An empirical approach to study the occurrence of ion exchange in the ionicmicellar-mediated semi-tonic reactions: Kinetics of the rate of reaction of piperidine with ionized phenyl salicylate in the presence of cationic micelles

Pseudo-First-order rate constants (k(obs))-obtained for the cleavage of ion ized phenyl salicylate (PS-) at constant [NaOH], [MeCN], [CTAZ](T) (total c oncentration of cetyltrimethylammoniurr chloride and bromide), [Pip](T), (t otal concentration of piperidine), and varying concentrations of sodium cin namate, acetate, and butanoate ([NaX])-follow the relationship: k(obs) = (k (o) + thetaK[NaX])/(1 + k[NaX]), where theta and K are empirical parameters . The values of theta are almost independent of [CTAZ](T), while K values d ecrease with the increase in [CTAZ], within its range 0.006-0.020 M. The va lues of theta and K are explained in terms of pseudophase model of micelle coupled with an empirical relationship: K-s = K-s(o)/(1 + Psi (x/s) [NaX]). where K-s is the CTAZ micellar binding constant of PS- in the presence of NaX. (C) 2001 John Wiley & Sons. Inc.