Purifying 2,3-pyridine-dicarboxylic acid used as intermediate for e.g. drugs, by treatment in solution with sulfur source, removal of precipitate and precipitation with acid, giving low heavy metal content

摘要

Production of 2,3-pyridine-dicarboxylic acid (I) having a reduced heavy metal content comprises: (a) adding at least one sulfur source comprising hydrosulfides, sulfides, polysulfides or sulfur, to a solution of (I) or its salts; (b) removing the obtained precipitate from the solution; (c) acidifying the solution with mineral acid, and (d) recovering the precipitated (I).