ISOLATION AND PURIFICATION OF 3-NITRO-ORTHO-TOLUIC ACID

摘要

PROBLEM TO BE SOLVED: To provide a method for efficiently isolating and purifying only 3-nitro- o-toluic acid from a mixture consisting essentially of 3-nitro-o-toluic acid and 5-nitro-o-toluic acid. SOLUTION: A mixture consisting essentially of 3-nitro-o-toluic acid and 5-nitro-o-toluic acid is suspended or dissolved in a solvent. An amine is added to the suspension or the solution and 3-nitro-o-toluic acid amine salt is preferentially isolated as a crystal by taking advantage of difference in solubility between 3-nitro-o-toluic acid amine salt and 5-nitro-o-toluic acid amine salt.