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Thymol

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Not to be confused withThymeol,Thymine,orThiamine.

Thymol
Thymol
Names
Preferred IUPAC name
5-Methyl-2-(propan-2-yl)phenol[1]
Systematic IUPAC name
5-Methyl-2-(propan-2-yl)benzenol
Other names
2-Isopropyl-5-methylphenol, isopropyl-m-cresol, 1-methyl-3-hydroxy-4-isopropylbenzene, 3-methyl-6-isopropylphenol, 5-methyl-2-(1-methylethyl)phenol, 5-methyl-2-isopropyl-1-phenol, 5-methyl-2-isopropylphenol, 6-isopropyl-3-methylphenol, 6-isopropyl-m-cresol, Apiguard, NSC 11215, NSC 47821, NSC 49142, thyme camphor,m-thymol, andp-cymen-3-ol
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.001.768Edit this at Wikidata
EC Number
  • 201-944-8
KEGG
UNII
  • InChI=1S/C10H14O/c1-7(2)9-5-4-8(3)6-10(9)11/h4-7,11H,1-3H3checkY
    Key: MGSRCZKZVOBKFT-UHFFFAOYSA-NcheckY
  • InChI=1/C10H14O/c1-7(2)9-5-4-8(3)6-10(9)11/h4-7,11H,1-3H3
    Key: MGSRCZKZVOBKFT-UHFFFAOYAS
  • CC(C)c1ccc(C)cc1O
Properties
C10H14O
Molar mass 150.221g·mol−1
Density 0.96 g/cm3
Melting point 49 to 51 °C (120 to 124 °F; 322 to 324 K)
Boiling point 232 °C (450 °F; 505 K)
0.9 g/L (20 °C)[2]
1.5208[3]
Pharmacology
QP53AX22(WHO)
Hazards
GHSlabelling:
GHS05: CorrosiveGHS07: Exclamation markGHS09: Environmental hazard
Warning
H302,H314,H411
P260,P264,P270,P273,P280,P301+P312,P301+P330+P331,P303+P361+P353,P304+P340,P305+P351+P338,P310,P321,P330,P363,P391,P405,P501
Except where otherwise noted, data are given for materials in theirstandard state(at 25 °C [77 °F], 100 kPa).

Thymol(also known as2-isopropyl-5-methylphenol,IPMP),C10H14O,is a naturalmonoterpenoidphenolderivative ofp-Cymene,isomericwithcarvacrol,found in oil ofthyme,andextractedfromThymus vulgaris(common thyme),ajwain,[4]and various other plants as a whitecrystallinesubstance of a pleasantaromaticodorand strongantisepticproperties.Thymol also provides the distinctive, strong flavor of theculinary herbthyme, also produced fromT. vulgaris.Thymol is only slightlysolublein water at neutralpH,but it is extremely soluble inalcoholsand other organic solvents. It is also soluble in stronglyalkalineaqueous solutions due todeprotonationof thephenol.Its dissociation constant (pKa) is10.59±0.10.[5]Thymol absorbs maximumUVradiation at 274 nm.[6]

Chemical synthesis[edit]

Thymol is produced by thealkylationofm-cresolandpropene:[7][8]

CH3C6H4OH + CH2CHCH3→ ((CH3)2CH)CH3C6H3OH

A predicted method of biosynthesis of thymol in thyme and oregano begins with the cyclization of geranyl diphosphate by TvTPS2 to γ-terpinene. Oxidation by acytochrome P450in the CYP71D subfamily creates adienolintermediate, which is then converted into a ketone by short-chain dehydrogenase. Lastly,keto-enol tautomerizationgives thymol.

Predicted biosynthesis of thymol in thyme and oregano. Reconstruction of figure 4 in Krause et. al. (2021).[9]

History[edit]

Ancient Egyptiansused thyme forembalming.[10]Theancient Greeksused it in their baths and burned it asincensein their temples, believing it was a source ofcourage.The spread of thyme throughout Europe was thought to be due to theRomans,as they used it to purify their rooms and to "give an aromatic flavour to cheese and liqueurs".[11]In the EuropeanMiddle Ages,the herb was placed beneath pillows to aid sleep and ward off nightmares.[12]In this period, women also often gaveknightsand warriors gifts that included thyme leaves, because it was believed to bring courage to the bearer. Thyme was also used as incense and placed oncoffinsduringfunerals,because it was supposed to ensure passage into the next life.[13]

The bee balmsMonarda fistulosaandMonarda didyma,North American wildflowers, are natural sources of thymol. TheBlackfootNative Americans recognized these plants' strongantisepticaction and usedpoulticesof the plants for skininfectionsand minorwounds.Atisanemade from them was also used to treat mouth and throatinfectionscaused by dentalcariesandgingivitis.[14]

