Micellar catalysis of nucleophilic aromatic substitution reactions between anionic nucleophiles and aromatic substrates containing anionic substituents

Abstract

Rate constants for S_NAr reactions between anionic nucleophiles and aromatic substrates bearing anionic substituents in the presence and absence of micelles of cetyltrimethylammonium bromide (ctab) have been measured. Micellar catalysis of this class of reaction seems to be of the same order of magnitude as for S_NAr reactions between anionic nucleophiles and dipolar organic substrates. Micellar catalysis ofS_NAr reactions of the ambident nitrite ion has also been studied. The magnitude of catalysis of S_NAr reactions of sodium nitrite by micelles of ctab is large compared to that for S_NAr reactions of hydroxide ions or azide ions. This suggests that nitrite ion is well solubilized by micelles of ctab and some consequences of this in biological systems are discussed. The ambident behaviour of nitrite ion in aqueous micellar solution towards organic substrates seems to mirror that in methanolic solution.