The terpinenes are a group of hydrocarbons that are classified as . They each have the same molecular formula and carbon framework, but they differ in the position of carbon-carbon double bonds. α-Terpinene has been isolated from cardamom and marjoram oils, and from other natural sources. β-Terpinene has no known natural source but has been prepared from sabinene. γ-Terpinene and δ-terpinene (also known as terpinolene) have been isolated from a variety of plant sources. They are all colorless liquids with a turpentine-like odor.
Production and uses
α-Terpinene is produced industrially by acid-catalyzed rearrangement of α-
pinene. It has perfume and flavoring properties but is mainly used to confer pleasant odor to industrial fluids. Hydrogenation gives the saturated derivative
P-Menthane.
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Biosynthesis of α-terpinene
The biosynthesis of α-terpinene and other terpenoids starts with the isomerization of geranyl pyrophosphate to linalyl pyrophosphate (LPP). LPP then forms a resonance-stabilized cation by loss of the pyrophosphate group. Cyclization is then completed thanks to this more favorable stereochemistry of the LPP cation, yielding a terpinyl cation.
Plants that produce terpinene
