Hydrochloric Acid → 1-Phenyl-1,2-propanedione

Participants

Reaction Steps

6.0 kg (44.78 moles) of propiophenone and 92 g of anhydrous aluminum chloride were added to 6 liters of ether followed by 17.2 kg (107.5 mole) of bromine at a rate to maintained a gentle reflux. When the addition was complete (approximately 6 hours), the mixture was heated to reflux overnight and then the solvent was removed under vacuum to obtain a lachrymatory dark red/orange oil. The oil was slowly added to a solution of 2.81 kg (122.2 mmole)of sodium in 45 l of methanol while maintaining the temperature below 20° C. When the addition was complete, 12.5 liters of concentrated hydrochloric acid were added and the mixture was stirred at room temperature for 1 hour. The precipitate was filtered off and the filtrate reduced in volume to approximately 25 liters by distillation of the methanol. The residue was partitioned between 10 liters of chloroform and 10 liters of water. Then, the organic phase was separated and the aqueous phase extracted twice with 5 liters of chloroform. The combined chloroform solutions were dried over sodium sulfate and evaporated to dryness. The residue was fractionally distilled under vacuum through a 30 cm Fenske column to obtain 5.7 kg of 1-phenylpropane-1,2-dione (86% yield) and a boiling point of 77°-85° C. at 1-2 mm Hg.

Provenance & Evidence