Process for producing 2,4′-dihydroxydiphenylsulfone

Details Process for producing 2,4′-dihydroxydiphenylsulfone Process for producing 2,4′-dihydroxydiphenylsulfone

2007-03-13

2007-03-13

Price, Elvis O. (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Sulfur containing

C568S028000, C568S032000, C568S033000

Reexamination Certificate

active

10500997

ABSTRACT:
A process for producing 2,4′-dihydroxydiphenylsulfone which comprises separating 4,4′-dihydroxydiphenylsulfone by crystallization from a mixture containing 4,4′-dihydroxydiphenylsulfone, 2,4′-dihydroxydiphenylsulfone, phenolsulfonic acid and phenol which is obtained by dehydration of phenol and sulfuric acid or phenolsulfonic acid to obtain a mixture having a content of 2,4′-dihydroxydiphenylsulfone greater than the content of 4,4′-dihydroxydiphenylsulfone, crystallizing 2,4′-dihydroxydiphenylsulfone by adjusting the composition of the solvent of the obtained mixture so that the ratio of the amounts by weight of phenol to water is 10:90 to 90:10, and separating 2,4′-dihydroxydiphenylsulfone by filtration; and a process as described above in which the filtrate obtained by the filtration is used as the raw material for the hydration.

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English-language International Preliminary Examination Report dated Sep. 23, 2004 of International application No. PCT/JP03/00571 filed Jan. 22, 2003, Applicants: NICCA Chemical Co., Ltd. et al.

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