C 4 H 6 N 4 O 3 or CO Q `, the NH-CO diureide of glyoxylic acid. It is found in the allantoic liquid of the cow, and in the urine of sucking calves. It can be obtained by the oxidation of uric acid by means of lead dioxide, manganese dioxide, ozone or potassium permanganate: C 5 H 4 N 4 O 3 + H 2 O + O = C 4 H 6 N 4 O 3 + C02.
It has been synthesized by E. Grimaux by heating one part of glyoxylic acid with two parts of urea for ten hours at ioo° C.: 2CO(NH 2) 2 + CH(OH) 2 Oooh = 3h 2 O + C4H6N403. It forms glancing prisms of neutral reaction slightly soluble in water. On standing with concentrated potassium hydroxide solution it gives potassium allantoate C 4 H 7 N 4 O 4 K. On heating with water it undergoes hydrolysis into urea and allanturic acid C 3 H 4 O 3 N 2. It is reduced by sodium amalgam to glycouril C 4 H 6 N 4 O 2, whilst with hydriodic acid it yields urea and hydantoin C 3 H 4 N 2 O 2. Hot concentrated sulphuric acid also decomposes allantoin, with production of ammonia, and carbon monoxide and dioxide. By dry distillation it gives ammonium cyanide.