Kinetics and Mechanism of the Oxidation of some Hydroxy Acids by Bis(2,2 '-bipyridyl)copper(II) Permanganate

Chemistry Department, Faculty of Science, Suez Canal University, Ismailia, Egypt

Manuscript received 10 April 1995, accepted 6 July 1995

The oxidation of glycollic, lactic, mandelic and nine monosubstituted mandelic acids by bis(2,2'-bipyridyl)copper(II) permanganate (BBCP) in aqueous acetic acid solution leads to the formation of the corresponding oxoacids. The reaction is first order with respect to BBCP. Michaelis-Meten type kinetics have been observed with respect to the hydroxy acid. The formation constants for the hydroxy acid-BBCP complexes and the rates of their decomposition have been evaluated. The rates of decomposition of the complexes show an excellent correlation with Hammett's σ values with negative reaction constants. Thermodynamic parameters for complex formation and the activation parameters for their decomposition have also been calculated. The reaction rate increases with an increase in the concentration of hydrogen ion. The decomposition of α deuteriomandelk acid-BBCP complex exhibited the presence of a substantial kinetic isotope effect. With an increase in the amount of acetic add in the solvent mixture of acetic acid and water, the rate increased. Addition of 2,2"-bipyridyl and acrylonitrile has no effect on the rate. Suitable mechanism have been proposed.