Kinetics and Mechanism of Reduction of Thallium(III) with Glyoxal in Perchloric Acid Medium

摘要

The kinetics and mechanism of reduction of thallium(III) with glyoxal has been studied in 0.5 mol dm~(-3) perchloric acid medium. The reaction is first order with respect to thallium(III) and glyoxal. An inverse hydrogen ion effect is observed. A lausible mechanistic pathway for the reaction is suggested which leads to the following rate law: rate = k_1[Tl~(3+)][H_2C_2O_2] + k_2[TlOH~(2+)][Gly] where k_1 and k_2 are the formation constants of the complex between thallium(III), TlOH~(2+) and glyoxal. The computed values fo E_a and DELTAS~* are 39.04 (+-) 1.04 kJ mol~(-1) and -11.66 (+-) 7.36 JK~(-1) mol~(-1), respectively.