Chloride-catalysed oxidation of thallium(I) by manganese(III) in aqueous perchlorate

Abstract

Manganese(III), in contrast with cobalt(III), does not react with thallium(I), except when manganese dioxide, from decomposition, or added chloride, are present. The observed rates in the presence of chloride are consistent with ‘reversible’ reaction of MnCl²⁺ with Cl^– to give Cl₂^–, which oxidises Tl¹ slowly and Tl^II rapidly. All Tl^III appears as TlCl₄^–. Curvature of rate plots at > 70–80% reaction may be due to the presence of unreactive polynuclear Mn^III, in perhaps <10% amounts. With an assumed association constant for MnCl²⁺+ 13·5 l mol^–1, the rate constant for MnCl²⁺+ Cl^– is 1·16 l mol^–1 s^–1.