Nucleophilically Assisted Deacylation in Sodium Dodecanoate and Dodecyl Sulfate Micelles. Quantitative Evidence on Premicellar Complexes

Article abstract of DOI:10.1021/j100098a042

Hydrolyses of 2,4-dinitrophenyl acetate and octanoate (DNPA and DNPO, respectively) and benzoic anhydride (Bz2O) in the pH range 8.9-10.2 are inhibited by anionic micelles of sodium dodecyl sulfate (SDS), and reactions of fully micellar-bound substrates are very slow.The effect of micellized sodium dodecanoate, SDOD, depends on pH.At high pH reactions of DNPA and Bz2O involve OH^- and are inhibited by SDOD, but there are significant rates at high .At low-pH reactions of DNPA and Bz2O are inhibited at low and assisted at high .The inhibition is due to formation of kinetically ineffective premicellar complexes and rate-surfactant profiles can be fitted quantitatively in terms of this model.When the substrates are fully micellar-bound rate constants in mixtures of SDOD and SDS follow the mole fraction of SDOD and second-order rate constants of nucleophilic attack by the dodecanoate ion at micellar surfaces are similar to those for the reactions of OAc^- in water.