Pinene

Pinene ( stress on the second syllable: pinene ) are monoterpene hydrocarbons, colorless liquids with molecular formula C10H16. Pinene are components of essential oils.

Representative

There are at least six pinene isomers, the two of α -pinene and β -pinene as well as four of δ - pinene; (-) for the latter ( )-cis- δ -pinene and in the literature -cis- δ -pinene described.

1907 were assigned as α, β - and γ -pinene by Otto Wallach three Pinene. 1921, another representative was discovered and hence referred to as δ - pinene. The assigned by Wallach constitution of " γ -pinene " in 1947 rejected by Harry Schmidt again, since it contradicts the Bredt rule. The called classical names of pinene ( α, β, γ, δ ) are still retained, as have been naturalized at that time in the literature.

Occurrence

The α - and β - pinene are, for example, myrtle, pine needles, dill, fennel, coriander and cumin before, also in products such as paints, oils and waxes. δ -pinene, for example, in rosemary. Turpentine oil consists of about 60 % of α - pinene.

Use

From Sandalore pinene, citronellal, camphor, linalool and myrcene can be synthesized.

Biosynthesis

α -pinene and β -pinene, both synthesized from geranyl pyrophosphate followed by rearrangement of a hydrogen atom by cyclization of linalool pyrophosphate.

Properties

Pinene are inflammatory, low volatile, colorless liquids with terpentinartigem odor. Their melting and boiling temperature and its density differ only slightly. α -pinene is harmful, β -pinene is irritating. α -pinene oxidized to verbenone usually, myrtenol, pinene oxide and other products. By the action of heat can β -pinene is converted to myrcene. A secondary oxidation product of pinene is the allergenic ascaridol why essential oils that include pinene, can cause allergies in a few days.

Related compounds

• Alpine borane
• Apoperin
• Pinan