Sulfuric Acid → 4-acetyl-1,5-dimethyl-3-trifluoromethyl-1H-pyrazole

HRID 1293153Notes

Reaction equation

HRID 1293153 reaction equation
[CH3:1][N:2]1[C:6]([CH3:7])=[CH:5][C:4]([C:8]([F:11])([F:10])[F:9])=[N:3]1.[C:12](OC(=O)C)(=[O:14])[CH3:13].OS(O)(=O)=O>>[C:12]([C:5]1[C:4]([C:8]([F:10])([F:9])[F:11])=[N:3][N:2]([CH3:1])[C:6]=1[CH3:7])(=[O:14])[CH3:13]

Participants

4

Reactant 3

HCID 1118Sulfuric Acid2×HCID 7918Acetic Anhydride2×HCID 127475251,5-Dimethyl-3-(trifluoromethyl)pyrazole

Product 1

HCID 118587194-acetyl-1,5-dimethyl-3-trifluoromethyl-1H-pyrazoleYield 21.8%

Procedure

22.6 g (0.138 mol) of 1,5-dimethyl-3-trifluoromethyl-1H-pyrazole are added dropwise at 0° C. to a solution of 156 ml (1.65 mol) of acetic anhydride and 0.5 ml of conc. H2SO4. The reaction mixture is stirred under reflux for approx. 8 days. After each 24 h of reaction time, 0.5 ml of H2SO4 each time is added to the reaction mixture. On completion of the reaction, excess acetic anhydride is distilled off under reduced pressure, the residue is taken up in 500 ml of CH2Cl2 and the organic phase is washed 3 times with 300 ml of water each time. The organic phase is dried over MgSO4 and concentrated by rotary evaporation. Distillation of the oily residue results in 6.20 g (0.030 mol; 21.8%) of 4-acetyl-1,5-dimethyl-3-trifluoromethyl-1H-pyrazole (b.p.: 142° C./0.4 mbar).

Workup

  1. temperatureunder reflux for approx. 8 days
  2. additionis added to the reaction mixture
  3. distillationis distilled off under reduced pressure
  4. washthe organic phase is washed 3 times with 300 ml of water each time
  5. dry with materialThe organic phase is dried over MgSO4
  6. concentrationconcentrated by rotary evaporation
  7. distillationDistillation of the oily residue

Sources & evidence

ORD record
ord-ef5653a3a6a64b28a7786acc76b27e48
Source dataset
uspto-grants-2007_07
Patent number
US07238722B2

Reaction notes

Loading…