CHOLINE 



5. M. Kriiger and P. Bergell, Ber., 1903, 36, 2901. 



6. R, Lucius, Arch. Pharm., 1907, 245, 246. 



7. G. Moruzzi, Z. physiol. Chem., 1908, 55, 352. 



8. H. MacLean, ihid., 360. 



3. PROPERTIES OF CHOLINE 



Choline is a strong base, which can be crystallised only with great 

 difficulty. It is hygroscopic and very soluble in water and absolute 

 alcohol, but insoluble in ether. It is generally made available as the 

 chloride, which forms colourless needles of no definite m.p. 



Choline chloride forms double salts with gold chloride, m.ercuric 

 chloride, and platinic chloride, and these can be used for the char- 

 acterisation of choline, although their melting-points vary with the 

 rate of heating. Thus, W. Gulewitsch ^ recorded m.ps. of 241 to 243° 

 C, 249 to 251° C. and 213 to 216° C. respectively, whilst M. Kriiger 

 and P. Bergell 2 obtained values of 233 to 234° C. and 245 to 246° C. 

 for the m.ps. of the platinic chloride and gold chloride double salts. 



References to Section 3 



1. W. Gulewitsch, Z. physiol. Chem., 1898, 24, 513. 



2. M. Kriiger and P. Bergell, Ber., 1903, 36, 2901. 



4. ESTI2V1ATION OF CHOLINE 



Chemical Estimation 



All the chemical methods now in use for the estimation of choline 

 depend on the precipitation of the sparingly soluble reineckate. This 

 was first used by F. J. R. Beattie,i who dissolved the reineckate in 

 acetone and measured the colour of the solution ; this was propor- 

 tional to the amount of choline originally present. A. D. Marenzi and 

 C. E. Cardini ^ also estimated choline by precipitation of the reineckate, 

 but estimated the amount of chromium in the precipitate by means 

 of Cazeneuve's reagent ^ (diphenylcarbazide), evaluating the colour so 

 formed in a photometer. Beattie's method was used, with slight 

 modifications, for the estimation of choline in foodstuffs by Jacobi 

 et al.,^ R. W. Engel ^ and D. Glick,^ all of whom precipitated the 

 reineckate from acid solution. Entenman et al."^ used almost exactly 

 the same method, but precipitated the reineckate from alkaline solu- 

 tion. The two methods gave similar results when applied to alcohol- 

 ether extracts of plasma, but Glick's method gave lower results than 

 that of Entenman et al. when applied to alcohol-ether extracts of 

 liver. 8 The use of the cadmium chloride complex has also been 

 suggested for the estimation of choline.^" 



586 



