442 V. CHEMISTRY OF PHOSPHATIDES AND CEREBROSIDES 



A preparation (cited by Renall) from cattle brain contained 87% of ni- 

 trogen in the form of amino nitrogen, while in that from sheep brain the 

 proportion was 97.5%. 



The procedure of Levene and Rolf'-'''^ is quite similar. Their preparations 

 were practically free from iion-amiiio iiili'ogon. The yield was 18 g. for 18 

 kg. of brain freed from e\ir;iiie()u.s menihraiie. 



c. Synthesis of Phosphatidylethanolamine, a- and /3-Cephalins were 

 successfully synthesized by Griin and Limpacher*^ by methods similar to 

 those employed for the preparation of lecithin, with the exception that col- 

 amine replaces choline. Q:,)S-Distearocephalin and a:,Q:'-distearocephalin 

 have been synthesized by this procedure. 



In the method of Kabashima®^'^" dipalmitocephalin was synthesized by 

 heating the monosilver salt of dipalmitoglycerophosphoric acid wit h brom- 

 ethylamine picrate. The method was also applicable to distearo-a-cepha- 

 lin.^^^ Rose^^^ has obtained cephalin synthetically by reacting either carbo- 

 benzoxyethanolamine or /J-hj^droxyethylphthalimide with crude dipalmito- 

 glycerophosphoryl chloride. The cephalin prepared by both of the latter 

 procedures was found by Rose to be identical with that synthesized by the 

 Kabashima method. 



d. Properties of Phosphatidylethanolamine. When carefully prepared, 

 cephalin is a colorless solid but, like lecithin, it readily darkens to a red- 

 dish bro^^■n color when exposed to light or air. It is very hydroscopic, but 

 maintains a constant weight in a vacuum desiccator. Brain cephalin 

 meltsatl74°tol75°C.2«o.26i 



Cephalin is insoluble in dry diethyl ether, but it dissolves in all p^-opor- 

 tions in ether containing 1% of water. It is soluble in such fat solvents as 

 chloroform, petroleum ether, carbon disulfide, benzene, and hot acetic acid. 

 However, it does not dissolve in alcohol or acetone. It differs from lecithin 

 by virtue of its insolubility in alcohol. Some cephalin is dissolved in alcohol 

 in the presence of lecithin. Cephalin forms an emulsion with water, from 

 which it may be precipitated by hydrochloric acid, other mineral acids, or 

 concentrated solutions of oxalic acid. Cephalin produces myelin forms in 

 the presence of water, in much the same way as does lecithin. Cephalin is 

 also precipitated from aqueous suspension by barium hydroxide, calcivun 

 hydroxide, platinum chloride, cadmium chloride, lead acetate, ammonia, 

 and by other metallic salts. "^^'^ The cadmium chloride compound has less 

 than an equivalent amount of the salt. The same is true in the case of the 



25^ I. Kabashima and B. Suzuki, Proc. Imp. Acad. Japan, 8, 492-495 (19.32). 

 2*8 I. Kabashima, Ber., 71, 1071-1073 (1938). 

 2M W. G. Rose, J. Am. Chem. Soc, 69, 1384-1387 (1947). 

 MO J. Parnas, Biochem. Z., 22, 411-432 (1909). 

 261 S. FrJinkel and E. Neubauer, Biochem. Z., 21, 321-3.3G (1909). 

 2*2 J. L. W. Thudichum, Die chemische Konstilulion des Gehirns de.9 Menschen nnd der 

 Tiere, Pietzcker, Tubingen, 1901. 



