Limonene

Source: Wikipedia, the free encyclopedia.
Not to be confused with Limonin.

Limonene
Skeletal structure of the (R)-isomer
Skeletal structure of the (R)-isomer
Ball-and-stick model of the (R)-isomer
Ball-and-stick model of the (R)-isomer
Limonene extracted from orange peels.
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 Edit this at Wikidata
KEGG
UNII
  • InChI=1S/C10H16/c1-8(2)10-6-4-9(3)5-7-10/h4,10H,1,5-7H2,2-3H3 checkY
    Key: XMGQYMWWDOXHJM-UHFFFAOYSA-N checkY
  • CC1=CCC(CC1)C(=C)C
Properties
C10H16
Molar mass 136.238 g·mol−1
Appearance colorless 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
Std enthalpy of
combustion
(ΔcH⦵298)
 −6.128 MJ mol−1
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
pulmonary oedema, pneumonitis, and death[1]
GHS labelling:
GHS02: FlammableGHS07: Exclamation markGHS08: Health hazardGHS09: Environmental hazard
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 four-colored diamondHealth 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 is a colorless liquid

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

centrifugal separation or steam distillation
.

Chemical reactions

Limonene is a relatively stable monoterpene and can be distilled without decomposition, although at elevated temperatures it cracks to form isoprene.[5] It oxidizes easily in moist air to produce carveol, carvone, and limonene oxide.[1][6] With sulfur, it undergoes dehydrogenation to p-cymene.[7]

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

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

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.[8] The final step involves loss of a proton from the cation to form the alkene.

Biosynthesis of limonene from geranyl pyrophosphate

In plants

(+)-Limonene is a major component of the aromatic scents and

Juniperus spp.).[1][failed verification] It contributes to the characteristic odor of orange peel, orange juice and other citrus fruits.[1][10] To optimize recovery of valued components from citrus peel waste, (+)-limonene is typically removed.[11]

Safety and research

(+)-Limonene applied to skin may cause irritation from

aquatic life.[1]

Uses

Limonene is common as a

botanical insecticide.[1][14] (+)-Limonene is used in the organic herbicides.[15] 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

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.[16]

Limonene is also used as a solvent for fused filament fabrication based

High Impact Polystyrene (HIPS), a polystyrene
plastic that is easily soluble in limonene.

In preparing

isopropanol) and with melted paraffin wax, in which specimens are embedded to facilitate cutting of thin sections for microscopy.[18][19][20]

Limonene, from orange peel oil, is also combustible and has been considered as a biofuel.[21]

See also

References

  1. ^
    US National Library of Medicine
    . 2017. Retrieved 22 December 2017.
  2. ^
    ISBN 978-3-527-30673-2
    .
  3. ^ "Molecule of the Week Archive: Limonene". ACS.org. 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. doi:10.1016/S0165-2370(00)00136-4
    .
  6. S2CID 46373225
    .
  7. doi:10.1021/ja01522a069
    .
  8. ISBN 0-582-06009-5
    .
  9. PMID 28355238
    .
  10. S2CID 32567584
    .
  11. ^
    PMID 28063510
    .
  12. S2CID 40274650
    .
  13. S2CID 21494625
    .
  14. ^ "Limonene" (PDF). EPA.gov. United States Environmental Protection Agency. September 1994. Archived from the original (PDF) on 16 October 2014. Retrieved 7 January 2022.
  15. ^ "Safety Data Sheet". Cutting Edge Formulations, Inc. 14 November 2014. Retrieved 7 January 2022 – via wsimg.com.
  16. American Philatelist. 124 (10). American Philatelic Society
    : 910–913.
  17. ^ "Using D-Limonene to Dissolve 3D Printing Support Structures". fargo3dprinting.com. Fargo 3D Printing. 26 April 2014. Retrieved 30 December 2015.
  18. doi:10.1179/014788894794710913
    – via ingentaconnect.com.
  19. ISBN 0-89189-411-X
    .
  20. ISBN 978-1-904842-42-2.{{cite book}}: CS1 maint: location missing publisher (link
    )
  21. ^ "Cyclone Power to Showcase External Combustion Engine at SAE Event". greencarcongress.com. Green Car Congress. 20 September 2007.

External links

Wikimedia Commons has media related to Limonene.
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