Skeletal formula of eugenol
Ball-and-stick model of the eugenol molecule
Preferred IUPAC name
Other names
  • 4-Allyl-2-methoxyphenol
  • 2-Methoxy-4-(2-propenyl)phenol
  • Eugenic acid
  • Caryophyllic acid
  • 1-Allyl-3-methoxy-4-hydroxybenzene
  • Allylguaiacol
  • 2-Methoxy-4-allylphenol
  • 4-Allylcatechol-2-methyl ether
3D model (JSmol)
ECHA InfoCard 100.002.355 Edit this at Wikidata
EC Number
  • 202-589-1
  • InChI=1S/C10H12O2/c1-3-4-8-5-6-9(11)10(7-8)12-2/h3,5-7,11H,1,4H2,2H3 checkY
  • InChI=1/C10H12O2/c1-3-4-8-5-6-9(11)10(7-8)12-2/h3,5-7,11H,1,4H2,2H3
  • Oc1ccc(cc1OC)CC=C
Molar mass 164.204 g·mol−1
Density 1.06 g/cm3
Melting point −7.5 °C (18.5 °F; 265.6 K)
Boiling point 254 °C (489 °F; 527 K)
Acidity (pKa) 10.19 at 25 °C
−1.021×10−4 cm3/mol
  • 9.12 mPa·s at 20 °C
  • 5.99 mPa·s at 30 °C[1]
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
Flash point 104 °C (219 °F; 377 K)
Related compounds
Related compounds
2-Phenethyl propionate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Eugenol /ˈjɪnɒl/ is an allyl chain-substituted guaiacol, a member of the allylbenzene class of chemical compounds.[2] It is a colorless to pale yellow, aromatic oily liquid extracted from certain essential oils especially from clove, nutmeg, cinnamon, basil and bay leaf.[3][4][5][6] It is present in concentrations of 80–90% in clove bud oil and at 82–88% in clove leaf oil.[7] Eugenol has a pleasant, spicy, clove-like scent.[8] The name is derived from Eugenia caryophyllata, the former Linnean nomenclature term for cloves. The currently accepted name is Syzygium aromaticum.[9]


The biosynthesis of eugenol begins with the amino acid tyrosine. L-tyrosine is converted to p-coumaric acid by the enzyme tyrosine ammonia lyase (TAL).[10] From here, p-coumaric acid is converted to caffeic acid by p-coumarate 3-hydroxylase using oxygen and NADPH. S-Adenosyl methionine (SAM) is then used to methylate caffeic acid, forming ferulic acid, which is in turn converted to feruloyl-CoA by the enzyme 4-hydroxycinnamoyl-CoA ligase (4CL).[11] Next, feruloyl-CoA is reduced to coniferaldehyde by cinnamoyl-CoA reductase (CCR). Coniferaldeyhyde is then further reduced to coniferyl alcohol by cinnamyl-alcohol dehydrogenase (CAD) or sinapyl-alcohol dehydrogenase (SAD). Coniferyl alcohol is then converted to an ester in the presence of the substrate CH3COSCoA, forming coniferyl acetate. Finally, coniferyl acetate is converted to eugenol via the enzyme eugenol synthase 1 and the use of NADPH.[citation needed]

Biosynthesis of eugenol


Eugenol and thymol possess general anesthetic properties. Like many other anesthetic agents, these 2-alkyl(oxy)phenols act as positive allosteric modulators of the GABAA receptor. Although eugenol and thymol are too toxic and not potent enough to be used clinically, these findings led to the development of 2-substituted phenol anesthetic drugs, including propanidid (later withdrawn) and the widely used propofol.[12] Eugenol and the structurally similar myristicin, have the common property of inhibiting MAO-A and MAO-B in vitro.[13][14]

In humans, complete excretion occurs within 24 hour and metabolites are mostly conjugates of eugenol.[15]



Eugenol is used as a flavor or aroma ingredient in teas, meats, cakes, perfumes, cosmetics, flavorings, and essential oils.[2][16][17] It is also used as a local antiseptic and anaesthetic.[18][19] Eugenol can be combined with zinc oxide to form zinc oxide eugenol which has restorative and prosthodontic applications in dentistry. For persons with a dry socket as a complication of tooth extraction, packing the dry socket with a eugenol-zinc oxide paste on iodoform gauze is effective for reducing acute pain.[20] Eugenol-zinc oxide paste is also used for root canal sealing.[21]

