A kinetic and mechanistic study of the solvolysis of aryitellurium trihalides in organic solvents

Abstract

When an aryltellurium trichloride reacts with methanol in a mixed solvent also containing benzene or dioxane the reaction can be followed by monitoring the generation of acid. The first Te–Cl bond cleavage is acid catalysed and is rate determining. It exhibits a small activation enthalpy, but a large and negative activation entropy. The other trihalides have similar activation parameters, The mechanism is believed to involve protonation of a co-ordinated Cl, with dissociative loss of HCl being rate determining. The compounds RTe(O)Cl and RTe(OMe)₂Cl have been isolated as solid products but, since the reactions occurring in solution are reversible, the products in dilute solution may be different from these. Kinetic experiments to study the variation of rate with the solvent composition and the nature of the alcohol are also reported, as are results of reactions in aqueous dioxane.