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Skeletal formula of acetonitrile Acetonitrile-2D-skeletal.svg
Skeletal formula of acetonitrile
Skeletal formula of acetonitrile with all explicit hydrogens added Acetonitrile-2D-flat.svg
Skeletal formula of acetonitrile with all explicit hydrogens added
Ball and stick model of acetonitrile Acetonitrile-3D-balls.png
Ball and stick model of acetonitrile
Spacefill model of acetonitrile Acetonitrile-3D-vdW.png
Spacefill model of acetonitrile
Preferred IUPAC name
Acetonitrile [1]
Systematic IUPAC name
Ethanenitrile [1]
Other names
  • Cyanomethane [2]
  • Ethyl nitrile [2]
  • Methanecarbonitrile [2]
  • Methyl cyanide [2]
  • MeCN
  • ACN
3D model (JSmol)
ECHA InfoCard 100.000.760 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 200-835-2
MeSH acetonitrile
PubChem CID
RTECS number
  • AL7700000
UN number 1648
  • InChI=1S/C2H3N/c1-2-3/h1H3 Yes check.svgY
  • CC#N
Molar mass 41.053 g·mol−1
AppearanceColorless liquid
Odor Faint, distinct, fruity
Density 0.786 g/cm3 at 25°C
Melting point −46 to −44 °C; −51 to −47 °F; 227 to 229 K
Boiling point 81.3 to 82.1 °C; 178.2 to 179.7 °F; 354.4 to 355.2 K
log P −0.334
Vapor pressure 9.71 kPa (at 20.0 °C)
530 μmol/(Pa·kg)
Acidity (pKa)25
UV-vismax)195 nm
Absorbance ≤0.10
−28.0×10−6 cm3/mol
91.69 J/(K·mol)
Std molar
149.62 J/(K·mol)
40.16–40.96 kJ/mol
−1256.03 – −1256.63 kJ/mol
GHS labelling:
GHS-pictogram-flamme.svg GHS-pictogram-exclam.svg
H225, H302, H312, H319, H332
P210, P280, P305+P351+P338
NFPA 704 (fire diamond)
Flash point 2.0 °C (35.6 °F; 275.1 K)
523.0 °C (973.4 °F; 796.1 K)
Explosive limits 4.4–16.0%
Lethal dose or concentration (LD, LC):
  • 2 g/kg (dermal, rabbit)
  • 2.46 g/kg (oral, rat)
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) [3]
16,000 ppm (dog, 4 hr) [3]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 40 ppm (70 mg/m3) [4]
REL (Recommended)
TWA 20 ppm (34 mg/m3) [4]
IDLH (Immediate danger)
500 ppm [4]
Related compounds
Related alkanenitriles
Related compounds
Supplementary data page
Acetonitrile (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

Acetonitrile, often abbreviated MeCN (methyl cyanide), is the chemical compound with the formula CH3CN and structure H3C−C≡N. This colourless liquid is the simplest organic nitrile (hydrogen cyanide is a simpler nitrile, but the cyanide anion is not classed as organic). It is produced mainly as a byproduct of acrylonitrile manufacture. It is used as a polar aprotic solvent in organic synthesis and in the purification of butadiene. [5] The N≡C−C skeleton is linear with a short C≡N distance of 1.16  Å. [6]


Acetonitrile was first prepared in 1847 by the French chemist Jean-Baptiste Dumas. [7]


Acetonitrile is used mainly as a solvent in the purification of butadiene in refineries. Specifically, acetonitrile is fed into the top of a distillation column filled with hydrocarbons including butadiene, and as the acetonitrile falls down through the column, it absorbs the butadiene which is then sent from the bottom of the tower to a second separating tower. Heat is then employed in the separating tower to separate the butadiene.

In the laboratory, it is used as a medium-polarity solvent that is miscible with water and a range of organic solvents, but not saturated hydrocarbons. It has a convenient liquid range and a high dielectric constant of 38.8. With a dipole moment of 3.92  D, [8] acetonitrile dissolves a wide range of ionic and nonpolar compounds and is useful as a mobile phase in HPLC and LC–MS.

