反应详情

A solution of 6-oxo-1,6-dihydropyridazine-3-carboxylic acid (British patent no. 856409) (52 g, 0.33 mol) in nBuOAc (80 ml) and butanol (80 ml) was treated with concentrated sulphuric acid (5 ml). The mixture was heated at reflux under a Dean-Stark trap. After 5 hours water production had ceased. The reaction was allowed to cool to ambient temperature and after standing overnight, the precipitate was filtered, washed with diethyl ether and dried to give butyl 6-oxo-1,6-dihydropyridazine-3-carboxylate as a white solid (55.2 g, 85%) m.p. 81-83° C.

1. temperatureThe mixture was heated
2. temperatureat reflux under a Dean-Stark trap
3. filtrationthe precipitate was filtered
4. washwashed with diethyl ether
5. customdried