Cyanide Structure Properties Reactions and Safety

Cyanide is defined as any compound that contains the monovalent combining group CN. In inorganic cyanides, such as sodium cyanide (NaCN), the cyanide group is present as the negatively charged cyanide ion. The compounds, which are regarded as salts of hydrocyanic acid, are said to be highly toxic. Organic cyanides are generally referred to as nitriles, and in these, the C.N. The group is further connected to the carbon-containing group, such as methyl (CH3) in methyl cyanide, by a covalent bond (otherwise called acetonitrile).

About Cyanide

Hydrocyanic acid, which is also called hydrogen cyanide (HCN), is defined as a highly volatile liquid. HCN is produced using the Andrussow process, which involves mixing ammonia, methane, and oxygen with a platinum metal catalyst. The HCN product can be used to prepare acrylonitrile that is used in the production of synthetic rubber, acrylic fibres, and plastics.

Cyanide chemicals are employed in several chemical processes, including fumigation, case hardening of steel and iron, electroplating, and also the concentration of ores. Substances that can be chemically converted into cyanide in nature are present in certain seeds, such as the seeds of apples (Malus domestica) and the pit of the black cherry (Prunus serotina).

Poisoning of cyanide results from ingesting HCN salts or inhaling HCN. Since cyanide works so rapidly, the speed at which an antidote, such as sodium nitrite, amyl nitrite, or sodium thiosulfate solution, is administered is vital in preventing death.

Nomenclature and Etymology

In the IUPAC nomenclature, organic compounds that contain a –C≡N functional group are referred to as nitriles. Therefore, nitriles are organic compounds. Examples of nitrile are given as acetonitrile, CH3CN, which is also called methyl cyanide. Usually, nitriles do not release cyanide ions. A functional group is having cyanide and hydroxyl bonded to similar carbon known as cyanohydrin. Unlike nitriles, cyanohydrins do release hydrogen cyanide. In inorganic chemistry, salts that contain the C≡N− ion are referred to as cyanides. However, the cyanide ion holds a carbon atom, which is usually not considered organic.

Since it was first obtained by heating the pigment known as Prussian blue, the term is derived from the Greek ‘kyanos’, which means dark blue.

Occurrence

Cyanides are produced by certain fungi, algae, and bacteria, and they are found in many plants. Cyanides are also found in substantial amounts in fruit stones and certain seeds. For example, those of apricots, bitter almonds (almonds cyanide), peaches, and apples. Chemical compounds, which release cyanide are called cyanogenic compounds. Usually, cyanides are bound to sugar molecules in plants in the form of cyanogenic glycosides, and they defend the plant against herbivores. Cassava roots (which are also called Manioc) are an important potato-like food grown in tropical countries (and the base where tapioca is made) also have cyanogenic glycosides.

The Madagascar bamboo, which is called Cathariostachys madagascariensis, produces cyanide as a grazing deterrent. As a result, the golden bamboo lemur, which consumes the bamboo, has gained a high cyanide tolerance.

Toxicity

Several cyanides are particularly poisonous. The cyanide anion is thought to be an inhibitor of cytochrome c oxidase (also known as aa3), which is present in the inner membrane of eukaryotic cells' mitochondria and is the electron transport chain’s fourth complex. Within this protein, it attaches to the iron. The binding of cyanide to this enzyme also prevents the transport of electrons from cytochrome-c to oxygen. Resultantly, the electron transport chain is disrupted, which means that the cell can no longer aerobically produce ATP for energy. Heart and central nervous system tissues, which rely heavily on aerobic respiration, are particularly affected. Histotoxic hypoxia is an example.

Antidote

Hydroxocobalamin reacts with cyanide to produce cyanocobalamin that can be safely eliminated by kidneys. This method has the advantage of avoiding methemoglobin formation. The antidote kit is marketed as Cyanokit and was licenced by the US Food and Drug Administration in 2006.

Cyanide Uses or Applications

Medical Uses

The cyanide compound named sodium nitroprusside is mainly used in clinical chemistry to measure urine ketone bodies, primarily as a follow-up to diabetic patients. On occasion, it is also used in situations of medical emergencies to produce a rapid decrease in blood pressure in humans. Also, it is used as a vasodilator in vascular research. The cobalt present in artificial vitamin B-12 comprises a cyanide ligand as an artifact of the purification process, and this must be removed by the body prior to the vitamin molecule being activated for biochemical use. The copper cyanide compound was briefly used by Japanese physicians to treat leprosy and tuberculosis during World War I.

Pest Control

M44 cyanide devices are used in the U.S. to kill coyotes, including other canids. Also, cyanide is used for pest control in New Zealand, specifically for possums, which is an introduced marsupial that threatens the conservation of native species and spreads tuberculosis amongst cattle. Possums may become bait shy, but the use of the pellets containing the cyanide reduces bait shyness.