Oxidation of Nicotinate Ion by Heptavalent Manganese: a Kinetic and Mechanistic Approach

The kinetics of oxidation of nicotinate ion by permanganate in alkaline medium at a constant ionic strength has been studied spectrophotometrically. The reaction between permanganate and nicotinate ion in alkaline medium exhibits 2 : 1 stoichiometry KMnO4 : Nicotinate ion). The reaction shows first order dependence of rate on permanganate concentration and less than unit order dependence each in nicotinate ion and alkali concentrations. Reaction rate increases with increase in ionic strength and decrease in solvent polarity of the medium. Initial addition of reaction products did not affect the rate significantly. A mechanism involving the formation of an intermediate complex between oxidant and substrate has been proposed. The rate and the activation parameters for the slow step have been evaluated.