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

Participants

Reaction Steps

To a stirred solution of 1,3-dimethylbarbituric acid (20.0 g, 128.09 mmol) in water (10 ml), phosphorous oxychloride (80 ml) was added slowly in externally cooling condition and then the reaction was slowly warmed to room temperature. After refluxing for 3 h the reaction mixture was allowed to cool to 0° C. and quenched with ice cold water (350 ml). The reaction mixture was extracted with chloroform (2×200 ml) and the combined organic extracts were washed with water (2×100 ml), dried over Na2SO4 and concentrated. The residue obtained was purified by silica gel column chromatography using 5% ethyl acetate in chloroform to obtain 21 g of the product as a pale brown solid; 1H NMR (300 MHz, CDCl3) δ 3.33 (s, 3H), 3.57 (s, 3H), 5.94 (s, 1H).

Provenance & Evidence