ISOLATION 



same year, Edie et al.^ prepared a concentrate from yeast (" torulin "), 

 also using the pigeon as test animal, whilst C. Funk ^ prepared con- 

 centrates from both rice-polishings and yeast. Several other workers 

 investigated the problem during the next twelve years or so, but no 

 further advance was made until 1926 when B. C. P. Jansen and W. F. 

 Donath,* working in Java, effected a much greater concentration than 

 earlier workers by treatment with acid clay ; this adsorbed the vitamin 

 from an aqueous solution of pB. 4-5, and it was then recovered by 

 elution with baryta. To detect activity, they used rice-birds {Munia 

 maja) which, like pigeons, readily develop polyneuritis when main- 

 tained on a vitamin B-free diet. By a series of operations terminating 

 in the formation of a platinic chloride complex, Jansen and Donath 

 eventually obtained the vitamin in the form of a crystalline hydro- 

 chloride, m.p. 250° C. 



The vitamin was also isolated from yeast by H. W. Kinnersley and 

 R. A. Peters,^ from wheat germ by B. C. Guha and J. C. Drummond,® 

 and from rice polishings by an improved method by R. R. Williams 

 et al. "^ This led to the production of sufficient aneurine to enable its 

 constitution to be worked out. 



The details of the methods of isolation used by different workers 

 vary greatly, a method applicable to one source being not necessarily 

 applicable to a different source. The method of Williams et al., in 

 which rice polishings were used as the starting material, was to prepare 

 an aqueous extract, adsorb the vitamin on to fullers' earth (Cerecedo 

 et al.^ recommend synthetic zeolites), elute with aqueous pyridine or 

 quinine, the latter giving a much better recovery, and then treat the 

 aqueous solution with benzoyl chloride in dilute alkali to benzoylate 

 impurities. These were removed by chloroform extraction, and the 

 vitamin was precipitated with silver nitrate, barium hydroxide and 

 phosphotungstic acid. Finally the aneurine was recrystallised from 

 acidified organic solvents, e.g. phenol and butanol or alcoholic hydro- 

 chloric acid. From one ton of rice polishings, Williams et al. obtained 

 5 to 10 g. of aneurine hydrochloride. 



D. S. Herr ^ has described a method of isolating aneurine and of 

 separating it from ribofiavine by means of synthetic ion exchange 

 resins. Amberlite IR-ioo in the acid form adsorbed 168 mg. of 

 aneurine per g. of dry resin and, provided the rate of flow through the 

 column of resin was not too high, recovery was complete ; the ad- 

 sorbed aneurine was completely eluted by 18 % or, better, 37 % 

 hydrochloric acid. It appears that elution was not due to true 

 chemical exchange, as a considerable excess of hydrochloric acid 

 was necessary. This is supported by the observation that when 

 aneurine was adsorbed on the basic form of Amberlite IR-ioo, it was 

 recovered to the extent of only 30 % by hot sodium chloride solution. 



II 



