In chemistry, an ester is a compound derived from an acid (organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group (−OH) of that acid is replaced by an organyl group (−R). Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well (i.e. esters of acidic SH, SeH, TeH, PoH and LvH groups). According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well (e.g. amides), but not according to the IUPAC.[1]

An ester of carboxylic acid. R stands for any group (organic or inorganic) and R′ stands for organyl group.

An example of an ester formation is the substitution reaction between a carboxylic acid (R−C(=O)−OH) and an alcohol (R'OH), forming an ester (R−C(=O)−O−R'), where R and R′ are organyl groups, or H in the case of esters of formic acid. Glycerides, which are fatty acid esters of glycerol, are important esters in biology, being one of the main classes of lipids, and making up the bulk of animal fats and vegetable oils. Esters of carboxylic acids with low molecular weight are commonly used as fragrances and found in essential oils and pheromones. Phosphoesters form the backbone of DNA molecules. Nitrate esters, such as nitroglycerin, are known for their explosive properties, while polyesters are important plastics, with monomers linked by ester moieties. Esters of carboxylic acids usually have a sweet smell and are considered high-quality solvents for a broad array of plastics, plasticizers, resins, and lacquers.[2] They are also one of the largest classes of synthetic lubricants on the commercial market.[3]

By number of R' group carbons (R−C(=O)−O−R')

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1 carbon

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2 carbons

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3 carbons

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4 carbons

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5 carbons

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7 carbons

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Name Structure
Benzyl acetate[55]

8 carbons

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Name Structure
Octyl acetate[56]

10 carbons

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By number of R group carbons (R−C(=O)−O−R')

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0 carbons

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Name Structure
Methyl nitrate

1 carbon

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2 carbons

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3 carbons

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4 carbons

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5 carbons

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6 carbons

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7 carbons

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8 carbons

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9 carbons

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10 carbons

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Name Structure
Ethyl decanoate

16 carbons

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Name Structure
Isopropyl palmitate

List of ester odorants

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Many esters of carboxylic acid have distinctive fruit-like odors, and many occur naturally in fruits and the essential oils of plants. This has also led to their common use in artificial flavorings and fragrances which aim to mimic those odors.

Ester name Structure Odor or occurrence
Allyl hexanoate pineapple
Benzyl acetate pear, strawberry, jasmine
Bornyl acetate pine
Butyl acetate apple, honey
Butyl butyrate pineapple
Butyl propanoate pear drops
Ethyl acetate nail polish remover, model paint, model airplane glue
Ethyl benzoate sweet, wintergreen, fruity, medicinal, cherry, grape
Ethyl butyrate banana, pineapple, strawberry
Ethyl hexanoate pineapple, waxy-green banana
Ethyl cinnamate cinnamon
Ethyl formate lemon, rum, strawberry
Ethyl heptanoate apricot, cherry, grape, raspberry
Ethyl isovalerate apple
Ethyl lactate butter, cream
Ethyl nonanoate grape
Ethyl pentanoate apple
Geranyl acetate geranium
Geranyl butyrate cherry
Geranyl pentanoate apple
Isobutyl acetate cherry, raspberry, strawberry
Isobutyl formate raspberry
Isoamyl acetate pear, banana (flavoring in Pear drops)
Isopropyl acetate fruity
Linalyl acetate lavender, sage
Linalyl butyrate peach
Linalyl formate apple, peach
Methyl acetate glue
Methyl anthranilate grape, jasmine
Methyl benzoate fruity, ylang ylang, feijoa
Methyl butyrate (methyl butanoate) pineapple, apple, strawberry
Methyl cinnamate strawberry
Methyl pentanoate (methyl valerate) flowery
Methyl phenylacetate honey
Methyl salicylate (oil of wintergreen) Modern root beer, wintergreen, Germolene and Ralgex ointments (UK)
Nonyl caprylate orange
Octyl acetate fruity-orange
Octyl butyrate parsnip
Amyl acetate (pentyl acetate) apple, banana
Pentyl butyrate (amyl butyrate) apricot, pear, pineapple
Pentyl hexanoate (amyl caproate) apple, pineapple
Pentyl pentanoate (amyl valerate) apple
Propyl acetate pear
Propyl hexanoate blackberry, pineapple, cheese, wine
Propyl isobutyrate rum
Terpenyl butyrate cherry

Lactones

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Lactones are a specific class cyclic carboxylic esters that are formed through intramolecular esterification.

