Ozonolysis of Unsaturated Acids in Aqueous Solution: Acrylic, Methacrylic, Maleic, Fumaric and Muconic Acids

The rate constants of ozone with acrylic, methacrylic, fumaric, maleic, muconic and dichloromaleic acids in aqueous solution were determined. Substituent effects and state of protonation strongly influence these rate constants. The reactions follow largely the Criegee mechanism (formation of carbonyl compound plus hydroxyalkylhydroperoxide). There is a pronounced regioselectivity in the decay reactions of the ozonide. Depending on their structures, the hydroxyhydroperoxidic intermediates decay by various routes: decarboxylation, H2O2 elimination or water elimination. Preliminary data on dicloromaleic acid indicate than an additional decay leading to chlorine atoms route must be envisaged.