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

Abstract

Abstract Reactivity of O-p-nitrophenyl-O,O-dimethylthiophosphate ( A ), O-p-nitrophenyl-O,O-diethylthiophosphate ( B ) and O-p-nitrophenyl-O,O-dimethylphosphate ( C ) in alkaline hydrolysis in the cetyldimethylethylammonium bromide (CDAB)/NaOH/water system in micellar (MI) and and hexagonal (E) phases was investigated with the help of the spectrophotometrical method. Kinetic parameters of micellar-catalysed reactions (binding constants and rate constants in micellar 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 times. 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 hydrolysis in the E phase for A and B .