| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for isolating carboxylic acid components, respectively, constituting a carboxylic acid isomer mixture comprising a pyridine carboxylic acid isomer mixture or an aromatic carboxylic acid isomer mixture by a simple method without giving wastes. SOLUTION: This method for separating a carboxylic acid isomer mixture comprises converting a known amount of a pyridine carboxylic acid isomer mixture or aromatic carboxylic acid mixture represented by general formula (1) (X is N or C-R6; one of R1-R5 and R6 is a carboxyl group, and the others are each independently hydrogen, a halogen, hydroxyl group, nitro group, amino group, carbamoyl group, cyano group, formyl group, an alkyl group, an alkoxy group, an alkylamino group, acetyl group, acetoxy group, acetamino group, sulfamoyl group, sulfonyl group or phenyl group; the meanings of X and R1-R6 are different from each other) into the corresponding alkali metal salt mixture, mixing the alkali metal salt mixture with an acid in an amount necessary for neutralizing a carboxylate salt first reaching a neutralization final point among the carboxylate salts constituting the carboxylic acid alkali metal salt mixture, when neutralized with the acid, crystallizing, depositing and separating the neutralized carboxylate salt as the free carboxylic acid, and subsequently, if necessary, repeating the operation.
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