反应详情

28.8 g (0.1 mole) of 2,2-dichlorovinyl 2,4-dichloro-5-fluoro-phenyl ketone are added in portions to a solution of 4.6 g of sodium in 80 ml of absolute ethanol at 0°-5° C., while cooling (ice/methanol) and stirring. When the exothermic reaction has subsided, the mixture is stirred at room temperature for a further 30 minutes, the solvent is stripped off in vacuo and the residue is taken up in 100 ml of methylene chloride. The mixture is shaken thoroughly with 100 ml of 2N sulphuric acid, the methylene chloride solution is separated off in a separating funnel and the aqueous phase is extracted another three times with 50 ml of methylene chloride each time. The combined methylene chloride solutions are washed with 100 ml of saturated sodium chloride solution and dried over sodium sulphate. The solvent is then distilled off in vacuo. The brown oily residue crystallizes on standing. Distillation under a fine vacuum gives 22.3 g (79.9%) of ethyl 2,4-dichloro-5-fluoro-benzoylacetate of boiling point 125°-126° C./0.16 mbar. Colorless crystals of melting point 44°-45° C.

1. customWhen the exothermic reaction
2. stirringthe mixture is stirred at room temperature for a further 30 minutes
3. customthe methylene chloride solution is separated off in a separating funnel
4. extractionthe aqueous phase is extracted another three times with 50 ml of methylene chloride each time
5. washThe combined methylene chloride solutions are washed with 100 ml of saturated sodium chloride solution
6. dry with materialdried over sodium sulphate
7. distillationThe solvent is then distilled off in vacuo
8. customThe brown oily residue crystallizes
9. distillationDistillation under a fine vacuum