Cyanogen bromide

(Bromine cyanide, bromocyanogen, cyanobromide)

CAS 506-68-3





Physical Properties

Colorless needles

bp 62 °C, mp 52 °C

Soluble in water



Penetrating odor


Vapor Pressure

100 mmHg at 22.6 °C


Toxicity Data

LCLO inhal (human)

92 ppm (398 mg/m3; 10 min)


LCLO inhal (mouse)

115 ppm (500 mg/m3; 10 min)

Major Hazards

High acute toxicity; severely irritating.


The acute toxicity of cyanogen bromide is high. Toxic effects are similar to but not as severe as those of hydrogen cyanide. Toxic symptoms may include cyanosis, nausea, dizziness, headache, lung irritation, chest pain, and pulmonary edema, which may be fatal.

Cyanogen bromide may cause chronic pulmonary edema.

Flammability and Explosibility

Cyanogen bromide is noncombustible. Impure material decomposes rapidly and can be explosive.

Reactivity and Incompatibility

Cyanogen bromide can react violently with large quantities of acid. It may decompose when exposed to heat, moist air, or water, producing toxic fumes of hydrogen cyanide and hydrogen bromide. Cyanogen bromide can polymerize violently on prolonged storage at ambient temperature.

Storage and Handling

Because of its high acute toxicity, cyanogen bromide should be handled using the "basic prudent practices" of Chapter 5.C, supplemented by the additional precautions for work with compounds of high toxicity (Chapter 5.D). In particular, work with BrCN should be conducted in a fume hood to prevent exposure by inhalation, and splash goggles and impermeable gloves should be worn at all times to prevent eye and skin contact. Containers of cyanogen bromide should be kept tightly sealed and stored under nitrogen in a secondary container in a refrigerator.


In the event of skin contact, immediately wash with soap and water and remove contaminated clothing. In case of eye contact, promptly wash with copious amounts of water for 15 min (lifting upper and lower lids occasionally) and obtain medical attention. If cyanogen

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