IMIDAZOLES, or Glyoxalines, organic chemical compounds containing the ring system
Imidazole itself was first prepared by H. Debus (Ann. 1858, 107, p. 254) by the action of ammonia on glyoxal, 2C2H2O2 + 2NH3 = C3H4N2 + H2CO2 + 2H2O. The compounds of this series may be prepared by the condensation of ortho-diketones with ammonia and aldehydes
from thioimidazolones by oxidation with dilute nitric acid (W. Marckwald, Ber., 1892, 25, p. 2361); by distillation of hydrobenzamide and similarly constituted bodies; and by the action of phosphorus pentachloride on symmetrical dimethyloxamide, a methylchlorglyoxaline being formed (O. Wallach, Ann., 1877, 184, p. 500).
The glyoxalines are basic in character, and the imide hydrogen is replaceable by metals and alkyl groups. They are stable towards reducing agents, and acidyl groups are only introduced with difficulty.
Imidazole (glyoxaline), C3H4N2, crystallizes in thick prisms which melt at 88-89° C. and boil at 253° C., and are readily soluble in alcohol and in water. It is unaffected by chromic acid, but potassium permanganate oxidizes it to formic acid. It forms salts with acids.
Lophine (triphenylglyoxaline),