Patent ID: 6346623
Filing Date: 2002-02-12
Classification: C07D

Abstract:
An improved process for the preparation of substituted pyridinecarboxylic acids by ozonolysis of quinolines, wherein a quinoline of the formula which is substituted in position 2 and/or 3 and/or 4 by R3, and in position 6 and/or 7 by R4, where R1 and R2 are H or a C1-C3-alkyl group and R3 and R4 are a group which is inert under the reaction conditions, and at least one of the radicals R1 and R2 is not H, is reacted with ozone in aqueous acidic solution at temperatures of from âˆ’5 to +40Â° C., the resulting solution is maintained at a temperature of from 0 to 100Â° C. for 0.5 to 15 hours with the introduction of oxygen or air for decomposition of the peroxides formed, and the corresponding substituted pyridinecarboxylic acid of the formula in which R3 is as defined above, and R5 and R6 are OH or C1 to C3-alkyl, where at least one of the radicals R5 and R6 is not OH, is isolated from the reaction mixture.