Phosphorus oxychloride → 6-Chloro-1,3-dimethyl-2,4(1H,3H)-pyrimidinedione

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Reaction Steps

To 110 g of the 1,3-dimethylbarbituric acid was added 32 ml of water, and 800 ml of phosphorus oxychloride was added dropwise thereto. After heating at reflux for 1.5 hours, the phosphorus oxychloride was distilled away under normal pressure, and the residue, while hot, was poured onto ice. The precipitated crystals were collected by filtration. The filtrate was extracted three times with chloroform and dried over anhydrous sodium sulfate. The chloroform was then removed by distillation, and the resulting residue was combined with the aforesaid crystals. Recrystallization from water gave 80 g of 6-chloro-1,3-dimethyluracil.

Provenance & Evidence