SYNTHESIS OF FUNCTIONAL POLY(PARA-PHENYLENE)S FROM SUBSTITUTED HYDROQUINONES VIA NICKEL-CATALYZED COUPLING OF THEIR BISTRIFLATES

This paper describes a novel method for the synthesis of soluble polyphenylenes, which consists of the Ni(0)-catalyzed homocoupling reaction of bis[[(trifluoromethyl)sulfonyl]oxy] derivatives of substituted hydroquinones, and compares it with the synthesis of the same polymers by the Ni(0)-catalyzed polymerization of the corresponding benzene derivatives having two bromine or chlorine leaving groups. The following monomers were synthesized and polymerized: 2,5-dichlorobiphenyl (3), 2,5-dibromobiphenyl (4), 2,5-bis-[[(trifluoromethyl)sulfonyl]oxy]biphenyl (8), methyl 2,5-dichlorobenzoate (11), methyl2,5-dibromobenzoate (12),methyl2,5-bis[[(trifluoromethyl)sulfonyl]oxy]benzoate (9), and 2-tert-butyl-1,4-bis[[(trifluoromethyl)-sulfonyl]oxy]benzene (10). The Ni(0) catalyst was prepared in situ according to two different methods using DMF and THF as solvent, respectively. Soluble substituted polyphenylenes with number-average molecular weights of up to 6300 were obtained.