Catalyse micellaire—I: Etude de la réactivite en milieu micellaire a l'aide de reactions compétitives

The limitations of macroscopic models of micellar solutions are revealed by thermodynamic and kinetic studies of micellar catalysis and in fact the properties of such media are essentially dependent on the microscopic organization. The micellar effects of CTAB C₁₆H₃₃N⁺(CH₃)₃Br^?] and SDS (C₁₂H₂₅SO₄^?Na⁺) on the competitive reactions (S_N1, S_N2 and E2) of 1-bromo-2-phenyl propane in basic medium and on the alkaline and neutral hydrolysis of α-phénylallylic esters has been studied. The specific effect of the micellar microenvironment is shown. The results are interpreted in terms of an enhancement of the nucleophilicity of the hydroxide ion and a diminution of the nucleophilic and electrophilic properties of water. The variation of the catalytic effect of cationic micelles with the concentration of the nucleophilic reagent is discussed.