Title: Acetonitrile
CAS Registry Number: 75-05-8
Additional Names: Methyl cyanide; cyanomethane; ethanenitrile
Molecular Formula: C2H3N
Molecular Weight: 41.05
Percent Composition: C 58.52%, H 7.37%, N 34.12%
Line Formula: CH3CN
Literature References: Small amounts occur in coal tar. Obtained commercially as a byproduct in manuf of acrylonitrile, q.v.: R. A. Smiley in Kirk-Othmer Encyclopedia of Chemical Technology vol. 15 (Wiley-Interscience, New York, 3rd ed., 1978) p 896. Prepn by dehydration of acetamide: Adkins, Nissen, J. Am. Chem. Soc. 46, 143 (1924); A. I. Vogel, Practical Organic Chemistry (Longmans, London, 3rd ed., 1959) p 407; Gattermann-Wieland, Praxis des Organischen Chemikers (de Gruyter, Berlin, 40th ed., 1961) p 125; or from acetylene and ammonia: DE 365432; Chem. Zentralbl. 1924 I, 2398; 1925 II, 1563. Review of purification methods: Techniques of Chemistry vol. II, entitled "Organic Solvents", J. A. Riddick, W. B. Bunger, Eds. (Wiley-Interscience, New York, 3rd ed., 1970) pp 798-805. Toxicity: H. F. Smyth, C. P. Carpenter, J. Ind. Hyg. Toxicol. 30, 63 (1968).
Properties: Liquid. Ether-like odor. Poisonous! Burns with a luminous flame. mp -45°. bp760 81.6°. Flash pt 12.8°C (55°F). d415 0.78745; d430 0.77125. nD15 1.34604, nD30 1.33934. Dielectric constant at 20° = 38.8. Surface tension at 20° = 29.04 dynes/cm. Misc with water, methanol, methyl acetate, ethyl acetate, acetone, ether, acetamide solutions, chloroform, carbon tetrachloride, ethylene chloride and many unsaturated hydrocarbons. Immiscible with many saturated hydrocarbons (petroleum fractions). Dissolves some in organic salts, e.g., silver nitrate, lithium nitrate, magnesium bromide. Constant boiling mixture with water contains 16% H2O and bp 76°. LD50 orally in rats: 3800 mg/kg (Smyth).
Melting point: mp -45°
Boiling point: bp760 81.6°; bp 76°
Flash point: Flash pt 12.8°C (55°F)
Index of refraction: nD15 1.34604; nD30 1.33934
Density: d415 0.78745; d430 0.77125
Toxicity data: LD50 orally in rats: 3800 mg/kg (Smyth)
CAUTION: Potential symptoms of overexposure are irritation of nose, throat; asphyxia; nausea, vomiting; chest pain; weakness; stupor, convulsions. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 4.
Use: In organic synthesis as starting material for acetophenone, a-naphthaleneacetic acid, thiamine, acetamidine. To remove tars, phenols, and coloring matter from petroleum hydrocarbons which are not soluble in acetonitrile. To extract fatty acids from fish liver oils and other animal and vegetable oils. Can be used to recrystallize steroids. As an indifferent medium in physicochemical investigations. Wherever a polar solvent having a rather high dielectric constant is required. As medium for promoting reactions involving ionization. As a solvent in non-aqueous titrations. As a non-aqueous solvent for inorganic salts.
Acetophenazine Acetophenone Acetosulfone Sodium Acetotoluide Acetoxime

Skeletal formula of acetonitrile Skeletal formula of acetonitrile with all explicit hydrogens added
Ball and stick model of acetonitrile Spacefill model of acetonitrile
CAS number 75-05-8 YesY
PubChem 6342
ChemSpider 6102 YesY
UNII Z072SB282N YesY
EC number 200-835-2
UN number 1648
MeSH acetonitrile
ChEBI CHEBI:38472 YesY
RTECS number AL7700000
Beilstein Reference 741857
Gmelin Reference 895
Jmol-3D images Image 1
Molecular formula C2H3N
Molar mass 41.05 g mol−1
Appearance Colorless liquid
Density 786 mg 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
Solubility in water Miscible
log P −0.334
Vapor pressure 9.71 kPa (at 20.0 °C)
kH 530 μmol Pa−1 kg−1
Acidity (pKa) 25
Basicity (pKb) −11
λmax 195 nm
Absorbance ≤0.10
Refractive index (nD) 1.344
Std enthalpy of
formation ΔfHo298
40.16–40.96 kJ mol−1
Std enthalpy of
combustion ΔcHo298
−1256.03–−1256.63 kJ mol−1
Standard molar
entropy So298
149.62 J K−1 mol−1
Specific heat capacity, C 91.69 J K−1 mol−1
MSDS External MSDS
GHS pictograms The flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
GHS hazard statements H225, H302, H312, H319, H332
GHS precautionary statements P210, P280, P305+351+338
EU Index 608-001-00-3
EU classification Flammable F Harmful Xn
R-phrases R11, R20/21/22, R36
S-phrases (S1/2), S16, S36/37
NFPA 704
NFPA 704.svg
Flash point 2.0 °C; 35.6 °F; 275.1 K
Autoignition temperature 523.0 °C; 973.4 °F; 796.1 K
Explosive limits 4.4–16.0%
  • 2 g kg−1 (dermal, rabbit)
  • 2.46 g kg−1 (oral, rat)
Related compounds
Related alkanenitriles
  • Hydrogen cyanide
  • Thiocyanic acid
  • Cyanogen iodide
  • Cyanogen bromide
  • Cyanogen chloride
  • Cyanogen fluoride
  • Aminoacetonitrile
  • Glycolonitrile
  • Cyanogen
  • Propanenitrile
  • Aminopropionitrile
  • Malononitrile
  • Pivalonitrile
  • Acetone cyanohydrin
Related compounds DBNPA
Supplementary data page
Structure and
n, εr, etc.
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Acetonitrile is the chemical compound with the formula CH
. 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.[3]

In the laboratory, it is used as a medium-polarity solvent that is miscible with water and 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,[4] 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.[5]

Acetonitrile was first prepared in 1847 by the French chemist Jean-Baptiste Dumas.[6]