Hydrolysis of phenyl trifluoroacetate in mixed surfactant systems

MARIANA ADELA FERNÁNDEZ; RITA HOYOS DE ROSSI; MARÍA FLORENCIA TORRES

JOURNAL OF PHYSICAL ORGANIC CHEMISTRY

JOHN WILEY & SONS LTD

Lugar: LOndres; Año: 2016 vol. 29 p. 665 - 671

0894-3230

The rate of spontaneous hydrolysis of phenyl trifluoroacetate (1) was measured in pure and mixed fluorocarbon/hydrocarbon surfactant systems. The reaction is inhibited by the surfactants when their concentration is higher than the critical micelle concentration (CMC). The same behaviour is observed in mixtures of surfactants. The kinetic analysis according to the pseudo-phase separation model indicates that the contribution of the micelle-associated substrate hydrolysis rate to the overall observed rate constant is negligible. In that condition the substrate is less available for water. The differences in inhibition observed for the hydrolysis reaction of 1 in the studied systems are due to the contribution of several effects: differences in polarity of the interfaces, protection of the substrate (reactive center) inside the micelles, stabilization of the transition state. The association constants of 1 with the surfactants and their mixtures were also determined.