| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing the subject desired compound in high yield and purity even in the presence of a relatively large amount of isoquinoline in the raw material. SOLUTION: This method comprises the following steps: in the 1st step, a guinolinic acid of formula II with the 6- and/or 7-position(s) substituted with R2 is reacted with ozone in an aqueous solution of sulfuric or nitric acid in the weight ratio of (1:2) to (1:3) at 0-50 deg.C to form the corresponding ozonolysis product, which is then reacted with an oxidizing agent at 0.5-4.0 mol per mol of the ozonolysis product at 0-100 deg.C followed by adjusting the reaction solution to pH 0.2-3, and the resultant mixture is thin cooled to 0-30 deg.C to effect precipitation, and the objective pyridinedicarboxylic acid of formula I thus precipitated is separated and collected. In formula I and formula II, R1 and R2 are each H, a 1-4C alkyl, 1-4C alkoxy, 1-4C alkoxy-1-4C alkyl, halogen, OH, nitro or the like.
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