Inorganic Chemicals

Formula : NH4CN; MW 44.056

Uses

NH4CN is used in organic synthesis. Unstable, it is not shipped or sold commercially.

Physical Properties

Colorless crystalline solid; cubic crystal; unstable; density 1.02 g/cm³; decomposes at 36°C; sublimes at 40°C; very soluble in cold water and alcohol; decomposes in hot water.

Preparation

Ammonium cyanide is prepared in solution by bubbling hydrogen cyanide into aqueous ammonia at low temperature:

HCN + NH3(aq) → NH4CN(aq)

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

Ca(CN)2 + (NH4)2CO3 → 2NH4CN + CaCO3

or barium cyanide and ammonium sulfate:

Ba(CN)2 + (NH4)2SO4 → 2NH4CN + BaSO4

In dry state, NH4CN is made by heating a mixture of potassium cyanide or potassium ferrocyanide with ammonium chloride and condensing the vapors into ammonium cyanide crystals:

KCN + NH4Cl → NH4CN + KCl

Reactions

Ammonium cyanide decomposes to ammonia and hydrogen cyanide; often forming black polymer of HCN:

NH4CN → NH3 + HCN

It undergoes double decomposition reactions in solution with a number of metal salts. It reacts with glyoxal producting glycine (aminoacetic acid)

NH4CN + (CHO)2 → NH2CH2COOH + HCN

Reactions with ketones yield aminonitriles:

NH4CN + CH3COCH3 → NH2CH2CH2CH2CN + H2O

Analysis

Elemental composition: H 9.15%, C 27.23%, N 63.55%. NH4CN may be analyzed by heating the salt and trapping the decomposed products HCN and ammonia in water at low temperatures. The aqueous solution is analyzed for cyanide ion by silver nitrate titrimetric method or an ionselective electrode method; and ammonia is measured by titration or electrode technique (Patnaik, P. 1997. Handbook of Environmental Analysis, Boca Raton, FL: Lewis Publishers).

Toxicity

The solid or its solution is highly toxic. Ingestion can cause death. Exposure to the solid can be harmful as it decomposes to highly toxic hydrogen cyanide and ammonia.