24.0 DERIVATIVES OF URIC ACID. 



out and parabanic acid remains in the mother liquor. 

 Large, colorless prisms, but sparingly soluble in cold, 

 easily in hot water. Is resolved, by heating with alka- 

 lies, into malonic acid (p. 157) and urea or its decom- 

 position products, carbonic anhydride and ammonia. 



Dibrombarbituric acid, CfEPBiW'O 8 , is produced 

 by the action of bromine on barbituric, violuric, or dilu- 

 turic acids. Crystallizes in laminee or prisms ; is diffi- 

 cultly soluble in cold water, easily in hot, in ether and 

 alcohol; it is decomposed by boiling with water, alloxan 

 being formed. When treated with reducing agents, 

 it yields different products, according to the nature of 

 the agent employed ; metallic zinc converts it into 

 monobrombarbituric acid ; sulphuretted hydrogen into 

 dialuric acid ; hydriodic acid, in small quantity, into 

 hydurilic acid. If a solution of the acid, saturated by 

 the aid of heat and then cooled, is allowed to stand 

 with bromine, or if chlorine is conducted into the 

 solution, carbonic anhydride is evolved and tribromacetyl- 

 urea, CO.N 2 H 3 (C 2 Br 3 0), is formed, which crystallizes in 

 needles or laminae; fuses at 148; is difficultly soluble 

 in water ; and is decomposed by boiling with it, yield- 

 ing bromoform. 



Monobrombarbituric acid, C 4 H 3 Br]$r 2 3 , is pro- 

 duced together with cyanogen bromide by the action 

 of aqueous hydrocyanic acid on dibrombarbituric acid. 

 White crusts, which consist of small needles, diffi- 

 cultly soluble in cold water. Its salts are formed by 

 the action of metals, hydroxides, or acetates on dibrom- 

 barbituric acid. By the action of baryta water at the 

 ordinary temperature, tribromacetyl-urea is formed at 

 the same time. 



Nitro-barbituric acid (Dilituric acid), C 4 IP(M) 2 ) 

 N 2 3 -f- 3H 2 0, is formed by treating barbituric acid with 

 fuming nitric acid and by heating hydurilic acid with 

 ordinary nitric acid. Colorless, quadratic prisms or 

 laminse, which effloresce in the air ; easily soluble in 

 hot water, with more difficulty in cold water, the solu- 



