Homolytic substitution of halogenobenzenes by arylthio- and arylsulphonyl radicals

Abstract

When arylthio- and arylsulphonyl radicals are generated in chloro-, bromo-, and iodo-benzene at 150–190 °C, the halogen atom is replaced by the arylthio- or arylsulphonyl group. The relative ease of displacement in the reaction with sulphonyl radicals is Cl : Br : I, 1 : 5·9 : 18·6; fluorobenzene does not react appreciably under these conditions and only a very low proportion of products formed by direct substitution of hydrogen atoms is present in the reaction mixtures. The reaction is facilitated by electron-releasing substituents on the halogeno-benzene. A mechanism for the reaction is proposed.