OXIDATION OF VALINE AND 2-AMINOISOBUTYRIC ACID BY DITELLURATOCUPRATE(III) IN ALKALINE MEDIUM. A KINETIC AND MECHANISTIC STUDY

Oxidation of valine and 2-aminoisobutyric acid by ditelluratocuprate(III) (DTC) in alkaline medium had been studied spectrophotometrically in the temperature range of 10 to 30 degrees C. It was found that the reaction was pseudo-first order in DTC and fractional order in valine, whereas 1<n(ap)<2 in 2-aminoisobutyric acid. The pseudo-first order rate constant, K-obs, decreased with an increase in [OH-] and [TeO42-]. There was negative salt effect. The rate of valine oxidation was higher than that of 2-aminoisobutyric acid in alkaline medium. A plausible mechanism involving pre-equilibriums before the rate-controlling step and a free radical mechanism was proposed based on the kinetic study. The rate equations derived from the mechanism can explain all experimental phenomena. In addition, the activation parameters at 298.2 K along with rate constants of the rate-determining step were computed by the slow step of the mechanism.