Hydrogen Bromide → 4-Bromo-1-(2,4,6-trichlorophenyl)-3-(trifluoromethyl)-1H-pyrazole
Reaction equation
[Br:1][C:2](=[CH:9]OCC)[C:3](=O)[C:4]([F:7])([F:6])[F:5].[Cl:13][C:14]1[CH:19]=[C:18]([Cl:20])[CH:17]=[C:16]([Cl:21])[C:15]=1[NH:22][NH2:23].Br>C(O)C>[Br:1][C:2]1[C:3]([C:4]([F:5])([F:6])[F:7])=[N:23][N:22]([C:15]2[C:16]([Cl:21])=[CH:17][C:18]([Cl:20])=[CH:19][C:14]=2[Cl:13])[CH:9]=1Participants
Procedure
2.3 g (0.01 mole) of 3-bromo-4-ethoxy-1,1,1-trifluorobut-3-en-2-one are added to a solution of 4.2 g (0.02 mol) of 2,4,6-trichlorophenyl-hydrazine in 100 ml of ethanol which contains 0.01 mole hydrogen bromide. The mixture is refluxed for 5 hours and then concentrated under reduced pressure, and ice water is added to the residue. Extraction with dichloromethane, washing with saturated sodium chloride solution until neutral, clarification over anhydrous sodium sulphate and concentration gives 4.6 g of a crude product, which is chromatographed on 120 g of silica gel using toluene/petroleum ether (ratio 1:1). 1.2 g of 4-bromo-1-(2,4,6-trichloro-phenyl)-3-trifluoromethylpyrazole of melting point 93°-94° C. (from petroleum ether) are obtained.
Workup
- temperatureThe mixture is refluxed for 5 hours
- concentrationconcentrated under reduced pressure, and ice water
- additionis added to the residue
- extractionExtraction with dichloromethane
- washwashing with saturated sodium chloride solution until neutral, clarification
- concentrationover anhydrous sodium sulphate and concentration
- customgives 4.6 g of a crude product, which
- customis chromatographed on 120 g of silica gel
Sources & evidence
- ORD record
- ord-e323f4fb137046658e9e11a4e3f5af54
- Source dataset
- uspto-grants-1989_10
- Patent number
- US04876393
Reaction notes
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