Benzenamine, 2,6-dimethoxy- → 5-(4-Amino-3,5-dimethoxyphenyl)-5-hydroxybarbituric acid

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Reaction Steps

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).

Provenance & Evidence