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-fluorobenzoylmalonate (3) in 50 ml of water. The mixture is heated to boiling, with thorough stirring, for 3 hours, the cooled emulsion is extracted several times with methylene chloride, the combined CH2Cl2 solutions are washed once with saturated NaCl solution, dried with Na2SO4 and the solvent is distilled out in vacuo. Fractionation of the residue under high vacuum provides 21.8 g of ethyl 2,4-dichloro-5-fluorobenzoylacetate (4) of boiling point 127°-142° C./0.09 mbar.

1. temperatureThe mixture is heated
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 out in vacuo