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Methyl salicylate

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Methyl salicylate
Skeletal formula
Ball-and-stick model
Space-filling model
Sample of a clear liquid
Names
Preferred IUPAC name
Methyl 2-hydroxybenzoate
Other names
  • Salicylic acid methyl ester
  • Oil of wintergreen
  • Betula oil
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.925 Edit this at Wikidata
EC Number
  • 204-317-7
KEGG
RTECS number
  • VO4725000
UNII
  • InChI=1S/C8H8O3/c1-11-8(10)6-4-2-3-5-7(6)9/h2-5,9H,1H3 checkY
    Key: OSWPMRLSEDHDFF-UHFFFAOYSA-N checkY
  • InChI=1/C8H8O3/c1-11-8(10)6-4-2-3-5-7(6)9/h2-5,9H,1H3
    Key: OSWPMRLSEDHDFF-UHFFFAOYAD
  • O=C(OC)c1ccccc1O
Properties
C8H8O3
Molar mass 152.149 g·mol−1
Appearance Colorless liquid
Odor Wintergreen
Density 1.181 g/cm3[1]
Melting point −8.6 °C (16.5 °F; 264.5 K)
Boiling point 222.6 °C (432.7 °F; 495.8 K)[1] Decomposes at 340–350 °C (644–662 °F; 613–623 K)
Critical point (T, P) 709 K (436 °C; 817 °F), 4.4 MPa[1]
  • 0.639 g/L (21 °C (70 °F; 294 K))
  • 0.697 g/L (30 °C (86 °F; 303 K))[2]
Solubility Very soluble in chloroform, ethanol, and diethyl ether.[1]
Solubility in acetone 10.1 g/g (30 °C (86 °F; 303 K))[2]
log P 2.55[3]
Vapor pressure
  • 1 Pa (0.0075 mmHg) (−1 °C (30 °F; 272 K))
  • 10 Pa (0.075 mmHg) (22 °C (72 °F; 295 K))
  • 100 Pa (0.75 mmHg) (51 °C (124 °F; 324 K))
  • 1 kPa (7.5 mmHg) (88.8 °C (191.8 °F; 361.9 K))
  • 10 kPa (75 mmHg) (141.8 °C (287.2 °F; 414.9 K))
  • 100 kPa (750 mmHg) (219.9 °C (427.8 °F; 493.0 K))[1]
Acidity (pKa) 9.8[4]
−86.3×10−6 cm3/mol[1]
1.535 (20 °C (68 °F; 293 K))[1]
Viscosity
  • 1.535 mPa·s[3]
  • 1.102 mPa·s (75 °C (167 °F))[1]
2.47 D[1]
Thermochemistry[1]
249.0 J⋅mol−1·K-1
46.7 kJ⋅mol−1 (222.6 °C (432.7 °F))
Hazards
GHS labelling:[5]
GHS08: Health hazardGHS05: CorrosiveGHS07: Exclamation mark
Danger
H302, H317, H318, H361, H412
P201, P202, P261, P264, P270, P272, P273, P280, P301+P312+P330, P302+P352, P305+P351+P338+P310, P308+P313, P333+P313, P363, P405, P501
NFPA 704 (fire diamond)
[3]
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 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
3
1
0
Flash point 96 °C (205 °F; 369 K)[5]
452.7 °C (846.9 °F; 725.8 K)[5]
Lethal dose or concentration (LD, LC):
887 mg/kg (oral, rat)[3]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Methyl salicylate (oil of wintergreen or wintergreen oil) is an organic compound with the formula C8H8O3. It is the methyl ester of salicylic acid. It is a colorless, viscous liquid with a sweet, fruity odor reminiscent of root beer (in which it is used as a flavoring),[6] but often associatively called "minty", as it is an ingredient in mint candies.[7] It is produced by many species of plants, particularly wintergreens. It is also produced synthetically, used as a fragrance and as a flavoring agent.

