Micellar Effects upon the Reaction of N-Alkyl-2-chloropyridinium Salts with Hydroxide Ion PDF

Keywords

cation, micellar, chemistry

Abstract

Cationic micelles of myristyltrimethylammonium bromide (MTABr) and cetyltrimethylammonium bromide (CTABr) inhibit the reactions of hydroxide ion with N-alkyl-2-chloropyridinium salts (alkyl = Me, Et, propyl, i.e., A1-3) because the substrates are largely in the aqueous pseudophase which is depleted in OH- by cationic micelles. Added Br- displaces OH- from the micelles and decreases micellar inhibition. The corresponding reaction of decyl (A4) and tetradecyl (A5) derivatives is catalyzed by both MTABr and CTABr which bind both reactants. These divers rate effects can be accounted for quantitatively in terms of the pseudophase ion-exchange model, which considers reactions in both the aqueous and micellar pseudophases and the distribution of both reactants between these pseudophases