Addition of sulphenyl chlorides to acetylenes. Part VII. Factors affecting the orientation of the addition

Abstract

The product of addition of benzenesulphenyl chlorides to phenylacetylene is solvent-dependent: in ethyl acetate anti-Markownikoff (A) orientation predominated, whereas in acetic acid Markownikoff addition (M) was favoured. In chloroform and acetonitrile both adducts were formed, in similar amounts. In contrast, addition to but-1-yne yielded the A-adduct in every solvent.

The o-nitrobenzenesulphenyl chloride showed a particularly low reactivity. A stronger tendency to yield M-adducts was observed both with but-1-yne and with phenylacetylene.

The results are discussed and a mechanism for the reaction is suggested.