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:
Nov. 17, 2009
Filed:
Sep. 27, 2004
Kiyoshi Katsuura, Takaoka, JP;
Tomoya Hidaka, Ichihara, JP;
Yutaka Takashina, Takahagi, JP;
Yasuo Ohnuki, Kitaibaraki, JP;
Kiyoshi Katsuura, Takaoka, JP;
Tomoya Hidaka, Ichihara, JP;
Yutaka Takashina, Takahagi, JP;
Yasuo Ohnuki, Kitaibaraki, JP;
Nippon Soda Co., Ltd., Tokyo, JP;
Abstract
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.