Cyanuric Chloride

(2,4,6-trichloro-l,3,5-triazine), the acid chloride of cyanuric acid; a white crystalline compound, with a pungent odor, a melting point of 146°C, a boiling point of 190°C, and a density of 1.32 g/cm³ (at 20°C).

Cyanuric chloride is readily soluble in acetone, chloroform, and other organic solvents but is very slightly soluble in water, in which it gradually hydrolyzes, forming cyanuric acid. The chlorine atoms in cyanuric chloride may be replaced by various functional groups, for example, RO— (by the action of alcohols and phenols), RNH— (by the action of primary amines), or NH₂— (by the action of ammonia).

The major industrial method for the preparation of cyanuric chloride is the catalytic trimerization of cyanogen chloride (3ClCN→C₃N₃Cl₃), which is carried out either in the gas phase, at temperatures of 350°–450°C in the presence of activated charcoal, or in the liquid phase, at a temperature of 300°C and a pressure of 4 meganewtons/m² (40 kilograms-force/cm²) in the presence of hydrochloric acid or ferric chloride.

Cyanuric chloride is used mainly in the production of herbicides; it is also used in the production of optical brighteners and active azo dyes.