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Reactive Group Datasheet

Cyanides, Inorganic

Flammability
Materials in this group are generally noncombustible, except hydrogen cyanide (HCN), which is flammable and dangerous because of its wide flammability limits. Cyanides are often flammable by chemical reaction with moisture or acid; they react readily to evolve flammable HCN. Heating inorganic cyanides to decomposition liberates toxic gases and flammable gases that include HCN if traces of moisture are present.
Reactivity
Materials in this group react slowly with water to evolve gaseous hydrogen cyanide (HCN). Acids cause the rapid evolution of HCN, which may polymerize; carbon dioxide from the air is sufficiently acidic to liberate HCN from solutions of cyanides. Inorganic cyanides are incompatible with isocyanates, nitrides, and peroxides. Cyanides have been known to initiate polymerization reactions of epoxides. Cyanides form compounds with metal salts; heat and hydrogen production may accompany these reactions. Some cyanides can detonate when exposed to shock, heat, or friction.
Toxicity
Many of these materials are corrosive to tissue and are extremely toxic by all routes of exposure. Cyanides bind hemoglobin in the blood, and many enzymes are inactivated in the presence of cyanide. Cyanogen chloride and bromide are lachrymators.
Other Characteristics
Compounds in this group contain the characteristic -CN group bound to metal atoms. Some of the combinations form such tightly bound molecules that not even sulfuric acid can liberate the cyanide. Cyanides are used as pesticides and in chemical synthesis.
Examples
Barium cyanide, calcium cyanide, copper cyanide, cyanogen chloride, hydrogen cyanide, lead cyanide, potassium cyanide, silver cyanide.