|Molar mass||136.23 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 noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
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
Geranyl pyrophosphate (GPP) is produced from the reaction of a resonance-stable allylic cation, formed from the loss of the diphosphate group from DMAPP, and isopentenyl pyrophosphate (IPP), and the subsequent loss of a proton. GPP then loses the diphosphate group to form the resonance-stable geranyl cation. The reintroduction of the diphosphate group to the cation produces GPP isomer, known as linalyl pyrophosphate (LPP). LPP then forms a resonance-stable cation by losing its diphosphate 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
- Dewick, P. M. (2009). Medicinal Natural Products: A Biosynthetic Approach. United Kingdom: John Wiley & Sons. pp. 187–197.
- 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.
- 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. doi:10.1016/j.aca.2009.05.030. PMID 19576388.
- 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.