Process for preparation of 2,3-pyridine dicarboxylic acid

Abstract

Process for the preparation of pure 2,3-pyridinedicarboxylic acids of the formula I which are substituted in position 4 and / or 5 and / or 6 by R1, where R1 is hydrogen, C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkoxy-C1-C4 alkyl, halogen, hydroxyl or nitro, from quinolines of the formula II in which R1 is as defined above, and which are substituted in position 6 and / or 7 by R2, where R2 is hydrogen, C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkoxy-C1-C4 alkyl, halogen, hydroxyl, nitro or amino, which are reacted in the first step in aqueous sulfuric acid or nitric acid solution with ozone in the ratio of from 1:2 to 1:3 at temperatures from 0 to +50 DEG C., and the resulting peroxide solution is then reacted at temperatures of from +0 to +100 DEG C. in the presence of 0.5-4.0 mol of oxidizing agent per mole of ozonolysis product formed, after which the pH of the reaction solution is adjusted to 0.2 to 3, the mixture is cooled to 0 to 30 DEG C., and the precipitated pyridinedicarboxylic acid is isolated.

Description

technical field [0001] 2,3-Pyridinedicarboxylic acid (PDCA) is an important raw material for the synthesis of pharmaceuticals and agricultural chemicals. Background technique [0002] Various methods of preparing PDCA are known from the literature. Some approaches are based on quinoline oxides and others on quinoline derivatives that are substituted on the aromatic ring to provide activity. [0003] At first by Hoogewerff and van Dorp in chemical communication, the method described in 425 pages etc. (1883) is to use the quinoline in the oxidation coal tar of potassium permanganate in alkaline medium, yet, this method except producing a large amount of by-products, only PDCA was produced in very low yield. [0004] Other methods for the oxidation of quinolines are essentially derived from the method described by Stix and Bulgatsch in Chemical Communications, p. 11 et al. (1932), which uses hydrogen peroxide for oxidation in the presence of copper salts. Because this reacti...

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Problems solved by technology

However, the purity of the obtained dipicolinic acid was not satisfactory according to the criteria of the experiment, or the color exhibited by the final product

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