136 CHOLIN. 



Cholin. C 5 H 15 N0 2 .(CH 3 ) 3 -N, trimethyloxy- 



ethyl-ammonium hydroxide. 



Discovered by Strecker 1 among the products of the decomposition of 

 pigs'-bile and subsequently of ox-bile, whence the name cholin. It does 

 not occur in the free state except as a product of the decomposition of 

 lecithin, but has been recently obtained in extracts of the suprarenals 2 . 

 It is a colourless fluid, of oily consistence, possesses a strong alkaline 

 reaction, and forms with acids very deliquescent salts. The salts with 

 hydrochloric acid and with the chlorides of platinum and of gold are the 

 most important. 



Cholin is a most unstable body, mere heating of its aqueous solution 

 sufficing to split it up into glycol, trimethylamin and ethylene oxide. 



Since it is a product of the decomposition of lecithin it is best 

 prepared from the yolk of egg 3 . The process is elaborate but consists 

 roughly in decomposing the residue of the yolk, left after complete 

 extraction with alcohol and ether, by boiling it for at least an hour 

 with caustic baryta. At the end of this period the barium is pre- 

 cipitated by a stream of carbonic acid, the nitrate is concentrated, 

 extracted with absolute alcohol and from this solution the cholin is 

 precipitated as a salt by the addition of platinum chloride. It is 

 finally separated from this salt by means of sulphuretted hydrogen. 



Wurtz 4 has obtained it synthetically, first by the action of glycol chlorhydrin 

 CH 2 .OH 



on trimethylamine, and then by that of ethylene oxide on a concentrated 

 CH 2 .C1 

 aqueous solution of trimethylamine. 



Cholin when pure is an oily liquid with a strong alkaline reaction 

 soluble in alcohol or ether. It yields crystalline compounds with acids 

 and some salts of which the double salts formed with hydrochloric acid 

 and the chlorides of either gold or platinum crystallise readily and are 

 employed for the detection and separation of the base. The platinum 

 salt is readily soluble in water, insoluble in alcohol. The gold salt is 

 but slightly soluble in cold water, but soluble in hot alcohol. 



When boiled in concentrated solution cholin is decomposed into 

 glycol and trimethylamine 



(CH 3 ) 3 S N = C 2 H 4 (OH). + N (CH 3 ) 3 . 



1 Ann. d. Chem. u. Pharm. Bd. cxxm. (1862), S. 353; Bd. CXLVIII. (1868), S. 76. 



2 Marino-Zuco, Bend. d. R. accad. d. Lincei, 1888, p. 835. 



3 Diakonow, for ref. and details see Hoppe-Seyler's Hdbch. d. phys.-path. diem. 

 Anal. 1883, S. 163. 



4 Ann. d. Chem. u. Pharm. Supl.-Bd. vi. Sn. 116, 201. Cf. Baeyer, Ibid. Bd. 

 CXL. (1866), S. 306. 



