Bromine → 4-Bromo-3-(difluoromethyl)-1-methyl-1H-pyrazole

Participants

Reaction Conditions

Reaction Steps

At 25° C., bromine (Br2, 3 g) was added dropwise to a solution of 3-difluoromethyl-N-methylpyrazole (2.0 g) in methylene chloride (80 ml). The reaction mixture was stirred for a total of 22 h at 25° C., and aqueous sodium thiosulfate solution (0.1 M, 210 ml) was then added. After phase separation, the organic phase was freed from the solvent under reduced pressure (40° C./5 mbar). Part of the residue obtained (2.4 g of 2.8 g) was separated by column chromatography (SiO2, ethyl acetate/cyclohexane 1:6). 4-bromo-3-difluoromethyl-1-methylpyrazole was isolated in an amount of 1.4 g.

Provenance & Evidence