An empirical approach to study the occurrence of ion exchange in the alkaline hydrolysis of phthalimide in the presence of cationic micelles and inert salts

Pseudo first-order rate constants, k(obs), for pH-independent hydrolysis of phthalimide, PTH, obtained at constant [CH3CN], [CTABr](T) (total concentration of cetyltrimethylammonium bromide), and varying concentrations of MX (MX=sodium acetate, sodium butanoate, disodium adipate, sodium phenoxyacetate, sodium 4-methoxybenzoate, sodium 3-, 4- and 2-toluate) follow a relationship derived from an empirical equation coupled with a pseudophase model of micelle. This relationship gives an empirical constant (K-X/S) whose magnitude is the measure of the ability of an ion, X-, to expel another counterion, S-, from a cationic micellar to the aqueous pseudophase. The empirical K-X/S is used to derive the usual ion-exchange constant (K-X(Y)). The values of K-X(Br) have been calculated for all X- ions of the present study, and most of the Br calculated values of K-X(Br) are comparable with the corresponding K-X(Br) values obtained directly by other physical techniques. (c) 2007 Elsevier B.V. All rights reserved.