ON A DIHYDRO-QUINOXALINE 



127 



gradually turns dark red. If this solution is filtered and shaken with 

 ether, a dihydro-quinoxaline, of the probable formula 



y\^ N \ 



C-CH, 



CH ■ CHI 



CH, 



\ 



CH, 



goes into solution, as indicated by the beautiful green-yellow fluores- 

 cence of the ether solution. The solution also contains a normal qui- 

 noxaline, probably of the formula 



CCH, 



I 



.CH, 



\S^NS 



CH( 



CH, 



It was attempted to isolate this from the ether solution, but unsuccess- 

 fully. That the normal quinoxaline is really present is shown by the 

 fact that, upon evaporating the ether, a thick oily substance remains, 

 whose odor is almost identical with that of quinoxaline, C 8 H 6 N 2 ; in 

 fact, it is difficult to distinguish between the two odors. This oily sub- 

 stance shows also the characteristic red color of the salts of ordinary 

 dihydro-quinoxalines on being moistened with mineral acids. It would 

 seem probable, then, that, in the case of hydrogen peroxide (also with 

 ferric chloride), besides an oxidation of the dihydro-quinoxaline to the 

 normal base, there has also been a rearrangement of the hydrogen 

 atoms in the sense, 



r V\\.ch, 



\l /CH 3 or 



rcH< 



NFT X CH, 



The base gives characteristic precipitates with solutions of several 

 salts, that with mercuric chloride being a beautiful lemon-yellow and 

 that with copper sulphate being light green. In the case of copper 

 sulphate, the solution changes first from blue to green on the addition 

 of a dilute water- alcohol solution of the base. 1 



1 This color change is not obtained when a copper sulphate solution and dilute alcohol of the same con- 

 centration as that in the experiment are mixed. The color change is therefore not due to the association of 

 Cu and S0 4 ions. 



