Kinetics and Mechanism of Oxidation of Some α -Hydroxy Acids by Pyridinium Dichromate in Aqueous Acetic Acid Medium

The Kinetics and mechanism of oxidation of some α hydroxy acids by pyridinium dichromate (PDC) has been studied by spectrophotometric method in 50% acetic acid -50% water (v/v) medium at 303K. Under the conditions of pseudo first order, the reaction follows first order kinetics with respect to hydroxy acid, [H⁺] and [PDC]. The reaction is catalysed by perchloric acid. There is no salt effect. The rate increases with increase in the percentage of acetic acid and the plot of log Kobs Versus 1/D is linear with a positive slope indicating the ion-dipole nature of the reaction. Activation parameters have been evaluated. Based on the experimental results, a suitable mechanism has been proposed.