Reactivity of Inorganic α-Nucleophiles in Acyl Transfer Processes in Water and Surfactant Micelles: III. Systems Based on Dimeric Cationic Imidazolium Surfactants in Alkaline Hydrolysis of Ethyl 4-Nitrophenyl Ethylphosphonate

Abstract

The kinetics of alkaline hydrolysis of ethyl 4-nitrophenyl ethylphosphonate in micelles formed by cationic dimeric imidazolium surfactants [AlkIm+(CH2)mIm+Alk]·2Br– (where Alk = C16H33–C10H21, m = 2, 3, 4) have been studied. The rate of the reaction in the micellar pseudophase depends on the efficiency of solubilization of the reactants, and the effect of reactant concentrating increases in parallel with the length of the alkyl “tail.” Micellar microenvironment is an important factor responsible for the nucleophilicity of hydroxide ion. The observed acceleration of alkaline hydrolysis of ethyl 4-nitrophenyl ethylphosphonate (micellar catalysis) is primarily related to these two factors. An obvious superiority of dimeric surfactants to monomeric ones is that equal reaction rates are attained at 1–2 orders of magnitude lower concentrations of the former.