BASIC HYDROLYSIS OF N-[N'-METHYL-N'-NITROSO(AMINOMETHYL)]BENZAMIDE IN AQUEOUS AND MICELLAR MEDIA

The kinetics of the alkaline hydrolysis of N-[N′-methyl-N′-nitroso(aminomethyl)]benzamide (NMAB) in the presence of surfactants have been studied. Incorporation of the substrate to the anionic surfactants inhibit the reaction, with electrostatic effects severely reducing the OH- concentration around the micelle. The cationic surfactants catalyze it. The reaction was studied in the presence of inert-ion cationic surfactants with different carbon chain lengths, and with the corresponding reactive-ion surfactants. For the inert-ion surfactants the results fit the pseudophase ion exchange model, similar rate constants in the micellar phase and similar competition among Br- and OH- ions for the micellar surface, independently of the surfactant, being observed. The micelle-substrate association constant increases with increasing surfactant hydrophobicity, however. These data show that hydrophobic forces predominate in the association between micelle and substrate and that the reaction occurs in the Stern layer, the characteristics of which do not depend on the length of the carbon chain. For the reactive-ion surfactants the data fit the ion exchange model or a mass-action model, the low constant for the micelle-substrate association not permitting discrimination between the two models. A method of discrimination based on comparison of the results with those obtained for the inert-ion micelles is used. The comparison suggests treating the data obtained with the mass-action model. © 1992.