Thymol was first isolated by German chemistCaspar Neumannin 1719.[15]In 1853, French chemist Alexandre Lallemand[16](1816-1886) named thymol and determined its empirical formula.[17]Thymol was first synthesized by Swedish chemist Oskar Widman[18](1852-1930) in 1882.[19]

Extraction[edit]

The conventional method ofextractingishydro-distillation(HD), but can also be extracted withsolvent-freemicrowaveextraction (SFME). In 30 minutes, SFME yields similar amounts of thymol with more oxygenated compounds than 4.5 hours of hydro-distillation at atmospheric pressures without the need for solvent.[20]

Uses[edit]

Thymol

Thymol during the 1910s was the treatment of choice forhookworm infectionin the United States.[21][22]People of the Middle East continue to useza'atar,a delicacy made with large amounts of thyme, to reduce and eliminate internal parasites.[23]It is also used as apreservativeinhalothane,ananaesthetic,and as an antiseptic in mouthwash. When used to reduce plaque and gingivitis, thymol has been found to be more effective when used in combination withchlorhexidinethan when used purely by itself.[24]Thymol is also the active antiseptic ingredient in some toothpastes, such asJohnson & Johnson'sEuthymol.Thymol has been used to successfully controlvarroa mitesand prevent fermentation and the growth ofmoldinbee colonies.[25]Thymol is also used as a rapidly degrading, non-persistingpesticide.[26]Thymol can also be used as a medical disinfectant and general purposedisinfectant.[27]Thymol is also used in the production ofmentholthrough the hydrogenation of the aromatic ring.[28]

List of plants that contain thymol[edit]

Toxicology and environmental impacts[edit]

In 2009, theU.S. Environmental Protection Agency (EPA)reviewed the research literature on the toxicology and environmental impact of thymol and concluded that "thymol has minimal potential toxicity and poses minimal risk".[43]

Environmental breakdown and use as a pesticide[edit]

Studies have shown that hydrocarbonmonoterpenesand thymol in particular degrade rapidly (DT5016 days in water, 5 days in soil[26]) in the environment and are, thus, low risks because of rapid dissipation and low bound residues,[26]supporting the use of thymol as a pesticide agent that offers a safe alternative to other more persistent chemical pesticides that can be dispersed in runoff and produce subsequent contamination. Though, there has been recent research into sustained released systems for botanically derived pesticides, such as using naturalpolysaccharideswhich would be biodegradable and biocompatible.[44]

Compendial status[edit]

See also[edit]

Notes and references[edit]

