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123-07-9 YesY
ChEBI CHEBI:49584 YesY
ChEMBL ChEMBL108475 YesY
ChemSpider 28982 YesY
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KEGG C13637 YesY
Molar mass 122.16 g/mol
Appearance White solid
Melting point 42 to 45 °C (108 to 113 °F; 315 to 318 K)
Boiling point 218 °C (424 °F; 491 K)
Irritant Xi
S-phrases S7/9 S26 S36/37/39 S45
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

4-Ethylphenol, often abbreviated to 4-EP, is a phenolic compound.

Natural occurrences[edit]

In wine and beer, it is produced by the spoilage yeast Brettanomyces. When it reaches concentrations greater than the sensory threshold (140 µg/L) it can give 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-ethylphenol 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-ethylphenol.

It is also a component of castoreum, the exudate from the castor sacs of the mature North American beaver (Castor canadensis) and the European beaver (Castor fiber), used in perfumery.


4-Ethylphenol is produced from the precursor p-coumaric acid. Brettanomyces converts this to 4-vinylphenol via the enzyme cinnamate decarboxylase.[2] 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.

The conversion of p-coumaric acid to 4-ethyphenol by Brettanomyces

See also[edit]


  1. ^ 4-Ethylphenol MSDS
  2. ^ Brettanomyces Monitoring by Analysis of 4-ethylphenol and 4-ethylguaiacol at etslabs.com

External links[edit]