Polymerization of aromatic nuclei. XVIII. Polymerization of benzene to poly‐p‐phenylene by aluminum chloride–air–water

Although the reaction of benzene with aluminum chloride has been quite thoroughly examined by prior investigators, the present report is the first one on formation of poly‐ p ‐phenylene in this system. Optimum conditions, which gave low yields, involved 7 days at 49–51deg;C. The presence of oxygen (oxidant) and presumably water (cocatalyst) was necessary in order for polymerization to occur. Physical and chemical properties, e.g., behavior toward Br 2 and H 2 O 2 –CH 3 CO 2 H, indicate that the polymer structure is slightly different from that of the material from C 6 H 6 –AlCl 3 –CuCl 2 . The polymer from C 6 H 6 –AlCl 3 may possess a lower molecular weight and exhibits a greater degree of structural irregularity in the form of dihydrobenzene, p ‐quinoid, or polynuclear regions. In the chemical studies, various compounds were used as models (tetrahydroquaterphenyl, triphenylene, and lower p ‐polyphenyls).