Homolytic aromatic substitution by phenylethynyl radicals

Abstract

Phenylethynyl radicals, generated by the photolysis of phenyliodoacetylene, react with aromatic compounds to give substitution products. From the orientation and the relative reactivity data obtained from their reaction with several monosubstituted benzenes it is concluded that the phenylethynyl radical possesses an electrophilic character; partial rate factors for the meta- and para-positions can be correlated with the Hammett σ parameters to give a negative ρ value. A number of new monosubstituted diphenylacetylenes are described.