24 THE SIMPLER NATURAL BASES 



in the formation of traces of the amine, and Ackermann, by heating 

 histidine with lime, could only obtain glyoxaline. Ewins and Pyman 

 [1911], however, obtained a 10-20 per cent, yield by heating benzoyl 

 histidine in a vacuum to 240 and subsequent hydrolysis, and a 24 

 per cent, yield by heating histidine hydrochloride with 20 per cent, 

 sulphuric acid to 265-270. The most convenient method of prepar- 

 ing iminazolyl-ethylamine is, however, by the synthetical method of 

 Pyman [1911]. Diaminoacetone dihydrochloride (I) (obtained from 

 citric acid) is heated with one molecular proportion of potassium 

 sulphocyanide ; the thiolglyoxaline (II), thus formed by 



CH a .NH 3 .HCl CH.NH, CH . NH X 



* i * f-^ CSH -> f- 



CH 2 .NH a .HCl JH..NH, CH 2 OH 



I II III 



I 



CH.NHv CH.NH, CH . NH 



11 X ~H II >XH II 



C N ^ C N< +_ C 



CH 2 . CH 2 . NH 2 CH 2 . CN CH 2 C1 



VI V IV 



Gabriel's general method, is oxidised with nitric acid ; the nitrous acid 

 formed in the reaction further attacks the amino-group so that a 

 glyoxaline alcohol (III) results. This is successively converted into 

 the chloro-compound (IV) and the cyano-compound (V) ; the latter 

 yields on reduction the desired amine (VI). 



The lower homologue, iminazolylmethylamine, has been prepared 

 by Windaus and Opitz [191 1]. 