Insects and fish

It is attractive to males of various species of orchid bees, which apparently gather the chemical to synthesize pheromones; it is commonly used as bait to attract and collect these bees for study.[22] It also attracts female cucumber beetles.[23]

Eugenol and isoeugenol, which both are floral volatile scent compounds, are catalyzed by a single type of enzyme in the genus Gymnadenia and the gene encoding for this enzyme is the first functionally characterized gene in these species.[24] Eugenol is an ingredient in some insecticides.[2]

Clove oil is common as an anesthetic for use on aquarium fish as well as on wild fish when sampled for research and management purposes.[25][26] Where readily available, it presents a humane method to euthanize sick and diseased fish either by direct overdose or to induce sleep before an overdose of eugenol.[27][28]


Eugenol is an ingredient in some fungicides and weed control products used in agricultural practices in the European Union.[2] It is used in hundreds of household products, such as pesticides, pet care, laundry, cleaning, and paper or vehicle products.[2]


Taken orally in high doses for chronic periods, eugenol may cause liver toxicity.[16] An overdose is possible, causing a wide range of symptoms such as hematuria (blood in urine), convulsions, diarrhea, nausea, unconsciousness, dizziness, tachycardia (rapid heart rate), or acute kidney injury.[16][29] N-acetylcysteine may be used to treat people with eugenol or clove oil overdose.[30]

As an allergenic

Eugenol is subject to restrictions on its use in perfumery[31] as some people may become sensitised to it, however, the degree to which eugenol can cause an allergic reaction in humans is disputed.[32]

Eugenol is a component of balsam of Peru, to which some people are allergic.[33][34] When eugenol is used in dental preparations such as surgical pastes, dental packing, and dental cement, it may cause contact stomatitis and allergic cheilitis.[33] The allergy can be discovered via a patch test.[33]

Natural occurrence

Eugenol naturally occurs in numerous plants, including the following:

See also


  1. ^ Bingham EC, Spooner LW (1932). "The Fluidity Method for the Determination of Association. I". Journal of Rheology. 3 (2): 221–244. Bibcode:1932JRheo...3..221B. doi:10.1122/1.2116455. ISSN 0097-0360.
  2. ^ a b c d e "Eugenol". PubChem, US National Library of Medicine. 16 October 2021. Retrieved 24 October 2021.
  3. ^ "Constituents of the essential oil from leaves and buds of clove (Syzigium caryophyllatum L.) Alston" (PDF). Bangladesh Council of Scientific and Industrial Research BCSIR Laboratories. 4: 451–454.
  4. ^ Mallavarapu GR, Ramesh S, Chandrasekhara RS, Rajeswara Rao BR, Kaul PN, Bhattacharya AK (1995). "Investigation of the essential oil of cinnamon leaf grown at Bangalore and Hyderabad". Flavour and Fragrance Journal. 10 (4): 239–242. doi:10.1002/ffj.2730100403.
  5. ^ Yield and Oil Composition of 38 Basil (Ocimum basilicum L.) Accessions Grown in Mississippi Archived 15 October 2010 at the Wayback Machine
  6. ^ "Typical G.C. for bay leaf oil". Archived from the original on 17 March 2014. Retrieved 27 April 2014.
  7. ^ Barnes J, Anderson LA, Phillipson JS (2007) [1996]. Herbal Medicines (PDF) (3rd ed.). London: Pharmaceutical Press. ISBN 978-0-85369-623-0. Archived from the original (PDF) on 1 July 2018. Retrieved 27 April 2015.
  8. ^ Wishart, David S.; Guo, An Chi; Oler, Eponine; Wang, Fel; Anjum, Afia; Peters, Harrison; Dizon, Raynard; Sayeeda, Zinat; Tian, Siyang; Lee, Brian L.; Berjanskii, Mark; Mah, Robert; Yamamoto, Mai; Jovel Castillo, Juan; Torres Calzada, Claudia; Hiebert Giesbrecht, Mickel; Lui, Vicki W.; Varshavi, Dorna; Varshavi, Dorsa; Allen, Dana; Arndt, David; Khetarpal, Nitya; Sivakumaran, Aadhavya; Harford, Karxena; Sanford, Selena; Yee, Kristen; Cao, Xuan; Budinsky, Zachary; Liigand, Jaanus; Zhang, Lun; Zheng, Jiamin; Mandal, Rupasri; Karu, Naama; Dambrova, Maija; Schiöth, Helgi B.; Gautam, Vasuk. "Showing metabocard for Eugenol (HMDB0005809)". Human Metabolome Database, HMDB. 5.0.
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