Violuric acid
Violuric acid is an organic compound with the formula HON=C(CONH)CO. It crystallizes as white or off-white monohydrate. The compound has attracted attention because its salts are deeply colored. Reactions. It readily deprotonated to give salts of the anion [ON=C(CONH)CO], which are often deeply colored. Preparation. It was prepared by Adolf Baeyer by reaction of barbituric acid with nitrous acid. It can also be produced by condensation of alloxan with hydroxylamine. as typical for forming the oxime of other carbonyl compounds.