反应详情

0.15 g of p-toluenesulphonic acid is added to an emulsion of 34.9 g of crude diethyl 2,4-dichloro-5-fluorobenzoyl-malonate (3) in 50 ml of water. The thoroughly stirred mixture is heated at the boil for 3 hours, the cooled emulsion is extracted several times with methylene chloride, the combined CH2Cl2 solutions are washed once with saturated NaCl solution and dried with Na2SO4, and the solvent is distilled off in vacuo. Fractionation of the residue in vacuo gives 21.8 g of ethyl 2,4-dichloro-5-fluoro-benzoyl-acetate (4) of boiling point 127°-142° C./0.09 mbar.

1. temperatureThe thoroughly stirred mixture is heated at the boil for 3 hours
2. extractionthe cooled emulsion is extracted several times with methylene chloride
3. washthe combined CH2Cl2 solutions are washed once with saturated NaCl solution
4. dry with materialdried with Na2SO4
5. distillationthe solvent is distilled off in vacuo