Hydrochloric Acid → HCID 178481857、化合物

8.3 g (180.6 mmoles) of methylhydrazine and 5 ml of concentrated hydrochloric acid were added to a solution of 30.0 g (180.6 mmoles) of ethyl difluoroacetoacetate dissolved in 200 ml of ethanol. The mixture was refluxed for 2 days with heating, to give rise to a reaction. After the completion of the reaction, the reaction mixture was subjected to vacuum distillation to remove the most part of the solvent contained therein. The residue was poured into water. The mixture was allowed to have a pH of 4 using citric acid and extracted with ethyl acetate. The resulting organic layer was washed with water and an aqueous sodium chloride solution in this order and then dried over anhydrous magnesium sulfate. The resulting solution was subjected to vacuum distillation to remove the solvent contained therein. The residue was purified by silica gel column chromatography (developing solvent: hexane-ethyl acetate mixed solvent) to obtain 8.9 g (yield: 33.3%) of 3-difluoromethyl-1-methyl-1H-pyrazol-5-ol.