Formation of Peracetic Acid upon Aging of Perborate in Acetic Acid. Kinetics of the Oxidation of S-Phenylmercaptoacetic Acids

Summary.

 Upon aging, perborate in glacial acetic acid generates peracetic acid and thus oxidizes S-phenylmercaptoacetic acid rapidly. Perborate dissolved in ethylene glycol, however, does not show the aging effect, and the corresponding oxidation proceeds smoothly. The oxidation is of second order and not acid catalyzed. Boric acid and borate do not influence the oxidation. In the smooth oxidation, is the reactive species. The oxidation of some para-substituted S-phenylmercaptoacetic acids conforms to the Exner relationship, indicating operation of a common mechanism. Also, the oxidation obeys the Hammett equation with a negative reaction constant. However, the oxidation of p-nitro-S-phenylmercaptoacetic acid follows a different kinetic pathway.