| IUPAC name
| Other names
|3D model (Jmol)||Interactive image|
|Molar mass||88.11 g/mol|
|Density||0.9697 g/cm3 at 0 °C|
|Melting point||−47 °C (−53 °F; 226 K)|
|Boiling point||155 °C (311 °F; 428 K)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|(what is ?)|
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), in vanilla 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 C4H8O2 but a different structure.
Isobutyric acid may be artificially prepared by the hydrolysis of isobutyronitrile with alkalis, by the oxidation of isobutanol with potassium dichromate and sulfuric acid, or by the action of sodium amalgam on methacrylic acid. Isobutyric acid is a liquid under common conditions with a somewhat unpleasant smell. It boils at 155 °C and has a specific gravity is 0.9697 (0 °C). When heated with a chromic acid solution to 140 °C, it decomposes to form 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.
Isobutyric acid is a retained trivial name under the IUPAC rules.
- Merck Index, 11th Edition, 5039
- Bjerrum, J., et al. Stability Constants, Chemical Society, London, 1958.
- I. Pierre and E. Puchot (1873). "New Studies on Valerianic Acid and its Preparation on a Large Scale". Ann. Chim. Phys. 28: 366.
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- Panico R, Powell WH, Richer JC, eds. (1993). "Recommendation R-9.1". A Guide to IUPAC Nomenclature of Organic Compounds. IUPAC/Blackwell Science. ISBN 0-632-03488-2.