Valeric acid or pentanoic acid is a straight-chain

alkyl In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl group is derived from a cy ...

carboxylic acid In organic chemistry, a carboxylic acid is an organic acid that contains a carboxyl group () attached to an Substituent, R-group. The general formula of a carboxylic acid is often written as or , sometimes as with R referring to an organyl ...

with the

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

. Like other low-molecular-weight carboxylic acids, it has an

unpleasant odor An odor (American English) or odour (English in the Commonwealth of Nations, Commonwealth English; American and British English spelling differences#-our, -or, see spelling differences) is a smell or a scent caused by one or more volatilized ...

. It is found in the perennial flowering plant ''

Valeriana officinalis Valerian (''Valeriana officinalis'', Caprifoliaceae) is a perennial flowering plant native to Eurasia. It produces a catnip-like response in cats. Crude extracts of valerian root may have sedative and anxiolytic effects; however, the clinical ...

'', from which it gets its name. Its primary use is in the synthesis of its

ester In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...

Salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

s and

s 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 Food additives are substances added to food to preserve flavor or enhance taste, appearance, or other sensory qualities. Some additives, such as vinegar ( pickling), salt ( salting), smoke (smoking) and sugar (crystallization), have been used for ...

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. The dried root of this plant has been used medicinally since antiquity. The related

isovaleric acid Isovaleric acid, also known as 3-methylbutanoic acid or β-methylbutyric acid, is a branched-chain alkyl carboxylic acid with the chemical formula (CH3)2CHCH2CO2H. It is classified as a short-chain fatty acid. Like other low-molecular-weight car ...

shares its unpleasant odor and their chemical identity was investigated by oxidation of the components of

fusel alcohol Fusel alcohols or fuselol, also sometimes called fusel oils in Europe, are mixtures of several higher alcohols (those with more than two carbons, chiefly amyl alcohol) produced as a by-product of alcoholic fermentation. The word ''Fusel'' is G ...

, which includes the five-carbon

amyl alcohol Amyl alcohols are alcohols with the formula C5H11OH. Eight are known. A mixture of amyl alcohols (also called amyl alcohol) can be obtained from fusel alcohol. Amyl alcohol is used as a solvent and in esterification, by which is produced amy ...

s. Valeric acid is one volatile component in swine manure. Other components include other carboxylic acids,

skatole Skatole or 3-methylindole is an organic compound belonging to the indole family. It occurs naturally in the feces of mammals and birds and is the primary contributor to fecal odor. In low concentrations, it has a flowery smell and is found in sever ...

trimethyl amine Trimethylamine (TMA) is an organic compound with the formula N(CH3)3. It is a trimethylated derivative of ammonia. TMA is widely used in industry. At higher concentrations it has an ammonia-like odor, and can cause necrosis of mucous membranes ...

, and

. It is also a flavor component in some foods.

Manufacture

In industry, valeric acid is produced by the

oxo process In organic chemistry, hydroformylation, also known as oxo synthesis or oxo process, is an industrial process for the production of aldehydes () from alkenes (). This chemical reaction entails the net addition of a formyl group () and a hydroge ...

from

1-butene 1-Butene (IUPAC name: But-1-ene, also known as 1-butylene) is the organic compound with the formula CH3CH2CH=CH2. It is a colorless gas, but easily condensed to give a colorless liquid. It is classified as a linear alpha-olefin (terminal alkene). ...

and

syngas Syngas, or synthesis gas, is a mixture of hydrogen and carbon monoxide in various ratios. The gas often contains some carbon dioxide and methane. It is principally used for producing ammonia or methanol. Syngas is combustible and can be used as ...

, forming

valeraldehyde Pentanal (also called valeraldehyde) is the organic compound with molecular formula . Classified as an alkyl aldehyde, it is a colorless volatile liquid. Its odor is described as fermented, bready, fruity, nutty, berry. Production Pentanal is ...

, which is

oxidised Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...

to the final product. : valeric acid It can also be produced from biomass-derived sugars via

levulinic acid Levulinic acid, or 4-oxopentanoic acid, is an organic compound with the chemical formula, formula CH3C(O)CH2CH2CO2H. It is classified as a keto acid. This white crystalline solid is soluble in water and polar organic solvents. It is derived from d ...

and this alternative has received considerable attention as a way to produce

biofuels Biofuel is a fuel that is produced over a short time span from biomass, rather than by the very slow natural processes involved in the formation of fossil fuels such as oil. Biofuel can be produced from plants or from agricultural, domestic ...