Biosynthesis and occurrence

[edit]

Methyl salicylate was first isolated (from the plant Gaultheria procumbens) in 1843 by the French chemist Auguste André Thomas Cahours (1813–1891), who identified it as an ester of salicylic acid and methanol.[8][9]

The biosynthesis of methyl salicylate arises via the hydroxylation of benzoic acid by a cytochrome P450 followed by reaction with a methyltransferase enzyme.[10]

Methyl salicylate as a plant metabolite

[edit]
Wintergreen plants (Gaultheria procumbens)

Many plants produce methyl salicylate in small quantities. Methyl salicylate levels are often upregulated in response to biotic stress, especially infection by pathogens, where it plays a role in the induction of resistance. Methyl salicylate is believed to function by being metabolized to the plant hormone salicylic acid. Since methyl salicylate is volatile, these signals can spread through the air to distal parts of the same plant or even to neighboring plants, whereupon they can function as a mechanism of plant-to-plant communication, "warning" neighbors of danger.[11] Methyl salicylate is also released in some plants when they are damaged by herbivorous insects, where they may function as a cue aiding in the recruitment of predators, notably hoverflies, lacewings, and lady beetles.[12][13]

Some plants produce methyl salicylate in larger quantities, where it likely involved in direct defense against predators or pathogens. Examples of this latter class include: some species of the genus Gaultheria in the family Ericaceae, including Gaultheria procumbens, the wintergreen or eastern teaberry; some species of the genus Betula in the family Betulaceae, particularly those in the subgenus Betulenta such as B. lenta, the black birch; all species of the genus Spiraea in the family Rosaceae, also called the meadowsweets; species of the genus Polygala in the family Polygalaceae. Methyl salicylate can also be a component of floral scents, especially in plants dependent on nocturnal pollinators like moths,[14] scarab beetles, and (nocturnal) bees.[15]

Commercial production

[edit]

Methyl salicylate can be produced by esterifying salicylic acid with methanol.[16] Commercial methyl salicylate is now synthesized, but in the past, it was commonly distilled from the twigs of Betula lenta (sweet birch) and Gaultheria procumbens (eastern teaberry or wintergreen).

Uses

[edit]
Chick embryo that was treated with methylene blue to stain the skeleton, then cleansed with two or three ethanol washes, and treated with methyl salicylate to make the surrounding tissues transparent

Methyl salicylate is used in high concentrations as a rubefacient and analgesic in deep heating liniments (such as Bengay) to treat joint and muscular pain. Randomised double blind trials report that evidence of its effectiveness is weak, but stronger for acute pain than chronic pain, and that effectiveness may be due entirely to counterirritation. However, in the body it metabolizes into salicylates, including salicylic acid, a known NSAID.[17][18][19]

Methyl salicylate is used in low concentrations (0.04% and under)[20] as a flavoring agent in root beer,[6] chewing gum, mints and medicine such as Pepto-Bismol. Its aroma is described as "wintergreen, minty, sweet, root beer, aromatic, phenolic, camphoreous".[21]

When mixed with sugar and dried, it is a potentially entertaining source of triboluminescence, for example by crushing Wint-O-Green Life Savers in a dark room. When crushed, sugar crystals emit light; methyl salicylate amplifies the spark because it fluoresces, absorbing ultraviolet light and re-emitting it in the visible spectrum.[22][23] It is used as an antiseptic in Listerine mouthwash produced by the Johnson & Johnson company.[24] It provides fragrance to various products and as an odor-masking agent for some organophosphate pesticides.[citation needed]

Methyl salicylate is used as a bait for attracting male orchid bees for study, which apparently gather the chemical to synthesize pheromones.[25] It has also been discovered that methyl salicylate works as a kairomone that attracts some insects, such as the spotted lanternfly. Unlike some other kairomones, methyl salicylate attracts all stages of the spotted lanternflies life.[26]

It is also used to clear plant or animal tissue samples of color, and as such is useful for microscopy and immunohistochemistry when excess pigments obscure structures or block light in the tissue being examined. This clearing generally only takes a few minutes, but the tissue must first be dehydrated in alcohol.[27]

Other niche uses include:

  • As a simulant or surrogate for the research of chemical warfare agent sulfur mustard, due to its similar chemical and physical properties.[28]
  • Restoring (at least temporarily) the elastomeric properties of old rubber rollers, especially in printers.[29]
  • As a transfer agent in printmaking (to release toner from photocopied images and apply them to other surfaces).[30]
  • As a historical substitute for cedar oil as an immersion oil in microscopy, given its refractive index (1.538) being close to that of crown glass (1.515) and being less prone to evaporation than cedar oil.[31]
  • as a penetrating oil to loosen rusted parts.

