KINETICS AND MECHANISM OF ELECTRON-TRANSFER REACTIONS OF AQUO-THALLIUM(III) WITH HEXITOLS IN ACID PERCHLORATE MEDIUM

The kinetics of electron transfer reactions of aquo-thallium(III) with D-mannitol, D-glucitol and D-galactitol have been investigated under the pseudo-first order conditions. The variation of rate constant with hexitol concentration suggests the formation of an intermediate compl ex prior to the rate-determining step of its disproportionation. The r ate decreases with increase in acidity, and Is strongly inhibited by c omplexing chloride and acetate ions. Equilibrium constants of the comp lex formation between thallium(iii) and acetic acid, chloro acetic aci d and propionic acid have been computed from the observed retardation in rate of the electron transfer reaction of thallium(III) with D-mann itol by these complexing monocarboxylic acids. Corresponding aldohexos es have been confirmed as initial reaction products. Free radical form ation has been confirmed by the induced polymerisation reaction with a crylnitrile and also by the epr spin trapping technique. Rate law has been derived from the proposed mechanistic steps to explain the kineti c and other results of this study.