THE CHEMICAL CONSTITUTION OF ITS UNITS 31 



and in 1864 by Kekule from monobromopropionic acid and alcoholic 

 ammonia. 



A synthesis of acetylalanine, from which alanine can be obtained 

 by hydrolysis, was described in 1900 by de Jong. Pyruvic acid was 

 neutralised with ammonium carbonate ; there was a considerable rise in 

 temperature, carbon dioxide was evolved and the ammonium salt of 

 acetylalanine crystallised out. The explanation of this reaction is based 

 upon Erlenmeyer and Kunlin's synthesis of phenylalanine from phenyl- 

 pyruvic acid and it proceeds as follows : 



Ammonium pyruvate, which is first formed, is tautomeric with a- 

 amino-oxypropionic acid, into which it changes : 



/OH 

 CH 3 . CO . COOH + NH 3 = CH 3 . CO . COONH 4 -> CH 3 . C<~COOH 



NH 2 

 This compound then reacts with pyruvic acid : 



OH 



OH CH 3 C COOH 



CH 3 C COOH + CH 3 . CO . COOH = NH 



NH 2 CH 3 C COOH 



OH 



and the compound thus formed loses carbon dioxide giving the com- 

 pound, 



OH 

 CH 3 C H 



NH 

 CH 3 C COOH 



OH 



which possesses the group, 



CHOH NH COH COOH. 



By intramolecular rearrangement and loss of water this becomes 



X NH CH COOH 



I 



The above compound by rearrangement and loss of water is thus 

 converted into acetylalanine : 



CH 3 .C=0 



NH 

 I 

 CH 3 . C . COOH 



H 



