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

Isopropanol 800 ml was added to pivaloylacetonitrile 600 g and heating and stirring were applied. Hydrazine hydrate 288 g was dropped thereto and heating and stirring were applied for 3 hours. After finishing the reaction, isopropanol 400 ml was distilled off under reduced pressure. Ethyl acetate 2000 ml and a saturated salt aqueous solution were added to a residue and stirring was applied. After leaving for standing for a while, an aqueous layer was removed and an ethyl acetate layer was washed twice with the saturated salt aqueous solution, followed by drying an ethyl acetate solution over magnesium sulfate anhydrous. This ethyl acetate solution was concentrated under reduced pressure and then n-hexane 2000 ml was added to a residue to precipitate crystal. This crystal was filtered off and dried, whereby 3-amino-5-t-butylpyrazole (Compound (A)) 643 g (96.2%) was obtained. The melting point was 74.0 to 75.0° C.

1. temperatureheating
2. temperatureheating
3. stirringstirring
4. distillationwas distilled off under reduced pressure
5. additionEthyl acetate 2000 ml and a saturated salt aqueous solution were added to a residue
6. stirringstirring
7. customAfter leaving
8. customan aqueous layer was removed
9. washan ethyl acetate layer was washed twice with the saturated salt aqueous solution
10. dry with materialby drying an ethyl acetate solution over magnesium sulfate anhydrous
11. concentrationThis ethyl acetate solution was concentrated under reduced pressure
12. additionn-hexane 2000 ml was added to a residue
13. customto precipitate crystal
14. filtrationThis crystal was filtered off
15. customdried

ORD record

ord-00cae52f6c57478ea2a2add53d8f780e

Source dataset

uspto-grants-2000_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06127088