Cyanogen
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Cyanogen is a chemical compound (CN)2. The CN entity behaves like a halogen. As do halogens, it forms molecules consisting of two CN groups, N≡C-C≡N. Compounds containing the CN group are called cyanides, cyanates, and isocyanates. "Cyanogen" refers to a single CN group in some molecules, such as cyanogen chloride (NCCl).
Cyanogen at room temperature is a colourless gas with a pungent odour. Its melting point is -27.9°C (-18.2°F) whilst its boiling point is -20.1°C (-4.2°F). Its density is approximately twice that of air at the same temperature and pressure. It is, like cyanides proper, very toxic because it inhibits the action of hemoglobin in allowing the uptake of oxygen to the blood when it is reduced to cyanide.
Cyanogen can be prepared in the laboratory by the heating of mercury cyanide. Industrially, it is made by oxidation of hydrogen cyanide, usually using chlorine over an activated silicon dioxide catalyst or nitrogen dioxide over a copper salt. Cyanogen is also formed when nitrogen (N 2) and acetylene (C2H2) are made to react by an electrical spark or discharge.
Cyanogen has a long history, having been probably first synthesised around 1782 by Carl Scheele when he studied hydrogen cyanide. It had definitely been synthesised by 1802, when it was used to make what we now know as cyanogen chloride. It became of importance with the growth of the fertilizer industry in the late nineteenth century and is still an important intermediate in the production of many fertilisers. It is also used a stabiliser in the production of nitrocellulose.
See also: pseudohalogen
External link
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