Substitution at saturated carbon. Part III. Effect of lithium perchlorate on the reactants and the transition states in the bimolecular electrophilic substitution of tetra-alkyltins by mercuric iodide in solvent 96% methanol–4% water

Abstract

Second-order rate coefficients for the substitution of tetraethyl-, tetra-n-propyl-, and tetra-n-butyl-tin by mercuric iodide in solvent 96% methanol–4% water have been determined at various concentrations of added lithium perchlorate. All three substitutions are subject to marked positive kinetic salt effects. Activity coefficients of the tetra-alkyltins and mercuric iodide in the above solvent containing lithium perchlorate have been obtained, and have been combined with the kinetic data to yield values of the activity coefficients of the transition states. It is shown that the positive kinetic salt effects are due to destabilisation of the reactants by lithium perchlorate; the transition states are, for the most part, but little affected by added lithium perchlorate.