Acetonitrile
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| Names | |||
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| Preferred IUPAC name
Acetonitrile[1] | |||
| Systematic IUPAC name
Ethanenitrile[1] | |||
Other names
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| Identifiers | |||
3D model (JSmol)
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| 741857 | |||
| ChEBI | |||
| ChEMBL | |||
| ChemSpider | |||
| ECHA InfoCard | 100.000.760 | ||
| EC Number |
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| 895 | |||
| MeSH | acetonitrile | ||
PubChem CID
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| RTECS number |
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| UNII | |||
| UN number | 1648 | ||
CompTox Dashboard (EPA)
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| Properties | |||
| C2H3N | |||
| Molar mass | 41.053 g·mol−1 | ||
| Appearance | Colorless liquid | ||
| Odor | ether-like (threshold 39.8 ppm)[2] | ||
| Density | 0.786 g/cm3 | ||
| 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 | ||
| Miscible | |||
| log P | −0.54[2] | ||
| Vapor pressure | 9.71 kPa (at 20 °C (68 °F; 293 K)) | ||
Henry's law
constant (kH) |
530 μmol/(Pa·kg) | ||
| Acidity (pKa) | 25 | ||
| UV-vis (λmax) | 195 nm | ||
| Absorbance | ≤ 0.10 | ||
| −28.0×10−6 cm3/mol | |||
Refractive index (nD)
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1.344[2] | ||
| Viscosity | 0.350 Pa·s (20 °C (68 °F; 293 K))[2] | ||
| 3.92 D[3] | |||
| Thermochemistry | |||
Heat capacity (C)
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91.69 J⋅K−1·mol-1 | ||
Std molar
entropy (S⦵298) |
149.62 J⋅K−1·mol-1 | ||
Std enthalpy of
formation (ΔfH⦵298) |
40.16 to 40.96 kJ⋅mol−1 | ||
Std enthalpy of
combustion (ΔcH⦵298) |
−1256.03 to −1256.63 kJ⋅mol−1 | ||
Enthalpy of fusion (ΔfH⦵fus)
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8.167 kJ⋅mol−1 (crystalline to liquid) | ||
Enthalpy of vaporization (ΔfHvap)
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| Hazards | |||
| GHS labelling:[2] | |||
 
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| Danger | |||
| H225, H302+H312+H332, H319 | |||
| P210, P233, P240, P241, P242, P243, P261, P264, P270, P271, P280, P301+P312+P330, P303+P361+P353, P304+P340+P312, P305+P351+P338, P337+P313, P370+P378, P403+P235, P501 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | 2.0 °C (35.6 °F; 275.1 K) | ||
| 523.0 °C (973.4 °F; 796.1 K)[2] | |||
| Explosive limits | 4.4%–16.0% | ||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose)
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LC50 (median concentration)
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LCLo (lowest published)
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16,000 ppm (dog, 4 hr)[4] | ||
| NIOSH (US health exposure limits):[6] | |||
PEL (Permissible)
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40 ppm (70 mg/m3, TWA) | ||
REL (Recommended)
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20 ppm (34 mg/m3, TWA) | ||
IDLH (Immediate danger)
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500 ppm | ||
| Related compounds | |||
Related alkanenitriles
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| 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).
