Abstract
Oxidation of hydroquinone to quinone under ultrasonic irradiation has been reported in acidic solutions (Sharma and Prasad). In neutral aqueous solution (pH=6-7), however, we found that this type of reaction does not take place, but another type ultra sonicreaction, production of 2, 5-dihydroxyquinone takes place instead. We inves tigatedthis latter type of reaction and obtained the following results:(i) ultrasonic irradiation produced hydrogen peroxide in solution, which led to the formation of 2, 5-dihydroxyquinone, and the concentration of H2O2 formed increased with the ultrasonic level;(ii) the formation reaction of 2, 5-dihydroxyquinone was accelerated by the ultrasonic local thermal action;(iii) the observed reaction was also accelerated by the vigorous ultrasonic stirring.
