CH. IV.] 



GLYCINE. 



77 



(viii.) Filter off the ether and transfer it to a distilling flask. 

 Connect this to another distilling flask as shewn in fig. 8. 



(ix.) Distil off the ether under reduced pressure, the receiving 

 flask being thoroughly cooled (best done by packing with 

 ice). 



(x.) When all the ether has been removed, change the receiving 

 flask and distil over the glycine ester, at a temperature of 

 44 C. and a pressure of n mm. mercury. The receiving 

 flask must be well cooled. 



(xi.) Transfer the distillate to a round-bottomed flask, add 10 

 times its volume of water, and boil on a sand bath under a 

 reflex condenser until the alkaline reaction has dis- 

 appeared. 



(xii.) Concentrate the solution in an evaporating basin on the 

 water bath. Crystals of glycine are obtained. 



Properties of Glycine. It crystallises from water in 

 hard, flattened, colourless prisms. On heating, it becomes 

 brown at 228, and melts at 2^2-2^6. The crystals have 

 a sweet taste, from which fact the original name of glyocoll 

 was derived (yXvicvs, sweet : xro'XAa, glue). It is readily 

 soluble in water ( i part of glycine in 4-3 parts of cold water). 

 It is insoluble in absolute alcohol, and in ether. When 

 boiled with concentrated alkali ammonia is evolved. On 

 treating the residue with hydrochloric acid, hydrocyanic 

 acid is evolved, and oxalic acid is found to be present. 



Aqueous solutions give a red colour with ferric chloride, 

 similar to that given by acetic acid. 



On shaking an aqueous solution with benzoyl chloride 

 and sodium carbonate, hippuric acid is formed. 



C 6 H 5 .COC1 + H 2 N.CH 2 .COOH = C 6 H 5 .CO.NH.CH 2 .COOH 



+ HCL 

 Benzoyl chloride. Glycine. Hippuric acid. 



79. Preparation of the copper salt of glycine. To a solution 

 of about 0-5 gram, of glycine in about 40 cc. of distilled water, 

 add an excess of freshly precipitated, well washed cupric hydroxide. 



