The Addition of the Cyanide Ion to the N-Methyl-3-carbamoylpyridinium Ion in Reversed Micelles

The addition reaction of the cyanide ion to the N-methyl-3-carbamoylpyridinium ion was carried out in reversed micelle systems, and the functions of the electric charge of surfactants and of the entrapped water in the micelle were studied by measuring the rate and equilibrium constants. Reversed micelles formed by hexadecyltrimethylammonium bromide (HTAB), a cationic surfactant, not only enhanced the reaction, but also stabilized the product, 4-cyano-1,4-dihydro-N-methylnicotinamide (P), which is thermodynamically unstable in aqueous media. This was in contrast to sodium 1,2-bis(2-ethylhexyloxycarbonyl)ethanesulfonate (AOT), an anionic surfactant, reversed micelles. In both reversed micelle systems the reaction could be controlled by varying the water content, although neither is favorable for the reaction at a higher water content. From the distribution measurements and spectroscopic studies, it can be suggested that the reaction occurred preferably in the micellar phase, especially in the water pool. Three kinds of effects were proposed for interpreting the enhancement as compared to the reaction in aqueous systems. The first was the local concentration of reaction species in the water pools, and the second was the lower micropolarity of water pools. The third concerned the electric nature of the surfactant and reactant ions.