Acetonitrile

C₂H₃NMolar mass41.053 g·mol Appearance Colorless liquid Odorether-like (threshold 39.8 ppm) Density0.786 g/cmMelting point−46 to −44 °C; −51 to −47 °F; 227 to 229 K Boiling point81.3 to 82.1 °C; 178.2 to 179.7 °F; 354.4 to 355.2 K Critical point (T, P) 545 K (272 °C), 4.87 MPa

Solubility in water

Miscible log P−0.54 Vapor pressure9.71 kPa (at 20 °C (68 °F; 293 K))

Henry's law
constant (k_H)

530 μmol/(Pa·kg)Acidity (pK_a) 25 UV-vis (λ_max) 195 nmAbsorbance≤ 0.10

Magnetic susceptibility (χ)

−28.0×10 cm/mol

Refractive index (n_D)

1.344 Viscosity0.350 mPa·s (20 °C (68 °F; 293 K))

Dipole moment

3.92 DThermochemistry

Heat capacity(C)

91.69 J⋅K·mol

Std molar
entropy(S₂₉₈)

149.62 J⋅K·mol

Std enthalpy of
formation(Δ_fH₂₉₈)

40.16 to 40.96 kJ⋅mol

Std enthalpy of
combustion(Δ_cH₂₉₈)

−1256.03 to −1256.63 kJ⋅mol

Enthalpy of fusion(Δ_fH_fus)

8.167 kJ⋅mol (crystalline to liquid)

Enthalpy of vaporization(Δ_fH_vap)

33.225 kJ⋅mol (25 °C (77 °F; 298 K))
29.75 kJ⋅mol (81.6 °C (178.9 °F; 354.8 K))

Hazards GHS labelling:

Pictograms

Signal word

Danger

Hazard statements

H225, H302+H312+H332, H319

Precautionary statements

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, P501NFPA 704 (fire diamond)

2

3

0

Flash point2.0 °C (35.6 °F; 275.1 K)

Autoignition
temperature

523.0 °C (973.4 °F; 796.1 K) Explosive limits4.4%–16.0%Lethal dose or concentration (LD, LC):

LD₅₀ (median dose)

2 g/kg (dermal, rabbit)
2.46 g/kg (oral, rat)
617 mg/kg (oral, mouse)

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)
6.022 mg/L (mouse, 4 hr)

LC_Lo (lowest published)

16,000 ppm (dog, 4 hr) NIOSH (US health exposure limits):

PEL (Permissible)

40 ppm (70 mg/m, TWA)

REL (Recommended)

20 ppm (34 mg/m, TWA)

IDLH (Immediate danger)

500 ppmRelated compounds

Related alkanenitriles

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).

verify ( ?)

Acetonitrile, often abbreviated MeCN (methyl cyanide), is the chemical compound with the formulaCH₃CN and structureH₃C−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. The N≡C−C skeleton is linear with a short C≡Ndistance of 1.16 Å.

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