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4-Ethylphenol^[1]
Names
	Preferred IUPAC name 4-Ethylphenol
	Other names p-Ethylphenol; 1-Ethyl-4-hydroxybenzene; 1-Hydroxy-4-ethylbenzene; 4-Hydroxyphenylethane
Identifiers
CAS Number	123-07-9 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:49584 ;
ChEMBL	ChEMBL108475 ;
ChemSpider	28982 ;
ECHA InfoCard	100.004.181
EC Number	204-598-6;
KEGG	C13637 ;
PubChem CID	31242;
UNII	AGG7E6G0ZC ;
CompTox Dashboard (EPA)	DTXSID4021977 ;
	InChI InChI=1S/C8H10O/c1-2-7-3-5-8(9)6-4-7/h3-6,9H,2H2,1H3 Key: HXDOZKJGKXYMEW-UHFFFAOYSA-N ; InChI=1/C8H10O/c1-2-7-3-5-8(9)6-4-7/h3-6,9H,2H2,1H3 Key: HXDOZKJGKXYMEW-UHFFFAOYAF;
	SMILES Oc1ccc(cc1)CC;
Properties
Chemical formula	C8H10O
Molar mass	122.167 g·mol−1
Appearance	White solid
Odor	leather-like
Melting point	45.1 °C (113.2 °F; 318.2 K)
Boiling point	218 °C (424 °F; 491 K)
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H314
Precautionary statements	P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P405, P501
NFPA 704 (fire diamond)	2 1 0
Flash point	104 °C (219 °F; 377 K)
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Ethylphenol (4-EP) is an organic compound with the formula C₂H₅C₆H₄OH. It is one of three isomeric ethylphenols. A white solid, it occurs as an impurity in xylenols and as such is used in the production of some commercial phenolic resins. It is also a precursor to 4-vinylphenol.^[3]

Natural occurrences

In wine and beer, 4-EP is produced by the yeast Brettanomyces. At concentrations greater than 140 μg/L (typical sensory threshold) it gives the wine aromas 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. Decarboxylation gives 4-vinylphenol as catalyzed by the enzyme cinnamate decarboxylase.^[4] 4-Vinylphenol is further reduced to 4-ethylphenol by the enzyme vinyl phenol reductase. Coumaric acid is sometimes added to microbiological media, enabling the positive identification of Brettanomyces by smell.

References

^ "4-Ethylphenol MSDS". Archived from the original on 2002-11-08. Retrieved 2002-11-08.
^ Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 690. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4. Only one name is retained, phenol, for C₆H₅-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.
^ Fiege, Helmut; Voges, Heinz-Werner; Hamamoto, Toshikazu; Umemura, Sumio; Iwata, Tadao; Miki, Hisaya; Fujita, Yasuhiro; Buysch, Hans-Josef; Garbe, Dorothea; Paulus, Wilfried (2000). "Phenol Derivatives". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_313. ISBN 3527306730.
^ Brettanomyces Monitoring by Analysis of 4-ethylphenol and 4-ethylguaiacol Archived 2008-02-19 at the Wayback Machine at etslabs.com