Hydrazine hydrate (1:1) → 3-Amino-5-tert-butylpyrazole

To 600 g of pivaloyl acetonitrile (compound I), there was added 800 ml of isopropanol. The mixture was heated with stirring, and 288 g of hydrazine hydrate was added dropwise thereto. The mixture was heated with stirring for 3 hours. After completion of the reaction, 400 ml of isopropanol was distilled off under reduced pressure. To the residue, there were added 2000 ml of ethyl acetate and saturated brine. The mixture was stirred and then left to stand for a while. The aqueous layer was removed, and the ethyl acetate layer was washed with saturated brine twice. The ethyl acetate solution was then dried over anhydrous magnesium sulfate, and then concentrated under reduced pressure. Subsequently, 2000 ml of n-hexane was added to the residue to precipitate a crystal. The crystal was recovered by filtration and dried. There was obtained 643 g (96.2%) of 3-amino-5-t-butylpyrazole (compound II). Melting point: 74.0° to 75.0° C.

1. temperatureThe mixture was heated
2. temperatureThe mixture was heated
3. stirringwith stirring for 3 hours
4. distillationwas distilled off under reduced pressure
5. additionTo the residue, there were added 2000 ml of ethyl acetate and saturated brine
6. stirringThe mixture was stirred
7. waitleft
8. customThe aqueous layer was removed
9. washthe ethyl acetate layer was washed with saturated brine twice
10. dry with materialThe ethyl acetate solution was then dried over anhydrous magnesium sulfate
11. concentrationconcentrated under reduced pressure
12. additionSubsequently, 2000 ml of n-hexane was added to the residue
13. customto precipitate a crystal
14. filtrationThe crystal was recovered by filtration
15. customdried

ORD record

ord-4b0546ce5a3d4538add109acf5d245c0

Source dataset

uspto-grants-1996_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05532377