126 CHEMISTRY OF THE PROTEIDS CHAP. 



detailed below. He had previously synthetised all the simple amino- 

 acids, had split racemic amino-acids into their optically active com- 

 ponents, see p. 20 , had substituted, in preparing the esters of amino- 

 acids, alkalies for the expensive silver-oxide-method of Curtius, 1 

 and had taught us to separate from one another the different amino- 

 acids, in the form of their esters, by means of fractional distillation. 

 Using these new methods he succeeded in demonstrating many amino- 

 acids, which had hitherto not been found amongst the dissociation- 

 products of albuminous substances, as already pointed out on p. 21. 



That amino-acids by the introduction of alcohol-radicals lose their 

 stability, as first noticed by Curtius, is a circumstance which has been 

 taken advantage of by Fischer throughout the whole of his research. 

 His aim has always been to unite amino-acids in the form of their 

 esters, and to prevent the NH 2 -radical from becoming split off. 



Fischer and Fourneau 2 having prepared glycocoll-ethyl-ester 

 according to the plan of Curtius and Goebel, see p. 116, converted it 

 then into the di-glycocoll-anhydride, or, as it is now usually called, 

 di-acipiperazin. This ring-compound was finally converted into the 

 open-chain glycyl-glycin 3 by being boiled for a short time with concen- 

 trated hydrochloric acid. Treating glycocoll-anhydride with alcoholic 

 hydrochloric acid on the other hand gave rise to glycyl-glycin-ester. 



NH 2 CH 2 CO. OH NH 2 CH 2 CO . OC 2 H 5 



Glycocoll. Glycocoll-ethyl-ester. 



o=c 



CH 2 NH x /CH 2 NH 2 



;c-o o = c( 



CH/ X NH CH 2 CO . OH 



Glycocoll anhydride + saturated boiling HC1 

 or diacipiperazin -- > Glycyl-glycin. 



/CH 2 NHL X CH 2 NH 9 



C< )C = 0*0< 



N NH CH/ N NH CH 2 CO . OC 2 H 5 



+ boiling alcoholic HC1 

 Glycocoll-anhydride -- > glycyl-glycin-ester. 



carboxylic acid), 37. 3071 (1904) ; Hermann Leuchs and Umetaro Suzuki [VI.], 

 ibid. 37. 3306 (1904) ; E. Fischer and Umetaro Suzuki [VII.], ' Derivatives 

 of Cystin,' ibid. 37. 4575 (1904); E. Fischer and Ernest Koenigs [VIII.], 'Poly- 

 peptids and Amides of Aspartic Acid,' ibid. 37. 4585 (1904) ; E. Fischer and Peter 

 Bergell, 'Dissociation of some Dipeptids by means of Pancreatic Ferment,' ibid. 37. 

 3103 (1904). E. Fischer [IX.] 'Chlorides of amino-acids and^ their acyl-derivatives, ' 

 ibid. 38. 605 (1905). For references of papers X.-XIIL, see p. 138. 



1 E. Fischer, Sitzber. d. Berl. Akad. (1900) 1062, and Ber. d. deutsch. diem. Ges. 

 34. 433 (1901). 



2 E. Fischer and E. Fournean, Ber. d. deutsch. chem. Ges. 34. 2868 (1901). 



3 Fisher and Fournean have given the term ' glycyl ' to the radical [NH 2 CH 2 CO ] 

 glycyl-glycin = 2 molecules of glycocoll, or glycin, minus one molecule of water. 



