TESTS OF THE PSEUDOPHASE MODEL OF MICELLAR CATALYSIS - ITS PARTIAL FAILURE

Acid hydrolyses of ρ-nitrobenzaldehyde acetals are effectively catalyzed by micelles of tetradecanesulfonic acid (1a) and ρ-ROC6H4SO3H, R = C8H17 and C12H25 (1b, c, respectively). The kinetic forms are explained quantitatively in terms of reactions in the aqueous and micellar pseudophases, and the effects of added HCI can be explained qualitatively in these terms. Conductivity measurements show that ca. 75% of the hydrogen ions are bound to micelles of 1c, and the second-order rate constants in the micellar pseudophase are in the range expected from earlier experiments using mixtures of HCI and sodium lauryl sulfate. The pseudophase model fails for reactions of 2, 4-dinitrochlorobenzene and -naphthalene in ρ- C8H1706H4CH2NMe3OH. The results can be explained by assuming that reaction occurs between reactants in the aqueous and micellar pseudophases, and also between OH- in water and substrate in the micelle. © 1979, American Chemical Society. All rights reserved.