PREPARATION OF 2-HYDROXYNICOTINIC ACID-BASED COMPOUND

PURPOSE:To obtain the titled compound useful as an intermediate for drugs, dye, agricultural chemicals, etc. by an easy reaction in a short reaction time in high yield in high purity, by hydrolyzing a 2-chloro-3-trichloromethylpyridine-based compound with sulfuric acid. CONSTITUTION:A 2-chloro-3-trifluoromethylpyridine-based compound shown by the formula I (X is H or Cl) is reacted with AlCl3 preferably in the presence of an inorganic compound such as KCl, Na2SO4, etc. as a retarding agent at 0-180 deg.C for 0.5-3hr to give a 2-chloro-3-trichloromethylpyridine-based compound (TCP for short) shown by the formula II, which is hydrolyzed in the presence of sulfuric acid at 50-130 deg.C for 1-3hr, to give the desired compound shown by the formula III existing as a tautomerism. The amount of sulfuric acid used is 0.1- 100mol based on 1mol TCP, and the concentration of sulfuric acid is 0.5-96wt%.