Ammonium cyanide explained

Ammonium cyanide is an unstable inorganic compound with the formula NH₄CN.

Uses

Ammonium cyanide is generally used in organic synthesis. Being unstable, it is not shipped or sold commercially.

Preparation

Ammonium cyanide is prepared by combining solutions of hydrogen cyanide and ammonia:

HCN + NH₃ → NH₄CN

It may be prepared by the reaction of calcium cyanide and ammonium carbonate:

Ca(CN)₂ + (NH₄)₂CO₃ → 2 NH₄CN + CaCO₃

In dry state, ammonium cyanide is made by heating a mixture of potassium cyanide or potassium ferrocyanide with ammonium chloride and condensing the vapours into ammonium cyanide crystals:

KCN + NH₄Cl → NH₄CN + KCl

Reactions

Ammonium cyanide decomposes to ammonia and hydrogen cyanide, often forming a black polymer of hydrogen cyanide:^[1]

NH₄CN → NH₃ + HCN

It undergoes salt metathesis reaction in solution with a number of metal salts to form metal–cyanide complexes.

Reaction with ketones and aldehydes yield aminonitriles, as in the first step of the Strecker amino acid synthesis:

NH₄CN + CH₃COCH₃ → (CH₃)₂C(NH₂)CN + H₂O

Toxicity

See also: Cyanide poisoning. Ammonium cyanide is highly toxic.

References

• A. F. Wells, Structural Inorganic Chemistry, 5th ed., Oxford University Press, Oxford, UK, 1984.

Notes and References

1. Book: 10.1007/3-540-54752-5_195. Hydrogen cyanide polymerization: A preferred cosmochemical pathway. Bioastronomy: The Search for Extraterrestrial Life—The Exploration Broadens. 390. 85–87. Lecture Notes in Physics. 1991. Matthews. Clifford N. 978-3-540-54752-5.