Oxidative chlorination of aromatic compounds in the presence of nitrogen-containing oxidizing agents

Mixtures of the chlorides and nitrates of alkali metals in aqueous trifluoroacetic acid can be used for the selective oxidative chlorination of benzene, halogenobenzenes, toluene, and p-toluic acid with preparative yields. By variation of the water content of the solvent and the nitrate-chloride ratio it is possible to suppress the nitration side reaction. In the presence of oxygen or air alkali-metal nitrites can also be used as oxidizing agents in this process. The chlorinating agent in these systems is molecular chlorine, as confirmed by a comparative study of the reactions of two groups of potential chlorinating agents (nitrosyl chloride and nitryl chloride) under these conditions. The reactions of naphthalene and polymethylbenzenes with nitrosyl chloride in trifluoroacetic acid, leading to the products from chlorination and dehydrooligomerization of the aromatic substrates, were also studied.