(Methyl cyanide, cyanomethane)

CAS 75-05-8





Physical Properties

Colorless liquid

bp 82 °C, mp - 46°C

Miscible with water (>100 g/100 mL)



Aromatic ether-like odor detectable at 40 ppm

Vapor Density

1.42 (air = 1.0)


Vapor Pressure

73 mmHg at 20 °C


Flash Point

6 °C


Autoignition Temperature

524 °C


Toxicity Data

LD50 oral (rat)

LD30 mg/kg


LD50 skin (rabbit)

1250 mg/kg


LC50 inhal (rat)

7551 ppm (8 h)



40 ppm (70 mg/m3)



60 ppm (105 mg/m3)



40 ppm (70 mg/m3)



60 ppm (105 mg/m3)

Major Hazards

Flammable liquid and vapor; liquid severely irritates the eyes.


Acetonitrile is slightly toxic by acute exposure through oral intake, skin contact, and inhalation. However, acetonitrile can be converted by the body to cyanide. Symptoms of exposure include weakness, flushing, headache, difficult and/or rapid breathing, nausea, vomiting, diarrhea, blue-gray discoloration of the skin and lips (due to a lack of oxygen), stupor, and loss of consciousness. Acetonitrile is severely irritating to the eyes and slightly irritating to the skin. Prolonged contact can lead to absorption through the skin and more intense irritation. Acetonitrile is regarded as having adequate warning properties.

Acetonitrile is not mutagenic in bacterial and animal cells and has not been found to be a carcinogen in humans. Single high-dose exposure in animals during pregnancy produced birth defects possibly due to the liberation of cyanide. Multiple oral doses during pregnancy did not produce birth defects. Repeated exposure in animals produced adverse lung effects.

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