Reactivity of cyclopropylalkenes with p-chlorobenzenesulfenyl chloride

Abstract

The reactivity of a series of cyclopropylalkenes, as well as norbornene and cyclohexene, with p-chlorobenzenesulfenyl chloride in CH2Cl2 at 25 °C have been measured. Rates of reaction of several of the substrates were also measured in acetic acid and 1,1,2,2,-tetrachloroethane so that factors for converting rates from one solvent to another could be obtained. The rates of the sulfenyl halide additions varied over a total range of 193 from the least reactive alkene, ethylene, to the most reactive, 1,1-dicyclopropylethylene. This relatively small variation is in accord with all of these reactions involving bridged rate-determining transition states. The corresponding range in reactivity for acid-catalyzed hydration, a reaction involving protonation on carbon to give an open carbonium ion, is 1016. These two reactions are proposed as bases for structure–reactivity comparisons to determine whether other reactions involve bridged or open transition states.