5-Nitrobarbituric acid can be obtained by nitration of barbituric acid with fuming nitric acid below 40°C with a yield of 85-90%.
Prisms and leaflets from water.Slightly soluble in water; soluble in
alcohol and sodium hydroxide solution; insoluble
in ether.
Microreagent for potassium.
Crystallise diliuric acid from water as the trihydrate (m 180-181o (dec). Drying over 70% H2SO4 converts the trihydrate to the dihydrate [Loeffler & Moore J Am Chem Soc 70 3650 1948]. [Beilstein 24 H 474, 24 II 273, 24 III/IV 1882.]
