Oxidation of L-Phenylalanine by Manganese(VII) in Concentrated Sulfuric Acid Medium

摘要

Kinetics and mechanism of manganese(VII) oxidation of L-phenylalanine has been studied in aqueous sulfuric acid medium. Various hypotheses for the mechanism of acid catalysis have been tested and it has been found that rate is related to the activity of water in accord with Bunnett's hypothesis. The energy and entropy of activation and frequency factor have been calculated using the Eyring and Arrhenius plots. Mechanisms in agreement with the observations are reported. The experimental rate law for the reaction was found to be (-d[Mn(VII)])/(dt) = k_0 [L-phenylalanine][Mn(VII)] The reaction appears to involve an acid catalysis and the data showed that role of water molecules in the rate-determining step facilitating proton transfer which satisfies Bunnett's theory.