  1. ^"Front Matter".Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book).Cambridge: TheRoyal Society of Chemistry.2014. p. 691.doi:10.1039/9781849733069-FP001.ISBN978-0-85404-182-4.
  2. ^"Thymol".PubChem.Retrieved1 April2016.
  3. ^Mndzhoyan, A. L. (1940). "Thymol fromThymus kotschyanus".Sbornik Trudov Armyanskogo Filial. Akad. Nauk.1940:25–28.
  4. ^O'Connell, John (27 August 2019).The book of spice: from anise to zedoary.New York: Pegasus.ISBN978-1681774459.OCLC959875923.
  5. ^CAS Registry: Data obtained from SciFinder[full citation needed]
  6. ^Norwitz, G.; Nataro, N.; Keliher, P. N. (1986). "Study of the Steam Distillation of Phenolic Compounds Using Ultraviolent Spectrometry".Anal. Chem.58(639–640): 641.doi:10.1021/ac00294a034.
  7. ^Stroh, R.; Sydel, R.; Hahn, W. (1963). Foerst, Wilhelm (ed.).Newer Methods of Preparative Organic Chemistry, Volume 2(1st ed.). New York: Academic Press. p. 344.ISBN9780323150422.
  8. ^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.ISBN3527306730.
  9. ^Krause, Sandra T.; Liao, Pan; Crocoll, Christoph; Boachon, Benoît; Förster, Christiane; Leidecker, Franziska; Wiese, Natalie; Zhao, Dongyan; Wood, Joshua C.; Buell, C. Robin; Gershenzon, Jonathan; Dudareva, Natalia; Degenhardt, Jörg (28 December 2021)."The biosynthesis of thymol, carvacrol, and thymohydroquinone in Lamiaceae proceeds via cytochrome P450s and a short-chain dehydrogenase".Proceedings of the National Academy of Sciences.118(52).doi:10.1073/pnas.2110092118.ISSN0027-8424.PMC8719858.PMID34930840.
  10. ^"A Brief History of Thyme - Hungry History".HISTORY.com.Archivedfrom the original on 13 June 2016.Retrieved9 June2016.
  11. ^Grieve, Mrs. Maud."Thyme. A Modern Herbal".botanical.com(Hypertext version of the 1931 ed.).Archivedfrom the original on 23 February 2011.Retrieved9 February2008.
  12. ^Huxley, A., ed. (1992).New RHS Dictionary of Gardening.Macmillan.
  13. ^"Thyme (thymus)".englishplants.co.uk.The English Cottage Garden Nursery.Archivedfrom the original on 27 September 2006.
  14. ^Tilford, Gregory L. (1997).Edible and Medicinal Plants of the West.Missoula, MT: Mountain Press Publishing.ISBN978-0-87842-359-0.
  15. ^Neuman, Carolo (1724)."De Camphora".Philosophical Transactions of the Royal Society of London.33(389): 321–332.doi:10.1098/rstl.1724.0061.On page 324, Neumann mentions that in 1719 he distilled some essential oils from various herbs. On page 326, he mentions that during these experiments, he obtained a crystalline substance from thyme oil, which he called "Camphora Thymi"(camphorof thyme). (Neumann gave the name "camphor" not only to the specific substance that today is called camphor but to any crystalline substance that precipitated from a volatile, fragrant oil from some plant.)
  16. ^Marie-Étienne-Alexandre Lallemand (December 25, 1816 - March 16, 1886)
  17. ^Lallemand, A. (1853)."Sur la composition de l'huile essentielle de thym"[On the composition of the essential oil of thyme].Comptes Rendus(in French).37:498–500.
  18. ^Karl Oskar Widman (aka Carl Oskar Widman) (January 2, 1852 - August 26, 1930)
  19. ^Widmann, Oskar (1882)."Ueber eine Synthese von Thymol aus Cuminol"[On a synthesis of thymol from cuminol].Berichte der Deutschen Chemischen Gesellschaft zu Berlin(in German).15:166–172.doi:10.1002/cber.18820150139.
  20. ^Lucchesi, Marie E; Chemat, Farid; Smadja, Jacqueline (23 July 2004)."Solvent-free microwave extraction of essential oil from aromatic herbs: comparison with conventional hydro-distillation".Journal of Chromatography A.1043(2): 323–327.doi:10.1016/j.chroma.2004.05.083.ISSN0021-9673.PMID15330107.
  21. ^Ferrell, John Atkinson (1914).The Rural School and Hookworm Disease.US Bureau of Education Bulletin. Vol. 20, Whole No. 593. Washington, DC: U.S. Government Printing Office.
  22. ^Milton, Joseph Rosenau (1913).Preventive Medicine and Hygiene.D. Appleton. p. 119.
  23. ^Inskeep, Steve; Godoy, Maria (11 June 2013)."Za'atar: A Spice Mix With Biblical Roots And Brain Food Reputation".NPR.Retrieved24 February2022.
  24. ^Filoche, S. K.; Soma, K.; Sissons, C. H. (2005). "Antimicrobial effects of essential oils in combination with chlorhexidine digluconate".Oral Microbiol. Immunol.20(4): 221–225.doi:10.1111/j.1399-302X.2005.00216.x.PMID15943766.
  25. ^Ward, Mark (8 March 2006)."Almond farmers seek healthy bees".BBC News.BBC.
  26. ^abcHu, D.; Coats, J. (2008). "Evaluation of the environmental fate of thymol and phenethyl propionate in the laboratory".Pest Manag. Sci.64(7): 775–779.doi:10.1002/ps.1555.PMID18381775.
  27. ^"Thymol"(PDF).US Environmental Protection Agency. September 1993.
