ON A DIHYDRO-QUINOXALINE FROM ORTHO- 

 PHENYLENE-DIAMINE AND MESITYLOXIDE 



By John B. Ekeley and Robert J. Wells 



/ N=CH 

 The series of organic bases of which quinoxaline, C 6 H 4 ^ , 



X N = CH 



is the first member has been shown to be closely related to two series 

 of hydro-compounds, the dihydro, of the general formula 



and the tetrahydro, of the general formula 



PA 



I 

 :hr- 



These hydro- compounds may be obtained either by direct reduction 

 of the normal quinoxalines or by condensations. The following are 

 examples of the latter: 



f /\/ #^ 0| =C C 6 H S 



+ 



S NH |H HO] HCC t H s 



C 6 H, 



CHC 6 H S 



-T-2H.0 , 



NH 



A JOH H ]HN-CH, r ^X^ N »s CH 



+ 



4-»H a O 



CH, 



X/ lOH HJ HN-CH, ^SV^fttf' 



Experience has shown that the addition of two hydrogen atoms to 

 the quinoxaline ring changes the colorless quinoxalines to yellow dihydro- 

 quinoxalines, which in dilute solution show a yellow-green fluorescence. 



123 



