{{Chembox | Watchedfields = changed | verifiedrevid = 477221780 | Reference=<ref>{{Cite web |url=http://physchem.ox.ac.uk/MSDS/ET/4-ethylphenol.html |title=4-Ethylphenol MSDS |access-date=2002-11-08 |archive-url=https://web.archive.org/web/20021108024845/http://physchem.ox.ac.uk/MSDS/ET/4-ethylphenol.html |archive-date=2002-11-08 |url-status=dead }}</ref> | Name = 4-Ethylphenol | ImageFile = P-Ethylphenol.svg | ImageSize = 50px | PIN = 4-Ethylphenol<ref name=iupac2013>{{cite book | title = Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = [[Royal Society of Chemistry|The Royal Society of Chemistry]] | date = 2014 | location = Cambridge | page = 690 | doi = 10.1039/9781849733069-FP001 | isbn = 978-0-85404-182-4 | quote = Only one name is retained, phenol, for C<sub>6</sub>H<sub>5</sub>-OH, both as a preferred name and for general nomenclature. The structure is substitutable at any position. Locants 2, 3, and 4 are recommended, not ''o'', ''m'', and ''p''.}}</ref> | OtherNames = ''p''-Ethylphenol<br />1-Ethyl-4-hydroxybenzene<br />1-Hydroxy-4-ethylbenzene<br />4-Hydroxyphenylethane |Section1={{Chembox Identifiers | ChEBI_Ref = {{ebicite|correct|EBI}} | ChEBI = 49584 | SMILES = Oc1ccc(cc1)CC | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 28982 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = AGG7E6G0ZC | EC_number = 204-598-6 | KEGG_Ref = {{keggcite|correct|kegg}} | KEGG = C13637 | InChI = 1/C8H10O/c1-2-7-3-5-8(9)6-4-7/h3-6,9H,2H2,1H3 | InChIKey = HXDOZKJGKXYMEW-UHFFFAOYAF | ChEMBL_Ref = {{ebicite|correct|EBI}} | ChEMBL = 108475 | PubChem = 31242 | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C8H10O/c1-2-7-3-5-8(9)6-4-7/h3-6,9H,2H2,1H3 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = HXDOZKJGKXYMEW-UHFFFAOYSA-N | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 123-07-9 | RTECS = }} |Section2={{Chembox Properties | C=8|H=10|O=1 | Appearance = White solid | Odor = leather-like | Solvent = solvent | MeltingPtC = 45.1 | MeltingPt_notes = | BoilingPtC = 218 | BoilingPt_notes = }} |Section7={{Chembox Hazards | NFPA-H = 2 | NFPA-F = 1 | NFPA-R = 0 | FlashPtC = 104 | GHSPictograms = {{GHS05}} | GHSSignalWord = Danger | HPhrases = {{H-phrases|314}} | PPhrases = {{P-phrases|260|264|280|301+330+331|303+361+353|304+340|305+351+338|310|321|363|405|501}} }} }}

'''Ethylphenol''' (4-EP) is an [[organic compound]] with the formula C<sub>2</sub>H<sub>5</sub>C<sub>6</sub>H<sub>4</sub>OH. It is one of three isomeric [[ethylphenol]]s. A white solid, it occurs as an impurity in [[xylenol]]s and as such is used in the production of some commercial [[phenolic resin]]s. It is also a precursor to 4-vinylphenol.<ref name=Ull>{{Ullmann |doi=10.1002/14356007.a19_313|title=Phenol Derivatives|year=2000|last1=Fiege|first1=Helmut|last2=Voges|first2=Heinz-Werner|last3=Hamamoto|first3=Toshikazu|last4=Umemura|first4=Sumio|last5=Iwata|first5=Tadao|last6=Miki|first6=Hisaya|last7=Fujita|first7=Yasuhiro|last8=Buysch|first8=Hans-Josef|last9=Garbe|first9=Dorothea|last10=Paulus|first10=Wilfried|isbn=3527306730}}</ref>

==Production== 4-Ethylphenol is produced by careful [[sulfonation]] of [[ethylbenzene]] to 4-ethylphenylsulfonic acid.<ref name=Ull/> The sulfonic acid is subsequently subjected to [[alkaline fusion]], the dissolution of the sulfonic acid in molten alkali metal base. The main steps in the synthesis are shown: :{{chem2|EtC6H5 + SO3 -> EtC6H4SO3H}} (Et = ethyl) :{{chem2|EtC6H4SO3H + NaOH -> EtC6H4ONa + NaHSO3}} :{{chem2|EtC6H4ONa + H+ -> ArOH + Na+}}

== Natural occurrences == In [[wine]] and [[beer]], 4-EP is produced by the [[yeast]] ''[[Brettanomyces]]''. At concentrations greater than 140&nbsp;μg/L (typical [[sensory threshold]]) it gives the wine [[aroma]]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]], the exudate from the castor sacs of the mature [[North American beaver]] (''Castor canadensis'') and the [[Eurasian beaver]] (''Castor fiber''), used in perfumery.

==Biochemistry== 4-EP is biosynthesized in two steps from [[p-coumaric acid|''p''-coumaric acid]]. Decarboxylation gives [[4-vinylphenol]] as catalyzed by the enzyme [[cinnamate decarboxylase]].<ref>[http://www.etslabs.com/scripts/ets/pagetemplate/blank.asp?pageid=193 Brettanomyces Monitoring by Analysis of 4-ethylphenol and 4-ethylguaiacol] {{webarchive|url=https://web.archive.org/web/20080219204946/http://www.etslabs.com/scripts/ets/pagetemplate/blank.asp?pageid=193 |date=2008-02-19 }} at etslabs.com</ref> 4-Vinylphenol is further reduced to 4-ethylphenol by the enzyme [[vinyl phenol reductase]]. Coumaric acid is sometimes added to [[growth medium|microbiological media]], enabling the positive identification of ''Brettanomyces'' by smell. :[[File:Coumaric acid to 4-ethyphenol.svg|left|thumb|290px|The conversion of [[p-Coumaric acid|''p''-coumaric acid]] to 4-EP by ''Brettanomyces'']]{{clear|left}}

== See also == * [[4-Ethylguaiacol]] * [[Yeast in winemaking]] * [[Wine fault]] * [[Wine chemistry]]

== References == <references/>

== External links == *[https://web.archive.org/web/20040105113802/http://wwwdb.mhlw.go.jp/ginc/cgi-bin/db1_search.pl?CAS=123-07-9&MID=177 4-Ethylphenol oral toxicity data]

{{DEFAULTSORT:Ethylphenol, 4-}} [[Category:Alkylphenols]] [[Category:4-Hydroxyphenyl compounds]]