The factors determining the micellar effects on nucleophilic substitution reactions

Kinetic study of the reaction of p-nitrophenyl diphenyl phosphate with 2-am inomethylphenols and the basic hydrolysis of ethyl p-nitrophenyl ethyl phos phonate have shown that in direct micelles the concentration factors is mai nly responsible for the acceleration of nucleophilic substitution reaction while the micellar microenvironment negatively affects the reactivity and r esults in a diminution in the micellar rate effect. The considerable contri bution to the micellar catalysis is made by the acid-base equilibrium shift of reagents. On the contrary, in reverse aggregates the micellar microenvi ronment favours the reaction and mostly underlies the mechanism of the cata lysis, while the concentration factors plays a minor role. (C) 2001 Elsevie r Science B.V. All rights reserved.