3-Methylbutanoic acid

3-Methylbutanoic acid
IUPAC name
3-Methylbutanoic acid
Other names
Delphinic acid
3-Methylbutyric acid
Isopentanoic acid
503-74-2 YesY
3D model (Jmol) Interactive image
ChEBI CHEBI:28484 YesY
ChEMBL ChEMBL568737 YesY
ChemSpider 10001 YesY
DrugBank DB03750 YesY
ECHA InfoCard 100.007.251
KEGG C08262 YesY
PubChem 10430
UNII 1BR7X184L5 YesY
Molar mass 102.13 g/mol
Density 0.925 g/cm3
Melting point −29 °C (−20 °F; 244 K)
Boiling point 175 to 177 °C (347 to 351 °F; 448 to 450 K)
Related compounds
butyric acid
β-hydroxybutyric acid
β-hydroxy β-methylbutyric acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

3-Methylbutanoic acid, also known as β-methylbutyric acid or more commonly isovaleric acid, is an organic compound with the formula (CH3)2CHCH2CO2H. It is sometimes classified as a fatty acid. It is a colourless liquid that is sparingly soluble in water, but highly soluble in most common organic solvents. The compound occurs naturally, including in essential oils.

Isovaleric acid has a strong pungent cheesy or sweaty smell, but its volatile esters have pleasing scents and are used widely in perfumery. It has been proposed that it is the anticonvulsant agent in valerian.[1] It is a major component of the cause of unpleasant foot odor, as it is produced by skin bacteria metabolizing leucine.[2]

Isovaleric acid is seen as the primary cause of the flavors added to wine caused by Brettanomyces yeasts.[3] Other compounds produced by Brettanomyces yeasts include 4-ethylphenol, 4-vinylphenol, and 4-ethylguaiacol.[4] An excess of isovaleric acid in wine is generally seen as a defect,[4] as it can smell sweaty, leathery, or like a barnyard, but in small amounts it can smell smokey, spicy, or medicinal.[3] These phenomena may be prevented by killing any Brettanomyces yeasts, such as by sterile filtration, by the addition of relatively large quantities of sulfur dioxide and sometimes sorbic acid, by mixing in alcoholic spirit to give a fortified wine of sufficient strength to kill all yeast and bacteria, or by pasteurization. Isovaleric acid can also be found in beer, and, excepting some English–style ales, is usually considered a flaw.[5] It can be produced by the oxidation of hop resins, or by Brettanomyces yeasts present.[5]


Isovaleric acid has been used to synthesize β-hydroxyisovaleric acid – otherwise known as β-hydroxy β-methylbutyric acid – via microbial oxidation by the fungus Galactomyces reessii.[6]

HMB synthesis diagram

β-hydroxy β-methylbutyric acid

Synthesis of β-hydroxy β-methylbutyric acid

See also


  1. Eadie, Mervyn J. (November 2004). "Could Valerian Have Been the First Anticonvulsant?". Epilepsia. 45 (11): 1338–1343. doi:10.1111/j.0013-9580.2004.27904.x. PMID 15509234. Retrieved December 22, 2012.
  2. Ara, Katsutoshi; Hama, Masakatsu; Akiba, Syunichi; Koike, Kenzo; Okisaka, Koichi; Hagura, Toyoki; Kamiya, Tetsuro; Tomita, Fusao (April 2006). "Foot odor due to microbial metabolism and its control". Canadian Journal of Microbiology. 52 (4): 357–364. doi:10.1139/w05-130. PMID 16699586. Retrieved February 22, 2014.
  3. 1 2 Jackson, Ron S. (2008). Wine Science: Principles and Applications (3rd ed.). Academic Press. p. 495. ISBN 9780123736468. Retrieved December 22, 2012.
  4. 1 2 Kirk-Othmer (2007). "Wine". Food and Feed Technology, Volume 2. John Wiley & Sons. p. 702. ISBN 9780470174487. Retrieved December 22, 2012.
  5. 1 2 Oliver, Garrett, ed. (2012). The Oxford Companion to Beer. Oxford University Press. p. 498. ISBN 9780195367133. Retrieved December 22, 2012.
  6. Lee IY, Nissen SL, Rosazza JP (1997). "Conversion of beta-methylbutyric acid to beta-hydroxy-beta-methylbutyric acid by Galactomyces reessii" (PDF). Applied and Environmental Microbiology. 63 (11): 4191–5. PMC 168736Freely accessible. PMID 9361403.

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