TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Compound: The transition metal compound is chosen from nickel compound, palladium compound, iron compound, zinc compound and manganese compound. Water is water or mineral salt aqueous solution.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compound: The aromatic compound has sulfur-containing group of formula: -S(=O)2-A, which is preferably of formula (2 or 3), or of formula: X-(((Ar1-Y1)a-Ar2-Z1((-Ar3-Y2)b-Ar4-Z2)c)h(-A r1-Y1)a-Ar2)-X.A=amino substituted by 1-20C hydrocarbyl or 1-20C alkoxy, in which hydrocarbyl and alkoxy are optionally substituted by fluoro, 1-20C alkoxy, 6-20C aryl, 6-20C aryloxy, 2-20C acyl or cyano;R1=fluoro, 1-20C alkyl, 1-20C alkoxy, 6-20C aryl, 6-20C aryloxy, 2-20C acyl or cyano, in which fluoro, cyano, 1-20C alkoxy, 6-20C aryl and 6-20C aryloxy are optionally substituted by fluoro, cyano, 1-20C alkoxy, 6-20C aryl or 6-20C aryloxy;X=chloro, bromo or iodo;m=1 or 2;k,j=0-3;a-c=0 or 1;h=5 or more;Ar1-Ar4=bivalent aromatic group, such as 1-20C alkyl, 1-20C alkoxy, 6-20C aryl, 6-20C aryloxy or 2-20C acyl, each optionally substituted by fluoro, cyano, 1-20C alkoxy or 6-20C aryloxy;Y1,Y2=single bond, -CO-, -SO2-, -C(CH3)2-, -C(CF3)2- or fluorene-9,9-diyl;andZ1,Z2=-O- or -S-.Preferred Solvents: The aprotic polar solvent is N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide or sulfolane. The oxygen containing organic solvent is ether solvent or ketone solvent. Preferred Acid: The acid is hydrochloric acid, sulfuric acid, hydrobromic acid, nitric acid or methanesulfonic acid. EXAMPLE - Toluene (in wt.pts) (50), sodium chloride aqueous solution (75), hydrochloric acid (12) and tetrahydrofuran (75) were added to polymerization reaction liquid containing polyarylene having structural unit of formula (A) and having weight average molecular weight of 164000 and number average molecular weight of 65000. The mixture was stirred at 60 degrees C for 15 minutes, and water layer and organic layer containing polyarylene were separated and cooled.