反应详情

温度

25 °C

A solution of 1-tert-butyl-5-methyl-1H-pyrazole-4-carboxylic acid methyl ester (2.0 g, 10.19 mmol) in methanol (6.8 mL) cooled to 0° C. was treated dropwise with a 4N aqueous sodium hydroxide solution (5.1 mL, 20.4 mmol). The reaction was allowed to slowly warm to 25° C. The reaction was stirred at 25° C. overnight. At this time, the reaction was concentrated in vacuo to remove methanol. The residue was diluted with water (25 mL) and was then extracted with ethyl acetate (1×25 mL). The aqueous layer was then acidified to pH=1 with a 3N aqueous hydrochloric acid solution. The resulting precipitate was collected by filtration, washed with water and hexanes, and then dried in vacuo to afford 1-tert-butyl-5-methyl-1H-pyrazole-4-carboxylic acid (1.43 g, 78%) as a white solid.

1. concentrationAt this time, the reaction was concentrated in vacuo
2. customto remove methanol
3. additionThe residue was diluted with water (25 mL)
4. extractionwas then extracted with ethyl acetate (1×25 mL)
5. filtrationThe resulting precipitate was collected by filtration
6. washwashed with water and hexanes
7. customdried in vacuo