MICELLAR CATALYSIS AND REACTANT INCORPORATION IN DEPHOSPHORYLATION AND NUCLEOPHILIC-SUBSTITUTION

The rate-surfactant profiles for the dephosphorvlation of p-nitrophenyl diphenyl phosphate by phenoxide and p-cresyl oxide ions and the reaction of phenoxide ion with 2.4-dinitrofluorobenzene (DNF) in micelles of cetyltrimethylammonium bromide (CTABr) can be treated quantitatively in terms of the distribution of both reactants between the aqueous and miccllar pscudophases. Distributions were measured directly under the reaction conditions. A similar treatment can be applied to the reaction of aniline with DNF catalyzed by micelles of CTABr or sodium lauryl sulfate (NaLS). For reactions of aryl oxide ions the rate enhancements of up to 4 X 103-fold can be explained almost completely in terms of increased reactant concentrations in the micellar pseudophase, but for the reaction of aniline this rate-enhancing effect is opposed by a negative —solvent– effect of the micelles stemming from the low polarity of their surface. © 1979, American Chemical Society. All rights reserved.