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Indexed by:期刊论文

Date of Publication:2010-07-01

Journal:JOURNAL OF SURFACTANTS AND DETERGENTS

Included Journals:SCIE、EI

Volume:13

Issue:3

Page Number:361-365

ISSN No.:1097-3958

Key Words:alpha-Chlorododecanoic acid; Trimethylamine; Zwitterionic surfactant; Bimolecular nucleophilic substitution mechanism; Rate equation; Activation entropy

Abstract:A nucleophilic substitution reaction was developed to synthesize the zwitterionic surfactant using a renewable natural fatty acid rather than a petroleum derivative as the raw material. The kinetics and mechanism of the nucleophilic substitution reaction of trimethylamine alpha-chlorododecyl carboxylate with trimethylamine were investigated in protic and dipolar aprotic solvents including water, ethanol and N, N-dimethyl formamide. The rate equations were derived using initial rates and the activation parameters in different solvents were determined empirically and compared with each other to obtain important information about the reaction mechanism. The overall second-order reaction number and the negative activation entropy supported a bimolecular nucleophilic substitution (S(N)2) mechanism, combined with the pseudo-first-order kinetics for each reactant. The experimental results also showed that the reaction reactivity diminishes with the decrease in polarity of protic solvents. The typical dipolar aprotic solvent dimethyl formamide distinctively promoted the reaction in. This fact was successfully explained by the solvation rule for S(N)2 reactions.