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Alpha terpinene.png
Beta terpinene.png
Gamma terpinene.png
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
3D model (JSmol)
ECHA InfoCard 100.029.440
Molar mass 136.24 g·mol−1
Density α: 0.8375 g/cm3
β: 0.838 g/cm3
γ: 0.853 g/cm3
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 [77 °F], 100 kPa).
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Infobox references

The terpinenes are a group of isomeric hydrocarbons that are classified as terpenes. 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 synthetically from sabinene. γ-Terpinene and δ-terpinene (also known as terpinolene) are natural and have been isolated from a variety of plant sources.


α-Terpinene is a perfume and flavoring chemical used in the cosmetics and food industries. Its use in both the pharmaceutical and the electronics semi-conductor manufacturing industries has also proven to be valuable.

Biosynthesis of α-terpinene[edit]

Biosynthesis of α-terpinene.[1] "P" indicates a phosphate group, -PO32−

The biosynthesis of α-terpinene and other terpenoids occurs via the mevalonate pathway because its starting reactant, dimethylallyl pyrophosphate (DMAPP), is derived from mevalonic acid.

Geranyl pyrophosphate (GPP) is produced from the reaction of a resonance-stable allylic cation, formed from the loss of the pyrophosphate group from DMAPP, and isopentenyl pyrophosphate (IPP), and the subsequent loss of a proton. GPP then loses the pyrophosphate group to form the resonance-stable geranyl cation. The reintroduction of the pyrophosphate group to the cation produces GPP isomer, known as linalyl pyrophosphate (LPP). LPP then forms a resonance-stable cation by losing its pyrophosphate group. Cyclization is then completed thanks to this more favorable stereochemistry of the LPP cation, now 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.

List of the plants that contain one of the chemicals[edit]


  1. ^ Dewick, P. M. (2009). Medicinal Natural Products: A Biosynthetic Approach. United Kingdom: John Wiley & Sons. pp. 187–197. 
  2. ^ 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. 
  3. ^ 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. PMID 19576388. doi:10.1016/j.aca.2009.05.030. 
  4. ^ 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. PMID 15631509. doi:10.1021/jf0487351.