PREPARATION OF POLY(P-PHENYLENE) VIA A NEW PRECURSOR ROUTE

Methyl 2,5-dichlorobenzoate (1) was polymerized in dimethylformamide w ith a catalyst system comprised of nickel(II) bromide, triphenylphosph ine, and zinc to produce poly[2- (methoxycarbonyl)phenylene-1,4-diyl] (2). The GPC measurements indicated that the molecular weight distribu tion of 2 was monomodal and the degree of polymerization was around 10 0. The hydrolysis of 2 yielded poly(2-carboxyphenylene-1,4-diyl) (3). Polymer 3 was soluble in quinoline and pyridine as well as aqueous sod ium hydroxide. The catalytic decarboxylation of 3 produced poly(p-phen ylene) (PPP) powder. Copper(II) oxide, basic copper(II) carbonate, and copper(I) oxide were effective catalysts for the decarboxylation. Bot h these catalysts with quinoline as solvent were necessary to cause th e decarboxylation. The IR spectrum indicates that the PPP has a regula r structure. The electrical conductivity of a pressed pellet was as hi gh as 18 S/cm after vapor-phase doping with antimony pentafluoride.