Valeric acid

Valeric acid or pentanoic acid is a straight-chain alkyl carboxylic acid with the chemical formula CH3(CH2)3COOH. Like other low-molecular-weight carboxylic acids, it has an unpleasant odor. It is found in the perennial flowering plant Valeriana officinalis, from which it gets its name. Its primary use is in the synthesis of its esters. Salts and esters of valeric acid are known as valerates or pentanoates. Volatile esters of valeric acid tend to have pleasant odors and are used in perfumes and cosmetics. Several, including ethyl valerate and pentyl valerate are used as food additives because of their fruity flavors.

Not to be confused with Valerenic acid.
Valeric acid[1]
Valeric acid
Names
IUPAC name
Pentanoic acid
Other names
1-Butanecarboxylic acid
Propylacetic acid
C5:0 (Lipid numbers)
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.344
EC Number
  • Valeric acid: 203-677-2
RTECS number
  • Valeric acid: YV6100000
UNII
  • InChI=1S/C5H10O2/c1-2-3-4-5(6)7/h2-4H2,1H3,(H,6,7) checkY
    Key: NQPDZGIKBAWPEJ-UHFFFAOYSA-N checkY
  • Valeric acid: InChI=1/C5H10O2/c1-2-3-4-5(6)7/h2-4H2,1H3,(H,6,7)
    Key: NQPDZGIKBAWPEJ-UHFFFAOYAU
  • Valeric acid: CCCCC(O)=O
Properties
C5H10O2
Molar mass 102.133 g·mol−1
Appearance Colorless liquid
Density 0.930 g/cm3
Melting point −34.5 °C (−30.1 °F; 238.7 K)
Boiling point 185 °C (365 °F; 458 K)
4.97 g/100 mL
Acidity (pKa) 4.82
-66.85·10−6 cm3/mol
Hazards[2]
GHS labelling:
GHS05: Corrosive
Danger
H314, H412
P273, P280, P303+P361+P353, P305+P351+P338+P310
NFPA 704 (fire diamond)
NFPA 704 four-colored diamond
3
1
0
Flash point 86 °C (187 °F; 359 K)
Related compounds
Related compounds
 Butyric acid, Hexanoic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

History

Valeric acid is a minor constituent of the perennial flowering plant valerian (Valeriana officinalis), from which it gets its name.[3] The dried root of this plant has been used medicinally since antiquity.[4] The related isovaleric acid shares its unpleasant odor and their chemical identity was investigated by oxidation of the components of fusel alcohol, which includes the five-carbon amyl alcohols.[5] Valeric acid is one volatile component in swine manure. Other components include other carboxylic acids, skatole, trimethyl amine, and isovaleric acid.[6] It is also a flavor component in some foods.[7]

Manufacture

In industry, valeric acid is produced by the oxo process from 1-butene and syngas, forming valeraldehyde, which is oxidised to the final product.[8]

H2 + CO + CH3CH2CH=CH2 → CH3CH2CH2CH2CHO → valeric acid

It can also be produced from biomass-derived sugars via levulinic acid and this alternative has received considerable attention as a way to produce biofuels.[9][10]

Reactions

Valeric acid reacts as a typical carboxylic acid: it can form amide, ester, anhydride, and chloride derivatives.[11] The latter, valeryl chloride is commonly used as the intermediate to obtain the others.

Uses

Valeric acid occurs naturally in some foods but is also used as a food additive.[12] Its safety in this application was reviewed by an FAO and WHO panel, who concluded that there were no safety concerns at the likely levels of intake.[13] The compound is used for the preparation of derivatives, notably its volatile esters which, unlike the parent acid, have pleasant odors and fruity flavors and hence find applications in perfumes, cosmetics and foodstuffs.[8] Typical examples are the methyl valerates,[14] ethyl valerates,[15] and pentyl valerates.[16]

Biology

In humans, valeric acid is a minor product[17] of the gut microbiome and can also be produced by metabolism of its esters found in food.[18] The restoration of levels of this acid in the gut has been suggested as the mechanism that results in control of Clostridioides difficile infection after fecal microbiota transplant.[19]

Valerate salts and esters

The valerate, or pentanoate, ion is C4H9COO−, the conjugate base of valeric acid. It is the form found in biological systems at physiological pH. A valerate, or pentanoate, compound is a carboxylate salt or ester of valeric acid. Many steroid-based pharmaceuticals, for example ones based on betamethasone or hydrocortisone, include the steroid as the valerate ester.

