Quantitative Treatment of Ketal Hydrolysis in Aqueous Solutions Containing Polymer-Surfactant Complexes Using a Pseudophase Kinetic Model

Article abstract of DOI:10.1021/j100098a034

The acid-catalyzed hydrolysis of 2-(p-methoxyphenyl)-1,3-dioxolane and benzaldehyde di-tert-butyl acetal has been studied in the presence and absence of poly(ethylene oxide)-sodium dodecyl sulfate (PEO-SDS) solutions.The kinetic data were interpreted in light of the pseudophase ion-exchange (PPIE) formalism by assuming that reaction can occur in three pseudophases, namely, aqueous, micellar, and PEO-SDS complex.The degree of ionization (α) for PEO-SDS complexes was determined from the ratio of the slopes of conductivity against above and below the critical aggregation concentration (cac) by the application of Evans equation.Values of 0.25 and 0.41 for SDS micelles and PEO-SDS complexes, respectively, were found.Free micelles are shown to be better catalysts than PEO-SDS complexes because of (i) the lower α value of free micelles and because (ii) second-order rate constants for the acid hydrolysis reactions in SDS micelles are higher than in PEO-SDS complexes.