BASES OF CHAPTER IV CHOLINE AND ALLIED SUBSTANCES. 



Preparation of Choline from Natural Sources. 



The best source is egg-yolk. Crude lecithin, obtained by extract- 

 ing the yolk with alcohol and ether, is hydrolysed by boiling with 

 saturated baryta solution for one hour ; after removal of the barium, 

 the solution is evaporated and the residue extracted with alcohol. 

 After acidification of the alcoholic solution with hydrochloric acid, 

 the choline is precipitated by alcoholic platinic chloride solution. 



According to the German patent No. 193449 f J- D. Riedel 

 [1908] lecithin is heated with twice its weight of 40 per cent, sul- 

 phuric acid, and after removal of the acid with baryta, choline is 

 precipitated with mercuric chloride (cf. also Moruzzi [1908] and 

 MacLean [1908]). To convert the platinichloride into the hydro- 

 chloride, the aqueous solution of the former salt is evaporated after 

 adding the calculated quantity of potassium chloride, and then the 

 choline chloride can be extracted by absolute alcohol. 



Schulze's Method of Separating Choline and other Plant Bases. 



This method [1909] for the more or less quantitative isolation 

 of choline, betaine and trigonelline, is more trustworthy than that of 

 Stanek (described below) when other bases are present, and is corres- 

 pondingly more complicated. 



An aqueous extract of the material (which is preferable to an 

 alcoholic one since it excludes phosphatides more completely) is puri- 

 fied with lead acetate, strongly acidified with sulphuric acid and 

 precipitated with phosphotungstic acid. After regeneration of the 

 precipitate with baryta, the purine bases and the histidine and arginine 

 fractions are removed by means of silver nitrate in the usual manner, 

 and the last filtrate is again precipitated with phosphotungstic acid ; 

 after regeneration the mixture of chlorides is dissolved in 95 per cent, 

 alcohol and precipitated with alcoholic mercuric chloride. Choline 

 mercurichloride is very little soluble in boiling water, the betaine 

 compound more so. The separation is completed by converting the 

 more and the less soluble mercurichlorides into the dry hydrochlorides 



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