反应详情

Ethyl 4-(2-hydroxy-ethylthio)-2-hydroxyimino-3-oxobutyrate (321 g.) is dissolved in boiling toluene (3.2 liters) and para-toluenesulphonic acid monohydrate (26 g.) is then added. Vigorous boiling occurs, with liberation of water, which is removed in a Dean-Stark apparatus. The heating of the reaction mixture is continued for 15 minutes. After cooling, the toluene solution is filtered and washed three times with water (a total of 1.5 liters), then with a saturated sodium bicarbonate solution (200 cc.) and finally with water (500 cc.). It is dried over magnesium sulphate, treated with decolourising charcoal, filtered and concentrated to dryness under reduced pressure (20 mm Hg). Ethyl α-hydroxyimino(5,6-dihydro-1,4-oxathiin-2-yl)acetate (273 g.) is obtained in the form of an oil which slowly solidifies.

1. additionis then added
2. customis removed in a Dean-Stark apparatus
3. temperatureThe heating of the reaction mixture
4. temperatureAfter cooling
5. filtrationthe toluene solution is filtered
6. washwashed three times with water (a total of 1.5 liters), then with a saturated sodium bicarbonate solution (200 cc.)
7. dry with materialIt is dried over magnesium sulphate
8. additiontreated with decolourising charcoal
9. filtrationfiltered
10. concentrationconcentrated to dryness under reduced pressure (20 mm Hg)