Safety and toxicity

[edit]

Most instances of human toxicity due to methyl salicylate are a result of overapplication of topical analgesics, as skin absorption occurs easily. Salicylic acid, the major metabolite of methyl salicylate, may accumulate in blood which may help professionals to confirm a diagnosis of poisoning in hospitalized patients.[32]

Incidents

[edit]

A 17 year old Staten Island high school track star died in April 2007 after overdose of methyl salicylate by excessive use of topical muscle-pain relief products.[33]

Compendial status

[edit]

See also

[edit]

References

[edit]
  1. ^ a b c d e f g h i j Haynes, William M., ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). Boca Raton, Florida: CRC Press. pp. 3–396, 3–578, 5–28, 6–77, 6–117, 6–148, 9–64. ISBN 9781498754293.
  2. ^ a b "Methyl salicylate". chemister.ru. Archived from the original on 2014-05-24. Retrieved 2014-05-23.
  3. ^ a b c d "SDS - Methyl salicylate". www.fishersci.com. ThermoFisher Scientific. 18 December 2025. Retrieved 22 April 2026.
  4. ^ Scully, F. E.; Hoigné, J. (January 1987). "Rate constants for reactions of singlet oxygen with phenols and other compounds in water". Chemosphere. 16 (4): 681–694. Bibcode:1987Chmsp..16..681S. doi:10.1016/0045-6535(87)90004-X.
  5. ^ a b c Sigma-Aldrich Co., Methyl salicylate.
  6. ^ a b Markus, John R. (13 February 2020). "Determination of Methyl Salicylate in Root Beer". Journal of AOAC International. 57 (4): 1002–1004. doi:10.1093/jaoac/57.4.1002.
  7. ^ "The Good Scents Company - Aromatic/Hydrocarbon/Inorganic Ingredients Catalog information". Archived from the original on 2019-12-06. Retrieved 2019-12-03.
  8. ^ Cahours, A. A. T. (1843). "Recherches sur l'huile de Gaultheria procumbens" [Investigations into the oil of Gaultheria procumbens]. Comptes Rendus. 16: 853–856. Archived from the original on 2015-11-24. Retrieved 2013-11-19.
  9. ^ Cahours, A. A. T. (1843). "Sur quelques réactions du salicylate de méthylène" [On some reactions of methyl salicylate]. Comptes Rendus. 17: 43–47. Archived from the original on 2015-11-25. Retrieved 2013-11-19.
  10. ^ Vogt, T. (2010). "Phenylpropanoid Biosynthesis". Molecular Plant. 3: 2–20. doi:10.1093/mp/ssp106. PMID 20035037.
  11. ^ Shulaev, V.; Silverman, P.; Raskin, I. (1997). "Airborne signalling by methyl salicylate in plant pathogen resistance". Nature. 385 (6618): 718–721. Bibcode:1997Natur.385..718S. doi:10.1038/385718a0. S2CID 4370291.
  12. ^ James, D. G.; Price, T. S. (2004). "Field-testing of methyl salicylate for recruitment and retention of beneficial insects in grapes and hops". Journal of Chemical Ecology. 30 (8): 1613–1628. doi:10.1023/B:JOEC.0000042072.18151.6f. PMID 15537163. S2CID 36124603.
  13. ^ Rodriguez-Saona, Cesar; Kaplan, Ian; Braasch, Joseph; Chinnasamy, Durairaj; Williams, Livy (November 2011). "Field responses of predaceous arthropods to methyl salicylate: A meta-analysis and case study in cranberries". Biological Control. 59 (2): 294–303. doi:10.1016/j.biocontrol.2011.06.017.
  14. ^ Knudsen, J. T.; Tollsten, L. (1993). "Trends in floral scent chemistry in pollination syndromes: floral scent composition in moth-pollinated taxa". Botanical Journal of the Linnean Society. 113 (3). Oxford Academic: 263–284. doi:10.1111/j.1095-8339.1993.tb00340.x.
  15. ^ Cordeiro, G. D.; Fernandes dos Santos, I. G.; da Silva, C. I.; Schlindwein, C.; Alves-dos-Santos, I.; Dötterl, S. (2019). "Nocturnal floral scent profiles of Myrtaceae fruit crops". Phytochemistry. 162: 193–198. doi:10.1016/j.phytochem.2019.03.011. PMID 30939396. S2CID 92997657.
  16. ^ Boullard, Olivier; Leblanc, Henri; Besson, Bernard (2012). "Salicylic Acid". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a23_477. ISBN 3527306730.
