:Valeric acid

{{chembox

| Reference=Merck Index, 13th Edition, 2001, page 1764.

| Name = Valeric acid

| ImageFile = Valeric_acid_acsv.svg

| ImageClass = skin-invert-image

| ImageSize = 150px

| ImageName = Valeric acid

| ImageFile2 = Valeric-acid-3D-balls.png

| ImageSize2 = 180px

| IUPACName = Pentanoic acid

| OtherNames = 1-Butanecarboxylic acid
Propylacetic acid
C5:0 (Lipid numbers)

|Section1={{Chembox Identifiers

| index_label = Valeric acid

| index1_label = Valerate

| IUPHAR_ligand = 1061

| SMILES = CCCCC(O)=O

| CASNo_Ref = {{cascite|correct|CAS}}

| CASNo = 109-52-4

| CASNo1 = 10023-74-2

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = GZK92PJM7B

| ChEBI = 17418

| ChEBI1 = 31011

| ChEMBL_Ref = {{ebicite|correct|EBI}}

| ChEMBL = 268736

| EINECS = 203-677-2

| PubChem = 7991

| PubChem1 = 114781

| RTECS = YV6100000

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 7701

| ChemSpiderID1 = 102757

| InChI = 1/C5H10O2/c1-2-3-4-5(6)7/h2-4H2,1H3,(H,6,7)

| InChIKey = NQPDZGIKBAWPEJ-UHFFFAOYAU

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 1S/C5H10O2/c1-2-3-4-5(6)7/h2-4H2,1H3,(H,6,7)

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = NQPDZGIKBAWPEJ-UHFFFAOYSA-N

}}

|Section2={{Chembox Properties

| C=5 | H=10 | O=2

| Appearance = Colorless liquid

| Density = 0.930 g/cm³

| Solubility = 4.97 g/100 mL

| MeltingPtC = −34.5

| BoilingPtC = 185

| pKa = 4.82

| Viscosity =

| MagSus = −66.85·10⁻⁶ cm³/mol

}}

|Section7={{Chembox Hazards

| Hazards_ref ={{cite web |url=https://www.sigmaaldrich.com/catalog/product/aldrich/W310107?lang=en®ion=GB |author=Sigma-Aldrich |title=Valeric acid |access-date=2020-09-29 }}

| GHSPictograms = {{GHS05}}

| GHSSignalWord = Danger

| ExternalSDS =

| NFPA-H = 3 | NFPA-F = 1 | NFPA-R = 0

| FlashPtC = 86

| HPhrases = {{H-phrases|314|412}}

| PPhrases = {{P-phrases|273|280|303+361+353|305+351+338+310}}

}}

|Section8={{Chembox Related

| OtherCompounds = Butyric acid, Hexanoic acid

}}

Valeric acid or pentanoic acid is a straight-chain alkyl carboxylic acid with the chemical formula {{chem2|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.

History

Valeric acid is a minor constituent of the perennial flowering plant valerian (Valeriana officinalis), from which it gets its name.{{cite EB1911 |wstitle=Valeric Acid |volume=27 |page=859}} The dried root of this plant has been used medicinally since antiquity.{{cite journal |doi=10.2478/v10136-009-0002-z |doi-access=free |title=Biomedically relevant chemical constituents of Valeriana officinalis |year=2010 |last1=Patočka |first1=Jiří |last2=Jakl |first2=Jiří |journal=Journal of Applied Biomedicine |volume=8 |pages=11–18 }} 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.{{cite journal |doi=10.1039/JS8682100074 |title=On the isomeric forms of valeric acid |year=1868 |last1=Pedler |first1=Alexander |journal=Journal of the Chemical Society |volume=21 |pages=74–76 |url=https://zenodo.org/record/2175638 }}

Valeric acid is one volatile component in swine manure. Other components include other carboxylic acids, skatole, trimethyl amine, and isovaleric acid.{{cite journal|doi=10.1016/j.chemosphere.2012.04.061|pmid=22682363|title=Volatile organic compounds at swine facilities: A critical review|journal=Chemosphere|volume=89|issue=7|pages=769–788|year=2012|last1=Ni|first1=Ji-Qin|last2=Robarge|first2=Wayne P.|last3=Xiao|first3=Changhe|last4=Heber|first4=Albert J.|bibcode=2012Chmsp..89..769N}} It is also a flavor component in some foods.{{cite journal |doi=10.1080/00021369.1970.10859653 |title=Studies on Flavor Components of Roasted Barley |year=1970 |last1=Wang |first1=Pao-Shui |last2=Kato |first2=Hiromichi |last3=Fujimaki |first3=Masao |journal=Agricultural and Biological Chemistry |volume=34 |issue=4 |pages=561–567 }}

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.

