Furazan

Furazan, or 1,2,5-oxadiazole, is an heterocyclic aromatic organic compound with a five-atom ring containing two oxygen and one nitrogen atom. Furazan and its derivatives are obtained by heating glyoximes (dioximes of ortho-diketones) with alkalis or ammonia.

Derivatives
3,4-Dimethylfurazan is prepared by heating dimethylglyoxime with an excess of ammonia for six hours at 165 °C. A liquid at ordinary temperature, it boils at 156 °C. Potassium permanganate oxidizes it first to methylfurazancarboxylic acid and then to furazandicarboxylic acid. Methylethylfurazan and diphenylfurazan are also known. By warming oxyfurazan acetic acid with excess of potassium permanganate to 100 °C, oxyfurazancarboxylic acid is obtained. It crystallizes in prisms, which melt at 175 °C. Furazancarboxylic acid is prepared by the action of a large excess of potassium permanganate on a hot solution of furazanpropionic acid. It melts at 107 °C, and dissolves in caustic soda, with a deep yellow color and formation of nitrosocyanacetic acid.

The furazan ring system is also found in the steroid furazabol.