306 CHEMISTBT OF THE PTOMAJJfS. 



N{CH,),I 

 = CH, 4- 2HL 



3,H CO,H 



GLTOOCOUi. Bbtain Iocid. 



mosochix>r- 

 A^CBTic Acid. 



Another method of synthesizing anhydrous betain consists in heat- 

 ing di-methyl amido-acetic methyl ester. The reaction is reversible 

 (Wildstatter, Ber., 35, 585, 597). 



' From the formulae of the salts of betain it is evident that betain 

 has properly the composition CjH^Oj which is expressed by the 

 structural formula : 



N(CH,),OH 



CH, 



00,H. 



The free base is, however, readily converted into the anhydrid, 

 CjHjjNOy trimethyl glycocoll, the structural formula of which is : 



s 



a^N(CH,), 



Betain aldehyde was prepared first by Berlinerblau and later by 

 Fischer. On oxidation with silver oxid it yields betain. 



Betain is ordinarily regarded as crystallizing with one molecule of 

 water, and the composition is expressed by the formula : CjHjjNOj 

 + HjO(= OH.N(CH3)j.CH^.COj^. It loses this water of crystal- 

 lization by heating at 100°, or on standing over sulphuric acid, 

 forming an anhydrid of the formula already given. The anhydrid 

 is very hygroscopic, and melts at 293° (Wildstatter). Liebreich 

 claimed that free betain possessed the formula C^HjiNO, because it 

 yielded a compound having the composition (C5HjjNO)ZnClj. The 

 free base separates from alcohol in large crystals which deliquesce on 

 exposure to the air. As obtained by Brieger from the hydrochlorid, 

 by treatment with moist silver oxid, it possessed a sweetish taste and 

 neutral reaction. When distilled with potassium hydrate, it yielded 

 trimethylamin and other bases, among which a base of the formula 

 CgHj^Oj occurred in the largest quantity. In 1893 Scheibler agsdn 

 studied the action of sodium hydrate on betain and found only tri- 

 methylamin ; no new base, but unchanged betain. 



The chlorid, CsHjjNOj.Cl, forms beautiful monoclinic plates 

 which are permanent in the air, and this fact can be made use of 

 to effect a separation from the cholin salt, which is deliquescent. 



