Sulfuric Acid → Diethyl 2-(2,4-dichloro-5-fluorobenzoyl)malonate

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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 ether is added dropwise, vigorous refluxing taking place. After the reaction has died down, the mixture is heated at the boil for a further 2 hours and cooled to -5° C. to -10° C. with dry ice/acetone, and a solution of 227.5 g of 2,4-dichloro-5-fluoro-benzoyl chloride (1) in 100 ml of absolute ether is slowly added dropwise at this temperature. The mixture is stirred for 1 hour at 0° C. to -5° C., and is allowed to reach room temperature overnight, and a mixture of 400 ml of ice water and 25 ml of concentrated sulphuric acid is allowed to run in, while cooling with ice. The phases are separated, and further extracted twice with ether. The combined ether solutions are washed with saturated NaCl solution and dried with Na2SO4, and the solvent is stripped off in vacuo. 349.5 g of diethyl 2,4-dichloro-5-fluoro-benzoyl-malonate (3) are obtained as a crude product.

Provenance & Evidence