696-22-0

25016-17-5

696-22-0

General procedure for the synthesis of 3-methyl-1H-pyrazole-5-carboxylic acid from methyl 5-methyl-1H-pyrazole-3-carboxylate: 75 ml of methanol solution of 10.1 g (71.8 mmol) of methyl 5-methyl-1H-pyrazole-3-carboxylate was added to the reaction flask and stirred until complete dissolution. Subsequently, 150 ml of an aqueous solution containing 4.4 g (110 mmol) of sodium hydroxide was slowly added. The reaction mixture was heated to 50°C and kept at this temperature for 2 hours. After completion of the reaction, the pH of the reaction solution was adjusted to 2 with 2 M hydrochloric acid solution, at which point a solid precipitated. The precipitate was collected by filtration and the filter cake was washed with an appropriate amount of water. Finally, the filter cake was dried to give a white solid product 3-methyl-1H-pyrazole-5-carboxylic acid in 99.8% yield.