SOLVENT EFFECT ON INTRAMOLECULAR GENERAL BASE-CATALYZED AMINOLYSIS OFIONIZED PHENYL SALICYLATE

The nucleophilic second-order rate constants (k1) for the reactions of ionized phenyl salicylate (PS-) with primary and secondary amines in 70% (v/v) ethanol-water reveal Bronsted plots of slopes beta(nuc1) = 0 .32 +/- 0.10 and beta(nuc2) = 0.22 +/- 0.02, respectively. Different B ronsted slopes obtained for the reactions of PS- with primary and seco ndary amines suggest the occurrence of different locations of the tran sition state in the critical rate-determining step. The change in wate r content from 99.2 to 70% (v/v) in EtOH - H2O causes reduction in k1 by ca. < 3-fold for all the amines studied. Ionization constants of al l the protonated amines turn out to be larger in 70% (v/v) EtOH - H2O than in pure water.