Nucleophilic Substitution at Sulfonyl Sulfur. Kinetic Investigation on the Reactions of Tosyl Chloride with p-Substituted Phenol(s) and Triethylamine in Acetone / Acetonitrile

Second order rate constants of the reactions of tosyl chloride with p- substituted phenol(s) and triethylamine in acetone / acetonitrile under equimolar conditions are determined. The reaction follow second order overall and first order with respect to each of the reactants viz substrate and nucleophile. The rate constant (k2) have been determined by conductometric method using Guggenheim principle at four different temperatures.The rate constant increases for electron with-drawing substituents and decreases for electron donating substituents in the nucleophile. Activation parameters are obtained by applying the usual methods. The Hammett and Bronsted plots have been found linear. This may be explained on the basis of electronic effects of substituents at the reaction centre. Kinetic data and product analyses indicate that the reaction proceeds through a synchronous direct bimolecular nucleophilic attack on the sulfur centre

Author(s): Nagarajan Vembu and Chandrasekaran Arunmozhithevan1

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