{{Short description|Chemical primarily responsible for cork taint in wines (TCA)}} {{chembox | Verifiedimages = changed | Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 477210787 | Name = 2,4,6-Trichloroanisole | ImageFile_Ref = {{chemboximage|correct|??}} | ImageFile = 2,4,6-TrichloroanisoleImproved.svg | ImageSize = 150 | ImageAlt = Chemical structure of 2,4,6-trichloroanisole | ImageFile1 = 2,4,6-Trichloroanisole-3D-balls.png | ImageSize1 = 150 | ImageAlt1 = Ball-and-stick model of the 2,4,6-trichloroanisole molecule | PIN = 1,3,5-Trichloro-2-methoxybenzene <!-- no substitution on anisole for PINs according to Subsection P-63.2.3 of ''Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book)'' --> | OtherNames = 2,4,6-Trichloroanisole<br />TCA<br/>2,4,6-Trichloromethoxybenzene |Section1={{Chembox Identifiers | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChEBI_Ref = {{ebicite|correct|EBI}} | ChEBI = 19333 | ChemSpiderID = 6620 | EC_number = 201-743-5 | KEGG_Ref = {{keggcite|correct|kegg}} | KEGG = C11510 | PubChem = 6884 | InChI = 1/C7H5Cl3O/c1-11-7-5(9)2-4(8)3-6(7)10/h2-3H,1H3 | SMILES1 = Clc1cc(Cl)cc(Cl)c1OC | InChIKey = WCVOGSZTONGSQY-UHFFFAOYAT | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C7H5Cl3O/c1-11-7-5(9)2-4(8)3-6(7)10/h2-3H,1H3 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = WCVOGSZTONGSQY-UHFFFAOYSA-N | CASNo_Ref = {{cascite|correct|CAS}} | CASNo = 87-40-1 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = 31O3X41254 | SMILES = COc1c(Cl)cc(Cl)cc1Cl | RTECS = MFCD00000588 }} |Section2={{Chembox Properties | C=7 | H=5 | Cl=3 | O=1 | Density = | MeltingPtC = 60 to 62 | BoilingPtC = 140 | BoilingPt_notes = at 28 Torr }} |Section7={{Chembox Hazards | GHSPictograms = {{GHS07}} | GHSSignalWord = Warning | HPhrases = {{H-phrases|302|319|413}} | PPhrases = {{P-phrases|264|270|273|280|301+312|305+351+338|330|337+313|501}} }} }} '''2,4,6-Trichloroanisole''' ('''TCA''') is an organic compound with the formula {{chem2|CH3OC6H2Cl3}}. It is one of several isomers of trichloroanisole. It is a colorless solid.
==Occurrence==
2,4,6-Trichloroanisole represents one of the strongest of off-flavors, substances "generated naturally in foods/beverages [that considerably] deteriorate the quality" of such products.<ref name = TakeuchiPNAS2013>{{Cite journal| doi = 10.1073/pnas.1300764110| issn = 1091-6490| author = Takeuchi, Hiroko; Kato, Hiroyuki & Kurahashi, Takashi | title = 2,4,6-Trichloroanisole is a Potent Suppressor of Olfactory Signal Transduction| journal = Proceedings of the National Academy of Sciences| date = 2013-09-16| volume=110| issue = 40| pages = 16235–16240| pmid=24043819| pmc=3791788| bibcode = 2013PNAS..11016235T| doi-access = free}}{{primary source inline|date = June 2023}}</ref><ref name=":0">{{Cite book |last=Jackson |first=Ron S. |title=Wine tasting: a professional handbook |date=2009 |publisher=Academic Press |isbn=978-0-12-374181-3 |edition=2nd |series=Food science and technology international series |language=En |chapter=Chapter 3: Olfactory Sensations}}</ref> It is also a component of some drinking waters.<ref>{{cite journal|doi= 10.1016/0043-1354(95)00173-5|title= Taste and odour threshold concentrations of potential potable water contaminants|date= 1996|last1= Young|first1= W.F.|last2= Horth|first2= H.|last3= Crane|first3= R.|last4= Ogden|first4= T.|last5= Arnott|first5= M.|journal= Water Research|volume= 30|issue= 2|pages= 331–340|bibcode= 1996WatRe..30..331Y}}</ref> It has also been detected in blood samples.