The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 13, 2007
Filed:
Jan. 22, 2003
Gou Yoshino, Nyu-gun, JP;
Yuichi Tomoda, Fukui, JP;
Norihiro Taniguchi, Fukui, JP;
Kazuaki Igarashi, Fukui, JP;
Takeo Hasegawa, Sakai-gun, JP;
Gou Yoshino, Nyu-gun, JP;
Yuichi Tomoda, Fukui, JP;
Norihiro Taniguchi, Fukui, JP;
Kazuaki Igarashi, Fukui, JP;
Takeo Hasegawa, Sakai-gun, JP;
Nicca Chemical Co., Ltd., Fukui, JP;
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.