TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compound: The aprotic polar solvent is N,N-dimethyl acetamide. Preferred Property: The content of water is 5 weight% or less with respect to dihalo biphenyl compound, after completion of concentration process. Preferred Processes: A nitrogen-containing biphenyl compound of formula (II) is reacted with copper halide (CuX1), and then a mixed organic solvent is extracted, to obtain the mixture containing water and dihalo biphenyl compound (I). A monomer containing dihalo biphenyl compound (I) and aromatic compound of formula (V) is polymerized in presence of nickel compound, to obtain a polyarylene containing phenyl group-containing repeating unit of formula (IV) and aromatic group-containing structural unit of formula (VI). Alternately, a monomer containing dihalo biphenyl compound (I) and dihalo aromatic compound of formula (VII) is polymerized in presence of nickel compound, to obtain a polyarylene containing phenyl group-containing repeating unit of formula (IV) and aromatic group-containing repeating unit of formula (VIII). The dihalo biphenyl compound (I) and chlorinating agent such as phosphorus pentachloride are reacted, to obtain an acid chloride compound (IX). The aromatic compound is of formula: X2-(((Ar1-Y1)n-Ar2-Z1-((Ar3-Y2)b-Ar4-Z2)c)n-(Ar1-Y1)a-Ar2)-X2 (V). The aromatic group-containing structural units are of formulae: -(((Ar1-Y1)n-Ar2-Z1-((Ar3-Y2)b-Ar4-Z2)c)n-(Ar1-Y1)a-Ar2)- (VI) and -Ar5- (VIII). The dihalo aromatic compound is of formula: X3-Ar5-X3 (VII).a-c=0 or 1;n=5 or more;Ar1-Ar5=bivalent aromatic group optionally substituted by group (A);group (A)=1-20C alkyl group optionally substituted by fluorine, cyano, 1-20C alkoxy, 6-20C aryl or 6-20C aryloxy, 1-20C alkoxy optionally substituted by fluorine, cyano, 1-20C alkoxy, 6-20C aryl or 6-20C aryloxy, 6-20C aryl optionally substituted by fluorine, cyano, 1-20C alkoxy or 6-10C aryloxy, 6-20C aryloxy optionally substituted by fluorine, cyano, 1-20C alkoxy or 6-20C aryloxy, or 2-20C acyl optionally substituted by fluorine, cyano, 1-20C alkoxy, 6-20C aryl or 6-20C aryloxy;Y1,Y2=single bond, -CO-, -SO2-, -C(CH3)2-, -C(CF3)2- or fluorene-9,9-diyl group;Z1,Z2=-O- or S-;andX2-X3=same as X1. EXAMPLE - Aqueous solution of 36% sodium nitrite (in g) (460.1) was dripped into 2,2'-benzidine disulfonic acid (350), stirred, and 35% of hydrochloric acid was added, and stirred, to obtain a solution (A). Copper chloride was dissolved in 35% of hydrochloric acid, and cooled to 10 degrees C, to obtain a solution (B). The obtained solution (A) was dripped into the solution (B), stirred, aqueous solution of 50% sodium hydroxide was added, neutralized, salt (93) was added and dissolved. Then, toluene (315) and 2-propanol (1258) were added into the mixed solution, stirred and extracted. Toluene (315) and 2-propanol (1258) were further added to the water, stirred at room temperature for 30 minutes and extracted. Then, an oil layer was extracted by adding sodium carbonate, copper compound was deposited and filtered, to obtain a mixture containing disodium 4,4'-dichloro-2,2'-biphenyl disulfonate and water. N,N-Dimethylacetamide (1861) was added into mixture (1130) containing disodium 4,4'-dichloro-2,2'-biphenyl disulfonate and water, and concentrated to contain water (5.09) and concentrated mass (1018), to obtain disodium 4,4'-dichloro-2,2'-biphenyldisulfonate concentrated solution. Disodium 4,4'-dichloro-2,2'-biphenyldisulfonate concentrated solution (1018) was dripped into a solution containing phosphorus pentachloride and toluene, stirred, the obtained reaction mixture was poured into water, and the water layer was removed. Then, aqueous solution of 5% sodium hydrogencarbonate was added into the resulting mixture, stirred, and concentrated by adding toluene solution (2662), to obtain 4,4'dichloro-2,2'-biphenyl disulfonic acid dichloride.