[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.[Cl:13]Cl>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]([Cl:13])=[CH:11][NH:10][N:9]=16.8 g (0.038 mol ) of 3-(2'-chlorophenyl)-1H-pyrazole, prepared as in Example 9, are dissolved, at temperature and with stirring, in 30 ml of acetic acid. 2.9 g (0.0409 mol) of chlorine are then introduced into the reaction mixture. Stirring is maintained for 1 hour at room temperature and then the acetic acid is 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 Na2SO4 before being concentrated to dryness. The residue is chromatographed on a silica column (eluent: heptane/ethyl acetate 60/40). 3.6 g of 3-(2'-chlorophenyl)-4-chloro-1H-pyrazole (compound 96) are obtained, which is of honey-like consistency (yield 44%).
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