Micellar-mediated general acid catalysed acetal hydrolysis. Reactions in comicelles

Abstract

Anionic micelles of sodium dodecyl sulfate (SDS) increase the rates of acid hydrolyses of dibutyl and di-tert-butyl benzaldehyde acetal (BBA and BTBA, respectively). The rate surfactant profiles are fitted by a pseudophase, ion-exchange, model and second-order rate constants in the micellar pseudophase are slightly lower than in water. In both media BTBA is considerably more reactive than BBA. The reaction of BTBA is general acid catalysed and with micellar-bound BTBA the first-order rate constant of hydrolysis in comicelles of SDS and sodium decyl hydrogenphosphate increases linearly with increasing mole fraction of the phosphate surfactant, which is a general acid catalyst in the micellar pseudophase. However, the rate constant of the specific hydrogen ion catalysed hydrolysis of BBA is independent of the mole fraction of the phosphate surfactant.