Effect of mixed CH3CN-H2O solvents on intramolecular general base-catalysed methanolysis of ionized phenyl salicylate (PS-) in the presence of cationic micelles

The increase in the content of CH3CN from 5 to 20%, v/v, decreases the cetyltrimethylammonium bromide (CTABr) micellar binding constant K-1 of PS- from 4500 to 190 M-1, increases the critical micellar concentration from 2.89 x 10(-4) to 39.8 x 10(-4) M and increases the pseudo-first-order rate constants k(M) for methanolysis of PS- in the micellar pseudo-phase from 1.42 x 10(-3) to 2.04 x 10(-3) s(-1). At constant concentrations of CH3CN and CH3OH, the rate constants k(1) decrease with increase in [CTABr] and the amount of this decrease increases with decrease in [CH3CN]. The presence of 2 x 10(-4) M PS- is concluded to enhance CTABr micelle formation. (C) 1997 Elsevier Science B.V.