120 CHEMISTRY OF THE PROTEIDS CHAP. 



extended the reaction to dibasic fatty acids, and prepared with Prings- 

 heim l by uniting succinyl-azide and glycocoll, succinylglycocoll : 



CH 2 CO . NHCH 2 . COOH 



CH 2 CO . NHCH 2 . COOH, 



and with Darmstaedter by combining adipinic-acid-azide with glycocoll, 

 the adipinylglycin : 



CO.NHCH 2 .COOH 



CO.NHCH 2 .COOH. 



Hallaway then subjected the azides of the substituted ammo-acids to 

 the Schotten-Baumann method, and found that they behaved as do 

 amino-acid chlorides. He prepared from m-nitro-hippurazid the 

 m-nitrohippuryl-amino-acetic acid : 



N0 2 . C 6 H 4 . CO . NHCH 2 CO . NHCH 2 . COOH. 



The readiness with which this compound is formed led Curtius to 

 reinvestigate the formation of hippuryl-glycins from hippurazide, and 

 he succeeded with the help of Wiistenf eld 2 in converting hippuryl- 

 amino-acetic acid : 



<O> CO . NHCH 2 CO . NH . CH 2 COOH 



into the -ester, -> hydrazide -> azide and then linking the latter 

 with glycyl-radials. In this way benzoyl-penta-glycylglycin was 

 obtained : 



. (NHCH 2 CO) 5 NH . CH 2 . COOH. 



This compound, as already pointed out, is the y-acid which Curtius 

 discovered in 1881. 



Curtius and Levy by employing the glycylglycin and diglycylglycin 

 discovered by Emil Fischer (see pp. 127, 128), have succeeded in 

 building up the hexaglycylglycinester 



NH 2 . CH 2 CO (NHCH 2 CO) 5 NH . CH 2 CO . OC 2 H 5 , 



and obtained also glycinhydrazide, NH 2 . CH 2 CO . NH . NH 2 , the 

 amino-hydrogen of which is as mobile as it is in the glycinester 

 itself, for which reason glycinhydrazide is very suitable for building 



1 Hans Pringsheim, Uber das Hydrazid d. Pentamethylendikarbonsaure, Inaug. 

 Dissert. Heidelberg, 1901. 



2 Wiistenfeld, Ber. d. deutsch. chem. Oes. 35. 3226 (1902). 