It is widely used in battery applications because of its relatively high dielectric constant and ability to dissolve electrolytes. For similar reasons it is a popular solvent in cyclic voltammetry.

Its ultraviolet transparency UV cutoff, low viscosity and low chemical reactivity make it a popular choice for high-performance liquid chromatography (HPLC).

Acetonitrile plays a significant role as the dominant solvent used in oligonucleotide synthesis from nucleoside phosphoramidites.

Industrially, it is used as a solvent for the manufacture of pharmaceuticals and photographic film. [9]

Organic synthesis

Acetonitrile is a common two-carbon building block in organic synthesis [10] of many useful chemicals, including acetamidine hydrochloride, thiamine, and α-napthaleneacetic acid. [11] Its reaction with cyanogen chloride affords malononitrile. [5]

As an electron pair donor

Acetonitrile has a free electron pair at the nitrogen atom, which can form many transition metal nitrile complexes. Being weakly basic, it is an easily displaceable ligand. For example, bis(acetonitrile)palladium dichloride is prepared by heating a suspension of palladium chloride in acetonitrile: [12]

A related complex is tetrakis(acetonitrile)copper(I) hexafluorophosphate [Cu(CH3CN)4]+. The CH3CN groups in these complexes are rapidly displaced by many other ligands.

It also forms Lewis adducts with group 13 Lewis acids like boron trifluoride. [13] In superacids, it is possible to protonate acetonitrile. [14]


Acetonitrile is a byproduct from the manufacture of acrylonitrile. Most is combusted to support the intended process but an estimated several thousand tons are retained for the above-mentioned applications. [15] Production trends for acetonitrile thus generally follow those of acrylonitrile. Acetonitrile can also be produced by many other methods, but these are of no commercial importance as of 2002. Illustrative routes are by dehydration of acetamide or by hydrogenation of mixtures of carbon monoxide and ammonia. [16] In 1992, 14,700 tonnes (32,400,000 lb) of acetonitrile were produced in the US.

Catalytic ammoxidation of ethylene was also researched. [17]

Acetonitrile shortage in 2008–2009

Starting in October 2008, the worldwide supply of acetonitrile was low because Chinese production was shut down for the Olympics. Furthermore, a U.S. factory was damaged in Texas during Hurricane Ike. [18] Due to the global economic slowdown, the production of acrylonitrile used in acrylic fibers and acrylonitrile butadiene styrene (ABS) resins decreased. Acetonitrile is a byproduct in the production of acrylonitrile and its production also decreased, further compounding the acetonitrile shortage. [19] The global shortage of acetonitrile continued through early 2009.[ needs update ]



Acetonitrile has only modest toxicity in small doses. [11] [20] It can be metabolised to produce hydrogen cyanide, which is the source of the observed toxic effects. [9] [21] [22] Generally the onset of toxic effects is delayed, due to the time required for the body to metabolize acetonitrile to cyanide (generally about 2–12 hours). [11]

Cases of acetonitrile poisoning in humans (or, to be more specific, of cyanide poisoning after exposure to acetonitrile) are rare but not unknown, by inhalation, ingestion and (possibly) by skin absorption. [21] The symptoms, which do not usually appear for several hours after the exposure, include breathing difficulties, slow pulse rate, nausea, and vomiting. Convulsions and coma can occur in serious cases, followed by death from respiratory failure. The treatment is as for cyanide poisoning, with oxygen, sodium nitrite, and sodium thiosulfate among the most commonly used emergency treatments. [21]

It has been used in formulations for nail polish remover, despite its toxicity. At least two cases have been reported of accidental poisoning of young children by acetonitrile-based nail polish remover, one of which was fatal. [23] Acetone and ethyl acetate are often preferred as safer for domestic use, and acetonitrile has been banned in cosmetic products in the European Economic Area since March 2000. [24]

Metabolism and excretion

CompoundCyanide, concentration in brain (μg/kg)Oral LD50 (mg/kg)
Potassium cyanide 700 ± 20010
Propionitrile 510 ± 8040
Butyronitrile 400 ± 10050
Malononitrile 600 ± 20060
Acrylonitrile 400 ± 10090
Acetonitrile28 ± 52460
Table salt (NaCl)3000
Ionic cyanide concentrations measured in the brains of Sprague-Dawley rats one hour after oral administration of an LD50 of various nitriles. [25]

