Nippon Soda Co., Ltd.

Nisso Fine Co., Ltd.

Ibarakikasei Chemicals Co. Ltd.

Yasuo Ohnuki

Tomoya Hidaka

Kiyoshi Katsuura

Yutaka Takashina

The present invention is to provide methods for producing highly pure 4,4'-dihydroxydiphenyl sulfone monoethers advantageously in industrial production. In a process for producing a compound represented by Formula (I) (wherein, Rand Rare each independently halogen, alkyl having 1 to 8 carbons or alkenyl having 2 to 8 carbons; m and n are each independently 0 or an integer of 1 to 4; and Ris alkyl having 1 to 8 carbons, alkenyl having 2 to 8 carbons, cycloalkyl having 3 to 8 carbons or optionally substituted aralkyl), (1) a pH adjustment is carried out twice or more in the purification process, (2) an excessive amount of alkyl halide used is removed, (3) a solvent, such as water, containing 0.05 ppm or less of iron components is used, (4) tanks with corrosion-resistant layers over the inner walls are used, (6) a chelating agent is added, and (7) a means of drying with mechanical stir is applied.

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Kitaibaraki, Japan

Yasuo Ohnuki