反应详情

A mixture of 11.2 g of 1-methyl-3-(4-cyano-3-(dimethylamino)-5-isothiazolyl)urea and 20 ml of concentrated sulfuric acid was heated at 85°-90° for 11/2 hours. The reaction mixture was poured into 300 ml of ice-water and the solid precipitate was collected by filtration. The solid was washed with water and a small amount of cold ethanol. The nmr spectrum of this solid (m.p. 243°, decomposes) indicated it to be the bisulfate salt of 1-methyl-3-(4-carbamoyl-3-(dimethylamino)-5-isothiazolyl)urea. The water-sulfuric acid filtrate was concentrated under reduced pressure, the concentrate was cooled and a solid precipitate was collected by filtration. This solid was combined with the bisulfate salt described above and was stirred with a saturated solution of sodium bicarbonate. A new solid was collected by filtration and purified by recrystallization from ethanol to give 9.2 g of 1-methyl-3-(4-carbamoyl-3-(dimethylamino)-5-isothiazolyl)urea; m.p. 221°. The nmr spectrum was consistent with the assigned structure.

1. temperaturewas heated at 85°-90° for 11/2 hours
2. filtrationthe solid precipitate was collected by filtration
3. washThe solid was washed with water
4. concentrationThe water-sulfuric acid filtrate was concentrated under reduced pressure
5. temperaturethe concentrate was cooled
6. filtrationa solid precipitate was collected by filtration
7. filtrationA new solid was collected by filtration
8. custompurified by recrystallization from ethanol