Butyric Acid

Title: Butyric Acid
CAS Registry Number: 107-92-6
CAS Name: Butanoic acid
Additional Names: n-butyric acid; ethylacetic acid
Molecular Formula: C4H8O2
Molecular Weight: 88.11
Percent Composition: C 54.53%, H 9.15%, O 36.32%
Line Formula: CH3CH2CH2COOH
Literature References: Discovered by Lieben and Rossi in 1869. Present in butter as an ester to the extent of 4-5%. Obtained by suitable fermentation of carbohydrates; prepn from n-propanol + CO at 200 atm in the presence of Ni(CO)4 and NiI2: Reppe et al., Ann. 582, 83 (1953); lab prepn from ethylmalonic acid: Gattermann-Wieland, Praxis des Organischen Chemikers (de Gruyter, Berlin, 40th ed., 1961) p 221. Toxicity study: Smyth et al., Arch. Ind. Hyg. Occup. Med. 10, 61 (1954).
Properties: Oily liq; unpleasant, rancid odor. d420 0.959. bp 163.5°. mp -7.9°. nD20 1.3991. Flash pt, closed cup: 170°F (77°C). Neutralization value 636.79. Miscible with water, alcohol, ether. The calcium salt of this acid is less soluble in hot than in cold water (difference from isobutyric acid). LD50 orally in rats: 8.79 g/kg (Smyth).
Melting point: mp -7.9°
Boiling point: bp 163.5°
Flash point: Flash pt, closed cup: 170°F (77°C)
Index of refraction: nD20 1.3991
Density: d420 0.959
Toxicity data: LD50 orally in rats: 8.79 g/kg (Smyth)
Derivative Type: Magnesium salt
Additional Names: Magnesium butyrate
Molecular Formula: C8H14MgO4
Molecular Weight: 198.50
Percent Composition: C 48.41%, H 7.11%, Mg 12.24%, O 32.24%
Properties: Deliquesc leaflets. Sol in water. Keep well closed.
Use: Manuf of esters, some of which serve as bases of artificial flavoring ingredients of certain liqueurs, soda-water syrups, candies; also for varnishes; as decalcifier of hides.
Butyric Anhydride Butyroin Butyrolactone Butyronitrile Buzepide

Butyric acid
Skeletal structure Flat structure
Space filling model
CAS number 107-92-6 YesY
PubChem 264
ChemSpider 259 YesY
EC number 203-532-3
UN number 2820
DrugBank DB03568
KEGG C00246 YesY
MeSH Butyric+acid
ChEBI CHEBI:30772 YesY
IUPHAR ligand 1059
RTECS number ES5425000
Jmol-3D images Image 1
Image 2
Molecular formula C4H8O2
Molar mass 88.11 g mol−1
Appearance Colorless liquid
Odor unpleasant and obnoxious
Density 0.9595 g/mL
Melting point −7.9 °C; 17.8 °F; 265.2 K
Boiling point 163.5 °C; 326.3 °F; 436.6 K
Solubility in water miscible
Solubility slightly soluble in CCl4
miscible with ethanol, ether
log P 0.79
Acidity (pKa) 4.82
Refractive index (nD) 1.3991 (20 °C)
Viscosity 0.1529 cP
heat capacity C
178.6 J/K mol
MSDS External MSDS
EU classification Harmful XnCorrosive C
R-phrases R20 R21 R22 R34 R36 R37 R38
NFPA 704
NFPA 704.svg
Flash point 72 °C; 162 °F; 345 K
Autoignition temperature 452 °C; 846 °F; 725 K
Explosive limits 2-10%
Related compounds
Other anions butyrate
Related carboxylic acids propionic acid
acrylic acid
succinic acid
malic acid
tartaric acid
crotonic acid
fumaric acid
pentanoic acid
Related compounds butanol
methyl butyrate
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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

Butyric acid (from Greek βούτυρο, meaning "butter"), also known under the systematic name butanoic acid, is a carboxylic acid with the structural formula CH3CH2CH2-COOH. Salts and esters of butyric acid are known as butyrates or butanoates. Butyric acid is found in milk, especially goat, sheep and buffalo milk, butter, Parmesan cheese, and as a product of anaerobic fermentation (including in the colon and as body odor). It has an unpleasant smell and acrid taste, with a sweetish aftertaste (similar to ether). It can be detected by mammals with good scent detection abilities (such as dogs) at 10 ppb, whereas humans can detect it in concentrations above 10 ppm.

Butyric acid was first observed (in impure form) in 1814 by the French chemist Michel Eugène Chevreul. By 1818, he had purified it sufficiently to characterize it.[1] The name of butyric acid comes from the Latin word for butter, butyrum (or buturum), the substance in which butyric acid was first found.