Kinetic and mechanistic study of oxidative degradation of isonicotinate ion by diperiodatonickelate(IV) in aqueous alkaline medium

Abstract

The kinetics of oxidation of isonicotinate ion by alkaline diperiodatonickelate(IV) has been studied spectrophotometrically. The reaction is first order with respect to [DPN] and is apparently less than unit order each in [isonicotinate ion] and [alkali] under the experimental conditions. However, the order in Lisonicotinate ion] and [alkali] changes from first order to zero order as their concentrations increase. Reaction rate increases with increase in ionic strength and decrease in solvent polarity of the medium. Addition of periodate has no effect on the reaction rate. A mechanism involving the deprotonated diperiodatonickelate(IV) (DPN) as the reactive oxidant species has been proposed. There is a good agreement between the observed and calculated rate constants under varying experimental conditions. The activation parameters with respect to the slow step of scheme have been discussed.