Lactone name Structure
β-propiolactone[64]
γ-butyrolactone (GBL)[65]
D-glucono-δ-lactone (E575)[66]
ε-caprolactone[67]

References

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  1. IUPAC, Compendium of Chemical Terminology, 5th ed. (the "Gold Book") (2025). Online version: (2006) "esters". doi:10.1351/goldbook.E02219
  2. Cameron Wright (1986). A worker's guide to solvent hazards. The Group. p. 48. ISBN 9780969054542.
  3. E. Richard Booser (21 December 1993). CRC Handbook of Lubrication and Tribology, Volume III: Monitoring, Materials, Synthetic Lubricants, and Applications. CRC. p. 237. ISBN 978-1-4200-5045-5.
  4. Reichel, Marco; Krumm, Burkhard; Vishnevskiy, Yury V.; Blomeyer, Sebastian; Schwabedissen, Jan; Stammler, Hans‐Georg; Karaghiosoff, Konstantin; Mitzel, Norbert W. (2019-12-16). "Solid‐State and Gas‐Phase Structures and Energetic Properties of the Dangerous Methyl and Fluoromethyl Nitrates". Angewandte Chemie International Edition. 58 (51): 18557–18561. doi:10.1002/anie.201911300. ISSN 1433-7851. PMC 6916544. PMID 31573130.
  5. Werner Reutemann and Heinz Kieczka "Formic Acid" in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a12_013
  6. "methyl formate". scentsandflavors.com. Retrieved 14 June 2026.
  7. Merck Index, 12th Edition, 6089.
  8. "methyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  9. "methyl acrylate". scentsandflavors.com. Retrieved 14 June 2026.
  10. "Methyl Propionate Hazardous Substance Fact Sheet" (PDF). New Jersey Department of Health and Senior Services.
  11. "methyl propionate". scentsandflavors.com. Retrieved 14 June 2026.
  12. "methyl butyrate". scentsandflavors.com. Retrieved 14 June 2026.
  13. "methyl valerate". scentsandflavors.com. Retrieved 14 June 2026.
  14. "methyl benzoate". scentsandflavors.com. Retrieved 14 June 2026.
  15. "methyl anthranilate". scentsandflavors.com. Retrieved 14 June 2026.
  16. "methyl salicylate". scentsandflavors.com. Retrieved 14 June 2026.
  17. "methyl phenyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  18. "methyl cinnamate". scentsandflavors.com. Retrieved 14 June 2026.
  19. "ethyl formate". scentsandflavors.com. Retrieved 14 June 2026.
  20. "ethyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  21. "ethyl propionate". scentsandflavors.com. Retrieved 14 June 2026.
  22. "ethyl lactate". scentsandflavors.com. Retrieved 14 June 2026.
  23. "ethyl butyrate". scentsandflavors.com. Retrieved 14 June 2026.
  24. "ethyl valerate". scentsandflavors.com. Retrieved 14 June 2026.
  25. "ethyl isovalerate". scentsandflavors.com. Retrieved 14 June 2026.
  26. "ethyl hexanoate". scentsandflavors.com. Retrieved 14 June 2026.
  27. "ethyl heptanoate". scentsandflavors.com. Retrieved 14 June 2026.
  28. "ethyl benzoate". scentsandflavors.com. Retrieved 14 June 2026.
  29. "ethyl salicylate". scentsandflavors.com. Retrieved 14 June 2026.
  30. "ethyl octanoate". scentsandflavors.com. Retrieved 14 June 2026.
  31. "ethyl cinnamate". scentsandflavors.com. Retrieved 14 June 2026.
  32. "ethyl decanoate". scentsandflavors.com. Retrieved 14 June 2026.
  33. "propyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  34. "propyl propionate". scentsandflavors.com. Retrieved 14 June 2026.
  35. "propyl hexanoate". scentsandflavors.com. Retrieved 14 June 2026.
  36. "allyl hexanoate". scentsandflavors.com. Retrieved 14 June 2026.
  37. "isopropyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  38. "isopropyl salicylate". scentsandflavors.com. Retrieved 14 June 2026.
  39. "isopropyl palmitate". scentsandflavors.com. Retrieved 14 June 2026.
  40. "butyl formate". scentsandflavors.com. Retrieved 14 June 2026.
  41. "butyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  42. "isobutyl formate". scentsandflavors.com. Retrieved 14 June 2026.
  43. "isobutyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  44. "sec-butyl formate". scentsandflavors.com. Retrieved 14 June 2026.
  45. "sec-butyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  46. "(+)-sec-butyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  47. "(-)-sec-butyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  48. "tert-butyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  49. "butyl butyrate". scentsandflavors.com. Retrieved 14 June 2026.
  50. "amyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  51. "amyl butyrate". scentsandflavors.com. Retrieved 14 June 2026.
  52. "amyl propionate". scentsandflavors.com. Retrieved 14 June 2026.
  53. "amyl hexanoate". scentsandflavors.com. Retrieved 14 June 2026.
  54. "2-pentyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  55. "benzyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  56. "octyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  57. "geranyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  58. "bornyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  59. "dextro-bornyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  60. "laevo-bornyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  61. "linalyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  62. "dextro-linalyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  63. "laevo-linalyl acetate". scentsandflavors.com. Retrieved 14 June 2026.
  64. "beta-propiolactone". scentsandflavors.com. Retrieved 14 June 2026.
  65. "gamma-butyrolactone". scentsandflavors.com. Retrieved 14 June 2026.
  66. "delta-gluconolactone". scentsandflavors.com. Retrieved 14 June 2026.
  67. "epsilon-caprolactone". scentsandflavors.com. Retrieved 14 June 2026.