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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.[7] The N≡C−C skeleton is linear with a short C≡N distance of 1.16 Å.[8]
Acetonitrile was first prepared in 1847 by the French chemist Jean-Baptiste Dumas.[9]
Applications
[edit]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.[citation needed]
In the laboratory, it is used as a medium-polarity non-protic solvent that is miscible with water and a range of organic solvents, but not saturated hydrocarbons. It has a convenient range of temperatures at which it is a liquid, and dissolves a wide range of ionic and nonpolar compounds and is useful as a mobile phase in HPLC and LC–MS.[citation needed]
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.[citation needed]
Its ultraviolet transparency UV cutoff, low viscosity and low chemical reactivity make it a popular choice for high-performance liquid chromatography (HPLC).[citation needed]
Acetonitrile plays a significant role as the dominant solvent used in oligonucleotide synthesis from nucleoside phosphoramidites.[citation needed]
Industrially, it is used as a solvent for the manufacture of pharmaceuticals and photographic film.[10]
Organic synthesis
[edit]Acetonitrile is a common two-carbon building block in organic synthesis of many useful chemicals, including acetamidine hydrochloride, thiamine, and 1-naphthaleneacetic acid, along with more complex nitriles.[11][12] Its reaction with cyanogen chloride affords malononitrile.[7]
As an electron pair donor
[edit]Acetonitrile has a free electron pair at the nitrogen atom, which can form many transition metal nitrile complexes. For example, bis(acetonitrile)palladium dichloride is prepared by heating a suspension of palladium chloride in acetonitrile:[13]
- PdCl2 + 2 CH3CN → PdCl2(CH3CN)2
A related complex is tetrakis(acetonitrile)copper(I) hexafluorophosphate [Cu(CH3CN)4]+. The CH3CN ligands in these complexes are rapidly displaced.[citation needed]
It also forms Lewis adducts with group 13 Lewis acids like boron trifluoride.[14] In superacids, it is possible to protonate acetonitrile.[15]
Production
[edit]Acetonitrile is a byproduct from the manufacture of acrylonitrile by catalytic ammoxidation of propylene. Most is combusted to support the intended process but an estimated several thousand tons are retained for the above-mentioned applications.[16] Production trends for acetonitrile thus generally follow those of acrylonitrile. In 1992[update], 14,700 tonnes (16,200 short tons) of acetonitrile were produced in the US.[citation needed]
Safety
[edit]Toxicity
[edit]Acetonitrile has only modest toxicity in small doses.[11][17] It can be metabolised to produce hydrogen cyanide, which is the source of the observed toxic effects.[10][18][19] 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 are rare but not unknown by inhalation and ingestion.[18] 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.[18]
It has been used in a formulation for removal of sculptured fingernails. At least two cases have been reported of accidental poisoning of young children by acetonitrile-based sculptured nail remover, one of which was fatal.[20] 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.[21][importance?]
Metabolism and excretion
[edit]| Compound | Cyanide, concentration in brain (μg/kg) | Oral LD50 (mg/kg) |
|---|---|---|
| Potassium cyanide | 700±200 | 10 |
| Propionitrile | 510±80 | 40 |
| Butyronitrile | 400±100 | 50 |
| Malononitrile | 600±200 | 60 |
| Acrylonitrile | 400±100 | 90 |
| Acetonitrile | 28±5 | 2460 |
| 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.[22] | ||
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.[23] 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.[17][18] 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 1/20 that for a propionitrile dose 60 times lower (see table).[22]
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 acetonitrile to be excreted unchanged before it is metabolised. The main pathways of excretion are by exhalation and in the urine.[17][18][19]
See also
[edit]- Trichloroacetonitrile – a derivative of acetonitrile used as a protecting group for hydroxyls, and also used as a reagent in the Overman rearrangement.
References
[edit]- ^ a b Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 902. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
- ^ a b c d e f g h Sigma-Aldrich Co., Acetonitrile.
- ^ Alston Steiner, P.; Gordy, W. (1966). "Precision measurement of dipole moments and other spectral constants of normal and deuterated methyl fluoride and methyl cyanide". Journal of Molecular Spectroscopy. 21 (1–4): 291–301. doi:10.1016/0022-2852(66)90152-4.
- ^ a b "Acetonitrile". Immediately Dangerous to Life or Health Concentrations. National Institute for Occupational Safety and Health.
- ^ "SDS - Acetonitrile". fishersci.com. Thermo Fisher Scientific. 13 January 2025. Retrieved 3 November 2025.
- ^ "NIOSH Pocket Guide to Chemical Hazards".
- ^ a b Ashford's Dictionary of Industrial Chemicals (PDF) (3rd ed.). p. 76. ISBN 978-0-9522674-3-0. Archived from the original (PDF) on 2011-05-16. Retrieved 2011-03-31.
- ^ Karakida, Ken'ichi; Fukuyama, Tsutomu; Kuchitsu, Kozo (1974). "Molecular Structures of Hydrogen Cyanide and Acetonitrile as Studied by Gas Electron Diffraction". Bulletin of the Chemical Society of Japan. 47 (2): 299–304. doi:10.1246/bcsj.47.299.
