SYNTHESIS OF SURFACTANTS BY MICELLAR AUTOCATALYSIS - N,N-DIMETHYLDODECYLAMINE N-OXIDE

The synthesis of N'N-dimethyldodecylamine N-oxide in aqueous solutions by micellar autocatalysis was investigated. Micellar autocatalysis is a novel variation of conventional micellar catalysis in which surfactant micelles catalyze the reaction by which the surfactant itself is synthesized. The lipophilic reactant, dimethyldodecylamine, was initially solubilized in micellar solutions of the amine oxide surfactant, resulting in substantially higher reaction rates. Amine conversions of 90-100% were obtained within 2 h at 70 degrees C. The effects of reactant concentrations, temperature, and initial surfactant concentration were studied. For systems with no surfactant at time zero, the system was initially an emulsion and reaction rates were low. A sharp increase in the rate was observed when enough surfactant had been produced to form micelles. Activation energy calculations indicate that enhancements of the rate were due primarily to the localized concentration of reactants in the micelle. A simple pseudophase model was used to model reactions under pseudo-first-order reaction conditions.