Effect of 1-Butanol upon SN2 Reactions in Cationic Micelles. A Quantitative Treatment

Article abstract of DOI:10.1021/j100378a050

Observed first-order rate constants for reaction of methyl naphthalene-2-sulfonate (2-MeONs) with Br^- in cetyltrimethylammonium and cetyltriethylammonium bromides (CTABr and CTEABr) are decreased by addition of 1-butanol.The inhibition can be treated quantitatively in terms of a pseudophase model in which the rate constant at the micellar surface follows the mole ratio of bound Br^- to micellized surfactant and bound 1-BuOH.The second-order rate constants in the micellar pseudophase, k_M, are independent of <1-BuOH> in the range 0-0.9 M.Conductometry and NMR line widths of ⁸¹Br^- show that the alcohol reduces micellar binding of Br^-, and spectral absorbance shows that binding of 2-MeONs is also reduced.