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:
May. 31, 2005
Filed:
Sep. 08, 2003
Toshio Sato, Kashima, JP;
Takeshi Namekata, Kashima, JP;
Toshio Sato, Kashima, JP;
Takeshi Namekata, Kashima, JP;
Hebei Sinochem Fuheng Co., Ltd., Hebei, CN;
Abstract
Highly pure 2,3-pyridinedicarboxylic acid is produced by a process suitable for application in commercial production with a high yield and with recirculation of waste liquor. The process comprises the steps of: (a) oxidizing quinoline or 8-hydroxyquinoline in a solvent in the presence of copper (II) ions to precipitate copper (II) salt of 2,3-pyridinedicarboxylic acid and then separate the precipitates, (b) reacting the separated copper (II) salt with an alkali in a solvent to obtain a solution of an alkali metal salt of 2,3-pyridinedicarboxylic acid, and (c) reacting the solution of the alkali metal salt with a mineral acid to precipitate 2,3-pyridinedicarboxylic acid and then separate the precipitates, and is characterized in that (A) part or all of the solution obtained after the precipitated 2,3-pyridinedicarboxylic acid is separated in step (c) is used as at least part of the solvent in step (a) or (b), or (B) copper or a copper compound is added to the solution obtained after the precipitated 2,3-pyridine-dicarboxylic acid is separated in step (c) to recover the 2,3-pyridinedicarboxylic acid remaining in the solution as its copper (II) salt.