反应详情

A mixture of 22.2 g of glyoxylic acid ethyl ester ethyl hemiacetal (0.15 mol), 30.0 g of urea (0.5 mol), 90 g of ethanol and 7.5 g of 8% strength ethanolic sulfuric acid was heated under reflux for 4 hours. Thereafter, the reaction had ended and the reaction mixture was cooled to room temperature, whereupon a colorless precipitate separated out, which was filtered off, washed three times with ethanol and dried in vacuo at 70° C. 24.5 g, that is to say 80% of theory, of allantoin acid ethyl ester were obtained by this reaction.

1. temperaturewas heated
2. temperatureunder reflux for 4 hours
3. customseparated out
4. filtrationwhich was filtered off
5. washwashed three times with ethanol
6. customdried in vacuo at 70° C