[Cl:1][C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][C:3]=1[C:8]1[CH:12]=[CH:11][NH:10][N:9]=1.[Br:13]Br>C(O)(=O)C.C(Cl)Cl>[Cl:1][C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][C:3]=1[C:8]1[C:12]([Br:13])=[CH:11][NH:10][N:9]=13.5 g of 3-(2-chlorophenyl)-1H-pyrazole, prepared as in Example 9, are dissolved, at room temperature and with stirring, in 20 ml of acetic acid. A solution of 3.76 g (0.0235 mol) of bromine in 20 ml of acetic acid is then run dropwise into the reaction mixture. Stirring is maintained for 1 hour at room temperature and then the acetic acid and the excess bromine are driven off under reduced pressure. The residue is taken up in methylene chloride and this organic solution is washed with an aqueous bicarbonate solution, then with water and then dried over MgSO4 before being concentrated to dryness. The residue is recrystallised from pentane. 3.3 g (0.0128 mol) of 3-(2'-chlorophenyl)-4-bromo-1H-pyrazole are obtained, which melts at 80° C. (yield 65%) (compound 94)
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