Kinetics and mechanism of oxidation of some amino acids by diperiodatonickelate(IV) complex in alkaline medium

The kinetics of oxidation of some amino acids by diperiodatonickelate(IV)(DPN) in aqueous alkaline medium have been studied spectrophotometrically. The order of the reaction is found to be fractional with respect to each reductant. The rate increases with the increase in [OH-]. Added periodate decreases the rate of reaction. Change in ionic strength does not influence the rate appreciably. The products of oxidation are identified as ammonia and the corresponding keto acids. A mechanism of reaction involving a pre-equilibrium between DPN and monoperiodatonickelate(IV)(MPN) is proposed, which can explain all experimental observations. Activation parameters of the rate-determining step have been calculated.