Kinetics and mechanism of the oxidation of substituted malonic acids by the hexachloroiridate(IV) ion
Abstract
The kinetics of oxidation of malonic acid (H2mal) and its n-butyl (H2bmal), benzyl (H2bzmal), and phenyl (H2pmal) derivatives by hexachloroiridate(IV) ion have been studied at ionic strength 0.50 mol dm–3 and at various temperatures, over a wide acidity range. The reactions are first order with respect to the concentrations of the oxidant and the reducing agents. The rates are enhanced by a decrease in the hydrogen-ion concentration, and are sensitive to the substituent group, increasing in the order H2mal < H2bmal < H2bzmal < H2pmal. A reaction mechanism is proposed and discussed. The first dissociation constant of the dicarboxylic acids and the corresponding thermodynamic parameters have also been obtained kinetically.