Kinetics and mechanism of reduction of thallium (III) with mesoxalic acid in perchloric acid medium

The kinetics and mechanism of reduction of thallum (III) with mesoxalic acid have been studied in 0.5 mol dm(-3) perchloric acid medium. The reaction is first order with respect to thallium (III) and mesoxalic acid. An inverse hydrogen ion and a negative ionic strength effects are observed. A plausible mechanistic path way for the reaction is suggested which leads to the following rate law: [GRAPHICS] where K is the formation constant of the complex between thallium (III) and mesoxalic acid, k-the rate constant. The computed values of E-a and Delta S* are (37.30+/-5.96) kJ mol(-1) and (-15.14+/-9.99) JK(-1) mol(-1), respectively.