Kinetics of the reaction of alkaline hydrolysis of thiophosphates in micellar and hexagonal phases of the cetyldimethylethylammonium bromide/NaOH/water system.

Reactivity of O-p-nitrophenyl-O,O-dimethylthiophosphate (A), O-p-nitropheny l-O,O-diethylthiophosphate CS) and O-p-nitrophenyl-O,O-dimethylphosphate (C ) in alkaline hydrolysis in the cetyldimethylethylammonium bromide (CDAB)/N aOH/water system in micellar (MI) and and hexagonal. (E) phases was investi gated with the help of the spectrophotometrical method. Kinetic parameters of micellar-catalysed reactions (binding constants and rate constants in mi cellar pseudophase) are defined from kinetic dependence k(obs) = f(C-CDAB) in accordance with the pseudophase model. The formation of micelles results in maximum acceleration of the alkaline hydrolysis A and C by 6 and 8 time s. The reaction becomes slower in an ordered E-phase in comparison with the Mi-phase for A, B and C by 16, 18 and 9 times, accordingly. The process is inhibited 3 and 5 times accordingly in comparison with aqueous alkaline hy drolysis in the E phase for A and B. (C) 2001 Elsevier Science B.V. All rig hts reserved.