Effects of anionic micelles on intramolecular general base-catalysed aminolysis of ionized phenyl salicylate (PS-)

The effects of micelles of sodium dodecyl sulphate (SDS) on the rates of re actions of ionized phenyl salicylate (PS-) with n-butylamine, piperidine an d pyrrolidine were studied at 35 degrees C. Pseudo-first-order rate constan ts (k(obs)) show a linear increase with increase in the total concentration of amine ([Am](T)) at a constant [SDS]. An increase in the total concentra tion of SDS from 0.0 to 0.2 mol dm(-3) results in a decrease in the observe d nucleophilic second-order rate constants by the factors of ca 2.6, 5.2 an d 3.9 for the reactions of PS- with n-butylamine, piperidine and pyrrolidin e, respectively. The rate constants, k(obs), show a non-linear increase wit h increase in [NaOH] from 0.0 to 0.04 mol dm-3 at a constant [SDS] and [Am] (T). The observed results of aminolysis of PS- in the presence of SDS micel les are rationalized in the light of the pseudophase model of micelles. Cop yright (C) 1999 John Wiley & Sons, Ltd.