Reactions

Valeric acid reacts as a typical carboxylic acid: it can form

amide In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a chemical compound, compound with the general formula , where R, R', and R″ represent any group, typically organyl functional group, groups or hydrogen at ...

anhydride An acid anhydride is a type of chemical compound derived by the removal of water molecules from an acid (chemistry), acid. In organic chemistry, organic acid anhydrides contain the functional group . Organic acid anhydrides often form when one ...

, and

chloride The term chloride refers to a compound or molecule that contains either a chlorine anion (), which is a negatively charged chlorine atom, or a non-charged chlorine atom covalently bonded to the rest of the molecule by a single bond (). The pr ...

derivatives. 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. Its safety in this application was reviewed by an

FAO The Food and Agriculture Organization of the United Nations; . (FAO) is a List of specialized agencies of the United Nations, specialized agency of the United Nations that leads international efforts to defeat hunger and improve nutrition ...

and

WHO The World Health Organization (WHO) is a specialized agency of the United Nations which coordinates responses to international public health issues and emergencies. It is headquartered in Geneva, Switzerland, and has 6 regional offices and 15 ...

panel, who concluded that there were no safety concerns at the likely levels of intake. The compound is used for the preparation of derivatives, notably its volatile

esters In chemistry, an ester is a chemical compound, compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds c ...

which, unlike the parent acid, have pleasant odors and fruity flavors and hence find applications in perfumes, cosmetics and foodstuffs. Typical examples are the methyl valerates, ethyl valerates, and pentyl valerates.

Biology

In humans, valeric acid is a minor product of the

gut microbiome Gut microbiota, gut microbiome, or gut flora are the microorganisms, including bacteria, archaea, fungi, and viruses, that live in the digestive tracts of animals. The gastrointestinal metagenome is the aggregate of all the genomes of the g ...

and can also be produced by metabolism of its esters found in food. 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 Fecal microbiota transplant (FMT), also known as a stool transplant, is the process of transferring fecal bacteria and other microbes from a healthy individual into another individual. FMT is an effective treatment for Clostridioides diffic ...

Valerate salts and esters

The valerate, or pentanoate,

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

is , the

conjugate base A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid gives a proton () to a base—in other words, it is a base with a hydrogen ion added to it, as it loses a hydrogen ion in the reve ...

of valeric acid. It is the form found in biological systems at

physiological pH Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a subdiscipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out chemical and ...

. A valerate, or pentanoate, compound is a

carboxylate salt In organic chemistry, a carboxylate is the conjugate base of a carboxylic acid, (or ). It is an anion, an ion with negative charge. Carboxylate salts are salts that have the general formula , where M is a metal and ''n'' is 1, 2,.... ...

or ester of valeric acid. Many

steroid A steroid is an organic compound with four fused compound, fused rings (designated A, B, C, and D) arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes t ...

-based

pharmaceuticals Medication (also called medicament, medicine, pharmaceutical drug, medicinal product, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the ...

, for example ones based on

betamethasone Betamethasone is a corticosteroid, steroid medication. It is used for a number of diseases including rheumatic disorders such as rheumatoid arthritis and systemic lupus erythematosus, skin diseases such as dermatitis and psoriasis, allergic co ...

hydrocortisone Hydrocortisone is the name for the hormone cortisol when supplied as a medication. It is a corticosteroid and works as an anti-inflammatory and by immune suppression. Uses include conditions such as adrenocortical insufficiency, adrenogenit ...

, include the steroid as the valerate ester.

Examples

Estradiol valerate Estradiol valerate (EV), sold for use oral administration, by mouth under the brand name Progynova and for use by injection (medicine), injection under the brand names Delestrogen and Progynon Depot among others, is an estrogen (medication), es ...

Testosterone valerate Testosterone valerate, or testosterone pentanoate, also known as androst-4-en-17β-ol-3-one 17β-valerate, is a synthetic, steroidal androgen and an androgen ester – specifically, the C17β valerate ester of testosterone – which is used in v ...

* Methyl valerate * Ethyl valerate * Pentyl valerate *

Betamethasone valerate Betamethasone valerate is a synthetic glucocorticoid ester. It is the 17-valerate ester of betamethasone Betamethasone is a corticosteroid, steroid medication. It is used for a number of diseases including rheumatic disorders such as rheum ...

* Hydrocortisone valerate

References

{{Authority control GABA analogues Fatty acids Alkanoic acids Foul-smelling chemicals