(Diazirine, azimethylene)

CAS 334-88-3





Physical Properties

Yellow gas

bp - 23 °C, mp -145 °C

Reacts with water



Musty odor (no accepted threshold value)

Vapor Density

1.4 (air = 1.0)


Autoignition Temperature

150 °C; impure material explodes at lower temperature

Toxicity Data

LCLO inhal (cat)

175 ppm (10 min)



0.2 ppm (0.4 mg/m3)



0.2 ppm (0.4 mg/m3)

Major Hazards

Powerful allergen with high acute toxicity; extremely unstable; may explode on contact with alkali metals, calcium sulfate (Drierite), or rough edges such as those found on ground glass.



Diazomethane vapor causes severe irritation of the skin, eyes, mucous membranes, and lungs. It is considered to be a substance with poor warning properties, and the effects of exposure may be delayed in onset. Symptoms of exposure may include headache, chest pain, cough, fever, severe asthmatic attacks, and pulmonary edema, which can be fatal. Exposure of the skin and mucous membranes to diazomethane may cause serious burns.

Diazomethane is a powerful allergen. Prolonged or repeated exposure to diazomethane can lead to sensitization of the skin and lungs, in which case asthma-like symptoms or fever may occur as the result of exposure to concentrations of diazomethane that previously caused no symptoms. Chronic exposure to diazomethane has been reported to cause cancer in experimental animals, but this substance has not been identified as a human carcinogen.

Note that diazomethane is often prepared in situ from precursors that may themselves be highly toxic and/or carcinogenic.

Flammability and Explosibility

Pure diazomethane gas and liquid are readily flammable and can explode easily. A variety of conditions have been reported to cause explosions of diazomethane, including contact with rough surfaces such as ground-glass joints, etched or scratched flasks, and glass tubing that has not been carefully fire-polished. Direct sunlight and strong artificial light

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement