The photochemical reactions of Oxybenzone and Parsol 1789

The photolytic reactions of Oxybenzone and Parsol 1789 were investigated to provide a chemical background for the photosensitization of the sunscreen agents by analyzing the actual photolyzed compounds of the sunscreen agents. Oxybenzone and Parsol 1789, which are currently used as UV-B and UV-A absorbers, were both photolyzed in cyclohexane for 100 hours each with a mercury vapor lamp (450 W). Oxybenzone in cyclohexane did not yield any photodecomposed products after irradiation. Irradiation of the Parsol 1789 in cyclohexane produced seven major compounds. Six compounds were identified: cyclohexanone, cyclohexanol, dicyclohexyl ether, t-butyl benzene, p-methoxy benzoic acid and p-t-butyl benzoic acid. The cyclohexanone, cyclohexanol and dicyclohexyl ether were derived from the solvent, t-butyl benzene, p-methoxy benzoic acid, p-t-butyl benzoic acid were derived from Parsol 1789.