Cyanogen iodide or iodine cyanide (ICN) is a pseudohalogen composed of

iodine Iodine is a chemical element with the Symbol (chemistry), symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , ...

and the

cyanide Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms. In chemistry, a cyanide () is a chemical compound that contains a functional group. This group, known as the cyano group, consists of ...

group. It is a highly toxic inorganic compound. It occurs as white crystals that react slowly with

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...

to form

hydrogen cyanide Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on a ...

Synthesis

Cyanogen iodide is prepared by combining I₂ and a

, most commonly

sodium cyanide Sodium cyanide is a poisonous compound with the formula Na C N. It is a white, water-soluble solid. Cyanide has a high affinity for metals, which leads to the high toxicity of this salt. Its main application, in gold mining, also exploits its h ...

in ice-cold

. The product is extracted with

ether In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again b ...

. :I₂ + NaCN → NaI + ICN

Applications

Cyanogen iodide has been used in taxidermy as a preservative because of its toxicity.

History

Cyanogen iodide was first synthesized in 1824 by the French chemist Georges-Simon Serullas (1774–1832). Cyanogen iodide was considered one of the impurities in commercially sold iodine before the 1930s.

Hazards

Cyanogen iodide is toxic if inhaled or ingested and may be fatal if swallowed or absorbed through the skin. Cyanogen iodide may cause convulsions, paralysis and death from respiratory failure. It is a strong irritant and may cause burns to the eyes and skin if contacted. If cyanogen iodide is heated enough to undergo complete decomposition, it may releases toxic fumes of

nitrogen oxides Nitrogen oxide may refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds: Charge-neutral *Nitric oxide (NO), nitrogen(II) oxide, or nitrogen monoxide *Nitrogen dioxide (), nitrogen(IV) oxide * Nitrogen trioxide (), or ...

, cyanide and iodide. A fire may cause the release of poisonous gas. Cyanogen iodide decomposes when contacted with acids, bases, ammonia, alcohols, and with heating. ICN slowly reacts with water or carbon dioxide to produce

. It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S.

Emergency Planning and Community Right-to-Know Act The Emergency Planning and Community Right-to-Know Act of 1986 is a United States federal law passed by the 99th United States Congress located at Title 42, Chapter 116 of the U.S. Code, concerned with emergency response preparedness. On Octo ...

(42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities.

Solutions in pyridine

Cyanogen iodide solutions in

pyridine Pyridine is a basic (chemistry), basic heterocyclic compound, heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakl ...

conduct electric current. Dilute solutions of ICN in pyridine are colorless at first, but upon standing become successively yellow, orange, red-brown and deep red-brown. This effect is due to a change in conductivity, which in turn is due to the formation of an electrolyte. When electrical conductivity of ICN is compared with that of iodine-pyridine solutions, the formation of the electrolyte in ICN proceeds much more slowly. Results confirm that cyanides are much weaker salts in pyridine than are iodides, although cyanogen iodide solutions are able to be dissolved in pyridine giving solutions with electrical conductivity that increases over time and results in maximum values.

External links

References

{{Authority control Iodine compounds Cyano compounds Nonmetal halides Pseudohalogens