Reaction #2171031

Reaction equation

1,2-Diamino-4-methylbenzene

benzil

→

6-methyl-2,3-diphenylquinoxaline

Solvents

ethanoic acid

Conditions

Workup

1. 1
   OtherThe solvent was evaporated in vacua
2. 2
   Otherthe black residue recrystallised three times from ethanol

Procedure

1,2-Diamino-4-methylbenzene (25.0 g, 0.20 mol) and benzil (43 g, 0.20 mol) were refluxed in ethanoic acid (250 ml) overnight. The solvent was evaporated in vacua and the black residue recrystallised three times from ethanol to give pale brown crystals of 6-methyl-2,3-diphenylquinoxaline, 39.6 g, 65% (m.pt. 114.5-116° C. (lit.i 115-116° C.)). 1H NMR (CDCl3, 300 MHz) δ 8.08 (d, J 8.4 Hz, 1H, Hs of quinoxaline), 7.97 (bs, 1H, Hs of quinoxaline), 7.60 (d of d, J 8.4 Hz, J 1.8 Hz, 1H, Hs of quinoxaline), 7.50-7.58 (m, 4H, phenyl rings), 7.30-7.38 (m, 6H, phenyl rings), 2.62 (s, 3H, CH3).

Source