Oxidation of alcohols by dimethyldioxirane

The kinetics of oxidation of a series of monoatomic alcohols (methanol, 2-propanol, 2-butanol, 2-methyl-1-propanol, 2-chloroerhanol, 1,3-dichloro-2-propanol, benzyl alcohol), hydroxyacetic acid, and 1,3-burandiol (ROH) by dimethyldioxirane (1) was studied. The reaction kinetics obeys the second order equation w = k[ROH][1]. The rate constants were measured in the range of 7-50 degrees C, and the activation parameters were found. To describe the reaction rate constants as a function of the ROH structure, the two-parametric Taft equation was used, which takes into account both the polar and resonance substituent effects. Alcohol oxidation produces the corresponding carbonyl compounds, viz., ketones from secondary alcohols and aldehydes from primary alcohols, in yields of at least 80%. The results were explained by the competition of the molecular (oxenoid) and radical mechanisms. The introduction of electron-withdrawing substituents into the alcohol molecule increases the contribution of the radical channel of the reaction.