[F:1][C:2]([F:18])([F:17])[CH2:3][C:4]1([C:13]([F:16])([F:15])[F:14])[O:8][C:7]2[CH:9]=[CH:10][CH:11]=[CH:12][C:6]=2[O:5]1.[Br:19]Br>C(Cl)(Cl)(Cl)Cl.[Fe](Cl)(Cl)Cl>[Br:19][C:11]1[CH:10]=[CH:9][C:7]2[O:8][C:4]([CH2:3][C:2]([F:1])([F:17])[F:18])([C:13]([F:15])([F:14])[F:16])[O:5][C:6]=2[CH:12]=154.4 g of 2-(2,2,2-trifluoroethyl)-2-trifluoromethyl-1,3-benzodioxole were dissolved in 300 ml of carbon tetrachloride, and 0.4 g of anhydrous iron(III) chloride was added. 32 g of bromine were then added dropwise at the reflux temperature and the mixture was subsequently stirred until conversion was complete (monitoring by gas chromatography). The reaction mixture was then left to cool, washed with 10% by weight aqueous sodium hydrogen-sulphite solution and water, dried over magnesium sulphate and concentrated. The residue was distilled under vacuum. The yield was 58 g (83% of theory) and the boiling point was 80° C. at 14 mbar. The characteristic absorptions in the NMR spectra were as follows: 19F NMR: -59.2 and -84.9 ppm. 1H NMR: 3.02 ppm.
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