THE LECITHINS 433 



(lie I3-U)vm^-''^^^-^^^ likewise occuiTed, as well as the a-compouiul.^^'^^'i^^-^os 

 Bailly^^ was able to prove that a crystalline sodium salt of /3-glycerophos- 

 phoric acid could be isolated from the lecithin prepared from egg and brain, 

 as well as an amorphous sodium salt of a-glycerophosphoric acid. The two 

 esters can be separated by virtue of the variability in solubility of their 

 sodium soaps. '^'' The a-form is the more soluble. On o.xidation of the 

 ester in solution, a ketone is formed which responds to Deniges' reaction. 

 This can only be interpreted to mean that it is an a-ester. 



Karrer and Salomon ^^ have de\'ised a quantitative method for the separa- 

 tion of the a- and ;S-glycerophosphates from water solution as the barium salts 

 by the addition of barium nitrate. The /3-ester precipitates almost quan- 

 titatively as the double salt with barium nitrate [(C3H706PBa)2-Ba(N03)2] 

 in a practically pure state. The barium a-glyceiophosphate can be removed 

 after concentration of the filtrate. These workers were also able to sepa- 

 rate the ^-glycerophosphate from the crude mixture as the dimethyl ester of 

 the dimethyl ether. 



Glycerophosphate can readily be prepared from lecithin by the method of 

 Willstatter and Liidecke.^^ This in^'ol^Tfe shaking the phosphatide with 

 10% barium hydroxide over a prolonged period at room temperature. The 

 hydrolysis may also be effected in a shorter period by refluxing the mixture 

 without influencing the end result. ^^^ After removal of the excess of barium 

 hydroxide with carbon dioxide, the filtrate is concentrated and the crude bar- 

 ium glycerophosphate is precipitated by the addition of alcohol. After 

 several reprecipitations from water by alcohol, it is obtained in pure form as 

 an amorphous white powder. 



Griin and Limpacher'^^'^^ \nive suggested the possibility that ;S-lecithin 

 does not occur in the natural state, or at least not in the proportions indi- 

 cated by analysis, but that it is formed during the analytical procedures. 

 However, this would seem improbable, according to the data of Karrer and 

 Benz,-"'^ since no such behavior occurred on saponification of synthetic a- 

 glycerophosphate with barium hj^droxide. Rae^^ has also found that no 

 migration of phosphate from the a- to the /3-position occurs during the hy- 

 drolysis of the phospholipid with baryta. 



The distribution of the glycerophosphates in lecithins and other phospho- 

 lipids is recorded in Table 5. 



The values for optical activity obser^'ed for the various glycerophos- 

 phates, which have usually been separated as their calcium or barium salts, 



»" F. B. Power and F. Tutin, J. Chem. Soc, 87, 249-257 (1905). 



"8 F. Tutin and A. C. O. Hann, /. Chem. Soc, 89, 1749-1758 (1906). 



•8^ L. Grimbert and O. Baillj-, Compt. rend., 160, 207-210 (1915). 



2o« P. Karrer and P. Benz, Helv. Chim. Acta, 10, 87-91 (1927). 



'-»i O. Bailly, Compt. rend., 160, 395-398 (1915). 



2''2 O. Bailly, Ann. chim., 6, 215-278 (1916). 



'"'^ O. Bailly, Bull. soc. chim. biol, 1, 152-162 (1919); Chem. Zenlr., 1919, I, 84. 



