p-Toluenesulfonic acid → Ethyl 2-chloro-3,5-difluoro-4-methylbenzoyl-acetate

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Reaction Steps

0.1 g of p-toluenesulphonic acid is added to an emulsion of 65.1 g of crude diethyl 2-chloro-3,5-difluoro-4-methyl-benzoyl-malonate in 70 ml of water. The mixture is heated to the boiling point for 4.5 hours, with thorough stirring, 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 under a fine vacuum gives 33 g of ethyl 2-chloro-3,5-difluoro-4-methylbenzoyl-acetate of boiling point 108°-118° C./0.09 mbar.

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