FATS LECITHIN CHOLESTEROL. 1 13 



On saponification with alkalies, we obtain fatty acids, glycerol, phos- 

 phoric acid, and choline. Dilute acids have little action on lecithin. 

 The fatty-acid component varies. We are acquainted with lecithins con- 

 taining stearic, palmitic, and oleic acids. Even two different acids may 

 participate in the constitution. We have not yet succeeded in pre- 

 paring lecithin synthetically. As it is optically active, it must contain an 

 asymmetric carbon atom. We are justified in making certain deductions 

 regarding the method of grouping of the glycerol and combined radicals, 

 as indicated by R. Willstadter and Karl Liidecke. 1 The following formulae 

 are possible ones: 



CH 2 O Choline phosphate CH 2 Fatty acid A 



*CH 



O Fatty acid *CH Choline phosphate 



H 2 Fatty acid CH 2 O Fatty acid B 



I II 



Formula II only contains an asymmetric carbon atom when the two fatty 

 acids are different. The investigators mentioned decided in favor of 

 formula I, because they succeeded in obtaining an optically active glycero- 

 phosphoric acid by hydrolysis. This is only possible when the molecule 

 has the following grouping: HO . CH 2 CH . OH CH 2 . O . PO 3 H 2 . 



The base choline is of much interest. It is a quaternary-ammonium 

 base, and has the following constitution: 



/CH 3 

 xCH 3 



N CH 2 -CH 2 OH 

 ^OH 



It is, therefore, to be considered as trimethylhydroxyethylammonium 

 hydroxide. Wurtz 2 proved this by synthesis. He combined ethylene 



/CH 3 

 oxide, C2H 4 0, trimethylamine N CH 3 and water. Choline can also be 



X CH 3 

 derived from glycol, as shown by the following formula: 



CH 2 OH 



-N-(CH 3 ) 3 

 )H 



\S *--*- 



CH 



1 R. Willstatter and K. Liidecke: Ber. 37, 3753 (1904). 



2 Ann. Sup. 6, 116 and 197 (1868). Cf. M. Kriiger and P. Bergell: Ber. 36, 2901 

 (1903). 



