Reactivity of Inorganic a-Nucleophiles in Acyl Transfer Processes in Water and Surfactant Micelles: III.1 Systems Based on Dimeric Cationic Imidazolium Surfactants in Alkaline Hydrolysis of Ethyl 4-Nitrophenyl Ethylphosphonate

The kinetics of alkaline hydrolysis of ethyl 4-nitrophenyl ethylphosphonate in micelles formed by cationic dimeric imidazolium surfactants [AlkIm(+)(CH2)(m)Im(+)Alk]center dot 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.

Automated summary

The kinetics of alkaline hydrolysis of ethyl 4-nitrophenyl ethylphosphonate in micelles formed by cationic dimeric imidazolium surfactants have been studied, with the efficiency of solubilization of reactants and the nucleophilicity of hydroxide ion in the micellar microenvironment playing important roles. Dimeric surfactants show significant advantages over monomeric ones in achieving equal reaction rates at lower concentrations.