Ethyl Acetate → 3,4-Dibromo-1H-pyrazole-1-ethanol

A solution of 9.7 g. (0.025 mole) ethyl 3,4,5-tribromopyrazole-1-acetate in 125 ml. dry ether was mixed with a suspension of 1.9 g. (0.05 mole) lithium aluminum hydride in 50 ml. dry ether. The reaction mixture was heated at the reflux temperature for two hrs. and then cooled. Ethyl acetate (5 ml.) and then water (30 ml.) were added and after settling the ether portion was decanted. The ether solution was washed with two 40-ml. portions of water and dried over anhydrous sodium sulfate. After removing the ether by evaporation, the oily residue was treated with decolorizing charcoal and crystallized from a mixture of ethyl ether and petroleum ether (boiling at the temperature range 30° C. to 60° C.). There was thus obtained 6.5 gms. (75% yield) of 3,4-dibromopyrazole-1-ethanol having a melting point of 64° to 66° C.

1. temperatureThe reaction mixture was heated at the reflux temperature for two hrs
2. temperatureand then cooled
3. customwas decanted
4. washThe ether solution was washed with two 40-ml
5. dry with materialportions of water and dried over anhydrous sodium sulfate
6. customAfter removing the ether
7. customby evaporation
8. additionthe oily residue was treated with decolorizing charcoal
9. customcrystallized from a mixture of ethyl ether and petroleum ether (
10. customboiling at the temperature range 30° C. to 60° C.

ORD record

ord-d17ea0a72f574d6b826e8c4b030e24f2

Source dataset

uspto-grants-1978_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04084955