cyanogen - Physical properties, Preparation, History, Toxic effects

N–­C–C–­N, boiling point ?21°C. A colourless, inflammable, poisonous gas, with a bitter almond smell. It bears the same relation to cyanide ion (CN^?) as chlorine (Cl₂) does to chloride ion (Cl^?).

Cyanogen molecules consist of two CN groups (analogous to diatomic halogen molecules, X2, where X = F, Cl, Br or I). The word “cyanogen” may refer to a single cyano group in some molecules that are considered derivatives of cyanogen. Cyanogen chloride (NCCl), for example, is considered (for the purposes of naming) to be cyanogen with one cyano group replaced with a chlorine atom.

Physical properties

Cyanogen, at room temperature, is a colorless gas with a pungent odor. It is, like most cyanides, very toxic because it is reduced to cyanide, which binds more strongly than oxygen to the cytochrome c oxidase complex, thus interrupting the mitochondrial electron transfer chain.

Preparation

Cyanogen can be prepared in the laboratory by heating mercuric cyanide . Cyanogen is also formed when nitrogen (N2) and acetylene (C2H2) are made to react by an electrical spark or discharge.

History

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.

Toxic effects

Cyanogen gas is irritant to the eyes and respiratory system.