ABSTRACT
The rate profiles obtained are characteristic of micellar catalyzed reactions. The addition of diethylheptadecylimidazolinium ethyl sulphate to the reaction medium causes an increase in the rate of hydrolysis up to a point where there is complete incorporation of the substrate in the micellar phase. In summary, the addition of surfactant to water solutions or water solutions containing 10% dimethyl sulfoxide (DMSO) by volume leads to a more structured transition state due to the presence of micelles and facilitates the occurrence of the reaction. Solutions containing 90% by volume of DMSO exhibited much higher rates and considerably more catalysis. The experimental results are explained in terms of specific solvent effects and the formation of the stoichiometric hydrate DMSO•2H2 O and the inhibitory effect of dimethyl sulfoxide on the formation of micelles. The rate profiles obtained for solutions with 10 to 50% DMSO by volume exhibited clear maxima that shifted to higher concentrations for both surfactants as a function of DMSO added.
