KCN

Potassium cyanide, chemical formula KCN, is an inorganic compound consisting of potassium ions and cyanide ions. It forms white, odorless or nearly odorless crystals and is highly soluble in water. In its solid form it is relatively stable, but it reacts vigorously with acids to produce hydrogen cyanide gas, a rapidly acting and extremely toxic compound.

Production and occurrence

KCN is produced industrially by reacting hydrogen cyanide with potassium compounds such as potassium hydroxide or potassium carbonate. It is principally manufactured for use in mining, electroplating, and organic synthesis, and it is handled under strict regulatory controls due to its toxicity.

Uses

The principal use of potassium cyanide is in gold and silver mining, where it participates in the cyanidation process to extract precious metals from ore. It is also used in electroplating, as a precursor in the synthesis of nitriles and other organic compounds, and in various specialized chemical processes. Historically, it has been employed as a poison and as a fumigant or pesticide, but such uses are now tightly restricted.

Safety and toxicity

Potassium cyanide is extremely toxic. Inhalation or ingestion can rapidly impair cellular respiration by inhibiting mitochondrial cytochrome c oxidase, leading to hypoxia and potentially death. Symptoms include headache, dizziness, weakness, confusion, seizures, and loss of consciousness. First aid emphasizes moving the person to fresh air, removing contaminated clothing, flushing skin or eyes with water, and seeking emergency medical care. Cyanide antidotes, notably hydroxocobalamin, may be used; older regimens include nitrite-based treatments in combination with thiosulfate. Avoid releasing cyanide gas by keeping solutions away from acids.

Handling and regulation

KCN is a controlled substance in many jurisdictions. It should be stored in a cool, dry place away from acids, oxidizers, and moisture, with appropriate containment and training for personnel.