{{chembox | Watchedfields = changed | verifiedrevid = 477221750 | Name = 4-Ethylguaiacol | ImageFile = 4-Ethylguaiacol.svg | PIN = 4-Ethyl-2-methoxyphenol | OtherNames = ''p''-Ethylguaiacol<br />Homocresol<br />Guaiacyl ethane<br />2-Methoxy-4-ethylphenol |Section1={{Chembox Identifiers | PubChem = 62465 | SMILES = Oc1ccc(cc1OC)CC | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 56245 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = C9NFD83BJ5 | InChI = 1/C9H12O2/c1-3-7-4-5-8(10)9(6-7)11-2/h4-6,10H,3H2,1-2H3 | InChIKey = CHWNEIVBYREQRF-UHFFFAOYAE | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C9H12O2/c1-3-7-4-5-8(10)9(6-7)11-2/h4-6,10H,3H2,1-2H3 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = CHWNEIVBYREQRF-UHFFFAOYSA-N | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 2785-89-9 }} |Section2={{Chembox Properties | C=9 | H=12 | O=2 | Appearance = Colorless liquid | MeltingPtC = 15 | BoilingPtC = 235.1 | BoilingPt_ref = <ref name="Mozaffari2020" /> | Density = 1064 kg/m<sup>3</sup> (20{{nbsp}}°C)<ref name="Mozaffari2020">{{Cite journal|last1=Mozaffari|first1=Parsa|last2=Järvik|first2=Oliver|last3=Baird|first3=Zachariah Steven|date=2020-10-28|title=Vapor Pressures of Phenolic Compounds Found in Pyrolysis Oil|url=https://doi.org/10.1021/acs.jced.0c00675|journal=Journal of Chemical & Engineering Data|volume=65|issue=11|pages=5559–5566|doi=10.1021/acs.jced.0c00675|s2cid=228958726 |issn=0021-9568|url-access=subscription}}</ref> }} |Section7={{Chembox Hazards | ExternalSDS = [https://fscimage.fishersci.com/msds/03311.htm External MSDS] | GHSPictograms = {{GHS07}} | GHSSignalWord = Warning | HPhrases = {{HPhrases|H315 | H319 | H335}} | PPhrases = {{PPhrases|P302 + P352 | P305 + P351 + P338}} | GHS_ref = <ref>GHS: [https://www.sigmaaldrich.com/product/ALDRICH/W243604 Sigma-Aldrich W243604] </ref> | NFPA-H = 2 | NFPA-F = 1 | NFPA-R = 0 }} }}
'''4-Ethylguaiacol''', often abbreviated to '''4-EG''', is a [[natural phenol|phenolic]] compound with the molecular formula C<sub>9</sub>H<sub>12</sub>O<sub>2</sub> that's a key aromatic component in various products, from food and beverages to cosmetics and pharmaceuticals.<ref>{{cite journal |last=Suezawa |first=Y. |last2=Suzuki |first2=M. |title=Bioconversion of Ferulic Acid to 4-Vinylguaiacol and 4-Ethylguaiacol and of 4-Vinylguaiacol to 4-Ethylguaiacol by Halotolerant Yeasts Belonging to the Genus Candida |journal=Bioscience, Biotechnology, and Biochemistry |date=2007 |volume=71 |issue=4 |pages=1058–1062 |doi=10.1271/bbb.71.1058}}</ref> It can be produced in [[wine]] and [[beer]] by ''[[Brettanomyces]]''.<ref name=":0" /> It is also frequently present in [[bio-oil]] produced by [[pyrolysis]] of [[lignocellulosic biomass]].<ref name=":1">{{Cite journal|last1=Lyu|first1=Gaojin|last2=Wu|first2=Shubin|last3=Zhang|first3=Hongdan|date=2015|title=Estimation and Comparison of Bio-Oil Components from Different Pyrolysis Conditions|journal=Frontiers in Energy Research|language=English|volume=3|doi=10.3389/fenrg.2015.00028|issn=2296-598X|doi-access=free}}</ref>
== Winemaking == It is produced along with [[4-Ethylphenol|4-ethylphenol]] (4-EP) in [[wine]] and [[beer]] by the spoilage yeast ''[[Brettanomyces]]''.<ref name=":0">{{cite journal | last1 = Caboni | first1 = Pierluigi | last2 = Sarais | first2 = Giorgia | last3 = Cabras | first3 = Marco | last4 = Angioni | first4 = Alberto | title = Determination of 4-Ethylphenol and 4-Ethylguaiacol in Wines by LC-MS-MS and HPLC-DAD-Fluorescence | journal = Journal of Agricultural and Food Chemistry | volume = 55 | pages = 7288–93 | year = 2007 | doi = 10.1021/jf071156m | issue = 18 | pmid = 17676867}}</ref> When it is produced by the yeast to concentrations greater than the [[sensory threshold]] of >600 μg/L, it can contribute bacon, spice, clove, or smoky aromas to the wine. On their own these characters can be quite attractive in a wine, however as the compound usually occurs with 4-EP whose aromas can be more aggressive, the presence of the compound often signifies a [[wine fault]]. The ratio in which 4-EP and 4-EG are present can greatly affect the [[organoleptic]] properties of the wine.
== Bio-oil == 4-Ethylguaiacol can also be produced by [[pyrolysis]] of [[lignocellulosic biomass]]. It is produced from the [[lignin]], along with many of the other phenolic compounds present in [[bio-oil]]. In particular, 4-ethylguaiacol is derived from [[guaiacyl]] in the lignin.<ref name=":1" />
== See also == * [[Yeast in winemaking]] * [[Wine chemistry]]
== References == <references/>
{{DEFAULTSORT:Ethylguaiacol, 4-}} [[Category:Natural phenols]] [[Category:Alkylphenols]] [[Category:Phenol ethers]]