  17. ^ "Topical analgesics introduction". Medicine.ox.ac.uk. 2003-05-26. Archived from the original on 2013-10-22. Retrieved 2026-04-21.
  18. ^ Mason, L.; Moore, R. A.; Edwards, J. E.; McQuay, H. J.; Derry, S.; Wiffen, P. J. (2004). "Systematic review of efficacy of topical rubefacients containing salicylates for the treatment of acute and chronic pain". British Medical Journal. 328 (7446): 995. doi:10.1136/bmj.38040.607141.EE. PMC 404501. PMID 15033879.
  19. ^ Tramer, M. R. (2004). "It's not just about rubbing—topical capsaicin and topical salicylates may be useful as adjuvants to conventional pain treatment". British Medical Journal. 328 (7446): 998. doi:10.1136/bmj.328.7446.998. PMC 404503. PMID 15105325.
  20. ^ "Wintergreen". www.drugs.com. Archived from the original on 2018-03-19.
  21. ^ "methyl salicylate". Scents and Flavors. Scents and Flavors. Retrieved 1 April 2026.
  22. ^ Harvey, E. N. (1939). "The luminescence of sugar wafers". Science. 90 (2324): 35–36. Bibcode:1939Sci....90...35N. doi:10.1126/science.90.2324.35. PMID 17798129.
  23. ^ "Why do Wint-O-Green Life Savers spark in the dark?". HowStuffWorks. Archived from the original on 2007-08-17. Retrieved 2008-04-27.
  24. ^ Listerine. "Original Listerine Antiseptic Mouthwash". Archived from the original on 17 February 2015. Retrieved 25 March 2015.
  25. ^ Schiestl, F. P.; Roubik, D. W. (2004). "Odor Compound Detection in Male Euglossine Bees". Journal of Chemical Ecology. 29 (1): 253–257. doi:10.1023/A:1021932131526. hdl:20.500.11850/57276. PMID 12647866. S2CID 2845587.
  26. ^ Cooperband, Miriam F.; Wickham, Jacob; Cleary, Kaitlin; Spichiger, Sven-Erik; Zhang, Longwa; Baker, John; Canlas, Isaiah; Derstine, Nathan; Carrillo, Daniel (2019-03-21). "Discovery of three kairomones in relation to trap and lure development for spotted lanternfly (Hemiptera: Fulgoridae)". Journal of Economic Entomology. 112 (2): 671–682. doi:10.1093/jee/toy412. ISSN 0022-0493. PMID 30753676.
  27. ^ Altman, J. S.; Tyrer, N. M. (1980). "Filling selected neurons with cobalt through cut axons". In Strausfeld, N. J.; Miller, T. A. (eds.). Neuroanatomical Techniques. Springer-Verlag. pp. 373–402. doi:10.1007/978-1-4612-6018-9_19. ISBN 978-1-4612-6020-2.
  28. ^ Bartlet-Hunt, S. L.; Knappe, D. R. U.; Barlaz, M. A. (2008). "A Review of Chemical Warfare Agent Simulants for the Study of Environmental Behaviour". Critical Reviews in Environmental Science and Technology. 38 (2): 112–136. doi:10.1080/10643380701643650. S2CID 97484598.
  29. ^ "MG Chemicals – Rubber Renue Safety Data Sheet" (PDF). Archived from the original (PDF) on 2015-06-26.
  30. ^ Modrak, Rebekah and Bill Anthes. "Image Transfer & Rubbing Techniques – Reframing Photography". www.reframingphotography.com. Retrieved 2021-09-07.
  31. ^ Lakshminarasimhan, A. (1986). "An Excellent and Inexpensive Substitute for Immersion Oil in Microscopy". Stain Technology. 61 (2): 122–123. doi:10.3109/10520298609110720. ISSN 0038-9153.
  32. ^ Baselt, R. (2008). Disposition of Toxic Drugs and Chemicals in Man (8th ed.). Foster City, CA: Biomedical Publications. pp. 1012–1014. ISBN 978-0-9626523-7-0.
  33. ^ "Muscle-Pain Reliever Is Blamed For Staten Island Runner's Death". New York Times. 10 June 2007. Archived from the original on 18 January 2018. Retrieved 22 February 2017.
  34. ^ The British Pharmacopoeia Secretariat (2009). "Index, BP 2009" (PDF). Archived from the original (PDF) on 11 April 2009. Retrieved 5 July 2009.
  35. ^ "NIHS Japan". Moldb.nihs.go.jp. Archived from the original on 2013-02-17. Retrieved 2013-07-01.
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