Alpha-pinene

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.

Properties

Chemical

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.

Physical

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.

Availability

α-pinene is readily available as one of the most major consitutents 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.

Preparation

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

Projects

• Homemade perfumes and fragrances

Handling

Safety

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.

Storage

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

Disposal

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.