84 THE CHEMICAL CONSTITUTION OF THE PROTEINS 



larger yields, only give about 20 per cent, but the method described 

 by Gabriel and Kroseberg, in 1889, who made use of Gabriel's phthali- 

 mide reaction, gives an almost theoretical yield of glycine, as was 

 first shown by Goedeckemayer ; this reaction takes place in the 

 following stages : 



Phthalimidoacetic ester is obtained by the action of chloracetic ester 

 upon potassium phthalimide ; this is first hydrolysed by alkali to glyco- 

 coll phthaloylic acid, and then by 20 per cent, hydrochloric acid to 

 glycocoll and phthalic acid : 



CH 4 / \NK + Cl . CH 2 . COOC 2 H 6 = KC1 + C 6 H/ \N . CH 2 . COOC 2 H 5 



Phthalimidoacetic ester 



/CO\ xCOOH 



C 6 H 4 / J>N.CH 2 .COOC 2 H 5 + 2H 2 O=C 6 H 4 <^ +C 2 H 5 OH 



^CCT ^CO . N H . CH 2 . COOH 



Glycocoll phthaloylic acid 



COOH xCOOH 



+ H 2 O = C 6 H 4 \ + (NH 2 ) . CH 2 . COOH 



CO.NH.CH 2 .COOH 



