CATALYZED CYCLIZATION OF 2-((3-HALOPROPYL)OXY)PHENOXIDE IONS IN ZWITTERIONIC AND NONIONIC MICELLES

Cyclization of 2-((3-halopropyl)oxy)phenoxide ion (halo = Br, I; PhBr7 and PhI7, respectively) in micelles is a model for S(N)2 reactions of nucleophilic anions at micelle-water interfaces. Sulfobetaine micelle s of dodecyldimethylammoniopropanesulfonate (C12H25N+ (CH3)(2)(CH2)(3) SO3-, SB3-12) modestly increase rates of cyclization of PhBr7 and PhI7 , and the effect is larger for the latter. The relative rate constants k(I)/k(Br) are indicators of medium polarity and their values indicat e that the surface polarity of micellized SB3-12 is slightly lower tha n that of a trimethylammonium micelle and significantly lower than tha t of water. Changes in H-1 chemical shifts of SB3-12 show that the mic ellar rate effects are not due ta-changes in micellar structure. Nonio nic micelles of polyoxyethylene(23) dodecyl ether (C12H25(OCH2CH2)(23) OH, Brij 35) modestly speed up cyclization, but reaction appears to be in the water-rich palisade layer of the micelle in conditions such th at the distinction between aqueous and micellar pseudophases is uncert ain.