290 CHEMISTRY OF THE PTOMAt'NS. 



Liebreich obtained it in the decomposition of protagon by baryta. 

 Gulewitsch (1899), however, was unable to confirm this change, nor 

 was he able to detect neurin in fresh brain matter. Liebreich's re- 

 sult may possibly be due to the use of partly decomposed organs, in 

 which neurin would be present as a result of the bacterial cleavage of 

 cholin. Brieger (I., 60) also has isolated it along with cholin 

 from fresh human brains by boiling with baryta, but did not obtain 

 it by digesting the brains on the water-bath with 2 per cent, hydro- 

 chloric acid. It has been found in putrid, and as a result of this 

 change, poisonous mushrooms (Berlinerblau, 1888). For its syn- 

 thetic preparation, see Gulewitsch (ZeifecA. /. p%sio?. Chem.,2Q, 175). 



The genesis of neurin is still rather obscure, and it is to be hoped 

 that future investigations may shed more light upon the mysterious 

 production of this highly poisonous base. Its occurrence in the 

 brain together with cholin would seem to indicate that it is either 

 derived from cholin by the removal of water, or that it exists to- 

 gether with cholin, partly replacing the latter in the molecule of 

 protagon (lecithin), according to the hypothesis put forward by 

 Lippmann (page 297). 



The question of its derivation from cholin by withdrawal of a 

 molecule of water was subjected early to an interesting experimental 

 discussion. Ch. Gram attempted to explain the production of neu- 

 rin and other muscarin-like ptomains as due to the dehydrating ac- 

 tion of the acids employed in the methods of extraction, and, indeed, 

 he claimed to have converted cholin platinochlorid, by heating with 

 hydrochloric acid, into neurin. This statement was disputed by 

 Briber, and by others, who showed that the platinochlorid of cholin, 

 as well as the hydrochlorid, may be heated with fifteen or thirty per 

 cent., or even concentrated hydrochloric acid, for six to eight hours 

 on a water-bath without any conversion whatever (III., 15). 



That neurin may be obtained from cholin, at least by chemical 

 processes, was shown by Baeyer, in 1866, who found that cholin 

 chlorid, when heated with several times its volume of concentrated 

 hydriodic acid and some red phosphorus, gave a compound CjHjjNI, 

 which, on digestion with fresh, moist silver oxid, yielded a vinyl 

 base identical with that previously obtained synthetically by Hof- 

 mann and now known as neurin. In Hofmann's method for the 

 synthesis of neurin the trimethylamin ethylene bromid (see synthesis 

 of cholin, p. 296) is treated with fresh moist silver oxid. Schmidt 

 and Bode have shown that the iodin compound resulting from the 

 action of hydriodic acid on cholin is the same as that formed by the 

 action of the acid on neurin ; and that on treatment with silver oxid 

 it yields neurin. Cholin, therefore, may be readily changed into 

 neurin. On the other hand, since neurin with hydriodic acid forms 

 the same compound, by heating with silver nitrate cholin is formed. 

 Hence neurin can be easily re-converted into cholin (Schmidt). 



