p-Toluenesulfonic acid → Ethyl 3-oxo-(2,3,4,5-tetrafluorophenyl)propanoate

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Reaction Steps

0.3 g of p-toluenesulphonic acid is added to an emulsion of 284.8 g of crude diethyl 2,3,4,5-tetrafluorobenzoyl-malonate (3) in 300 ml of water. The mixture is heated to the boil for 5 hours, while stirring thoroughly, the cold 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 a fine vacuum gives 160.2 g of ethyl 2,3,4,5-tetrafluorobenzoyl-acetate (4) of boiling point 100°-110° C./0.09-0.1 mbar. Melting point 47°-49° C.

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