反应详情

25 g of 2,6-dimethoxyaniline were added to a solution of 35 g of alloxan tetrahydrate in 120 ml of water. While stirring vigorously, the initially heterogeneous mixture changed after one hour into a brown solution from which grey crystals separated after a short time. The reaction mixture was stirred at room temperature for an additional 24 hours until dimethoxyaniline was no longer detectable according to thin-layer chromatography (cyclohexane/ethyl acetate/water=60:30:1). The reaction mixture was suction filtered, the residue on the suction filter was suspended with 4 portions of water to 80 ml and sucked dry. The solid was dried at 100°/16 mbar for 16 hours. There were obtained 44.2 g of 5-(4-amino-3,5-dimethoxyphenyl)-5-hydroxybarbituric acid as a light grey powder of m.p. 240°-243° (under decomposition). For purification, the powder can be recrystallized from 1-butanol, there being obtained a product of m.p. 242°-244° (decomposition).

1. customseparated after a short time
2. stirringThe reaction mixture was stirred at room temperature for an additional 24 hours until dimethoxyaniline
3. filtrationfiltered
4. filtrationthe residue on the suction filter
5. customsucked dry
6. customThe solid was dried at 100°/16 mbar for 16 hours