Limonene

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Limonene
Skeletal structure of the (R)-isomer (R)-Limonene.svg
Skeletal structure of the (R)-isomer
Ball-and-stick model of the (R)-isomer Limonene-from-xtal-3D-bs.png
Ball-and-stick model of the (R)-isomer
Limonene (R)-isomer
Limonene.jpg
Limonene extracted from orange peel
Names
Preferred IUPAC name
1-Methyl-4-(prop-1-en-2-yl)cyclohex-1-ene
Other names
1-Methyl-4-(1-methylethenyl)cyclohexene
4-Isopropenyl-1-methylcyclohexene
p-Menth-1,8-diene
Racemic:DL-Limonene; Dipentene
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.004.856 OOjs UI icon edit-ltr-progressive.svg
KEGG
PubChem CID
UNII
  • InChI=1S/C10H16/c1-8(2)10-6-4-9(3)5-7-10/h4,10H,1,5-7H2,2-3H3 Yes check.svgY
    Key: XMGQYMWWDOXHJM-UHFFFAOYSA-N Yes check.svgY
  • CC1=CCC(CC1)C(=C)C
Properties
C10H16
Molar mass 136.238 g·mol−1
Appearancecolorless liquid
Odor Orange
Density 0.8411 g/cm3
Melting point −74.35 °C (−101.83 °F; 198.80 K)
Boiling point 176 °C (349 °F; 449 K)
Insoluble
Solubility Miscible with benzene, chloroform, ether, CS2, and oils
soluble in CCl4
87–102°
1.4727
Thermochemistry
−6.128 MJ mol−1
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Skin sensitizer / Contact dermatitis – After aspiration, pulmonary oedema, pneumonitis, and death [1]
GHS labelling:
GHS-pictogram-flamme.svg GHS-pictogram-exclam.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
Danger
H226, H304, H315, H317, H410
P210, P233, P235, P240, P241, P242, P243, P261, P264, P272, P273, P280, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P312, P333+P313, P362, P370+P378, P391, P403+P233, P405, P501
NFPA 704 (fire diamond)
NFPA 704.svgHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
2
0
Flash point 50 °C (122 °F; 323 K)
237 °C (459 °F; 510 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Limonene ( /ˈlɪmənˌiːn/ ) is a colorless liquid aliphatic hydrocarbon classified as a cyclic monoterpene, and is the major component in the essential oil of citrus fruit peels. [1] The (+)-isomer, occurring more commonly in nature as the fragrance of oranges, is a flavoring agent in food manufacturing. [1] [2] It is also used in chemical synthesis as a precursor to carvone and as a renewables-based solvent in cleaning products. [1] The less common (-)-isomer has a piny, turpentine-like odor, and is found in the edible parts of such plants as caraway, dill, and bergamot orange plants. [3]

Limonene takes its name from Italian limone ("lemon"). [4] Limonene is a chiral molecule, and biological sources produce one enantiomer: the principal industrial source, citrus fruit, contains (+)-limonene (d-limonene), which is the (R)-enantiomer. [1] (+)-Limonene is obtained commercially from citrus fruits through two primary methods: centrifugal separation or steam distillation.

In plants

Limonene contributes to the characteristic odor of orange peel, orange juice and other citrus fruits. NIH citrus.jpg
Limonene contributes to the characteristic odor of orange peel, orange juice and other citrus fruits.

(+)-Limonene is a major component of the aromatic scents and resins characteristic of numerous coniferous and broadleaved trees: red and silver maple ( Acer rubrum , Acer saccharinum ), cottonwoods ( Populus angustifolia ), aspens ( Populus grandidentata , Populus tremuloides ) sumac ( Rhus glabra ), spruce ( Picea spp.), various pines (e.g., Pinus echinata , Pinus ponderosa ), Pinus leucodermis , [5] Douglas fir ( Pseudotsuga menziesii ), larches ( Larix spp.), true firs ( Abies spp.), hemlocks ( Tsuga spp.), cannabis ( Cannabis sativa spp.), [6] cedars ( Cedrus spp.), various Cupressaceae, and juniper bush ( Juniperus spp.). [1] [ failed verification ] It contributes to the characteristic odor of orange peel, orange juice and other citrus fruits. [1] [7] To optimize recovery of valued components from citrus peel waste, (+)-limonene is typically removed. [8]