: {{chem2|H2 + CO + CH3CH2CH\dCH2 → 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.{{cite journal |doi=10.1002/anie.201000655 |title=Valeric Biofuels: A Platform of Cellulosic Transportation Fuels |year=2010 |last1=Lange |first1=Jean-Paul |last2=Price |first2=Richard |last3=Ayoub |first3=Paul M. |last4=Louis |first4=Jurgen |last5=Petrus |first5=Leo |last6=Clarke |first6=Lionel |last7=Gosselink |first7=Hans |journal=Angewandte Chemie International Edition |volume=49 |issue=26 |pages=4479–4483 |pmid=20446282 |doi-access=free }}{{cite journal|doi=10.1039/C7GC02503C|title=Conversion of levulinic acid and alkyl levulinates into biofuels and high-value chemicals|journal=Green Chemistry|volume=19|issue=23|pages=5527–5547|year=2017|last1=Yan|first1=Long|last2=Yao|first2=Qian|last3=Fu|first3=Yao}}

Reactions

Valeric acid reacts as a typical carboxylic acid: it can form amide, ester, anhydride, and chloride derivatives.{{cite book |doi=10.1039/9781847556196-00096 |chapter=Carboxylic acids and derivatives |title=General and Synthetic Methods |year=1985 |last1=Jenkins |first1=P. R. |volume=7 |pages=96–160 |isbn=978-0-85186-884-4 }} 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.{{cite journal |doi=10.1080/10408398609527435 |title=Meat flavor volatiles: A review of the composition, techniques of analysis, and sensory evaluation |year=1986 |last1=Shahidi |first1=Fereidoon |last2=Rubin |first2=Leon J. |last3=d'Souza |first3=Lorraine A. |last4=Teranishi |first4=Roy |last5=Buttery |first5=Ron G. |journal=CRC Critical Reviews in Food Science and Nutrition |volume=24 |issue=2 |pages=141–243 |pmid=3527563 }} 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.{{cite web |url=http://www.inchem.org/documents/jecfa/jecmono/v040je10.htm |title=Safety evaluation of certain food additives and contaminants |author=FAO/WHO Expert Committee on food additives |date=1998 |access-date=2020-09-30}} 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.{{Ullmann|first1=Wilhelm|last1=Riemenschneider|title=Carboxylic Acids, Aliphatic|year=2002|doi=10.1002/14356007.a05_235}} Typical examples are the methyl valerates,{{cite web |url=http://www.thegoodscentscompany.com/data/rw1008901.html |title=Methyl valerate |website=The Good Scents Company |access-date=2020-09-30 }} ethyl valerates,{{cite web |url=http://www.thegoodscentscompany.com/data/rw1000701.html |title=Ethyl valerate |website=The Good Scents Company |access-date=2020-09-30 }} and pentyl valerates.{{cite web |url=http://www.thegoodscentscompany.com/data/rw1005951.html |title=Amyl valerate |website=The Good Scents Company |access-date=2020-09-30 }}

Biology

In humans, valeric acid is a minor product{{cite journal |doi=10.3390/nu12041107 |title=The Effect of Probiotics on the Production of Short-Chain Fatty Acids by Human Intestinal Microbiome |year=2020 |last1=Markowiak-Kopeć |first1=Paulina |last2=Śliżewska |first2=Katarzyna |journal=Nutrients |volume=12 |issue=4 |page=1107 |pmid=32316181 |pmc=7230973 |s2cid=216075062 |doi-access=free }} of the gut microbiome and can also be produced by metabolism of its esters found in food.{{cite web |url=https://hmdb.ca/metabolites/HMDB0000892 |title=Metabocard for Valeric acid |website= Human Metabolome Database |access-date=2020-09-30 |date=2020-04-23 }} 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.{{cite journal |doi=10.1053/j.gastro.2018.07.014 |title=Inhibiting Growth of Clostridioides difficile by Restoring Valerate, Produced by the Intestinal Microbiota |year=2018 |last1=McDonald |first1=Julie A.K. |last2=Mullish |first2=Benjamin H. |last3=Pechlivanis |first3=Alexandros |last4=Liu |first4=Zhigang |last5=Brignardello |first5=Jerusa |last6=Kao |first6=Dina |last7=Holmes |first7=Elaine |last8=Li |first8=Jia V. |last9=Clarke |first9=Thomas B. |last10=Thursz |first10=Mark R. |last11=Marchesi |first11=Julian R. |journal=Gastroenterology |volume=155 |issue=5 |pages=1495–1507.e15 |pmid=30025704 |pmc=6347096 }}

Valerate salts and esters

The valerate, or pentanoate, ion is {{chem2|C4H9COO-|auto=yes}}, 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.