Effects of Monoalkyl Phosphate Surfactants upon the Acid Hydrolysis of Dioxolanes

Article abstract of DOI:10.1021/j100182a080

The pseudophase ion-exchange (PPIE) model was tested in the presence and absence of buffer for the acid-catalyzed hydrolysis of 2-(p-methoxyphenyl)-1,3-dioxolane (p-MPD) and 2-(2,4-dimethoxyphenyl)-2-ethyl-1,3-dioxolane (2,4-DPED) in the presence of sodium monoalkyl phosphate surfactants.The maximum increase in the observed rate constant was about 10-fold for both substrates.The second-order rate constant for the acid hydrolysis of 2,4-DPED in the micellar phase of the phosphate surfactants (k_2,m = 14.3 M^-1 s^-1) is similar to that observed in the bulk aqueous phase (k_2,w = 12.7 M^-1 s^-1).When p-MPD was used as a substrate, a modest 3-fold enhancement in the second-order rate constant is found.The application of the PPIE model requires careful pH measurements, since the surfactant itself is a weak acid.