Acetonitrile sample and its original bottle.
| IUPAC name
| Systematic IUPAC name
| Other names
|Molar mass||41.05 g/mol|
|Melting point||−46 to −44 °C (−51 to −47 °F; 227 to 229 K)|
|Boiling point||81.3 to 82.1 °C (178.3 to 179.8 °F; 354.4 to 355.2 K)|
|Solubility||Miscible with acetone, ethanol, methyl ethyl ketone, toluene, xylene|
|Vapor pressure||9.71 kPa (at 20.0 °C)|
Std enthalpy of
|Safety data sheet||ScienceLab|
|Flash point||2.0 °C|
|Lethal dose or concentration (LD, LC):|
LD50 (Median dose)
| 2 g/kg (dermal, rabbit)|
2.46 g/kg (oral, rat)
LC50 (Median concentration)
| 5655 ppm (guinea pig, 4 hr)|
2828 ppm (rabbit, 4 hr)
53,000 ppm (rat, 30 min)
7500 ppm (rat, 8 hr)
2693 ppm (mouse, 1 hr)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Acetonitrile, also known as cyanomethane, ethanenitrile or methyl cyanide is a organic chemical compound, mainly used as a solvent in chemistry. It has the formula CH3CN.
Acetonitrile reacts with aldehydes to form hydroxynitriles.
- R-CHO + CH3CN → R-CH(OH)-CH2(CN)
Palladium chloride will form a complex with acetonitrile:
- PdCl2 + 2 CH3CN → PdCl2[CH3CN]2
Pyrolysis of acetonitrile yields primarily methane and hydrogen cyanide.
Acetonitrile burns in air with a gray-pinkish flame.
Acetonitrile is a colorless liquid, with a faint ether-like or sweet-burnt smell. It is miscible with a variety of organic solvents, but immiscible with saturated hydrocarbons. Acetonitile is hygroscopic, and will readily absorb water from air if kept in open air over time. It has a melting point between −46 to −44 °C and a boiling point between 81.3 to 82.1 °C.
Acetonitrile can be purchased from chemical suppliers. ScienceStuff sells 1 liter at $76.88 + UPS hazardous material surcharge of $28.50 per shipment. In most places it's difficult to acquire due to being a cyanide compound.
- CH3COONH4 → CH3C(O)NH2 + H2O
- CH3C(O)NH2 → CH3CN + H2O
Phosphorus pentoxide is is widely used as catalyst. Other dehydrating agents include titanium(IV) chloride, thionyl chloride and trifluoroacetic anhydride. Dehydration is know to produce lots of side products, which form a hard to remove goo.
The book Catalysis in organic chemistry by P. Sabatier (see Library below) mentions several authors which claim that it's possible to obtain acetonitrile by dehydrating acetamide, via refluxing at 250-260 °C, for 4 hours, using readily available materials as catalyst.
|Catalyst||Alumina||Lamp black||Pumice||Powdered glass||Sand||Horse teeth|
By carrying the amide in a current of air over the catalyst heated to 420 °C, the yields are improved:
Aqueous palladium(II) chloride can convert primary amides into nitriles, in a water-acetonitrile 1:1 mixture, the conversion takes place at room temperature over the course of several hours.
Heating methylurea with ammonium sulfamate will yield acetonitrile.
- Ethylamine synthesis
Acetonitrile has modest toxicity in small doses, but it will be metabolised by the organism to produce hydrogen cyanide, which is very toxic. This occurs several hours after the exposure. Acetonitrile can be absorbed through the skin and via inhalation, so proper protection, such as gloves and a mask should be worn. See cyanide for antidotes and methods of treatment.
Acetonitrile however, has a much lower toxicity than the other simple nitriles, with a LD50 of 2,460 mg/kg, while the next primary nitriles (propionitrile, butyronitrile, malononitrile, acrylonitrile) have LD50 values between 40-90 mg/kg.
Acetontrile is very hygroscopic and must be stored in closed bottles. Anhydrous calcium chloride pellets are usually added to keep the solvent dry.