Nucleophilic Dephosphorylation of p-Nitrophenyl Diphenyl Phosphate in Cationic Micellar Media

Abstract

The kinetics of nucleophilic dephosphorylation of p-nitrophenyl diphenyl phosphate by hydroxamate ions (R'(C=O)N(RO-)) have been investigated in aqueous cationic micellar media at pH 9.12 and 27 degrees C. The pseudo-first-order rate constant-surfactant profiles show micelle-assisted bimolecular reactions involving interfacial ion exchange between bulk aqueous media and micellar pseudophase. N-Substituted hydroxamate ion shows higher reactivity over the unsubstituted hydroxamate ions in cationic micellar media. The kinetic data are discussed in terms of the pseudophase ion exchange model.

Nucleophilic debenzoylation of p‐nitrophenyl benzoate in cationic micellar media

“…to N-O − form plays an important role for the cleavage of carboxylic esters [18]. Table III lists the nucleophile concentrationdependent Þrst-order rate constants of the debenzoylation of PNPB at different concentrations of aceto, benzo, and salicyl hydroxamate ions.…”

Cationic Mixed Micelles as Reaction Medium for Hydrolysis Reactions

“…Most hydrolysis reactions provide an excellent opportunity for comparisons of micellar medium effects. Based on the mechanisms of these hydrolytic processes, one expects that the properties of the micelles, including the lower local water concentration in the micellar Stern region, the polarity of the micelles and the local charge in the micellar Stern region resulting from incomplete counterion binding, play an important role in the catalysis or inhibition of these processes [3,4]. Kinetic studies in these systems may be interpreted on the basis of the pseudophase model [5,6], which allowed us to explain a large number of kinetic results [7][8][9], with the simple assumption of reaction distribution between the two pseudophases.…”

Decontamination of Chemical Warfare Agents

“…Freeze-dried nerve agenthydrolysing enzyme preparations have been shown to be effective in decontaminating gaseous nerve agents 8 . In previous years, a large number of research studies have been published on this subject [9][10][11][12][13] and one of the most promising carrier systems for active decontaminants is microemulsions [14][15][16][17][18][19][20] . Aqueous foam, a broad spectrum formulation 21 with enhanced physical stability has already been developed.…”