反应详情

温度

70 °C

358 g of N,N'-dibutylthiourea and 225 g of malonic acid are dissolved in 850 ml of glacial acetic acid, with warming, 190 ml of acetic anhydride are added dropwise at 60° C., with stirring, the mixture is warmed at 70° C. for 2 hours, 100 ml of acetic anhydride are added dropwise, the resulting mixture is warmed at 70° C. for 1 hour, a further 100 ml of acetic anhydride are added dropwise, the resulting mixture is warmed at 90° C. for 3 hours and 70 ml of water are added dropwise at 60°-90° C. The solvent is distilled off in vacuo at 50°-90° C. and the residue is stirred with 1 l of methanol. The crystalline precipitate is filtered off, washed with methanol and dried in vacuo at 40° C. 212 g of N,N'-dibutyl-5-acetyl-thiobarbituric acid are obtained.

1. temperaturewith warming
2. temperaturethe resulting mixture is warmed at 70° C. for 1 hour
3. temperaturethe resulting mixture is warmed at 90° C. for 3 hours
4. distillationThe solvent is distilled off in vacuo at 50°-90° C.
5. stirringthe residue is stirred with 1 l of methanol
6. filtrationThe crystalline precipitate is filtered off
7. washwashed with methanol
8. customdried in vacuo at 40° C