NOTE ON THE TKANSFORMATION OF AMMONIUM 

 CYANATE INTO UREA.* 



Chattaway^ says, " The course of the reaction which takes 

 place when ammonium cyanate is transformed into carbamide 

 has never been satisfactorily explained. Up to a few years 

 ago it was universally regarded as a peculiar case of isomeric 

 change and no consideration was given to the process by which 

 the conversion was effected." He then states that various spe- 

 cified reactions of carbamide, cyanic acid, isocyanic acid and 

 their esters may be simply explained " by regarding them as 

 instances of the well known tendency of the carbonyl group to 

 add groups such as R2NH and ROH, followed by a subsequent 

 atomic rearrangement involving only the transference of a hy- 

 drogen atom from an oxygen atom to a nitrogen atom connected 

 with it through the doubly linked carbon atom, thus: 



OH 

 N:C:0 -^ -N :C< -> -NHCON: 



N: 



The conversion of ammonium cyanate into carbamide should 

 therefore be formulated as follows :" 



OH 

 NH4 -N :CO?^H N :C :0+NH3^H N :C< ?^H.N CO -NH.. 



NHa 



The three stages, then, in the transformation are (1) the break- 

 ing up of ammonium cyanate into cyanic acid and ammonia, 

 {2) the formation of an addition compound, and (3) a re- 

 arrangement of this compound. 



A simpler explanation eliminates this addition compound and 

 its rearrangement. I find in my note book on the lectures in 

 Organic Chemistry by Professor H. B. Hill at Harvard Univer- 

 sity in 1896, this statement: Ammonium cyanate breaks up 

 with heat into HNCO and NH3 and then the NH3 adds itself 



as follows: 



H.N:C:0 



^ 1^ =H2N-CO-NH2 

 H NH2 



* Reprinted from The Journal of the American Chemical Society, Vol. XXXIV, 

 No. 9, September, 1912. 



