2-methylpentane. With the aid of $^{14}$C-labelling at different skeletal positions, it has been shown, by separation and degradation of the various combustion products, that the carbonyl carbon atom in the ketone is always derived from the 2-position in the hydrocarbon. Acetone and methyl n-propyl ketone probably arise by a mechanism involving the abstraction of hydrogen by tertiary peroxy radicals from other hydrocarbon molecules. Tracer experiments show, however, that the methyl ethyl ketone formed incorporates the 2- and 3-positions but not the 4- and 5-positions in the hydrocarbon, and it is evident that some form of intramolecular rearrangement of tertiary peroxy radicals must take place. If allowance is made for the formation of ketones in addition to carbon monoxide, it can be shown that at 242 degrees C the overall pattern of initial oxidative attack is strongly in favour of the tertiary position. It appears, however, that although this position may be the most frequently attacked, the most effective oxidation of the hydrocarbon follows from initial attack on the secondary positions.