Reaktion #8157

Reaktionsgleichung

o-nitrophenylhydrazine

2-acetyl-3-oxo-butyric acid ethyl ester

pyridine

→

3,5-dimethyl-1-(2-nitrophenyl)-1H-pyrazole-4-carboxylic acid ethyl ester

Lösungsmittel

hexane

chloroform

ethanol

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturheated
2. 2
   Temperaturunder reflux
3. 3
   SonstigeThe solvents then were removed under vacuum
4. 4
   WaschenThe resulting mixture was washed with water
5. 5
   Trocknendried over NaSO4
6. 6
   FiltrationThe solids then were filtered
7. 7
   Sonstigethe solvents removed under vacuum
8. 8
   SonstigeA precipitate formed when the oily solid
9. 9
   SonstigeThe solid was collected
10. 10
    Sonstigethe filtrate was purified over silica gel
11. 11
    Sonstigewas further purified by recrystallization from ethanol
12. 12
    Sonstigeto yield a solid

Vorschrift

Similar to Example 1, o-nitrophenylhydrazine (20 mmol, 3.4 g) and 2-acetyl-3-oxo-butyric acid ethyl ester (20 mmol, 3.4 g) were mixed in a solution of 50% pyridine in ethanol and heated under reflux. The solvents then were removed under vacuum, and the residue was resuspended in chloroform. The resulting mixture was washed with water and dried over NaSO4. The solids then were filtered, and the solvents removed under vacuum. A precipitate formed when the oily solid was dissolved in a solution of 20% hexane in chloroform. The solid was collected and discarded, and the filtrate was purified over silica gel. The named product was contaminated, then was further purified by recrystallization from ethanol to yield a solid having a melting point of 128° C.–130° C.

Quelle