Kinetics of chlorine isotope exchange reaction between sodium chloride-36 and triphenyltin chloride in mixed solvents

Isotope exchange reaction between NaCl-36 and triphenyltin chloride in dioxane-water (80:20% w/w) and ethanol-water (90:10% w/w) mixed solvents has been studied at 25, 35 and 50 deg C. The exchange reaction was found to proceed via a bimolecular SN2, limiting mechanism with reaction rates depending on the solvent used. Inhibition of the exchange in ethanol-water is probably due to solvation of chloride ion through hydrogen bond formation. The rate laws for the exchange reactions are: Re=3.24x109 e-65550/RT [Ph3SnCl] α [NaCl] in dioxane-water and Re=6.61x108 e-69600/RT [Ph3SnCl] α [NaCl] and Reis the rate of exchange in mol 1-1s-1. The activation parameters ΔH*, ΔS* and ΔG* are reported. (author) 15 refs.; 3 figs.; 1 tab