A QUANTITATIVE TREATMENT OF MICELLAR EFFECTS UPON DEPHOSPHORYLATION BY THE HYDROPEROXIDE ANION

Dephosphorylation of p-nitrophenyl diphenyl phosphate by the hydroperoxide ion (HO2-) is speeded by micelles of cetyl trimethylammonium chloride and mesylate (CTACl and CTAOMs). Added Cl- competes with HO2- at the micellar surface and almost completely eliminates the micellar rate enhancement. The micellar and salt effects are fitted by a pseudophase model in which the concentration of HO2- at the micellar surface is calculated by solving the Poisson-Boltzmann equation in spherical symmetry. The calculated second-order rate constant at the micellar surface is lower than that in water by a factor of ca. 5.