Bromoform → 5-Bromo-4-nitro-1-(2,3,5,6-tetrafluoro-4-trifluoromethyl-phenyl)-pyrazole

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Reaction Steps

21.6 ml (0.18 mol) of t-butylnitrite are added dropwise to 20.6 g (0.06 mol) of 5-amino-4-nitro-1-(2,3,5,6-tetrafluoro-4-trifluoromethyl-phenyl)-pyrazole in 100 ml (1.125 mol) of bromoform in the course of 10 minutes, while stirring, whereupon the temperature of the reaction mixture rises to 50° C. When the addition has ended, the mixture is stirred at the reflux temperature for a further two hours and is concentrated in vacuo, the residue is taken up in methylene chloride, the mixture is washed several times with saturated sodium bicarbonate solution, 2n-hydrochloric acid and water and dried over sodium sulphate and the solvent is stripped off in vacuo. 22 g (89.9% of theory) of 5-bromo-4-nitro-1-(2,3,5,6-tetrafluoro-4-trifluoromethyl-phenyl)-pyrazole are obtained as a brown oil.

Provenance & Evidence