Bromine → 4′-Bromo-5′-(difluoromethoxy)-1′-methyl-4-nitro[1,3′-bi-1H-pyrazol]-5-amine

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Reaction Steps

8.3 g (0.052 mol) Bromine was added dropwise at room temperature to 13 g (0.047 mol) 5-amino-4-nitro-1-(5-difluoromethoxy-1-methyl-3-pyrazolyl)pyrazole dissolved in 260 ml acetic acid and the mixture stirred for 30 minutes. It was then concentrated and the residue taken up in the ethyl acetate and shaken with 5% aqueous sodium hydrogen carbonate. The phases were separated and the organic phase dried over magnesium sulfate. This was concentrated and the residue purified by silica gel column chromatography (hexane/ethyl acetate 3:1).

Provenance & Evidence