反应详情

9.2 g (0.2 mol) of methylhydrazine were added dropwise to a mixture of 34.4 g (0.2 mol) of pivaloylacetic acid ethyl ester, 10.8 g (0.2 mol) of sodium methylate and 100 ml of methanol at 20° C. When the exothermic reaction had subsided, the reaction mixture was heated for 2 hours under reflux and then concentrated, the residue was taken up in 200 ml of water and this solution was acidified with concentrated hydrochloric acid to a pH of ca. 6. The resulting precipitate was filtered off, dried and recrystallized from isopropanol. 27 g (87% of theory) of 1-methyl-3-tert.-butyl-5-hydroxy-pyrazole were obtained in the form of colorless crystals of melting point 150° C.

1. customWhen the exothermic reaction
2. temperaturethe reaction mixture was heated for 2 hours
3. temperatureunder reflux
4. concentrationconcentrated
5. filtrationThe resulting precipitate was filtered off
6. customdried
7. customrecrystallized from isopropanol