In common with other nitriles, acetonitrile can be metabolised in microsomes, especially in the liver, to produce hydrogen cyanide, as was first shown by Pozzani et al. in 1959. [26] The first step in this pathway is the oxidation of acetonitrile to glycolonitrile by an NADPH-dependent cytochrome P450 monooxygenase. The glycolonitrile then undergoes a spontaneous decomposition to give hydrogen cyanide and formaldehyde. [20] [21] Formaldehyde, a toxin and a carcinogen on its own, is further oxidized to formic acid, which is another source of toxicity.

The metabolism of acetonitrile is much slower than that of other nitriles, which accounts for its relatively low toxicity. Hence, one hour after administration of a potentially lethal dose, the concentration of cyanide in the rat brain was 120 that for a propionitrile dose 60 times lower (see table). [25]

The relatively slow metabolism of acetonitrile to hydrogen cyanide allows more of the cyanide produced to be detoxified within the body to thiocyanate (the rhodanese pathway). It also allows more of the acetonitrile to be excreted unchanged before it is metabolised. The main pathways of excretion are by exhalation and in the urine. [20] [21] [22]

See also

Related Research Articles

<span class="mw-page-title-main">Cyanide</span> Any molecule with a cyano group (–C≡N)

In chemistry, a cyanide is a chemical compound that contains a C≡N functional group. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom.

Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure H−C≡N. It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at 25.6 °C (78.1 °F). HCN is produced on an industrial scale and is a highly valued precursor to many chemical compounds ranging from polymers to pharmaceuticals. Large-scale applications are for the production of potassium cyanide and adiponitrile, used in mining and plastics, respectively. It is more toxic than solid cyanide compounds due to its volatile nature.

<span class="mw-page-title-main">Sodium cyanide</span> Chemical compound

Sodium cyanide is a poisonous compound with the formula NaCN. It is a white, water-soluble solid. Cyanide has a high affinity for metals, which leads to the high toxicity of this salt. Its main application, in gold mining, also exploits its high reactivity toward metals. It is a moderately strong base.

Acrylonitrile is an organic compound with the formula CH2CHCN and the structure H2C=CH−C≡N. It is a colorless, volatile liquid although commercial samples can be yellow due to impurities. It has a pungent odor of garlic or onions. Its molecular structure consists of a vinyl group linked to a nitrile. It is an important monomer for the manufacture of useful plastics such as polyacrylonitrile. It is reactive and toxic at low doses. Acrylonitrile was first synthesized by the French chemist Charles Moureu (1863–1929) in 1893.

1,3-Butadiene is the organic compound with the formula CH2=CH-CH=CH2. It is a colorless gas that is easily condensed to a liquid. It is important industrially as a precursor to synthetic rubber. The molecule can be viewed as the union of two vinyl groups. It is the simplest conjugated diene.

<span class="mw-page-title-main">Cyanohydrin</span> Functional group in organic chemistry

In organic chemistry, a cyanohydrin or hydroxynitrile is a functional group found in organic compounds in which a cyano and a hydroxy group are attached to the same carbon atom. The general formula is R2C(OH)CN, where R is H, alkyl, or aryl. Cyanohydrins are industrially important precursors to carboxylic acids and some amino acids. Cyanohydrins can be formed by the cyanohydrin reaction, which involves treating a ketone or an aldehyde with hydrogen cyanide (HCN) in the presence of excess amounts of sodium cyanide (NaCN) as a catalyst:

In organic chemistry, a nitrile is any organic compound that has a −C≡N functional group. The prefix cyano- is used interchangeably with the term nitrile in industrial literature. Nitriles are found in many useful compounds, including methyl cyanoacrylate, used in super glue, and nitrile rubber, a nitrile-containing polymer used in latex-free laboratory and medical gloves. Nitrile rubber is also widely used as automotive and other seals since it is resistant to fuels and oils. Organic compounds containing multiple nitrile groups are known as cyanocarbons.

