in ON THE SYNTHESIS OF ALBUMINS 131 



Theodor Curtius and his pupils obtained by means of the azides ; see 

 p. 119. 



Free amino-acids, with the exception of glycocoll, react with PC1 5 , 

 giving rise to chlorinated amino-acid chlorides, according to the general 

 formula : 



R.CH.COC1 



NH 3 C1. 



Leucyl-chloride hydrochlorate, C 4 H 9 . CH (NH 3 C1). COC1, is pre- 

 pared by placing 5 grammes of pure, synthetic, inactive leucin, 

 carefully powdered and dried into 1 00 ccm. of fresh acetyl chloride in 

 a glass cylinder of 200 ccm. capacity with a well-fitting glass stopper. 

 This mixture is cooled and then 8 grammes ( = 1 mol.) of fresh PC1 5 

 are rapidly finely divided and added to the mixture, which is then 

 shaken for two hours at the ordinary temperature. The PC1 5 

 disappears completely, and the leucin is converted into the chlori- 

 nated chloride. To ensure that no free leucin is present, add 

 another 1*5 grammes of finely divided PC1 5 and shake for another 

 hour. To isolate the compound, filter it off and wash it out with 

 acetyl chloride and petroleum ether. A special apparatus is required 

 for keeping out all moisture. 



Leucyl-chloride is very important in manufacturing polypeptids. 

 In combination with glycocoll-ester it gives rise to leucyl-gly cm-ester, 

 which splits off alcohol and then passes into leucyl-gly cin-anhydride : 



CO NIL 



C^riq . HCv yGH 9 . 



X NH CCT 



It is therefore possible to build up polypeptids from the amino- 

 acids over the chlorides of the latter. 



The last method requiring special mention is that of forming 

 dipeptids by splitting up diacipiperazins, 1 by means of dilute cold 

 alkalies, instead of using acids as Fischer had done at first. 2 Thus, 

 shaking finely powdered glycin-anhydride with equi-molecular amounts 

 of normal soda solution, produces a salt of glycyl-glycin. If this 

 solution be then shaken with acid-chlorides, such as benzoyl-chloride 

 or brom-iso-capronyl-chloride, the corresponding acyl-derivatives are 

 formed, namely benzoyl-glycyl-glycin and brom-iso-capronyl- glycyl- 

 glycin. 



The ready dissociation of diacipiperazin -rings under the action 



1 See p. 126. 2 For some compounds, acids are still indispensable. 