<ref>{{cite journal |doi=10.1007/s002440010298 |title=Identification of Hydroxylated PCB Metabolites and Other Phenolic Halogenated Pollutants in Human Blood Plasma |date=2002 |last1=Hovander, t. Malmberg, m. Athanasia |first1=L. |last2=Malmberg |first2=T. |last3=Athanasiadou |first3=M. |last4=Athanassiadis |first4=I. |last5=Rahm |first5=S. |last6=Bergman |first6=A. |last7=Wehler |first7=E. K. |journal=Archives of Environmental Contamination and Toxicology |volume=42 |issue=1 |pages=105–117 |pmid=11706375 |bibcode=2002ArECT..42..105H }}</ref>
===Wine=== As of 2000, TCA was considered the primary chemical compound responsible for the phenomenon of cork taint in wines,<ref>{{cite book | author = Marsili, R. | date = 2000 | chapter = Solid-Phase Microextraction: Food Technology Applications | title = Encyclopedia of Separation Science | editor = Wilson, Ian D. | location = New York, NY | publisher = Academic Press | chapter-url = https://www.sciencedirect.com/science/article/abs/pii/B0122267702067910 | doi = 10.1016/B0-12-226770-2/06791-0 | pages = 4178–4190 | isbn = 9780122267703 | quote = Over the last two decades, the incidence of mouldy and musty off-flavours in cork-sealed wines has increased significantly. 2,4,6-Trichloroanisole (TCA) has been identified as the primary chemical responsible for cork taint. The human olfactometry threshold for TCA is 4–10 ng L−1 in white wine and 50 ng L−1 in red wine. In the case of wine, a worldwide loss of roughly US$1 billion per year is attributed to cork taint.}}</ref><ref name = TakeuchiPNAS2013/> and it has an unpleasant earthy, musty and moldy smell.<ref name=":0" />
===Coffee=== TCA has also been suggested as cause of the "Rio defect" in coffees from Brazil and other parts of the world,<ref>These include Central and South America.{{citation needed|date = June 2023}}</ref> which refers to a taste described as "medicinal, phenolic, or iodine-like".<ref name = SpadoneJAFC1990/> In investigation of the mechanism of its role in producing off-flavor effects, it was found to "attenuate olfactory transduction by suppressing cyclic nucleotide-gated channels, without evoking odorant responses."<ref name = TakeuchiPNAS2013/>
==Formation== TCA is formed by the methylation of 2,4,6-trichlorophenol.<ref>{{Citation |last=Pereira |first=Helena |title=Chapter 14 - Wine and cork |date=2007-01-01 |url=https://www.sciencedirect.com/science/article/pii/B9780444529671500169 |work=Cork |pages=305–327 |editor-last=Pereira |editor-first=Helena |access-date=2024-01-14 |place=Amsterdam |publisher=Elsevier Science B.V. |isbn=978-0-444-52967-1}}</ref><ref name = SpadoneJAFC1990>{{Cite journal | author = Spadone, Jean Claude; Takeoka, Gary & Liardon, Remy| title = Analytical Investigation of Rio Off-Flavor in Green Coffee| journal = Journal of Agricultural and Food Chemistry| doi = 10.1021/jf00091a050 | year = 1990| volume = 38| pages = 226–233}} Note, at best, this source states that 2,4,6-trichlorophenol is "the probable precursor of TCA".</ref> More generally, it may be produced when naturally occurring airborne fungi and bacteria are presented with chlorinated phenolic compounds, which they then convert into chlorinated anisole derivatives.