Micellar catalysis of organic reactions. VII. The effect of the micellar counter ion in nucleophilic reactions of hydroxide and nitrite ions

Abstract

The rates of basic hydrolysis of N-methyl-N-(4'-nitrophenyl)octanamide and N,4-dimethyl-N- (3'-nitrophenyl)benzamide in the presence of cetyltrimethylammonium fluoride and acetate and the SNAr reactions of sodium nitrite with 2,4-dinitrofluorobenzene and 1-chloro-2,4-dinitrobenzene in the presence of cetyltrimethylammonium fluoride have been measured and compared to the rate in the presence of cetyltrimethylammonium bromide. The identity of the micellar counter ion (i.e. fluoride, acetate or bromide) has only a small effect on the rate of reaction despite quite substantial differences in exchange constants for the appropriate nucleophile/counter ion pairs; this is explained by a considerable amount of reaction between substrate molecules in the micellar pseudophase and the nucleophile in the aqueous intermicellar phase.