Isobutyric acid

Isobutyric acid[1]
IUPAC name 2-Methylpropanoic acid
Other names Isobutyric acid 2-Methylpropionic acid Valerianic acid Isobutanoic acid
Identifiers
CAS number	79-31-2 Y
ChemSpider	6341 Y
UNII	8LL210O1U0 Y
DrugBank	DB04305
KEGG	C02632 Y
ChEBI	CHEBI:16135 Y
ChEMBL	CHEMBL108778 Y
Jmol-3D images	Image 1
SMILES O=C(O)C(C)C
InChI InChI=1S/C4H8O2/c1-3(2)4(5)6/h3H,1-2H3,(H,5,6) Y Key: KQNPFQTWMSNSAP-UHFFFAOYSA-N Y InChI=1/C4H8O2/c1-3(2)4(5)6/h3H,1-2H3,(H,5,6) Key: KQNPFQTWMSNSAP-UHFFFAOYAB
Properties
Molecular formula	C4H8O2
Molar mass	88.11 g/mol
Density	0.9697 g/cm3 at 0 °C
Melting point	-47 °C, 226 K, -53 °F
Boiling point	155 °C, 428 K, 311 °F
Acidity (pKa)	4.86[2]
Y acid (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Isobutyric acid, also known as 2-methylpropanoic acid, is a carboxylic acid with structural formula (CH₃)₂-CH-COOH. It is found in the free state in carobs (Ceratonia siliqua) and in the root of Arnica dulcis, and as an ethyl ester in croton oil.

Isobutyric acid is an isomer of n-butyric acid; they have the same chemical formula C₄H₈ O₂ but a different structure.

Production

Isobutyric acid may be artificially prepared by the hydrolysis of isobutyronitrile with alkalis, by the oxidation of isobutanol with potassium dichromate and sulfuric acid,^[3] or by the action of sodium amalgam on methacrylic acid. It is a liquid of somewhat unpleasant smell, boiling at 155 °C. Its specific gravity is 0.9697 (0 °C). Heated with chromic acid solution to 140 °C, it gives carbon dioxide and acetone. Alkaline potassium permanganate oxidizes it to α-hydroxyisobutyric acid, (CH₃)₂-C(OH)-COOH. Its salts are more soluble in water than those of butyric acid.

Biological production

Isobutyric acid can also be manufactured commercially using engineered bacteria using a sugar feedstock.^[4]

Isobutyric acid is a retained trivial name under the IUPAC rules.^[5]

References

1. ^ Merck Index, 11th Edition, 5039
2. ^ Bjerrum, J., et al. Stability Constants, Chemical Society, London, 1958.
3. ^ I. Pierre and E. Puchot (1873). "New Studies on Valerianic Acid and its Preparation on a Large Scale". Ann. de chim. et de phys. 28: 366. 
4. ^ "Biological pathways to produce methacrylate". http://www.license.umn.edu/Products/Biological-Pathways-Produce-Isobutyric-Acid-Using-Renewable-Resources__20110077.aspx. 
5. ^ IUPAC, the Blue Book; Oxford: Blackwell Science (1993). ISBN 0-632-03488-2. Online edition: "Recommendation R-R-9.1.".

 This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press.