Importance

Loading Importance Indicators...

Abstract

Process for the preparation of pure 2,3-pyridinedicarboxylic acids of the formula I ##STR1## which are substituted in position 4 and/or 5 and/or 6 by R.sub.1, where R.sub.1 is hydrogen, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.4 alkoxy-C.sub.1 -C.sub.4 alkyl, halogen, hydroxyl or nitro, from quinolines of the formula II ##STR2## in which R.sub.1 is as defined above, and which are substituted in position 6 and/or 7 by R.sub.2, where R.sub.2 is hydrogen, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, C.sub.1 -C.sub.4 alkoxy-C.sub.1 -C.sub.4 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.degree. C., and the resulting peroxide solution is then reacted at temperatures of from +0 to +100.degree. 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.degree. C., and the precipitated pyridinedicarboxylic acid is isolated.

Loading the Abstract Image...

First Claim