Hydrogen cyanide

Currently hydrogen cyanide is produced in high quantities by three processes. In the year 2000, 1.615 billion pounds (732,552 tons) were produced in the US.[2] The most important process for the production of hydrogen cyanide is the platinum catalyst:^[2]

CH₄ + NH₃ + 1.5O₂ → HCN + 3H₂O

The energy needed for the reaction is provided by the part oxidation of methane and ammonia.

Of lesser importance is the Degussa process (BMA process) in which no oxygen is added and the energy must be transferred indirectly through the reactor wall:^[3]

CH₄ + NH₃ → HCN + 3H₂

This reaction is akin to steam reforming, the reaction of methane and water. In another process, practiced at formamide is heated and split into hydrogen cyanide and water:

CH(O)NH₂ → HCN + H₂O

In the laboratory, small amounts of HCN are produced by the addition of acids to cyanide salts of alkali metals:

H⁺ + NaCN → HCN + Na⁺

This reaction is sometimes the basis of accidental poisonings because the acid converts a nonvolatile cyanide salt into the gaseous HCN.

Reactions

HCN adds to methyl methacrylate.^{[citation needed]}

In Nylon 66.

Occurrence and applications

Cyanide is used in ethyl acetate (C₄H₈O₂) has now largely replaced the use of cyanide in insect killing jars. Cyanide is also being used for capital punishment.

Fruits that have a pit, such as plastics.

100 g of crushed apple seeds can yield 217 mg of Amygdalin which can generate ~10 mg of HCN.^{[citation needed]}

HCN and the origin of life

Hydrogen cyanide has been discussed as a precursor to amino acids and nucleic acids. It is possible, for example, that HCN played a part in the origin of life. Leslie Orgel, among many researchers, has written extensively on the condensation of HCN.^[7] Although the relationship of these chemical reactions to the origin of life remains speculative, studies in this area have led to discoveries of new pathways to organic compounds derived from condensation of HCN.^[8]

Hydrogen cyanide as a chemical weapon

See also: cyanide poisoning

An HCN concentration of 300 Zyklon B) was perhaps most infamously employed by the Nazi regime in mid-20th century as a method of mass murder. More recent examples include the usage of this gas in gas chambers.

Hydrogen cyanide is commonly listed amongst OPCW.

Although there have been no verified instances of this compound being used as a weapon, it has been reported that hydrogen cyanide may have been employed by Iraq in the war against Iran and against the Kurds in northern Iraq during the 1980s^[11].

In 1995 a device was discovered in a restroom in the Kayabacho Tokyo subway station consisting of bags of sulfuric acid with a remote controlled motor to rupture them in what was believed to be an attempt to produce toxic amounts of hydrogen cyanide gas by the Aum Shinrikyo cult^[12] . In 2003, Al Qaeda reportedly planned to attack the New York City Subway using hydrogen cyanide gas but aborted the attack for unknown reasons.^[13]

Hydrogen cyanide gas in air is explosive at concentrations over 5.6%, equivalent to 56,000 ppm^[14].

References

Institut national de recherche et de sécurité (1997). "Cyanure d'hydrogène et solutions aqueuses". Fiche toxicologique n° 4, Paris:INRS, 5pp. (PDF file, in French)