Photooxidation of 2-Phenylbenzotriazoles

Abstract

Irradiation, with ultraviolet light, of 2-phenylbenzotriazole in aerated solvents resulted in oxidation of the benzo ring to yield the diacid 2-phenyl-1,2,3-triazole-4,5-dicarboxylic acid. A possible intermediate, 2-phenylbenzotriazole-4,7-dione, also yielded the diacid on photooxidation . The methyl ether of the commercial photostabilizer Tinuvin P undergoes an analogous reaction to produce the corresponding diacid.