The Polymerization of Benzene Catalyzed by a Copper(I) Chloride–Aluminium Chloride–Oxygen System

Abstract

Abstract The polymerization of benzene to poly(1,4-phenylene) (PPP) has been done successfully using copper(I) chloride and aluminium chloride as catalysts under oxygen. Since copper(I) chloride and aluminium chloride form a double salt (aluminium copper(I) chloride, AlCuCl4) and are soluble in benzene, a high homogeneity of the reaction system has been achieved and the polymerization reaction proceeds without any evolution of hydrogen chloride. The polymerization products contained an insoluble dark brown solid and a benzene-soluble tarry mass. The solid product has been determined to be PPP by comparison with an authentic sample. The product PPP was obtained in a yield of more than 100%, based on the molar quantity of copper(I) chloride, by controlling the quantity of aluminium chloride. For example, the treatment of benzene with aluminium chloride and copper(I) chloride (20:3:1 in molar ratio) under 1 atm of oxygen at 70 °C for 24 h gave PPP in a 187% yield, based on copper(I) chloride. This reaction could be carried out by the use of oxidants other than oxygen and by the use of low-valent metal salts other than copper(I) chloride, although a copper(I) chloride–aluminium chloride–oxygen system is most suitable for the polymerization of benzene in terms of the yield of PPP and the convenience of the reaction.