On boiling their solution in caustic alkalis, ammonia is liberated.
Uracil and its homologues may be obtained in many cases from the hydrouracils by the action of bromine, and subsequent elimination of the elements of hydrobromic acid; or by the condensation of aceto-acetic ester and related substances with urea, thiourea, guanidine, &c. Uracil, C4H402N2, crystallizes in colourless needles, is soluble in hot water and melts with decomposition at 335° C. Hydrouracil, C4H602N2, is obtained by the action of bromine and caustic alkalis on succinamide (H.
The powder is soluble in alcohol and strong solutions of alkalis, such as ammonia.
Alkalis decompose it into picro-podophyllic acid and picro-podophyllin, minute traces of both of which occur in a free state in the rhizome.
It is a liquid which boils at 93° C. and with caustic alkalis polymerizes to diacetyldicyanide.