Kinetics of the neutral and alkaline hydrolysis of aromatic sulphonyl chlorides in water

Abstract

The hydrolyses of various substituted benzenesulphonyl chlorides (substituents: p-H,o-NO₂,m-NO₂,p-NO₂,p-F,p-Me,p-OMe) in water in the pH range 3–11 have been studied. Rate coefficients and activation parameters have been determined for the neutral water (solvolysis) reaction and the alkaline hydrolysis reaction. The data are in agreement with an S_N2 mechanism for both reactions. In solvolysis, bond-making and bond-breaking are comparable in the transition state, but in alkaline hydrolysis bond-formation predominates. The alkaline hydrolysis rates follow the Hammett equation with a ρ-value of +1·564. The solvolysis rates give a curved Hammett plot.