140 



GLYCIN. SARKOSIN. 



2. Glycin. C 2 H 6 N0 2 . [CH 2 (NH 2 ) . COOHJ. (Amido-acetic acid.) 

 ^Also called Glycocoll and Glycocine.) 



Does not occur in the free state in the animal body, but enters 

 into the composition of several important substances, more espe- 

 cially hippuric and glycocholic acids. It is also a product of the 

 action of hydriodic acid on uric acid, and of boiling acids and 

 caustic alkalis on gelatin : hence the name glycocoll or gelatiii; 



FIG. 7. GLYCIN CRYSTALS. (After Funke). 



sugar, since it possesses a sweet taste. It crystallises in large, 

 colourless, hard rhombohedra, or four-sided prisms, which are 

 easily soluble in water (1 in 4-3), insoluble in cold, slightly solu- 

 ble in hot alcohol, insoluble in ether. 



Its solutions possess an acid reaction, but a sweet taste. Glycin 

 has also the characteristic property of uniting with both acids and 

 bases, to form crystallisable compounds, as also with salts. In 

 this it exhibits its amidic nature, which is further clearly evi- 

 denced by the method of its synthetic production by the action 

 of monochloracetic acid on ammonia: 



CH 2 (Cl) . COOH -f 2NH 3 = CH 2 (NH 2 ) . COOH + NH 4 Cl. 1 



Preparation. Either synthetically as above or more usually by 

 the decomposition of hippuric acid by prolonged boiling with 

 hydrochloric acid, whereby it is split up into glycin and benzoic 

 acid, the latter being separated by crystallisation and shaking up 

 with ether in which glycin is insoluble. 



3. Sarkosin. C 3 H 7 N0 2 . [CH 2 . KH (CH 3 ) . COOH]. (Methyl- 

 glycin.) 



Like glycin in its general chemical properties it further resem- 

 bles it in that it is never found in the free state as a constituent 



1 Mauthner u. Suida, Monatshefte f. Chem. Bd. xi. (1890), S. 373. 