Chemical reactions

Limonene is a relatively stable monoterpene and can be distilled without decomposition, although at elevated temperatures it cracks to form isoprene. [9] It oxidizes easily in moist air to produce carveol, carvone, and limonene oxide. [1] [10] With sulfur, it undergoes dehydrogenation to p-cymene. [11]

Limonene occurs commonly as the (R)-enantiomer, but racemizes at 300 °C. When warmed with mineral acid, limonene isomerizes to the conjugated diene α-terpinene (which can also easily be converted to p-cymene). Evidence for this isomerization includes the formation of Diels–Alder adducts between α-terpinene adducts and maleic anhydride.

It is possible to effect reaction at one of the double bonds selectively. Anhydrous hydrogen chloride reacts preferentially at the disubstituted alkene, whereas epoxidation with mCPBA occurs at the trisubstituted alkene.

In another synthetic method Markovnikov addition of trifluoroacetic acid followed by hydrolysis of the acetate gives terpineol.

The most widely practiced conversion of limonene is to carvone. The three-step reaction begins with the regioselective addition of nitrosyl chloride across the trisubstituted double bond. This species is then converted to the oxime with a base, and the hydroxylamine is removed to give the ketone-containing carvone. [2]

Biosynthesis

In nature, limonene is formed from geranyl pyrophosphate, via cyclization of a neryl carbocation or its equivalent as shown. [12] The final step involves loss of a proton from the cation to form the alkene.

Limonene Biosynthesis (coloured).svg

Uses

As the main fragrance of citrus peels, D-limonene is used in food manufacturing and some medicines, such as a flavoring agent to mask the bitter taste of alkaloids, and as a fragrance in perfumery, aftershave lotions, bath products, and other personal care products. [1] (+)-Limonene is also used as a botanical insecticide. [1] [13] (+)-Limonene is used in the organic herbicides. [14] It is added to cleaning products, such as hand cleansers, to give a lemon or orange fragrance (see orange oil) and for its ability to dissolve oils. [1] In contrast, (-)-limonene has a piny, turpentine-like odor.

Limonene is used as a solvent for cleaning purposes, such as adhesive remover, or the removal of oil from machine parts, as it is produced from a renewable source (citrus essential oil, as a byproduct of orange juice manufacture). [8] It is used as a paint stripper and is also useful as a fragrant alternative to turpentine. Limonene is also used as a solvent in some model airplane glues and as a constituent in some paints. Commercial air fresheners, with air propellants, containing limonene are used by stamp collectors to remove self-adhesive postage stamps from envelope paper. [15]

Limonene is also used as a solvent for fused filament fabrication based 3D printing. [16] Printers can print the plastic of choice for the model, but erect supports and binders from high impact polystyrene (HIPS), a polystyrene plastic that is easily soluble in limonene.

In preparing tissues for histology or histopathology, D-limonene is often used as a less toxic substitute for xylene when clearing dehydrated specimens. Clearing agents are liquids miscible with alcohols (such as ethanol or isopropanol) and with melted paraffin wax, in which specimens are embedded to facilitate cutting of thin sections for microscopy. [17] [18] [19]

Limonene, from orange peel oil, is also combustible and has been considered as a biofuel. [20]

Safety and research

Applied to skin, limonene may cause irritation from contact dermatitis, but otherwise appears to be safe for human use. [21] [22] Limonene is flammable as a liquid or vapor and it is toxic to aquatic life. [1]

Cancer

There is no evidence that the limonene in peel oils of citrus fruits affects the onset or progress of cancer, with one national agency stating, "There is no consistent evidence that people with cancer who consume limonene—either in supplement form or by eating citrus fruits—get better or are more likely to be cured". [23]

See also

Related Research Articles

<span class="mw-page-title-main">Kaffir lime</span> Citrus fruit native to tropical Southeast Asia

Citrus hystrix, called the kaffir lime, Thai lime or makrut lime, is a citrus fruit native to tropical Southeast Asia.

<span class="mw-page-title-main">Terpene</span> Class of oily organic compounds found in plants

Terpenes are a class of natural products consisting of compounds with the formula (C5H8)n for n ≥ 2. Terpenes are major biosynthetic building blocks. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. In plants, terpenes and terpenoids are important mediators of ecological interactions, while some insects use some terpenes as a form of defense. Other functions of terpenoids include cell growth modulation and plant elongation, light harvesting and photoprotection, and membrane permeability and fluidity control.

