p-Toluenesulfonic acid → Ethyl (pentafluorobenzoyl)acetate

Participants

Reaction Steps

A mixture consisting of 100 g (0.47 mol) of pentafluorobenzoic acid, 900 ml of benzene and 350 ml (4.80 mol) of thionyl chloride was heated under reflux for 40 hours. After completion of the reaction, the reaction solution was concentrated under a reduced pressure. After repetition of evaporation with benzene (900 ml×2), the resulting residue was dissolved in 500 ml of ether. A mixture consisting of 11.5 g (0.47 mol) of magnesium, 450 ml of ethanol and 20 ml of carbon tetrachloride was stirred at room temperature for 1 hour, and 71.6 ml (0.47 mol) of diethyl malonate dissolved in 900 ml of ether was added dropwise thereto. After 17 hours of stirring at the same temperature, the reaction solution was evaporated to dryness under a reduced pressure, and the residue was dissolved in 1,500 ml of ether. To this was added dropwise the above acid chloride at room temperature, followed by 63 hours of stirring at the same temperature. After completion of the reaction, the reaction solution was washed with 10% citric acid and water in that order, and then dried over anhydrous sodium sulfate, subsequently evaporating the solvent. The residue was mixed with 300 ml of water and 1.00 g (5.81 mol) of p-toluenesulfonic acid, heated under reflux for 6 hours, mixed with 2,500 ml of benzene and then washed with water. The organic layer was dried over anhydrous sodium sulfate and the solvent was evaporated. The resulting residue was purified by distillation under a reduced pressure (10 mmHg, 118°-120° C.) to yield 89.7 g (67%) of the title compound.

Provenance & Evidence