THE CHEMICAL CONSTITUTION OF THE UNITS 95 



Benzoyl-a-amidocinnamic acid is also converted by the action of 

 ammonia into a compound, which yields phenylalanine on hydrolysis. 



The mechanism of this reaction was explained by Erlenmeyer and 

 Kunlin in 1 899. Just as benzoyl-a-amidocinnamic acid is converted by 

 alkali into phenylpyruvic acid and benzamide, so also does this reaction 

 take place with ammonia ; the phenylpyruvic acid then reacts with 

 ammonia, giving a body of the composition, 



c 6 H B 



CH 2 CH 2 



| X)HHO\ I 



c \ / c 



\ ^ KH ' \ 



coon COOH 

 which loses carbonic acid, yielding, 



C 6 H 5 C 6 H 6 



CH 2 CH 2 



I /OHHOv | 



CC >CH , 



\ ^ NH ' 

 COOH 



This substance contains the group, 



CHOH NH COH COOH 



which, by rearrangement and by the loss of a molecule of water, becomes 



CO NH CH COOH 



I 



and it therefore changes into phenylacetyl-phenylalanine : 



C 6 H 5 C 6 H 5 



CH 2 



CH NH 

 COOH 



CH 2 

 CO 



Phenylalanine and phenylacetic acid result by subsequent hydro- 

 lysis. The proof of this reaction was given by the synthesis of phenyl- 

 acetyl-phenylalanine by condensing benzaldehyde with phenaceturic 

 acid : 



/NHCO . CH 2 .C 6 H 5 /N = C . CH 2 .C 6 H 5 



r M POH j_ PH / r> -a nu n/ , tr rv 



v^ 6 rij . ^/un + ^n a ' =t/ 6 rl 5 L/rl = L/f + 2rl a O 



\COOH \CO-O 



and hydrolysing the resulting azlactone, just as in the case of benzoyl- 

 a-amidocinnamic acid, and reducing it with sodium amalgam : 



