Mechanism of cooxidation of benzaldehyde and oxalic acid by pyridinium chlorochromate

The kinetics and mechanism of cooxidation of benzaldehyde and oxalic acid by pyridinium chlorochromate (PCC) have been studied in 50% acetic acid-50% water(v/v) mixture. The reaction is first-order each in benzaldehyde, oxalic acid, PCC and H + . The products of cooxidation are benzoic acid and carbon dioxide. Addition of aluminium chloride retards the reaction rate significantly. Based on the observed experimental facts, a suitable mechanism involving the formation of a cyclic ternary complex in a slow step has been proposed.