Polymerization of aromatic nuclei. X. Polymerization of benzene to p‐polyphenyl oligomers by nitrogen dioxide—aluminum chloride

Benzene was polymerized to p‐polyphenyl oligomers by nitrogen dioxide–aluminum chloride. Polymer production was favored by AlCl3:NO2 ratios of at least 2, long reaction times, and higher temperatures. Evidence for the polymer structure was obtained from elemental analyses, oxidative degradation, solubility, molecular weight, functional group tests, low molecular weight products, and infrared and ultraviolet spectra. The chains contained small amounts of chloro, amino, hydroxyl, and carboxyl substituents. Molecular weight data on the benzene‐soluble portion (40–71%) revealed an average of 4–6 phenylene units per chain. Under altered conditions nitrobenzene could be obtained as the major product, indicating the sensitivity of the system to changes in reaction variables. With nitrobenzene as oxidant, a similar type of polymer resulted. The theoretical aspects are discussed.