Kinetics of oxidative decarboxylation and deamination of L-glutamine by diperiodatonickelate(IV) in aqueous alkaline medium

摘要

The kinetics of oxidation of L-glutamine by diperiodatonickelate (IV) (DPN) in aqueous alkaline medium at a constant ionic strength of 0.5 mol dm~(-3) has been studied spectrophotometrically.The reaction is first order in [DPN] and is an apparent less than unit order,each in [L-glutamine] and [alkali] under the experimental conditions.However,the order in [L-glutamine] and [alkali] changes from first order to zero order as the concentrations change from lower to higher concentrations.Addition of periodate has no effect on the rate of reaction.Effect of added products,ionic strength and dielectric constant of the reaction medium have been investigated.A mechanism involving the deprotonated diperiodatonickelate(IV) as the reactive species of the oxidant has been proposed.The reaction constants involved in the different steps of mechanism are evaluated and thermodynamic quantities are also calculated.