DEPHOSPHORYLATION BY PEROXYANIONS IN MICELLES AND MICROEMULSIONS

Dephosphorylation of p‐nitrophenyl diphenylphosphate (pNPDPP) by OH− in aqueous cationic micelles of cetyltrimethylammonium hydroxide (CTAOH) is inhibited by tert‐butyl hydroperoxide (t‐BuO2H), which reduces the binding of OH−, and whose anion is a relatively ineffective nucleophile. Reaction is faster in microemulsions of CTACl, n‐octane and OH−, with t‐BuO2H as cosurfactant, than in otherwise similar microemulsions with t‐butyl alcohol as cosurfactant. Dephosphorylation by m‐chloroperoxybenzoate ion is slower in microemulsions of cetyltrimethylammonium mesylate or benzenesulfonate, with n‐octane and tert‐butyl alcohol, than in cationic micelles, but a wide range of concentrations can be examined. The reaction rates qualitatively follow the concentration of peroxy acid relative to surfactant, and inert anions slow the reaction. Dephosphorylation by peroxyphthalate dianion in micelles of CTACl fits a pseudophase kinetic model, except in very dilute surfactant where reaction is faster than predicted. Copyright © 1990 John Wiley & Sons Ltd.