Acetic Acid → 1H-Pyrazole-5-carboxylic acid, 1-methyl-3-propyl-, ethyl ester

HRID 990249Notizen

Reaktionsgleichung

Reaktionsgleichung von HRID 990249
C(O[C:4](=O)[C:5]([O:7][CH2:8][CH3:9])=[O:6])C.[CH3:11][C:12](=O)[CH2:13][CH2:14][CH3:15].[Na].C(O)(=O)C.[CH3:22][NH:23][NH2:24]>C(O)C>[CH3:22][N:23]1[C:4]([C:5]([O:7][CH2:8][CH3:9])=[O:6])=[CH:11][C:12]([CH2:13][CH2:14][CH3:15])=[N:24]1

Komponenten

7

Edukt 5

HCID 176Acetic AcidHCID 6061MethylhydrazineHCID 7268Diethyl OxalateHCID 78952-PentanoneHCID 5360545Sodium

Produkt 1

HCID 101765321H-Pyrazole-5-carboxylic acid, 1-methyl-3-propyl-, ethyl esterAusbeute 15,5 %

Reagenzien, Katalysatoren, Lösungsmittel 1

HCID 702EthanolLösungsmittel

Reaktionsbedingungen

Temperatur
60 °C

Versuchsvorschrift

A solution of diethyloxalate (27.2 ml, 0.2 mol) in 2-pentanone (21.2 ml, 0.2 mol) was added dropwise to a solution of sodium (4.83 g, 0.21 mol) in ethanol (200 ml), and the reaction stirred at 60° C. for 5 hours, then cooled in an ice-bath. The solution was neutralised using acetic acid (11.5 ml, 0.2 mol) and N-methyl hydrazine (10.6 ml, 0.2 mol) then added dropwise. The mixture was stirred for a further 4 hours at room temperature and concentrated under reduced pressure. The residue was partitioned between dichloromethane (300 ml) and water (200 ml), and the phases separated. The aqueous layer was extracted with dichloromethane (3×100 ml), the combined organic solutions were dried (MgSO4) and evaporated under reduced pressure. The crude product was purified by column chromatography on silica gel, using ethyl acetate: hexane (25:75) as eluant to give ethyl 1-methyl-3-n-propyl-pyrazole-5-carboxylate (6.1 g) and the title compound (22.1 g, 56%).

Aufarbeitung

  1. temperaturecooled in an ice-bath
  2. additionthen added dropwise
  3. stirringThe mixture was stirred for a further 4 hours at room temperature
  4. concentrationconcentrated under reduced pressure
  5. customThe residue was partitioned between dichloromethane (300 ml) and water (200 ml)
  6. customthe phases separated
  7. extractionThe aqueous layer was extracted with dichloromethane (3×100 ml)
  8. dry with materialthe combined organic solutions were dried (MgSO4)
  9. customevaporated under reduced pressure
  10. customThe crude product was purified by column chromatography on silica gel

Quellen und Nachweise

ORD-Eintrag
ord-02f6c9c913c8436aa9b1a51c5bd9b4fd
Quelldatensatz
uspto-grants-2002_10
Patentnummer
US06458951B2

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