Mononuclear rearrangement of heterocycles in zwitterionic micelles of amine oxide surfactants

[Display omitted] ► Zwitterionic micelles of amine oxide surfactants have been used as a reaction medium. ► The mononuclear heterocyclic rearrangements have been kinetically followed. ► Rates and binding constants have been obtained. ► The data obtained provide insight into the nature of the micelles. Rate constants for the mononuclear rearrangement (MRH) of Z-phenylhydrazones of some 5-substituted-3-benzoyl-1,2,4-oxadiazoles in water have been measured in the presence of zwitterionic micelles. The use of micellized N-tetradecyl-N,N-dimethylamineoxide (C14DMAO) as the reaction medium allowed to solubilize the otherwise water-insoluble oxadiazoles. Micellar rate effects were analyzed by using a simple pseudo-phase model and compared with those obtained in non-ionic micelles (Triton X-100). Evidence that both the rate of the rearrangement reaction and the binding of the substrates to the micelles are mainly governed by substrate hydrophobicity is obtained. The disagreement with the primarily sterically controlled MRH in Triton X-100 micelles highlights large and intriguing differences between the two micellar environments.