<span class="mw-page-title-main">Essential oil</span> Hydrophobic liquid containing volatile aroma compounds from plants

An essential oil is a concentrated hydrophobic liquid containing volatile chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the oil of the plant from which they were extracted, such as oil of clove. An essential oil is essential in the sense that it contains the essence of the plant's fragrance—the characteristic fragrance of the plant from which it is derived. The term "essential" used here does not mean indispensable or usable by the human body, as with the terms essential amino acid or essential fatty acid, which are so called because they are nutritionally required by a living organism.

<span class="mw-page-title-main">Aroma compound</span> Chemical compound that has a smell or odor

An aroma compound, also known as an odorant, aroma, fragrance or flavoring, is a chemical compound that has a smell or odor. For an individual chemical or class of chemical compounds to impart a smell or fragrance, it must be sufficiently volatile for transmission via the air to the olfactory system in the upper part of the nose. As examples, various fragrant fruits have diverse aroma compounds, particularly strawberries which are commercially cultivated to have appealing aromas, and contain several hundred aroma compounds.

<span class="mw-page-title-main">Linalool</span> Chemical compound with a floral aroma

Linalool refers to two enantiomers of a naturally occurring terpene alcohol found in many flowers and spice plants. Together with geraniol, nerol, citronellol, linalool is one of the rose alcohols. Linalool has multiple commercial applications, the majority of which are based on its pleasant scent.

<span class="mw-page-title-main">Carvone</span> Chemical compound

Carvone is a member of a family of chemicals called terpenoids. Carvone is found naturally in many essential oils, but is most abundant in the oils from seeds of caraway, spearmint, and dill.

<span class="mw-page-title-main">Neroli</span> Essential oil of the bitter orange blossom

Neroli oil is an essential oil produced from the blossom of the bitter orange tree. Its scent is sweet, honeyed and somewhat metallic with green and spicy facets. Orange blossom is also extracted from the same blossom and both extracts are extensively used in perfumery. Orange blossom can be described as smelling sweeter, warmer and more floral than neroli. The difference between how neroli and orange blossom smell and why they are referred to with different names, is a result of the process of extraction that is used to obtain the oil from the blooms. Neroli is extracted by steam distillation and orange blossom is extracted via a process of enfleurage or solvent extraction.

<span class="mw-page-title-main">Pine oil</span> Chemical compound

Pine oil is an essential oil obtained from a variety of species of pine, particularly Pinus sylvestris. Typically, parts of the trees that are not used for lumber — stumps, etc. — are ground and subjected to steam distillation. As of 1995, synthetic pine oil was the "biggest single turpentine derivative." Synthetic pine oils accounted for 90% of sales as of 2000.

<span class="mw-page-title-main">Pinene</span> Oily organic chemical found in plants

Pinene is a collection of unsaturated bicyclic monoterpenes. Two geometric isomers of pinene are found in nature, α-pinene and β-pinene. Both are chiral. As the name suggests, pinenes are found in pines. Specifically, pinene is the major component of the liquid extracts of conifers. Pinenes are also found in many non-coniferous plants such as camphorweed (Heterotheca) and big sagebrush.

<span class="mw-page-title-main">Eucalyptol</span> Chemical compound

Eucalyptol is a monoterpenoid colorless liquid, and a bicyclic ether. It has a fresh camphor-like odor and a spicy, cooling taste. It is insoluble in water, but miscible with organic solvents. Eucalyptol makes up about 70–90% of eucalyptus oil. Eucalyptol forms crystalline adducts with hydrohalic acids, o-cresol, resorcinol, and phosphoric acid. Formation of these adducts is useful for purification.

<span class="mw-page-title-main">Orange oil</span> Essential oil produced in rind of oranges

Orange oil is an essential oil produced by cells within the rind of an orange fruit. In contrast to most essential oils, it is extracted as a by-product of orange juice production by centrifugation, producing a cold-pressed oil. It is composed of mostly d-limonene, and is often used in place of pure d-limonene. D-limonene can be extracted from the oil by distillation.

