Micellar catalysis of organic reactions. Part 33. Amide hydrolysis in neutral solution in the presence of a copper-containing micelle

Abstract

The hydrolysis of 5-nitro-2-(trifluoroacetylamino)benzoic acid (1) has been studied at pH 7 in water and in the presence of micelles of cetyltrimethylammonium bromide (ctab) and of copper-containing micelles formed from the reaction of N,N,N′-trimethyl-N′-hexadecylethylenediamine and cupric chloride. It has been found that the hydrolysis of 1 is inhibited by micelles of ctab but strongly catalysed by the copper-containing micelle at this pH. At a higher pH where the hydroxide ion reaction becomes important the reaction is catalysed by micelles of ctab as well, but the catalysis is stronger by the copper-containing micelle. The effect of added sodium chloride on the rate of reaction is shown to be larger for reaction in the presence of ctab than for reaction in the presence of the copper micelles. Also reported are the effects of the buffer concentration on the rate of reaction at various pH for both micelles. It is concluded that the mechanism of reaction in the copper-containing micelle involves a metal-bound hydroxyl rather than a free hydroxide ion loosely associated with the cationic micelle surface. It is interesting that the catalysis of this reaction by the copper-containing micelle is large enough to allow amide hydrolysis at a reasonable rate at neutral pH at ambient temperature.