in ON THE SYNTHESIS OF ALBUMINS 135 



which, when acted upon by watery ammonia, is changed into 

 pyrrolidin-carboxylic-acid-alanin, or shortly * prolyl-alanin,' the term 

 prolin standing for pyrrolidin-carboxylic acid. 

 Prolyl-alanin has the formula : 



/COOH 

 CH 2 . CH 9 . CEL . CH . CO . NH . CH/ 



CH 3 



^N. .S 



Nfif 



It possesses a slightly acid reaction towards litmus, is nearly taste- 

 less, very soluble in water, very slightly soluble in absolute-alcohol, and 

 nearly insoluble in ether, benzol, chloroform, petrolether. The neutral 

 as well as the acid solutions (H 2 S0 4 ) are precipitated by phospho- 

 tungstic acid. 



Derivatives of Phenyl-alanin (IV.) 



To enable Fischer to couple the phenyl-alanin radical with other 

 amino-acids he required the chloride of a phenyl-a-halogen propionic 

 acid, and therefore prepared phenyl-a-brompropionic acid or a-brom- 

 hydrocinnamic acid, C 6 H 5 . CH 2 . CHBr - COOH, from benzyl-malonic 

 acid, which Conrad l had used for the preparation of hydrocinnamic 

 acid, by introducing bromine and then decomposing by heat the 

 benzyl-brom-malonic acid : 



/COOH 

 C 6 H 5 . CH 2 . CBr/ 



X COOH 



After the conversion of the phenyl-a-brompropionic acid into the 

 chloride, this compound was coupled with glycyl-glycin and with 

 phenyl-alanin. Cinnamoyl-plenyl-alanin and cinnamoyl-glycyl-glycin 

 were also obtained. 



The constitutional formula of phenyl-alanin is given on p. 47. 



Phenyl-alanyl-glycyl-glycin : 



C 6 H 5 . CH 2 . CH(NH 2 ) . CO . NHCH 2 CO . NHCH 2 . COOH. 

 Phenyl-alanyl-phenyl-alanin : 



C 6 H 5 . CH 2 . CH . CO . NH . CH . CH 2 . C H 5 



NH 2 COOH. 



Cinnamoyl-phenyl-alanin : 



C 6 H 5 . CH : CH . CO . NH . CH . CH 2 . C 6 H 5 



COOH. 



1 M. Conrad, Liebigs Ann. d. Chem. 2O4. 174 (1880). 



