Kinetics and mechanism of pyridinium chlorochromate oxidation of thallium(I)

307-310The oxidation of TI(I) by pyridinium chlorochromate has been studied in 2.0 mol dm-3 hydrochloric acid. The reaction exhibits total second order kinetics, first order in each reactant and it is catalysed by hydrogen and chloride ions. The active species have been found to be protonated pyridinium chlorochromate of the oxidant and TICl2- of the reductant respectively. Added products, TI(III) , and Mn(II) have no significant effect on the reaction. The protonation constant of the pyridinium chlorochromate has also been evaluated as 8.0×10-2 dm3 mol-1 from the [H+] dependence of the reaction. A plausible mechanism is proposed based on the experimental observations