4-ethylphenol
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Ethylphenol (4-EP) is an
organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...
with the formula C2H5C6H4OH. It is one of three isomeric
ethylphenol Ethylphenol may refer to: * 2-Ethylphenol * 3-Ethylphenol * 4-Ethylphenol * Ethyl phenyl ether Ethyl phenyl ether (or phenetole) is an organic compound that belongs to a class of compounds called ethers. Ethyl phenyl ether has the same properti ...
s. A white solid, it occurs as an impurity in xylenols and as such is used in the production of some commercial
phenolic resin Phenol formaldehyde resins (PF) or phenolic resins (also infrequently called phenoplasts) are synthetic polymers obtained by the reaction of phenol or substituted phenol with formaldehyde. Used as the basis for Bakelite, PFs were the first commerc ...
s. It is also a precursor to 4-vinylphenol.


Natural occurrences

In
wine Wine is an alcoholic drink typically made from Fermentation in winemaking, fermented grapes. Yeast in winemaking, Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different ...
and
beer Beer is one of the oldest and the most widely consumed type of alcoholic drink in the world, and the third most popular drink overall after water and tea. It is produced by the brewing and fermentation of starches, mainly derived from ce ...
, 4-EP is produced by the
yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constit ...
''
Brettanomyces ''Brettanomyces'' is a non-spore forming genus of yeast in the family Saccharomycetaceae, and is often colloquially referred to as "Brett". The genus name ''Dekkera'' is used interchangeably with ''Brettanomyces'', as it describes the teleomorp ...
''. At concentrations greater than 140 μg/L (typical
sensory threshold In psychophysics, sensory threshold is the weakest stimulus that an organism can sense. Unless otherwise indicated, it is usually defined as the weakest stimulus that can be detected half the time, for example, as indicated by a point on a proba ...
) it gives the wine
aroma An odor (American English) or odour (Commonwealth English; see spelling differences) is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and animals can perceive via their sens ...
s described as ''barnyard'', ''medicinal'', ''band-aids'', and ''mousy''. In certain Belgian beer styles, a high 4-EP level may be desirable; however, very high levels of the compound in wine can render it undrinkable. The level of 4-EP is roughly proportional to ''Brettanomyces'' concentration and activity, and can therefore be used as an indicator of the yeast's presence. There are significant differences between strains of ''Brettanomyces'' in their ability to produce 4-EP. 4-EP is also a component of
castoreum Castoreum is a yellowish exudate from the castor sacs of mature beavers. Beavers use castoreum in combination with urine to scent mark their territory. Both beaver sexes have a pair of castor sacs and a pair of anal glands, located in two cavities ...
, the exudate from the castor sacs of the mature
North American beaver The North American beaver (''Castor canadensis'') is one of two extant beaver species, along with the Eurasian beaver (''Castor fiber''). It is native to North America and introduced in South America ( Patagonia) and Europe (primarily Finland ...
(''Castor canadensis'') and the
Eurasian beaver The Eurasian beaver (''Castor fiber'') or European beaver is a beaver species that was once widespread in Eurasia, but was hunted to near-extinction for both its fur and castoreum. At the turn of the 20th century, only about 1,200 beavers survi ...
(''Castor fiber''), used in perfumery.


Biochemistry

4-EP is biosynthesized in two steps from ''p''-coumaric acid. Decarboxylation gives 4-vinylphenol as catalyzed by the enzyme
cinnamate decarboxylase 4-Hydroxycinnamate decarboxylase is an enzyme that uses ''p''-coumaric acid to produce 4-ethylphenol. ''p''-Coumaric acid is the precursor of 4-ethylphenol produced by the yeast ''Saccharomyces'' and ''Brettanomyces'' in wine. The yeast converts ...
.Brettanomyces Monitoring by Analysis of 4-ethylphenol and 4-ethylguaiacol
at etslabs.com 4-Vinylphenol is further reduced to 4-ethylphenol by the enzyme
vinyl phenol reductase Vinylphenol reductase is an enzyme that catalyses the reaction : 4-vinylphenol + NAD+ + 3 H+ ⇔ 4-ethylphenol + NADH It is found in ''Brettanomyces bruxellensis'', a yeast responsible of the presence of ethyl phenols in wine formed from p-cou ...
. Coumaric acid is sometimes added to microbiological media, enabling the positive identification of ''Brettanomyces'' by smell. :


See also

* 4-Ethylguaiacol *
Yeast in winemaking The role of yeast in winemaking is the most important element that distinguishes wine from fruit juice. In the :wikt:anaerobic, absence of oxygen, yeast converts the sugar in wine, sugars of the fruit into ethanol, alcohol and carbon dioxide throu ...
*
Wine fault A wine fault or defect is an unpleasant characteristic of a wine often resulting from poor winemaking practices or storage conditions, and leading to wine spoilage. Many of the compounds that cause wine faults are already naturally present in wine ...
*
Wine chemistry Wine is a complex mixture of chemical compounds in a hydro-alcoholic solution with a pH around 4. The chemistry of wine and its resultant quality depend on achieving a balance between three aspects of the berries used to make the wine: their sugar ...


References


External links


4-Ethylphenol oral toxicity data
{{DEFAULTSORT:Ethylphenol, 4- Alkylphenols