[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([CH:8]([OH:13])[C:9]([F:12])([F:11])[F:10])=[CH:4][N:3]=1.Cl[O-].[Na+]>S([O-])(O)(=O)=O.C([N+](CCCC)(CCCC)CCCC)CCC.C(OCC)(=O)C>[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([C:8](=[O:13])[C:9]([F:11])([F:12])[F:10])=[CH:4][N:3]=121.13 g (0.1 mol) of 2-chloro-5-(2,2,2-trifluoro-1-hydroxyethyl)pyridine and 1.8 g (0.005 mol) of tetrabutylammonium hydrogen sulfate are dissolved in 200 ml of ethyl acetate at room temperature. 61 ml (0.12 mol) of an approximately 12% strength sodium hypochlorite solution are metered in within 15 minutes with vigorous stirring and the mixture is stirred for a further 2 hours during which the reaction temperature rises to 40° C. The phases are separated, the aqueous phase is extracted several times with ethyl acetate and the combined organic phases are washed with saturated aqueous sodium chloride solution. After drying the organic phase with sodium sulfate, the volatiles are distilled off. Following distillation of the crude product at 0.3 mbar, 15.6 g (74.4% of theory) of 2-chloro-5-trifluoroacetylpyridine with a boiling point of 50°-51° C. are obtained, which, according to GC, is 99.8% pure. nD20 : 1.4887.
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