Furazan, or 1,2,5-oxadiazole, is a

heterocyclic A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic organic chemistry is the branch of organic chemistry dealing with the synthesis, proper ...

aromatic In organic chemistry, aromaticity is a chemical property describing the way in which a conjugated system, conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibits a stabilization stronger than would be expected from conjugati ...

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

consisting of a five-atom ring containing 1 oxygen and 2 nitrogen atoms. The furazan ring system is also found in the steroid furazabol. Furazan and its derivatives are obtained from the

oxime In organic chemistry, an oxime is an organic compound belonging to the imines, with the general Chemical formula, formula , where R is an organic Side chain, side-chain and R' may be hydrogen, forming an aldoxime, or another organic functional g ...

derivatives of 1,2- diketones.

Synthesis

In theory the simplest means of producing furazan is the cyclic-dehydration of (the di-

glyoxal Glyoxal is an organic compound with the chemical formula OCHCHO. It is the smallest dialdehyde (a compound with two aldehyde groups). It is a crystalline solid, white at low temperatures and yellow near the melting point (15 °C). The liquid ...

), however the instability of furazan to high temperature or extremes of pH requires that this process be performed carefully. The formation of furazan from glyoxime is also exothermic and takes place with the copious evolution of noxious gases. The reaction may be achieved by heating glyoxime to 150 °C in the presence of succinic anhydride. Furazan will evaporate at that temperature, which continuously removes the product from the reaction mixture.

Derivatives

;3,4-Dimethylfurazan 3,4-Dimethylfurazan ( b.p. 154–159 °C) is prepared by an analogous process by dehydrating dimethylglyoxime. A variety of related derivatives are known, including diphenyl- and methylethylfurazan. ;Carboxylic acid derivatives

Potassium permanganate Potassium permanganate is an inorganic compound with the chemical formula KMnO4. It is a purplish-black crystalline salt, which dissolves in water as K+ and ions to give an intensely pink to purple solution. Potassium permanganate is widely us ...

oxidizes 3,4-dimethylfurazan first to methylfurazancarboxylic acid and then to furazandicarboxylic acid. By warming oxyfurazan acetic acid with excess of potassium permanganate, oxyfurazancarboxylic acid is obtained. It crystallizes as prisms ( m.p. 175 °C). Furazancarboxylic acid (m.p. 107 °C) is prepared by oxidation of furazanpropionic acid with potassium permanganate. It dissolves in base to give nitrosocyanacetate. ;Diaminofurazan The energetic precursor, diaminofurazan, can be prepared by heating diaminoglyoxime with

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which utili ...

followed by cooling to give white crystals. Like many other furazans, diaminofurazan forms stable complexes with copper(II) salts. ;Furoxan Furoxan may be formed by dimerization of nitrile oxides

References

*{{cite EB1911 , wstitle=Furazanes, volume=11, page=357 Oxadiazoles