HPLC Study of the Cinnamic Acid Ozonation Reaction Products in Aqueous Medium I. González, R. Pérez-Rey, L. A. Fernández, Ch. Baluja. Ozone Research Center, Cuba. Cinnamic acid was taking as a model for the study of the ozonation reaction in aqueous medium. Water solutions of cinnamic acid (10-3 M) were ozonized at pH values of 2.5 and 7.0, T=25 oC to completion in a 100 mL bubbling reactor. The composition of the reaction mixture were followed by HPLC. Surprisingly, benzaldehyde was found to be formed in all cases in an almost 1:1 ratio respect to cinnamic acid consumed. It means that the carbonyl moeity of the Criegee mechanism is only formed in the aryl side of the double bond, contrasting with data reported before the ozonation of similar compounds in organic solvents of varying polarity. An explanation based on the selective solvation stabilization of the carbonyl oxide alkyl moeity by water molecules is advanced. Source: 2nd International Symposium on Ozone Applications Havana, Cuba - Mach 24-26, 1997.