<span class="mw-page-title-main">Myrcene</span> Chemical compound

Myrcene, or β-myrcene, is a monoterpene. A colorless oil, it occurs widely in essential oils. It is produced mainly semi-synthetically from Myrcia, from which it gets its name. It is an intermediate in the production of several fragrances. An less-common isomeric form, having one of the three alkene units in a different position, is α-myrcene.

β-Pinene Chemical compound

β-Pinene is a monoterpene, an organic compound found in plants. It is the less abundant of the two isomers of pinene, the other being α-pinene. It is a colorless liquid soluble in alcohol, but not water. It has a woody-green pine-like smell.

<span class="mw-page-title-main">Fragrance extraction</span> Separation process of aromatic compounds from raw materials

Fragrance extraction refers to the separation process of aromatic compounds from raw materials, using methods such as distillation, solvent extraction, expression, sieving, or enfleurage. The results of the extracts are either essential oils, absolutes, concretes, or butters, depending on the amount of waxes in the extracted product.

Monoterpenes are a class of terpenes that consist of two isoprene units and have the molecular formula C10H16. Monoterpenes may be linear (acyclic) or contain rings (monocyclic and bicyclic). Modified terpenes, such as those containing oxygen functionality or missing a methyl group, are called monoterpenoids. Monoterpenes and monoterpenoids are diverse. They have relevance to the pharmaceutical, cosmetic, agricultural, and food industries.

<span class="mw-page-title-main">Terpineol</span> Chemical compound

Terpineol is any of four isomeric monoterpenoids. Terpenoids are terpene that are modified by the addition of a functional group, in this case, an alcohol. Terpineols have been isolated from a variety of sources such as cardamom, cajuput oil, pine oil, and petitgrain oil. Four isomers exist: α-, β-, γ-terpineol, and terpinen-4-ol. β- and γ-terpineol differ only by the location of the double bond. Terpineol is usually a mixture of these isomers with α-terpineol as the major constituent.

The enzyme (R)-limonene synthase (EC 4.2.3.20) catalyzes the reversible chemical reaction

<span class="mw-page-title-main">Bergamot essential oil</span> Cold-pressed essential oil

Bergamot essential oil is a cold-pressed essential oil produced by cells inside the rind of a bergamot orange fruit. It is a common flavouring and top note in perfumes. The scent of bergamot essential oil is similar to a sweet light orange peel oil with a floral note.

