3-Methylbutanoic acid

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. 3-methylbutanoic acid can be found in a lot of common house items, such as cheese, soy milk, and apple juice. The compound occurs naturally.

3-Methylbutanoic acid
Names
IUPAC name
3-Methylbutanoic acid
Other names
Delphinic acid
3-Methylbutyric acid
Isopentanoic acid
Isovaleric acid
Identifiers
CAS Number
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.007.251
KEGG
PubChem CID
UNII
Properties
Chemical formula
 C5H10O2
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)
Magnetic susceptibility (χ)
 -67.7·10−6 cm3/mol
Related compounds
Related carboxylic acids
 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).
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Infobox references

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]

Uses

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]

acetone
diacetone alcohol
β-methylbutyric acid
Synthesis of β-hydroxy β-methylbutyric acid

See also

References
  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.
  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. CiteSeerX 10.1.1.1013.4047. doi:10.1139/w05-130. PMID 16699586.
  3. Jackson, Ron S. (2008). Wine Science: Principles and Applications (3rd ed.). Academic Press. p. 495. ISBN 9780123736468. Retrieved December 22, 2012.
  4. Kirk-Othmer (2007). "Wine". Food and Feed Technology, Volume 2. John Wiley & Sons. p. 702. ISBN 9780470174487. Retrieved December 22, 2012.
  5. 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 168736. PMID 9361403.
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