Reaction of ferric chloride with benzene

Black, insoluble organic material was obtained, together with chlorobenzene in low yield, from the reaction of benzene with ferric chloride. Small amounts of Brönsted acids, such as water, hydrogen sulfide, acetic acid, and nitroethane, markedly promoted the formation of black solid. The principal product, whose properties were investigated, is believed to be formed by a cationic polymerization of benzene, leading to chlorinated polynuclear hydrocarbons. In contrast, under similar conditions aluminum chloride yielded a high‐boiling oil, but no black solid.