Contents

Pinene

• (mixture): 1330-16-1 ^Y

(1R-α): 7785-70-8 ^Y

(1S-α): 7785-26-4 ^Y

(1R-β): 19902-08-0 ^Y

(1S-β): 18172-67-3 ^Y

100.029.170

• (mixture): 996299PUKB ^Y

(1R-α): H6CM4TWH1W ^Y

(1S-α): TZR3GM95PR ^Y

(1R-β): IGO73S04D5 ^Y

(1S-β): AFN153A7SU ^Y

C₁₀H₁₆

136.24 g/mol

Liquid

0,86 g·cm⁻³ (alpha, 15 °C)^[1][2]

−62 to −55 °C (−80 to −67 °F; 211 to 218 K) (alpha)^[1]

155 to 156 °C (311 to 313 °F; 428 to 429 K) (alpha)^[1]

Practically insoluble in water

Infobox references

Pinene is a collection of unsaturated bicyclic monoterpenes. Two geometric isomers of pinene are found in nature, α-pinene and β-pinene. Both are chiral. As the name suggests, pinenes are found in pines. Specifically, pinene is the major component of the liquid extracts of conifers.^[3] Pinenes are also found in many non-coniferous plants such as camphorweed (Heterotheca)^[4] and big sagebrush (Artemisia tridentata).

Isomers[edit]

X

X

X

X

(1R)-(+)-α-pinene

(1S)-(−)-α-pinene

(1R)-(+)-β-pinene

(1S)-(−)-β-pinene

7785-70-8

7785-26-4

19902-08-0

18172-67-3

Biosynthesis[edit]

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[edit]

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[edit]

β-Pinene can be converted to α-pinene in the presence of strong bases.^[14]

Selective oxidation of pinene occurs at the allylic position to give verbenone, along with pinene oxide, as well as verbenol and its hydroperoxide.^[15][16]

Hydrogenation of pinene gives pinane, precursor to a useful pinanehydroperoxide.

The hydroboration of α-pinene has been extensively examined. With borane-dimethylsulfide, two equivalents of α-pinene react to give (diisopinocampheyl)borane.^[17] Reaction with 9-BBN gives the reagent called alpine borane. This sterically crowded chiral trialkylborane can stereoselectively reduce aldehydes in what is known as the Midland Alpine borane reduction.^[18]

Use[edit]

Pinenes, especially α, are the primary constituents of turpentine, a nature-derived solvent and fuel.^[3]

The use of pinene as a biofuel in spark ignition engines has been explored.^[19] Pinene dimers have been shown to have heating values comparable to the jet fuel JP-10.^[5]

References[edit]

^ ^{a b} Sarria S, Wong B, Martín HG, Keasling JD, Peralta-Yahya P (2014). "Microbial Synthesis of Pinene". ACS Synthetic Biology. 3 (7): 466–475. doi:10.1021/sb4001382. PMID 24679043.

Bibliography[edit]

• Mann, J.; Davidson, R. S.; Hobbs, J. B.; Banthorpe, D. V.; Harborne, J. B. (1994). Natural Products. Harlow, UK: Addison Wesley Longman Ltd. pp. 309–311. ISBN 978-0-582-06009-8.