<ref name=":1">{{Cite journal |last=Cravero |first=Maria Carla |last2=Bonello |first2=Federica |last3=Pazo Alvarez |first3=Maria del Carmen |last4=Tsolakis |first4=Christos |last5=Borsa |first5=Daniela |date=24 June 2015 |title=The sensory evaluation of 2,4,6-trichloroanisole in wines: The sensory evaluation of 2,4,6-trichloroanisole in wines |url=https://onlinelibrary.wiley.com/doi/10.1002/jib.230 |journal=Journal of the Institute of Brewing |language=en |volume=121 |issue=3 |pages=411–417 |doi=10.1002/jib.230|doi-access=free }}</ref> Species implicated include those of the genera ''Aspergillus'', ''Penicillium'', ''Actinomycetes'', ''Botrytis'' (e.g. ''Botrytis cinerea''), ''Rhizobium'', or ''Streptomyces''.<ref>{{Cite web |last=Crane |first=Louise |title=Trichloroanisole: Cork taint |url=https://www.chemistryworld.com/podcasts/trichloroanisole-cork-taint/3010280.article |access-date=2024-01-14 |website=Chemistry World |language=en |publication-date=22 March 2019}}</ref><ref>With regard to circumstantial evidence, Spodone, et al., op. cit., note that Rio off-flavor is associated with "beans heavily infested with various fungi (Aspergilli, Fusaria, Penicillia, Rhizopus, etc.) and bacteria (Lactobacilli, Streptrococci)".</ref><ref name=":1" />
The chlorophenol precursor, 2,4,6-trichlorophenol, is used as a fungicide; more generally, related compounds can originate as contaminants found in some pesticides and wood preservatives, or as by-products of the chlorine bleaching process used to sterilize or bleach wood, paper, and other materials.<ref>NTP (National Toxicology Program). 2021. "2,4,6-Trichlorophenol", ''Report on Carcinogens, Fifteenth Edition.'' Research Triangle Park, NC: U.S. Department of Health and Human Services, Public Health Service. <nowiki>[https://web.archive.org/web/20220118142253/https://ntp.niehs.nih.gov/whatwestudy/assessments/cancer/roc/index.html?utm_source=direct&utm_medium=prod&utm_campaign=ntpgolinks&utm_term=roc15 nih.gov]</nowiki>
DOI: <nowiki>https://doi.org/10.22427/NTP-OTHER-1003</nowiki></ref>
==Further reading== * {{cite book | author = Marsili, R. | date = 2000 | chapter = Solid-Phase Microextraction: Food Technology Applications | title = Encyclopedia of Separation Science | editor = Wilson, Ian D. | location = New York, NY | publisher = Academic Press | chapter-url = https://www.sciencedirect.com/science/article/abs/pii/B0122267702067910 | doi = 10.1016/B0-12-226770-2/06791-0 | pages = 4178–4190 | isbn = 9780122267703 | quote = Over the last two decades, the incidence of mouldy and musty off-flavours in cork-sealed wines has increased significantly. 2,4,6-Trichloroanisole (TCA) has been identified as the primary chemical responsible for cork taint. The human olfactometry threshold for TCA is 4–10 ng L−1 in white wine and 50 ng L−1 in red wine. In the case of wine, a worldwide loss of roughly US$1 billion per year is attributed to cork taint.}} * {{cite web | author = Science Direct Staff | date = June 2023 | title = 2-4-6-Trichloroanisole | format = ''Science Direct'' citation sample/listing | url = https://www.sciencedirect.com/topics/chemistry/2-4-6-trichloroanisole | access-date = June 26, 2023}} * {{cite journal | author = Buser, H.R.; Zanier, C. & Tanner, H.| title = Identification of 2,4,6-Trichloroanisole as a Potent Compound Causing Cork Taint in Wine. | journal = Journal of Agricultural and Food Chemistry| doi = 10.1021/jf00110a037| year = 1982 | volume = 30 | issue = 2 | pages = 359–362}} An early primary research report on the role of TCA in cork taint.
== See also == * 2,4,6-Tribromoanisole
==References== {{Reflist}}
{{DEFAULTSORT:Trichloroanisole, 2, 4, 6-}} Category:Chlorobenzene derivatives Category:Phenol ethers