Butyric acid

InChI=1S/C4H8O2/c1-2-3-4(5)6/h2-3H2,1H3,(H,5,6)
Key: FERIUCNNQQJTOY-UHFFFAOYSA-N
Butyric acid: InChI=1/C4H8O2/c1-2-3-4(5)6/h2-3H2,1H3,(H,5,6)
Key: FERIUCNNQQJTOY-UHFFFAOYAP

SMILES

Butyric acid: O=C(O)CCC

Properties

Chemical formula

C
₃H
₇COOHMolar mass88.106 g·mol Appearance Colorless liquid OdorUnpleasant, similar to vomit or body odor Density1.135 g/cm (−43 °C)
0.9528 g/cm (25 °C) Melting point−5.1 °C (22.8 °F; 268.0 K) Boiling point163.75 °C (326.75 °F; 436.90 K)

Sublimation
conditions

Sublimes at −35 °C
Δ_sublH = 76 kJ/mol

Solubility in water

Miscible SolubilityMiscible with ethanol, ether. Slightly soluble in CCl₄ log P0.79 Vapor pressure0.112 kPa (20 °C)
0.74 kPa (50 °C)
9.62 kPa (100 °C)

Henry's law
constant (k_H)

5.35·10 L·atm/mol Acidity (pK_a) 4.82

Magnetic susceptibility (χ)

−55.10·10 cm/mol Thermal conductivity1.46·10 W/m·K

Refractive index (n_D)

1.398 (20 °C) Viscosity1.814 cP (15 °C)
1.426 cP (25 °C) Structure

Crystal structure

Monoclinic (−43 °C)

Space group

C2/m

Lattice constant

a = 8.01 Å, b = 6.82 Å, c = 10.14 Å

α = 90°, β = 111.45°, γ = 90°

Dipole moment

0.93 D (20 °C) Thermochemistry

Heat capacity(C)

178.6 J/mol·K

Std molar
entropy(S₂₉₈)

222.2 J/mol·K

Std enthalpy of
formation(Δ_fH₂₉₈)

−533.9 kJ/mol

Std enthalpy of
combustion(Δ_cH₂₉₈)

2183.5 kJ/mol Hazards GHS labelling:

Pictograms

Signal word

Danger

Hazard statements

H314

Precautionary statements

P280, P305+P351+P338, P310NFPA 704 (fire diamond)

3

2

0

Flash point71 to 72 °C (160 to 162 °F; 344 to 345 K)

Autoignition
temperature

440 °C (824 °F; 713 K) Explosive limits2.2–13.4% Lethal dose or concentration (LD, LC):

LD₅₀ (median dose)

2000 mg/kg (oral, rat) Safety data sheet (SDS) External MSDSRelated compounds

Related carboxylic acids

Propionic acid, Pentanoic acid

Related compounds

1-Butanol
Butyraldehyde
Methyl butyrate

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Butyric acid (; from Ancient Greek: βούτῡρον, meaning "butter"), also known under the systematic name butanoic acid, is a straight-chain alkyl fatty acid with the chemical formulaCH₃CH₂CH₂COOH. It is an oily, colorless liquid with an unpleasant odor. Isobutyric acid (2-methylpropanoic acid) is an isomer. Salts and esters of butyric acid are known as butyrates or butanoates. The acid itself does not occur widely in nature, but its esters are widespread. It is a common industrial chemical and an important component in the mammalian gut.