Acetonitrile
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| Names | |||
|---|---|---|---|
| IUPAC name
Acetonitrile[2]
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| Other names | |||
| 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 | ||
| Density | 0.786 g mL−1 | ||
| 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 | −0.334 | ||
| Vapor pressure | 9.71 kPa (at 20.0 °C) | ||
Henry's law
constant (kH) |
530 μmol Pa−1 kg−1 | ||
| Acidity (pKa) | 25 | ||
| Basicity (pKb) | −11 | ||
| UV-vis (λmax) | 195 nm | ||
| Absorbance | ≤0.10 | ||
Refractive index (nD)
|
1.344 | ||
| Thermochemistry | |||
Heat capacity (C)
|
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) |
40.16–40.96 kJ mol−1 | ||
Std enthalpy of
combustion (ΔcH⦵298) |
−1256.03–−1256.63 kJ mol−1 | ||
| Hazards | |||
| GHS labelling: | |||
 
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| Danger | |||
| 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): | |||
LD50 (median dose)
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LC50 (median concentration)
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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)[4] | ||
LCLo (lowest published)
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16,000 ppm (dog, 4 hr)[4] | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible)
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TWA 40 ppm (70 mg/m3)[3] | ||
REL (Recommended)
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TWA 20 ppm (34 mg/m3)[3] | ||
IDLH (Immediate danger)
|
500 ppm[3] | ||
| Related compounds | |||
Related alkanenitriles
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Related compounds
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DBNPA | ||
| 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 is the chemical compound with the formula CH
3CN. 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]
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,[6] acetonitrile dissolves a wide range of ionic and nonpolar compounds and is useful as a mobile phase in HPLC and LC-MS. The N-C-C skeleton is linear with a short C-N distance of 1.16 Å.[7]
Acetonitrile was first prepared in 1847 by the French chemist Jean-Baptiste Dumas.[8]
Applications
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.
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 the manufacture of DNA oligonucleotides from monomers.
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]
Ligand in coordination chemistry
In inorganic chemistry, acetonitrile is employed as a solvent and often an easily displaceable ligand. For example, PdCl
2(CH
3CN)
2 is prepared by heating a suspension of (polymeric) palladium chloride in acetonitrile:[citation needed]
- PdCl
2 + 2 CH
3CN → PdCl
2(CH
3CN)
2
A related complex is [Cu(MeCN)4]+. The CH
3CN groups in these complexes are rapidly displaced by many other ligands.
Production
Acetonitrile is a by-product 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.[13] 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.[14] In 1992[update], 32.3 million pounds (14,700 t) of acetonitrile were produced in the US.
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.[15] Due to the global economic slowdown, the production of acrylonitrile that is used in acrylic fibers and acrylonitrile-butadiene-styrene (ABS) resins decreased. Because acetonitrile is a byproduct in the production of acrylonitrile, its production has also decreased.[16] The global shortage of acetonitrile continued through early 2009.
Safety
Toxicity
Acetonitrile has only a modest toxicity in small doses.[11][17] It can be metabolised to produce hydrogen cyanide, which is the source of the observed toxic effects.[9][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 (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.[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 formulations for nail polish remover, despite its low but significant toxicity.[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]
Metabolism and excretion
| Compound | Brain cyanide concentration (µg/kg) | Oral LD50 (mg/kg) |
|---|---|---|
| Acetonitrile | 28±5 | 2460 |
| Propionitrile | 508±84 | 40 |
| Butyronitrile | 437±106 | 50 |
| Malononitrile | 649±209 | 60 |
| Acrylonitrile | 395±106 | 90 |
| Potassium cyanide | 748±200 | 10 |
| 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 one-twentieth 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 of the acetonitrile to be excreted unchanged before it is metabolised. The main pathways of excretion are by exhalation and in the urine.[17][18][19]
References
- ^ a b c d e "Material Safety Data Sheet" (PDF).
- ^ "acetonitrile - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification. Retrieved 5 June 2012.
- ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0006". National Institute for Occupational Safety and Health (NIOSH).
- ^ a b "Acetonitrile". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
- ^ a b [1], Ashford's Dictionary of Industrial Chemicals, Third edition, 2011, page 76.
- ^ Steiner, P. A., and Gordy, W., 1966, J. molec. Spectrosc., 21, 291.
- ^ 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 (1847). "Action de l'acide phosphorique anhydre sur les sels ammoniacaux". Comptes rendus. 25: 383–384.
{{cite journal}}: Unknown parameter|trans_title=ignored (|trans-title=suggested) (help) - ^ a b Spanish Ministry of Health (2002), Acetonitrile. Summary Risk Assessment Report (PDF), Ispra (VA), Italy: European Chemicals Bureau, Special Publication I.01.65
- ^ DiBiase, S. A.; Beadle, J. R.; Gokel, G. W. "Synthesis of α,β-Unsaturated Nitriles from Acetonitrile: Cyclohexylideneacetonitrile and Cinnamonitrile". Organic Syntheses
{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 7, p. 108. - ^ a b c Philip Wexler, ed. (2005), Encyclopedia of Toxicology, vol. Vol. 1 (2nd ed.), Elsevier, pp. 28–30, ISBN 0-12-745354-7
{{citation}}:|volume=has extra text (help) - ^ "Complex Organic Molecules Discovered in Infant Star System". ESO Press Release. Retrieved 22 April 2015.
- ^ Pollak, Peter; Romeder, Gérard; Hagedorn, Ferdinand; Gelbke, Heinz-Peter (2000), Nitriles, doi:10.1002/14356007.a17_363.
- ^ US 4179462, Olive, G. & Olive, S., "Process for preparing acetonitrile", published 1979-12-18, assigned to Monsanto Company
- ^ Lowe, Derek (2009), The Great Acetonitrile Shortage, Corante
- ^ A. Tullo. "A Solvent Dries Up". Chemical & Engineering News. 86: 27. doi:10.1021/cen-v086n047.p027.
- ^ a b c Institut national de recherche et de sécurité (INRS) (2004), Fiche toxicologique nº 104 : Acétonitrile (PDF), Paris: INRS, ISBN 2-7389-1278-8
- ^ a b c d e International Programme on Chemical Safety (1993), Environmental Health Criteria 154. Acetonitrile, Geneva: World Health Organization
- ^ a b Greenberg, Mark (1999), Toxicological Review of Acetonitrile (PDF), Washington, D.C.: U.S. Environmental Protection Agency
- ^ At least two cases have been reported of accidental poisoning of young children by acetonitrile-based nail polish remover, one of which was fatal: Caravati, EM; 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. OJEC L65 of 2000-03-14, pp. 22–25.
- ^ a b Ahmed, AE; Farooqui, MYH (1982), "Comparative toxicities of aliphatic nitriles", Toxicol. Lett., 12 (2–3): 157–64, doi:10.1016/0378-4274(82)90179-5, PMID 6287676
- ^ Pozzani, UC; Carpenter, CP; Palm, PE; Weil, CS; Nair, JH (1959), "An investigation of the mammalian toxicity of acetonitrile", J. Occup. Med., 1 (12): 634–642, doi:10.1097/00043764-195912000-00003, PMID 14434606
External links
- WebBook page for C2H3N
- International Chemical Safety Card 0088
- National Pollutant Inventory - Acetonitrile fact sheet
- NIOSH Pocket Guide to Chemical Hazards
- Chemical Summary for Acetonitrile (CAS No. 75-05-8), Office of Pollution Prevention and Toxics, U.S. Environmental Protection Agency
- Simulation of acetonitrile
