Exchange reactions in two-phase catalytic systems. 3. Kinetics of nucleophilic substitution in the presence of a solid ionophore

Abstract

1. The nucleophilic substitution of bromine by chlorine in hexyl bromide in the presence of a solid ionophore and tetrabutylammonium bromide in toluene follows the rules for a reversible reaction of the first order in the substrate. 2. The dependence of the rate constants of the forward and the reverse reactions on the concentrations of hexylbromide and of tetrabutylammonium bromide has been studied. The reaction is first order in all components at low concentrations, and less than unity at higher concentrations. 3. One of the reaction products, the solid salt, inhibits the replacement, reducing the rate of both the forward and the reverse reactions. 4. A reaction scheme is proposed whereby the process occurs on the surface of the solid ionophore via a ternary complex, the breakdown of which produces the reaction products.