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IUPAC name
(1S,5S)-2,6,6-Trimethylbicyclo[3.1.1]hept-2-ene ((−)-α-Pinene)
Other names
Jmol-3D images Image
Molar mass 136.24 g/mol
Appearance Colorless liquid
Odor Pine, turpentine-like
Density 0.858 g/cm3 (at 20 °C)
Melting point −64 °C (−83 °F; 209 K)
Boiling point 155 °C (311 °F; 428 K)
0.000249 g/100 ml (25 °C)
Solubility Miscible with glacial acetic acid, acetone, chloroform, diethyl ether, ethanol, isopropanol
Almost insoluble in glycerol, propylene glycol
Vapor pressure 4.75 mmHg at 25 °C
Safety data sheet Sigma-Aldrich
Flash point 33 °C (91 °F; 306 K)
Related compounds
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

α-pinene(also written alpha-pinene) is an organic compound with chemical formula C10H16 belonging to the terpenes, a group of biologically important hydrocarbons. It is the most commonly encountered and well researched of the two pinene isomers, and has a number of niche uses in organic synthesis.



α-pinene and related compounds are commonly utilized in the fragrance industry, and as such, it is a precursor to many of these compounds. Hydration to α-terpineol can be accomplished by the reflux of α-pinene with aqueous sulfuric acid and acetone for a few hours, or by the action of concentrated sulfuric acid in ethanol]. The ester α-terpinyl acetate can be produced by esterification with glacial acetic acid. It can also be rearranged into camphene by strong acid catalysis in glacial acetic acid as a step in the production of camphor. With dilute acids, terpin hydrate becomes the major product.

Addition of iodine or phosphorus trichloride causes aromatisation, leading to p-cymene.


α-pinene is a lightweight, clear, colorless liquid in pure form, nearly insoluble in water but miscible with organic solvents. The odor of commercial α-pinene depends on its source; as it can be separated from turpentine by distillation, the odor often matches this. α-pinene boils at 155 °C (311 °F) and is only mildly flammable.


α-pinene is readily available as one of the most major constituents of turpentine and can be distilled in reasonably pure form from it. Turpentine is available as a solvent and paint stripper at many hardware and department stores.


α-pinene is more likely to be extracted from turpentine rather than synthesized in the home lab.


  • Homemade perfumes and fragrances



While not strongly toxic, α-pinene produces vapors that can cause respiratory problems and may act as a skin irritant as well. It should not be used near open flame due to its flammability.


Due to its volatility, α-pinene should be kept in airtight containers away from sources of open flames.


α-pinene is commonly encountered in biological systems and does not pose a significant threat to the environment nor to humans. Given its low density and immiscibility with water, pouring it down a sink may not be a good course of action for disposal, with an outdoor trash can presenting a better option. However, it's best to have it soaked in a porous material, like sand or charcoal, to reduce any leaks on the ground or pavement.


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