Substitution accompanying addition in the reactions of chlorobenzene and benzonitrile with chlorine under free radical conditions

Abstract

Reaction of liquid chlorobenzene or benzonitrile with chlorine under free radical conditions at 100–170° gives, apart from the well known products of additive chlorination, small amounts of dichlorobenzenes and chlorobenzonitriles, respectively. Relative rate and isomer patterns resemble those of the gas-phase, thermal chlorination, known to take place at ca. 300° and above in a flow system. In our opinion this substitution occurs via intermediate aryl radicals, arising through (endothermal) hydrogen abstraction by chlorine atoms.