Examples

See also
Look up valeric acid in Wiktionary, the free dictionary.

References
  1. Merck Index, 13th Edition, 2001, page 1764.
  2. Sigma-Aldrich. "Valeric acid". Retrieved 2020-09-29.
  3. Chisholm, Hugh, ed. (1911). "Valeric Acid" . Encyclopædia Britannica. Vol. 27 (11th ed.). Cambridge University Press. p. 859.
  4. Patočka, Jiří; Jakl, Jiří (2010). "Biomedically relevant chemical constituents of Valeriana officinalis". Journal of Applied Biomedicine. 8: 11–18. doi:10.2478/v10136-009-0002-z.
  5. Pedler, Alexander (1868). "On the isomeric forms of valeric acid". Journal of the Chemical Society. 21: 74–76. doi:10.1039/JS8682100074.
  6. Ni, Ji-Qin; Robarge, Wayne P.; Xiao, Changhe; Heber, Albert J. (2012). "Volatile organic compounds at swine facilities: A critical review". Chemosphere. 89 (7): 769–788. Bibcode:2012Chmsp..89..769N. doi:10.1016/j.chemosphere.2012.04.061. PMID 22682363.
  7. Wang, Pao-Shui; Kato, Hiromichi; Fujimaki, Masao (1970). "Studies on Flavor Components of Roasted Barley". Agricultural and Biological Chemistry. 34 (4): 561–567. doi:10.1080/00021369.1970.10859653.
  8. Riemenschneider, Wilhelm (2002). "Carboxylic Acids, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a05_235.
  9. Lange, Jean-Paul; Price, Richard; Ayoub, Paul M.; Louis, Jurgen; Petrus, Leo; Clarke, Lionel; Gosselink, Hans (2010). "Valeric Biofuels: A Platform of Cellulosic Transportation Fuels". Angewandte Chemie International Edition. 49 (26): 4479–4483. doi:10.1002/anie.201000655. PMID 20446282.
  10. Yan, Long; Yao, Qian; Fu, Yao (2017). "Conversion of levulinic acid and alkyl levulinates into biofuels and high-value chemicals". Green Chemistry. 19 (23): 5527–5547. doi:10.1039/C7GC02503C.
  11. Jenkins, P. R. (1985). "Carboxylic acids and derivatives". General and Synthetic Methods. Vol. 7. pp. 96–160. doi:10.1039/9781847556196-00096. ISBN 978-0-85186-884-4.
  12. Shahidi, Fereidoon; Rubin, Leon J.; d'Souza, Lorraine A.; Teranishi, Roy; Buttery, Ron G. (1986). "Meat flavor volatiles: A review of the composition, techniques of analysis, and sensory evaluation". CRC Critical Reviews in Food Science and Nutrition. 24 (2): 141–243. doi:10.1080/10408398609527435. PMID 3527563.
  13. FAO/WHO Expert Committee on food additives (1998). "Safety evaluation of certain food additives and contaminants". Retrieved 2020-09-30.
  14. "Methyl valerate". The Good Scents Company. Retrieved 2020-09-30.
  15. "Ethyl valerate". The Good Scents Company. Retrieved 2020-09-30.
  16. "Amyl valerate". The Good Scents Company. Retrieved 2020-09-30.
  17. Markowiak-Kopeć, Paulina; Śliżewska, Katarzyna (2020). "The Effect of Probiotics on the Production of Short-Chain Fatty Acids by Human Intestinal Microbiome". Nutrients. 12 (4): 1107. doi:10.3390/nu12041107. PMC 7230973. PMID 32316181. S2CID 216075062.
  18. "Metabocard for Valeric acid". Human Metabolome Database. 2020-04-23. Retrieved 2020-09-30.
  19. McDonald, Julie A.K.; Mullish, Benjamin H.; Pechlivanis, Alexandros; Liu, Zhigang; Brignardello, Jerusa; Kao, Dina; Holmes, Elaine; Li, Jia V.; Clarke, Thomas B.; Thursz, Mark R.; Marchesi, Julian R. (2018). "Inhibiting Growth of Clostridioides difficile by Restoring Valerate, Produced by the Intestinal Microbiota". Gastroenterology. 155 (5): 1495–1507.e15. doi:10.1053/j.gastro.2018.07.014. PMC 6347096. PMID 30025704.
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