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Terpinene

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Terpinenes
α-Terpinene
β-Terpinene
γ-Terpinene
δ-Terpinene
(terpinolene)
Names
IUPAC names α: 4-Methyl-1-(1-methylethyl)-1,3-cyclohexadiene
β: 4-Methylene-1-(1-methylethyl)cyclohexene
γ: 4-Methyl-1-(1-methylethyl)-1,4-cyclohexadiene
δ: 1-Methyl-4-(propan-2-ylidene)cyclohex-1-ene
Identifiers
CAS Number
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.029.440 Edit this at Wikidata
EC Number
  • (α): 202-795-1
  • (β): 202-793-0
  • (γ): 202-794-6
  • (δ): 209-578-0
KEGG
PubChem CID
UNII
InChI
  • InChI=1S/C10H16/c1-8(2)10-6-4-9(3)5-7-10/h6,8H,3-5,7H2,1-2H3Key: SCWPFSIZUZUCCE-UHFFFAOYSA-N
  • (β): InChI=1S/C10H16/c1-8(2)10-6-4-9(3)5-7-10/h6,8H,3-5,7H2,1-2H3Key: SCWPFSIZUZUCCE-UHFFFAOYSA-N
  • (γ): InChI=1S/C10H16/c1-8(2)10-6-4-9(3)5-7-10/h4,7-8H,5-6H2,1-3H3Key: YKFLAYDHMOASIY-UHFFFAOYSA-N
  • (δ): InChI=1S/C10H16/c1-8(2)10-6-4-9(3)5-7-10/h4H,5-7H2,1-3H3Key: MOYAFQVGZZPNRA-UHFFFAOYSA-N
SMILES
  • (α): CC1=CC=C(C(C)C)CC1
  • (β): C=C1CC=C(C(C)C)CC1
  • (γ): CC1=CCC(C(C)C)=CC1
  • (δ): C/C(C)=C1CCC(C)=CC/1
Properties
Chemical formula C10H16
Molar mass 136.238 g·mol
Density α: 0.8375 g/cm
β: 0.838 g/cm
γ: 0.853 g/cm
Melting point α: 60-61 °C
Boiling point α: 173.5-174.8 °C
β: 173-174 °C
γ: 183 °C
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). checkY verify (what is  ?) Infobox references
Chemical compound

The terpinenes are a group of isomeric hydrocarbons that are classified as monoterpenes. They each have the same molecular formula and carbon framework, but they differ in the position of carbon-carbon double bonds. α-Terpinene has been isolated from cardamom and marjoram oils, and from other natural sources. β-Terpinene has no known natural source but has been prepared from sabinene. γ-Terpinene and δ-terpinene (also known as terpinolene) have been isolated from a variety of plant sources. They are all colorless liquids with a turpentine-like odor.

Production and uses

α-Terpinene is produced industrially by acid-catalyzed rearrangement of α-pinene. It has perfume and flavoring properties but is mainly used to confer pleasant odor to industrial fluids. Hydrogenation gives the saturated derivative p-menthane.

Biosynthesis of α-terpinene

Biosynthetic pathway to alpha-terpinene from geranyl pyrophosphate.

The biosynthesis of α-terpinene and other terpenoids starts with the isomerization of geranyl pyrophosphate to linalyl pyrophosphate (LPP). LPP then forms a resonance-stabilized cation by loss of the pyrophosphate group. Cyclization is then completed thanks to this more favorable stereochemistry of the LPP cation, yielding a terpinyl cation. Finally, a 1,2-hydride shift via a Wagner-Meerwein rearrangement produces the terpinen-4-yl cation. It is the loss of a hydrogen from this cation that generates α-terpinene.

Plants that produce terpinene

References

  1. ^ M. Eggersdorfer (2005). "Terpenes". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a26_205. ISBN 3-527-30673-0.
  2. Dewick, P. M. (2009). Medicinal Natural Products: A Biosynthetic Approach. United Kingdom: John Wiley & Sons. pp. 187–197.
  3. Christianson, David W. (2017). "Structural and Chemical Biology of Terpenoid Cyclases". Chemical Reviews. 117 (17): 11570–11648. doi:10.1021/acs.chemrev.7b00287. PMC 5599884. PMID 28841019.
  4. Li, Rong; Zi-Tao Jiang (2004). "Chemical composition of the essential oil of Cuminum cyminum L. from China". Flavour and Fragrance Journal. 19 (4): 311–313. doi:10.1002/ffj.1302.
  5. Wang, Lu; Wang, Z; Zhang, H; Li, X; Zhang, H; et al. (2009). "Ultrasonic nebulization extraction coupled with headspace single drop microextraction and gas chromatography–mass spectrometry for analysis of the essential oil in Cuminum cyminum L.". Analytica Chimica Acta. 647 (1): 72–77. Bibcode:2009AcAC..647...72W. doi:10.1016/j.aca.2009.05.030. PMID 19576388.
  6. Iacobellis, Nicola S.; Lo Cantore, P; Capasso, F; Senatore, F; et al. (2005). "Antibacterial Activity of Cuminum cyminum L. and Carum carvi L. Essential Oils". Journal of Agricultural and Food Chemistry. 53 (1): 57–61. doi:10.1021/jf0487351. PMID 15631509.
  7. Hillig, Karl W (October 2004). "A chemotaxonomic analysis of terpenoid variation in Cannabis". Biochemical Systematics and Ecology. 32 (10): 875–891. Bibcode:2004BioSE..32..875H. doi:10.1016/j.bse.2004.04.004. ISSN 0305-1978.
  8. Shahwar, Muhammad Khuram; El-Ghorab, Ahmed Hassan; Anjum, Faqir Muhammad; Butt, Masood Sadiq; Hussain, Shahzad; Nadeem, Muhammad (2012-07-01). "Characterization of Coriander (Coriandrum sativum L.) Seeds and Leaves: Volatile and Non Volatile Extracts". International Journal of Food Properties. 15 (4): 736–747. doi:10.1080/10942912.2010.500068. ISSN 1094-2912.
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