ION-EXCHANGE IN MICELLAR SOLUTIONS .2. BINDING OF HYDROXIDE ION TO POSITIVE MICELLES

A kinetic study of the alkaline hydrolysis of a substrate (N-methy-4-cyanopyridinium ion, MCP) which resides exclusively in the intermicellar aqueous phase provides direct evidence for the binding of -OH ion to positive micelles. The observed rate behavior as a function of total detergent concentration can be adequately described by the ion-exchange model in micellar solutions. This treatment provides selectivity coefficients KOH/Br = 0.08 ± 0.02 for the binding of -OH to hexadecyltrimethylammonium bromide micelles and KOH/Cl = 0.14 ± 0.02 for the binding of -OH to tetradecyltrimethylammonium chloride micelles. This work represents the first quantitative description of the interaction of -OH with positive micelles. © 1979 American Chemical Society.