hydrogen cyanide (HCN)

Hydrogen cyanide (HCN) is a colorless liquid or gas at normal temperatures, which is completely miscible with water, burns in air, smells of bitter almonds, and polymerizes on standing. Hydrogen cyanide forms salts known as cyanides (RCN) and isocyanides (RNC). It is used in organic and synthetic fiber synthesis and as a fumigant, and is a very strong poison.


Hydrogen cyanide is central in the prebiotic synthesis of amino acids and purines. The fact that it occurs abundantly in comets has fueled speculation that cometary collisions may have played a significant role in supplying some of the raw materials for prebiotic evolution.


density relative to water 0.70 (at 22 °C)
melting point -14 °C
boiling point 26 °C