Oxidation of L-Valine by Manganese(III) in Pyrophosphate Medium: Kinetics and Mechanism

Kinetics of oxidation of L-valine (Val) by manganese(III) pyrophosphate has been studied as a function of pH (0.94-1.90) at 313 K. The reaction shows a first-order dependence of rate each on (Mn(III)) and (Val), a fractional-order on (H + ), and an inverse fractional-order each on (Na4P2O7) and (Mn(II)). Effects on the rate of anions, such as (F - ), (Cl - ) and (ClO4 - ), and the dielectric constant of the solvent medium have been studied. Solvent isotope studies have been performed in D 2O medium. Activation parameters have been determined from Arrhenius and Eyring plots. A mechanism consistent with the observed kinetics is proposed and discussed.