<span class="mw-page-title-main">Allyl chloride</span> Chemical compound

Allyl chloride is the organic compound with the formula CH2=CHCH2Cl. This colorless liquid is insoluble in water but soluble in common organic solvents. It is mainly converted to epichlorohydrin, used in the production of plastics. It is a chlorinated derivative of propylene. It is an alkylating agent, which makes it both useful and hazardous to handle.

In organic chemistry, hydrocyanation is a process for conversion of alkenes to nitriles. The reaction involves the addition of hydrogen cyanide and requires a catalyst. This conversion is conducted on an industrial scale for the production of precursors to nylon.

<span class="mw-page-title-main">Butyronitrile</span> Chemical compound

Butyronitrile or butanenitrile or propyl cyanide, is a nitrile with the formula C3H7CN. This colorless liquid is miscible with most polar organic solvents.

<span class="mw-page-title-main">Dimethylacetamide</span> Chemical compound

Dimethylacetamide (DMAc or DMA) is the organic compound with the formula CH3C(O)N(CH3)2. This colorless, water-miscible, high-boiling liquid is commonly used as a polar solvent in organic synthesis. DMA is miscible with most other solvents, although it is poorly soluble in aliphatic hydrocarbons.

<span class="mw-page-title-main">Succinonitrile</span> Chemical compound

Succinonitrile, also butanedinitrile, is a nitrile, with the formula of C2H4(CN)2. It is a colorless waxy solid which melts at 58 °C.

<span class="mw-page-title-main">Adiponitrile</span> Chemical compound

Adiponitrile is an organic compound with the chemical formula (CH2)4(CN)2. This viscous, colourless dinitrile is an important precursor to the polymer nylon 66. In 2005, about one million tonnes of adiponitrile were produced.

Acetone cyanohydrin (ACH) is an organic compound used in the production of methyl methacrylate, the monomer of the transparent plastic polymethyl methacrylate (PMMA), also known as acrylic. It liberates hydrogen cyanide easily, so it is used as a source of such. For this reason, this cyanohydrin is also highly toxic.

In organic synthesis, cyanation is the attachment or substitution of a cyanide group on various substrates. Such transformations are high-value because they generate C-C bonds. Furthermore nitriles are versatile functional groups.

<span class="mw-page-title-main">Ammoxidation</span> Chemical process for producing nitriles from ammonia and oxygen

In organic chemistry, ammoxidation is a process for the production of nitriles using ammonia and oxygen. It is sometimes called the SOHIO process, acknowledging that ammoxidation was developed at Standard Oil of Ohio. The usual substrates are alkenes. Several million tons of acrylonitrile are produced in this way annually:

Glycolonitrile, also called hydroxyacetonitrile or formaldehyde cyanohydrin, is the organic compound with the formula HOCH2CN. It is the simplest cyanohydrin and it is derived from formaldehyde. It is a colourless liquid that dissolves in water and ether. Because glycolonitrile decomposes readily into formaldehyde and hydrogen cyanide, it is listed as an extremely hazardous substance. In January 2019, astronomers reported the detection of glycolonitrile, another possible building block of life among other such molecules, in outer space.

Methacrylonitrile, MeAN in short, is a chemical compound that is an unsaturated aliphatic nitrile, widely used in the preparation of homopolymers, copolymers, elastomers, and plastics and as a chemical intermediate in the preparation of acids, amides, amines, esters, and other nitriles. MeAN is also used as a replacement for acrylonitrile in the manufacture of an acrylonitrile/butadiene/styrene-like polymer. It is a clear and colorless liquid, that has a bitter almond smell.

Propionitrile, also known as ethyl cyanide and propanenitrile, is an organic compound with the formula CH3CH2CN. It is a simple aliphatic nitrile. The compound is a colourless, water-soluble liquid. It is used as a solvent and a precursor to other organic compounds.

<span class="mw-page-title-main">Transition metal nitrile complexes</span> Class of coordination compounds containing nitrile ligands (coordinating via N)

Transition metal nitrile complexes are coordination compounds containing nitrile ligands. Because nitriles are weakly basic, the nitrile ligands in these complexes are often labile.


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