THE CEPHALINS 439 



or with phosphorus pentoxide with or without anhydrous phosphoric 

 g^gj(j6o,6i,24o.24i,243,244 qj. ethyl metaphosphate.^^^ Another type of proce- 

 dure involves the phosphorylation of ethylene dichlorohydrin by phosphorus 

 oxychloride24o.243.245.246 yj. g^^yl metaphosphate,24''.247.248 followed by the 



transformation of phosphorylethylenechlorohydrin into phosphorylcholine 

 by means of trimethylamine. Baer and McArthur'^" have recently intro- 

 duced an improved procedure involving the use of diphenylphosphoryl- 

 chloride as the phosphorylating agent. By a slight modification of this 

 procedure, Baer^^^ has been able to dispense with the use of the gold salts 

 without essentially altering the yield or sacrificing the purity of the product. 



{10) Hydroleciihin 



Hydrolecithin is a completely saturated compound which was first iso- 

 lated as a natural product by Lesuk and Anderson 2^" fj-Q^ Cysticercus fascio- 

 laris (which is the larval form of the tapeworm, Taenia crassicolUs, of cats) . 

 Dihydrosphingosine was also found. Thannhauser and co-workers^^^ have 

 more recently identified the glycerol-containing contaminant in sphingomy- 

 elin preparations of beef lung as dihydrolecithin. This new phosphatide 

 occurs in a proportion of 20 to 40% of the total sphingomyelin. Consider- 

 able amounts likewise occur in the brain and spleen. 



Hydrolecithin was tentatively identified as dipalmitolecithin.^^^ In a 

 later report,-^- it was shown that the product is probably identical with that 

 obtained from the tapeworm by Lesuk and Anderson. ^^^ It was found to 

 differ markedly from the saturated lecithins prepared by hydrogenation of 

 egg-yolk,**'^®' 2^^ as well as from that obtained from brain b}' Levene and 

 Rolf.^^ It is also distinct from synthetic distearolecithins.*^"'^^ 



4. The Cephalins 



(1) Multiple Nature of the Cephalins 



Until the demonstration by Folch-^ of the multiple nature of the cephalin 

 complex, it was assumed that only two types of cephalin existed, which were 



2" E. L. Jackson, /. Am. Chem. Soc, 57, 1903-1905 (1935). 



2" F. Inukai and W. Nakabara, Proc. Imp. Acad. Tokyo, 11, 260-261 (1935). 



^** E. Abderhalden, H. Paffrath, and H. Sickel, Arch. ges. Physiol. (Pfiiiger's), £07, 

 241-253 (1925). 



2« R. R. Renshaw and C. Y. Hopkins, J. Am. Chem. Soc, 51, 953-954 (1929). 



2« K. Langhekl, Ber., 44, 2076-2087 (1911). 



2« T. L. McMeekin, /. Am. Chem. Soc, 59, 2383-238G (1937). 



"9 E. Baer, J. Am. Chem. Soc, 6.9, 1253-1254 (1947). 



260 A. Lesuk and R. J. Anderson, J. Biol. Chem., 139, 457-469 (1941). 



251 S. J. Thannhauser, .1. Benotti, and N. F. Boncoddo, ■/. Biol. Chem., 166, 669-675 

 (1946). 



»*« S. J. Thannhauser and N. F. Boncocido, ./. Biol. Chem., 172, 135-139 (1948). 



»» C. Paal and H. Oehme, Ber., 46, 1297-1304 (1913). 



