反应详情

1-Methyl-3-(4-cyano-3-(dipropylamino)-5-isothiazolyl)urea (4.2 g) was slowly stirred into 10 ml of concentrated sulfuric acid and the resulting solution was warmed to 80° where it was maintained for about 16 hours. The solution was poured into 200 ml of ice-water and the solution was brought to pH 10 by adding a mixture of sodium bicarbonate, sodium carbonate, and ammonium hydroxide. The white precipitate was collected by filtration, but thin-layer chromatographic analysis showed the white solid to be a mixture of starting material and product. The solid was again placed in 10 ml of concentrated sulfuric acid. The solution was heated on a steam bath and then poured into 100 ml of water. This mixture was brought to pH 10 with aqueous ammonium hydroxide. The solid precipitate was collected by filtration and dried to give 4.2 g of 1-methyl-3-(4-carbamoyl-3-(dipropylamino)-5-isothiazolyl)urea, m.p. 168°-169°. The nmr and ir spectra were consistent with the assigned structure.

1. temperaturethe resulting solution was warmed to 80° where it
2. temperaturewas maintained for about 16 hours
3. additionby adding
4. filtrationThe white precipitate was collected by filtration, but thin-layer chromatographic analysis
5. additiona mixture of starting material and product
6. temperatureThe solution was heated on a steam bath
7. additionpoured into 100 ml of water
8. filtrationThe solid precipitate was collected by filtration
9. customdried