Patent ID: 6900330

Claim:
A process for producing 2,3-pyridinedicarboxylic acid comprising (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 separating 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 separating the precipitates, wherein 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).