  28. ^"Menthol | Definition, Structure, & Uses | Britannica".www.britannica.com.6 October 2023.Retrieved30 October2023.
  29. ^Novy, P.; Davidova, H.; Serrano Rojero, C. S.; Rondevaldova, J.; Pulkrabek, J.; Kokoska, L. (2015)."Composition and Antimicrobial Activity ofEuphrasia rostkovianaHayne Essential Oil ".Evid Based Complement Alternat Med.2015:1–5.doi:10.1155/2015/734101.PMC4427012.PMID26000025.
  30. ^Baser, K. H.C.; Tümen, G. (1994). "Composition of the Essential Oil ofLagoecia cuminoidesL. from Turkey ".Journal of Essential Oil Research.6(5): 545–546.doi:10.1080/10412905.1994.9698448.
  31. ^Donata Ricci; Francesco Epifano; Daniele Fraternale (February 2017). Olga Tzakou (ed.)."The Essential Oil of Monarda didyma L. (Lamiaceae) Exerts Phytotoxic Activity In Vitro against Various Weed Seeds".Molecules (Basel, Switzerland).22(2).Molecules:222.doi:10.3390/molecules22020222.PMC6155892.PMID28157176.
  32. ^Zamureenko, V. A.; Klyuev, N. A.; Bocharov, B. V.; Kabanov, V. S.; Zakharov, A. M. (1989). "An investigation of the component composition of the essential oil ofMonarda fistulosa".Chemistry of Natural Compounds.25(5): 549–551.doi:10.1007/BF00598073.ISSN1573-8388.S2CID24267822.
  33. ^Escobar, Angélica; Pérez, Miriam; Romanelli, Gustavo; Blustein, Guillermo (1 December 2020)."Thymol bioactivity: A review focusing on practical applications".Arabian Journal of Chemistry.13(12): 9243–9269.doi:10.1016/j.arabjc.2020.11.009.hdl:11336/139451.ISSN1878-5352.
  34. ^abBouchra, Chebli; Achouri, Mohamed; Idrissi Hassani, L. M.; Hmamouchi, Mohamed (2003). "Chemical composition and antifungal activity of essential oils of seven Moroccan Labiatae againstBotrytis cinereaPers: Fr ".Journal of Ethnopharmacology.89(1): 165–169.doi:10.1016/S0378-8741(03)00275-7.PMID14522450.
  35. ^Liolios, C. C.; Gortzi, O.; Lalas, S.; Tsaknis, J.; Chinou, I. (2009). "Liposomal incorporation of carvacrol and thymol isolated from the essential oil ofOriganum dictamnusL. and in vitro antimicrobial activity ".Food Chemistry.112(1): 77–83.doi:10.1016/j.foodchem.2008.05.060.
  36. ^Ozkan, Gulcan; Baydar, H.; Erbas, S. (2009). "The influence of harvest time on essential oil composition, phenolic constituents and antioxidant properties of Turkish oregano (Origanum onitesL.) ".Journal of the Science of Food and Agriculture.90(2): 205–209.doi:10.1002/jsfa.3788.PMID20355032.
  37. ^Lagouri, Vasiliki; Blekas, George; Tsimidou, Maria; Kokkini, Stella; Boskou, Dimitrios (1993). "Composition and antioxidant activity of essential oils from Oregano plants grown wild in Greece".Zeitschrift für Lebensmittel-Untersuchung und -Forschung A.197(1): 1431–4630.doi:10.1007/BF01202694.S2CID81307357.
  38. ^Kanias, G. D.; Souleles, C.; Loukis, A.; Philotheou-Panou, E. (1998). "Trace elements and essential oil composition in chemotypes of the aromatic plantOriganum vulgare".Journal of Radioanalytical and Nuclear Chemistry.227(1–2): 23–31.doi:10.1007/BF02386426.S2CID94582250.
  39. ^Figiel, Adam; Szumny, Antoni; Gutiérrez Ortíz, Antonio; Carbonell Barrachina, Ángel A. (2010). "Composition of oregano essential oil (Origanum vulgare) as affected by drying method ".Journal of Food Engineering.98(2): 240–247.doi:10.1016/j.jfoodeng.2010.01.002.
  40. ^abGoodner, K.L.; Mahattanatawee, K.; Plotto, A.; Sotomayor, J.; Jordán, M. (2006). "Aromatic profiles ofThymus hyemalisand SpanishT. vulgarisessential oils by GC–MS/GC–O ".Industrial Crops and Products.24(3): 264–268.doi:10.1016/j.indcrop.2006.06.006.
  41. ^Lee, Seung-Joo; Umano, Katumi; Shibamoto, Takayuki; Lee, Kwang-Geun (2005). "Identification of volatile components in basil (Ocimum basilicumL.) and thyme leaves (Thymus vulgarisL.) and their antioxidant properties ".Food Chemistry.91(1): 131–137.doi:10.1016/j.foodchem.2004.05.056.
  42. ^Moldão Martins, M.; Palavra, A.; Beirão da Costa, M. L.; Bernardo Gil, M. G. (2000). "Supercritical CO2extraction ofThymus zygisL. subsp.sylvestrisaroma ".The Journal of Supercritical Fluids.18(1): 25–34.doi:10.1016/S0896-8446(00)00047-4.
  43. ^74FR12613
  44. ^Campos, Estefânia V. R.; Proença, Patrícia L. F.; Oliveira, Jhones L.; Bakshi, Mansi; Abhilash, P. C.; Fraceto, Leonardo F. (1 October 2019)."Use of botanical insecticides for sustainable agriculture: Future perspectives".Ecological Indicators.105:483–495.doi:10.1016/j.ecolind.2018.04.038.hdl:11449/179822.ISSN1470-160X.S2CID89798604.
  45. ^The British Pharmacopoeia Secretariat (2009)."Index, BP 2009"(PDF).Archived fromthe original(PDF)on 11 April 2009.Retrieved5 July2009.
  46. ^"Japanese Pharmacopoeia"(PDF).Archived fromthe original(PDF)on 22 July 2011.Retrieved21 April2010.

External links[edit]

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