Pinene
From Wikipedia, the free encyclopedia
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IUPAC names
(1S,5S)-2,6,6-trimethylbicyclo[3.1.1]hept-2-ene
(1S,5S)-6,6-dimethyl-2-methylenebicyclo[3.1.1]heptane | |
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3D model (JSmol)
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ChEBI |
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ChemSpider | |
ECHA InfoCard | 100.029.170 |
EC Number |
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PubChem CID
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UNII |
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CompTox Dashboard (EPA)
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Properties | |
C10H16 | |
Molar mass | 136.24 g/mol |
Appearance | Liquid |
Density | 0,86 g·cm−3 (alpha, 15 °C)[1][2] |
Melting point | −62 to −55 °C (−80 to −67 °F; 211 to 218 K) (alpha)[1] |
Boiling point | 155 to 156 °C (311 to 313 °F; 428 to 429 K) (alpha)[1] |
Practically insoluble in water | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Pinene (C10H16) is a bicyclic monoterpene chemical compound. There are two structural isomers of pinene found in nature: α-pinene and β-pinene. As the name suggests, both forms are important constituents of pine resin; they are also found in the resins of many other conifers, as well as in non-coniferous plants such as camphorweed (Heterotheca)[3] and big sagebrush (Artemisia tridentata). Both isomers are used by many insects in their chemical communication system. The two isomers of pinene, especially α, constitute the major component of turpentine.[4]
Isomers
skeletal formula | ||||
perspective view | X | X | ||
ball-and-stick model | X | X | ||
name | (1R)-(+)-α-pinene | (1S)-(−)-α-pinene | (1R)-(+)-β-pinene | (1S)-(−)-β-pinene |
CAS number | 7785-70-8 | 7785-26-4 | 19902-08-0 | 18172-67-3 |
Biosynthesis
α-Pinene and β-pinene are both produced from geranyl pyrophosphate, via cyclisation of linaloyl pyrophosphate followed by loss of a proton from the carbocation equivalent. Researchers at the Georgia Institute of Technology and the Joint BioEnergy Institute have been able to synthetically produce pinene with a bacterium.[5]
Plants
Alpha-pinene is the most widely encountered terpenoid in nature[6] and is highly repellent to insects.[7]
Alpha-pinene appears in conifers and numerous other plants.[8] Pinene is a major component of the essential oils of Sideritis spp. (ironwort)[9] and Salvia spp. (sage).[10] Cannabis also contains alpha-pinene[8] and beta-pinene.[11] Resin from Pistacia terebinthus (commonly known as terebinth or turpentine tree) is rich in pinene. Pine nuts produced by pine trees contain pinene.[8]
Makrut lime fruit peel contains an essential oil comparable to lime fruit peel oil; its main components are limonene and β-pinene.[12]
The racemic mixture of the two forms of pinene is found in some oils like eucalyptus oil.[13]
Reactions
Selective oxidation of pinene occurs at the allylic position to give verbenone, along with pinene oxide, as well as verbenol and its hydroperoxide.[14]
- Pinenes are the primary constituents of turpentine.
- The use of pinene as a biofuel in spark ignition engines has been explored.[15]
- Pinene dimers have been shown to have heating values comparable to the jet fuel JP-10.[5]
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