Nucleophilic substitution in the side chain of 5-membered heterocycles.II. Reactions of 2-furan, 2- and 3-thiophene,and benzene-sulphonyl chlorides with aniline in acetonitrile and in benzene

The reaction kinetics of 2-furan,2- and 3-thiophene-, and benzene-sulphonyl chlorides with aniline have beeb studied in acetonitrile and benzene solutions. These reactions follow a second order kinetics in acetonitrile, first order with respect to each reactant. In benzene, the kinetics behaviour is more complex, depending on the association of the nucleophile,which acts also as a catalyst. The reactions in acetonitrile are faster than in benzene; in both solvents the reactivity sequence of sulphonyl chlorides is: benzene>3-thiophene>2-furan>2-thiophene-sulphonyl chloride, in agreement with the mesomeric interactions between the ring and the reaction centre.