Cyanide

Structure of the cyanide anion

Cyanide is a chemical compound that contains a C≡N functional group (a substituent which causes the molecule's characteristic chemical reactions). This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom.

In inorganic cyanides, the cyanide group is present as the anion −C≡N. Soluble salts such as sodium cyanide (NaCN) and potassium cyanide (KCN) are highly toxic. Hydrocyanic acid (HCN), also known as hydrogen cyanide, is a highly volatile liquid that is produced on a large scale industrially. It is obtained by acidification of cyanide salts.

Organic cyanides are usually called nitriles. In nitriles, the C≡N group is linked by a covalent bond to carbon. Although nitriles generally do not release cyanide ions, the cyanohydrins do and are thus rather toxic. Do not eat!

In order to extract an 'effective' dose of cyanide for a person who weighs, let's say 180 pounds. You would only need 80-325 milligrams to kill them. Cyanide is so lethal that even a half-milligram of it per kilogram of body weight is enough to kill. The symptoms of cyanide poisoning include nausea, headaches, vomiting, elevated breathing, respiratory failure, loss of consciousness, and death.

Manufacturing

The principal process used to manufacture cyanides is the the Andrussow process. It involves the reaction of methane, ammonia, and oxygen. The process is catalyzed by a platinum-rhodium alloy.

2 CH4 + 2 NH3 + 3 O2 → 2 HCN + 6 H2O

Cyanide is also found in apple seeds and bitter almonds. Crushing bitter almonds in water can create deadly amounts of cyanide quickly, and is not recommended.

Toxicity

Among the most toxic cyanides are hydrogen cyanide (HCN), sodium cyanide (NaCN), potassium cyanide (KCN), and calcium cyanide. Ingestion of a small quantity of solid cyanide or a cyanide solution of as little as 200 mg, or exposure to airborne cyanide of 270 parts per million, is sufficient to cause death within minutes.

Applications

Illegal fishing and poaching

Cyanides are illegally used to capture live fish near coral reefs for the aquarium and seafood markets. The practice is controversial, dangerous, and damaging but is driven by the lucrative exotic fish market.

Poachers in Africa have been known to use cyanide to poison waterholes, to kill elephants for their ivory.

Pest control

M44 cyanide devices are used in the United States to kill coyotes and other canids. Cyanide is also used for pest control in New Zealand, particularly for possums, an introduced marsupial that threatens the conservation of native species and spreads tuberculosis amongst cattle. Possums can become bait shy but the use of pellets containing the cyanide reduces bait shyness. Cyanide has been known to kill native birds, including the endangered kiwi (not the fruit). Cyanide is also effective for controlling the dama wallaby, another introduced marsupial pest in New Zealand. A licence is required to store, handle and use cyanide in New Zealand.

Cyanides are used as insecticides for fumigating ships. Cyanide salts are used for killing ants, and have in some places been used as rat poison (the less toxic poison arsenic is more common).

Dependencies

• Carbon
• Nitrogen

See also

• Carbon dioxide
• Hydrogen
• Potassium
• Sodium
• Chemical compounds

References

• ATSDR medical management guidelines for cyanide poisoning (US)
• HSE recommendations for first aid treatment of cyanide poisoning (UK)
• Hydrogen cyanide and cyanides (CICAD 61)
• IPCS/CEC Evaluation of antidotes for poisoning by cyanides
• National Pollutant Inventory – Cyanide compounds fact sheet
• Eating apple seeds is safe despite the small amount of cyanide
• Toxicological Profile for Cyanide, U.S. Department of Health and Human Services, July 2006

This article uses material from the Wikipedia article Cyanide, which is released under the Creative Commons Attribution-ShareAlike 3.0 Unported License (view authors).