PHOTOCHEMICAL OXIDATION OF MANDELIC ACID BY BROMINE WITH TUNGSTIC ACID SOL AS SENSITISER IN ULTRAVIOLET LIGHT OF 254 μμ.

A detailed investigation has been made on the oxidation of mandelic add by bromine with tongstic acid sol as the sensitiser in ultraviolet light of 254 μμ. The reaction is unimolecular with respect to bromine and also with respect to mandelic acid. The velocity constant passes through a maximum at pH 4.05 and it is indepen­dent of the concentration of sodium tungstate so long as the pH is constant. The velocity constant is proportional to the intensity of radiation absorbed by tungstic add sol. Temperature coefficient is small and the quantum efficiency is more than unity. A mechanism has been suggested.