Kinetics of bromine addition to unsaturated sulphones. Part 2.—Effect of conjugation

Abstract

The rates of bromine addition to several α,β- and β,γ-unsaturated sulphones in glacial acetic acid at 30° follow second-order kinetics. β,γ-unsaturated sulphones add bromine at a slightly faster rate than the corresponding α,β-unsaturated sulphones, indicating that the electrophilic mechanism of addition is operating. The absence of significant decrease in the rate of bromine addition to an α,β-, as compared to the corresponding β,γ-unsaturated sulphone, indicates the absence of significant conjugation of the sulphonyl group with the ethylenic link in the ground state of α,β-unsaturated sulphones.