Glyoxal → 6-Methylquinoxaline

Participants

Reaction Conditions

Reaction Steps

A solution of 3,4-diaminotoluene (Aldrich, 100 g, 0.82 mol) in 600 mL of hot water (temp. 70-75° C.) was added rapidly to a 60° C. slurry of glyoxal-sodium bisulfite adduct (Aldrich, 239.5 g, 0.9 mol, 1.1 eq) in 400 mL of water. The resulting dark-brown clear solution was heated at 60° C. for 1 hr, then 5 g (0.02 mol) of additional glyoxal adduct was added. The mixture was allowed to cool to r.t. and filtered through a paper filter. The filtrate was neutralized with 5 M aq. NaOH to pH 7.5-7.8 and then extracted with ether (4×400 mL). The extract was dried over Na2SO4 and concentrated on a rotary evaporator to afford 92 g of brown oil which was distilled in vacuum (bp. 100-102° C. at 10 mm Hg; Cavagnol, J. C.; Wiselogle, F. Y. J. Am. Chem. Soc. 1947, 69, 795; 86° C. at 1 mm Hg). Yield 89 g (75%) as a pale-yellow oil.

Provenance & Evidence