KINETICS OF OZONATION OF ALDEHYDES IN RELATION TO THEIR OZONE-INITIATED AUTOXIDATION

Abstract

The rates of ozonation of aliphatic aldehydes and monosubstituted benzaldehydes are measured in carbon tetrachloride solutions, and the reaction order and the rate constants are determined on the basis of the theory of gas absorption accompanied by chemical reactions. It is found that the reaction is first order with respect to both ozone and benzaldehyde, and also that the second order rate constants for n- and iso-butyraldehydes are much higher than those for the substituted benzaldehydes studied. The order of reactivity of substituted benzaldehydes is anisaldehyde> p-tolualdehyde> benzaldehyde> p- and m-chlorobenzaldehydes> p- and m-nitrobenzaldehydes. It is also found that the rate of ozonation of substituted benzaldehyde follows Hammett''s rule.
Furthermore, the kinetics of liquid-phase autoxidation of benzaldehyde with ozone-oxygen mixture is studied, and the observed oxidation rates are found to be approximately consistent with those predicted on the assumption that the reaction of ozone with aldehyde is an initiation reaction of the autoxidation.