Sulfuric Acid → 1,3-Diethyl 2-(2,3,4,5-tetrafluorobenzoyl)propanedioate

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Reaction Steps

24.3 g of magnesium turnings are suspended in 50 ml of anhydrous ethanol. 5 ml of carbon tetrachloride are added and, when the reaction has started, a mixture of 160 g of diethyl malonate, 100 ml of absolute ethanol and 400 ml of anhydrous toluene is added dropwise at 50°-60° C. The mixture is then heated at 50°-60° C. for 1 hour, cooled to 5° C. to -10° C. with dry ice/acetone and, at this temperature, a solution of 212.5 g of 2,3,4,5-tetrafluorobenzoyl chloride in 80 ml of absolute toluene is slowly added dropwise. The mixture is stirred at 0° to -5° C. for 1 hour, allowed to reach room temperature overnight, and, while cooling in ice, a mixture of 400 ml of ice-water and 25 ml of concentrated sulphuric acid is allowed to run in. The phases are separated and two further extractions with toluene are carried out. The combined toluene solutions are washed with saturated NaCl solution, dried with Na2SO4, and the solvent is removed in vacuo. 335 g of diethyl 2,3,4,5-tetrafluorobenzoylmalonate are obtained as a crude product.

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