- ^ Dumas, J.-B. (1847). "Action de l'acide phosphorique anhydre sur les sels ammoniacaux" [Action of anhydrous phosphoric acid on ammonium salts]. Comptes rendus. 25: 383–384.
- ^ a b Spanish Ministry of Health (2002). Acetonitrile. Summary Risk Assessment Report (PDF) (Report). Ispra (VA), Italy: European Chemicals Bureau: Ministry of Health (Spain). Special Publication I.01.65. Archived from the original (PDF) on 2008-12-17.
- ^ a b c Wexler, Philip, ed. (2005). Encyclopedia of toxicology. Vol. 1 (2nd ed.). Oxford: Elsevier. pp. 28–30. ISBN 0-12-745354-7.
- ^ DiBiase, S. A.; Beadle, J. R.; Gokel, G. W. "Synthesis of α,β-Unsaturated Nitriles from Acetonitrile: Cyclohexylideneacetonitrile and Cinnamonitrile". Organic Syntheses; Collected Volumes, vol. 7, p. 108.
- ^ Jürgen-Hinrich., Fuhrhop (2003). Organic synthesis : concepts and methods. Li, Guangtao, Dr. (3rd, completely rev. and enl. ed.). Weinheim: Wiley-VCH. p. 26. ISBN 9783527302727. OCLC 51068223.
- ^ Swanson, Basil; Shriver, Durward F.; Ibers, James A. (October 1969). "Nature of the donor-acceptor bond in acetonitrile-boron trihalides. The structures of the boron trifluoride and boron trichloride complexes of acetonitrile". Inorganic Chemistry. 8 (10): 2182–2189. doi:10.1021/ic50080a032.
- ^ Haiges, Ralf; Baxter, Amanda F.; Goetz, Nadine R.; Axhausen, Joachim A.; Soltner, Theresa; Kornath, Andreas; Christe, Kalr O. (2016). "Protonation of nitriles: isolation and characterization of alkyl- and arylnitrilium ions". Dalton Transactions. 45 (20): 8494–8499. doi:10.1039/C6DT01301E. PMID 27116374.
- ^ Pollak, Peter; Romeder, Gérard; Hagedorn, Ferdinand; Gelbke, Heinz-Peter. "Nitriles". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a17_363. ISBN 978-3-527-30673-2.
- ^ a b c Fiche toxicologique no. 104: Acétonitrile (PDF). www.inrs.fr (Report). paris: Institut national de recherche et de sécurité (INRS). 2004. ISBN 2-7389-1278-8. Archived from the original (PDF) on 2011-07-28. Retrieved 2008-08-19.
- ^ a b c d e "Environmental Health Criteria 154. Acetonitrile". Geneva: World Health Organization: International Programme on Chemical Safety. 1993.
- ^ a b Greenberg, Mark (1999). Toxicological Review of Acetonitrile (PDF) (Report). Washington, DC: U.S. Environmental Protection Agency. Archived from the original (PDF) on February 4, 2011.
- ^ Caravati, E. M.; Litovitz, T. (1988). "Pediatric cyanide intoxication and death from an acetonitrile-containing cosmetic". J. Am. Med. Assoc. 260 (23): 3470–73. doi:10.1001/jama.260.23.3470. PMID 3062198.
- ^ Twenty-Fifth Commission Directive 2000/11/EC of 10 March 2000 adapting to technical progress Annex II to Council Directive 76/768/EEC on the approximation of laws of the Member States relating to cosmetic products. Official Journal of the European Communities (Report). Vol. L65. 2000-03-14. pp. 22–25.
- ^ a b Ahmed, Ahmed E.; Farooqui, Mohammed Y.H. (July 1982). "Comparative toxicities of aliphatic nitriles". Toxicology Letters. 12 (2–3): 157–163. doi:10.1016/0378-4274(82)90179-5. PMID 6287676.
- ^ Pozzani, U C; Carpenter, C P; Palm, P E; Weil, C S; Nair, J H (December 1959). "An Investigation of the Mammalian Toxicity of Acetonitrile:". Journal of Occupational and Environmental Medicine. 1 (12): 634–642. doi:10.1097/00043764-195912000-00003. PMID 14434606.
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