| 摘要 |
PCT No. PCT/JP90/01179 Sec. 371 Date May 1, 1991 Sec. 102(e) Date May 1, 1991 PCT Filed Sep. 14, 1990 PCT Pub. No. WO91/04245 PCT Pub. Date Apr. 4, 1991.The present invention provides a process for preparing 4,4'-dihydroxydiphenylsulfone which comprises subjecting a phenol and a sulfonating agent to dehydration reaction in the presence of mesitylene as a reaction medium while the produced 4,4'-dihydroxydiphenylsulfone is suspended in the mesitylene, and a process for preparing 4,4'-dihydroxydiphenylsulfone, characterized in that after the foregoing dehydration reaction, the 4,4'-dihydroxydiphenysulfone obtained as suspended in the mesitylene and/or retained in a liquid-free solid form is subjected to reaction for isomerization of 2,4'-dihydroxydiphenylsulfone produced as a by-product into 4,4'-dihydroxydiphenylsulfone with heating at a temperature of not lower than that for isomerization of 2,4'-dihydroxydiphenylsulfone into 4,4'-dihydroxydiphenylsulfone.
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