TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The fuming sulfuric acid has 20-65 wt.% of sulfur trioxide. The equivalent ratio of sulfur trioxide in the fuming sulfuric acid to (I) is 2-30:1.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The elevated pressure is higher than 0.12 MPa. The method further comprises: reacting (I) with fuming sulfuric acid, and then neutralizing the reaction mixture, and removing the solvent in it; redissolving the reaction mixture with a solvent, removing the undissolved matter, and then removing the solvent; and recrystallizing the reaction mixture in a solvent. Preferred Components: The solvent used in the redissolving step is at least one of dimethyl sulfoxide, thionyl chloride, 4,4'-diaminodiphenyl sulfone, 4,4'-sulfonyl diphenol, 4,4'-dimethyl diphenyl sulfoxide, sulfolane, diphenyl sulfone or phenyl sulfoxide. (I) is benzenesulfonic acid compound of formula (III). Preferred Definitions:    X = ketone; and    Y1 = F.    SPECIFIC COMPOUNDS - 5 Disclosed compounds (II) are prepared i.e. 4,4'-difluoro-3,3',5,5'-tetrasulfonate benzophenone-tetrasodium of formula (IIa), 4,4'-dichloro-3,3',5,5'-tetrasulfonate benzophenone-tetrasodium, 4,4'-dibromo-3,3',5,5'-tetrasulfonate benzophenone-tetrasodium, 4,4'-difluoro-3,3',5,5'-tetrasulfonate benzophenone-tetrapotassium, and 4,4'-difluoro-3,3',5,5'-tetrasulfonate benzophenone-tetraammonium.    EXAMPLE - 4,4'-Difluorobenzophenone (22.9 mmol) and fuming sulfuric acid with a sulfur trioxide (126.1 mmol) were placed in an autoclave, and reacted at 175 degrees C and under a pressure of 0.15 MPa for 16 hours. After completion of the reaction, the reaction mixture was poured into deionized water, and then neutralized with sodium hydroxide until the pH value reached to 7, and then a crude product was obtained by vaporizing the mixture solution. The obtained crude product was completely dissolved in dimethyl sulfoxide (DMSO) and the undissolved matter was separated by centrifugation. The DMSO solution of reaction product was precipitated in ethanol, filtered and dried at 120 degrees C in vacuum for 24 hours, the resulting product was obtained. The obtained product was recrystallized in a mixture of ethanol and deionized water (volume ratio of 2:1) and purified to obtain 4,4'-difluoro-3,3,5,5'-tetrasulfonate benzophenone-tetrasodium.