192 Hydrolysis of the Soluble Protein of Swede Turnips 



Liberation of the esters from^ the ester hydrochlorides. 



The filtrate and washings were evaporated down under reduced 

 pressure at 40° C. until as much as possible of the alcohol was removed. 

 The thick dark residue of hydrochlorides was dissolved in dry chloro- 

 form and filtered from a small insoluble residue. This residue is mainly 

 ammonium chloride which is slightly soluble in alcohol, but insoluble 

 in chloroform. The clear filtrate and washings were poured into a two- 

 litre flask, 270 grams of anhydrous baryta added, and the mixture 

 thoroughly shaken. A slight rise in temperature occurred, and after 

 standing for twenty minutes the flask was cooled under the tap. The 

 liquid was then filtered of?, the baryta and barium chloride thoroughly 

 washed, and the chloroform removed from the filtrate under reduced 

 pressure at 40° C. The residue was then extracted wnth dry ether. It 

 did not dissolve satisfactorily, showing that the liberation of the esters 

 from their hydrochlorides had been incomplete. Upon adding a few 

 drops of water to a test portion of the chloroform solution, however, 

 and adding dry baryta, the filtrate became free from chlorides. The 

 ester hydrochlorides were now redissolved in chloroform, 20 c.c. of 

 water added, and then about 550 grms. of dry baryta. The baryta 

 swelled up and became granular while the whole mixture became quite 

 hot. The mixture was thoroughly shaken from time to time. After 

 forty-five minutes the liquid was cooled and the baryta and barium 

 chloride filtered of?. The filtrate did not give the chloride reaction. 

 The baryta and barium chloride mixture was thoroughly washed with 

 dry chloroform, and the filtrate and washings evaporated down in vacuo. 

 The residue dissolved readily in dry ether, only a slight deposit of 

 dark brown pasty matter remaining adhering to the sides of the flask. 

 The ethereal solution of the esters was allowed to stand over fused 

 sodium sulphate for a few days. The weight of dried baryta and barium 

 chloride obtained was 649 grms. which contained 19-5 grms. of nitrogen. 



The addition of water to the ester hydrochloride as described above 

 was quite unnecessary ; it was found during the preparation of a second 

 yield of esters from the residues of the first esterification that the 

 addition of more baryta liberated the esters from the hydrochlorides 

 without any addition of water (see page 191). The water added must 

 have lowered the yield of esters considerably owing to saponification. 



Foreman in his hydrolysis of casein referred to previously, only 

 obtained 25 grms. of esters from 288 grms. of casein by the application 



