ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 17, Number 3
JKCSEZ 17(3)
June 20, 1973 

The rates and activation parameters for the halide (Cl-, Br-, I-) exchange reactions of substituted benzenesulfonyl-chloride, X-C6H4SO2Cl (X : p-MeO, H, p-Cl, p-Br, p-NO2) in dry acetone at two temperatures have been determined. It was found that the ion-pair of metal halide, M+X-, have negligible reactivity compared to free halide ions. It was also found that the nucleophilic order is Cl- > Br- > I- for electron-donating substituent, and Cl- > I- > Br- for electron-withdrawing substituents. These results and convex nature of the Hammett plot are interpreted in the light of simple SN2 mechanism with the bond breaking becoming important for compounds with the electron withdrawing substituents.