Binary Phase Chlorination of Aromatic Hydrocarbons with Solid Copper(II) Chloride: Reaction Mechanism

Anthracene is selectively chlorinated with solid copper(II) chloride to give a quantitative yield of 9-chloroanthracene. The tentative reaction mechanisms so far proposed fail to explain the nonreactivity of some other hydrocarbon homologues, e.g. naphthalene and phenanthrene, toward copper(II) chloride. The present study revealed that the oxidative half-wave potentials (E1⁄2ox) of all reactive hydrocarbon homologues were less than 1.26 V. On the basis of this finding we postulate a reaction mechanism involving one electron transfer from hydrocarbon to copper(II) chloride.