<span class="mw-page-title-main">Lavandulol</span> Chemical compound

Lavandulol is a monoterpene alcohol found in a variety of essential oils such as lavender oil. The term refers to either of two enantiomers. The (R)-enantiomer is natural and has an aroma described as "weak floral, herbal odor with slightly lemon-like, fresh citrus fruity nuance"; the (S)-enantiomer has only a weak odor.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 "D-Limonene". PubChem, US National Library of Medicine. 11 May 2024. Retrieved 18 May 2024.
  2. 1 2 Fahlbusch, Karl-Georg; Hammerschmidt, Franz-Josef; Panten, Johannes; et al. (2003). "Flavors and Fragrances". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a11_141. ISBN   978-3-527-30673-2.
  3. ↑ "Molecule of the Week Archive: Limonene". American Chemical Society. 1 November 2021. Retrieved 5 November 2021.
  4. ↑ "limonene". merriam-webster.com. Merriam-Webster. 22 September 2023. Retrieved 23 September 2023.
  5. ↑ Graikou, K.; Gortzi, O.; Mantanis, G.; Chinou, I. (2012). "Chemical composition and biological activity of the essential oil from the wood of Pinus heldreichii Christ. var. leucodermis". European Journal of Wood and Wood Products. 70 (5): 615–620. doi:10.1007/s00107-012-0596-9. ISSN   0018-3768.
  6. ↑ Booth, Judith K.; Page, Jonathan E.; Bohlmann, Jörg (29 March 2017). Hamberger, Björn (ed.). "Terpene synthases from Cannabis sativa". PLOS ONE. 12 (3): e0173911. Bibcode:2017PLoSO..1273911B. doi: 10.1371/journal.pone.0173911 . ISSN   1932-6203. PMC   5371325 . PMID   28355238.
  7. ↑ Perez-Cacho, Pilar Ruiz; Rouseff, Russell L. (10 July 2008). "Fresh squeezed orange juice odor: A review". Critical Reviews in Food Science and Nutrition. 48 (7): 681–695. doi:10.1080/10408390701638902. ISSN   1040-8398. PMID   18663618. S2CID   32567584.
  8. 1 2 Sharma, Kavita; Mahato, Neelima; Cho, Moo Hwan; Lee, Yong Rok (2017). "Converting citrus wastes into value-added products: Economic and environmentally friendly approaches". Nutrition. 34: 29–46. doi:10.1016/j.nut.2016.09.006. ISSN   0899-9007. PMID   28063510.
  9. ↑ Pakdel, H. (2001). "Production of DL-limonene by vacuum pyrolysis of used tires". Journal of Analytical and Applied Pyrolysis. 57 (1): 91–107. Bibcode:2001JAAP...57...91P. doi:10.1016/S0165-2370(00)00136-4.
  10. ↑ Karlberg, Ann-Therese; Magnusson, Kerstin; Nilsson, Ulrika (1992). "Air oxidation of D-limonene (the citrus solvent) creates potent allergens". Contact Dermatitis. 26 (5): 332–340. doi:10.1111/j.1600-0536.1992.tb00129.x. PMID   1395597. S2CID   46373225.
  11. ↑ Weitkamp, A. W. (1959). "I. The Action of Sulfur on Terpenes. The Limonene Sulfides". Journal of the American Chemical Society. 81 (13): 3430–3434. doi:10.1021/ja01522a069.
  12. ↑ Mann, J. C.; Hobbs, J. B.; Banthorpe, D. V.; Harborne, J. B. (1994). Natural Products: Their Chemistry and Biological Significance . Harlow, Essex: Longman Scientific & Technical. pp.  308–309. ISBN   0-582-06009-5.
  13. ↑ "Limonene" (PDF). EPA.gov. United States Environmental Protection Agency. September 1994. Archived from the original (PDF) on 16 October 2014. Retrieved 7 January 2022.
  14. ↑ "Safety Data Sheet". Cutting Edge Formulations, Inc. 14 November 2014. Archived from the original on 21 January 2022. Retrieved 7 January 2022– via wsimg.com.
  15. ↑ Butler, Peter (October 2010). "It's Like Magic; Removing Self-Adhesive Stamps from Paper" (PDF). American Philatelist . 124 (10). American Philatelic Society: 910–913.
  16. ↑ "Using D-Limonene to Dissolve 3D Printing Support Structures". fargo3dprinting.com. Fargo 3D Printing. 26 April 2014. Retrieved 30 December 2015.
  17. ↑ Wynnchuk, Maria (1994). "Evaluation of Xylene Substitutes for a Paraffin Tissue Processing". Journal of Histotechnology (2): 143–149. doi:10.1179/014788894794710913 (inactive 19 November 2024) – via ingentaconnect.com.{{cite journal}}: CS1 maint: DOI inactive as of November 2024 (link)
  18. ↑ Carson, F. (1997). Histotechnology: A Self-Instructional Text. Chicago: ASCP Press. pp. 28–31. ISBN   0-89189-411-X.
  19. ↑ Kiernan, J. A. (2008). Histological and Histochemical Methods (4th ed.). Banbury, UK: Scion Publishing, Ltd. pp. 54, 57. ISBN   978-1-904842-42-2.
  20. ↑ "Cyclone Power to Showcase External Combustion Engine at SAE Event". greencarcongress.com. Green Car Congress. 20 September 2007.
  21. ↑ Kim, Y.-W.; Kim, M.-J.; Chung, B.-Y.; et al. (2013). "Safety evaluation and risk assessment of D-Limonene". Journal of Toxicology and Environmental Health, Part B. 16 (1): 17–38. Bibcode:2013JTEHB..16...17K. doi:10.1080/10937404.2013.769418. PMID   23573938. S2CID   40274650.
  22. ↑ Deza, Gustavo; García Bravo, Begoña; Silvestre, Juan F.; et al. (2017). "Contact sensitization to limonene and linalool hydroperoxides in Spain: A GEIDAC prospective study" (PDF). Contact Dermatitis. 76 (2): 74–80. doi:10.1111/cod.12714. hdl: 10230/33527 . PMID   27896835. S2CID   21494625.
  23. ↑ "Lemons cannot cure cancer". US National Academies of Sciences, Engineering, and Medicine. 2024. Archived from the original on 28 April 2024.
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