alpha-Phellandrene is a colourless to light yellow oily liquid, exuding a distinctive black pepper, fresh, citrus, minty, and herbaceous complex aroma. As an important monoterpene compound, it is widely found in various plant essential oils and exists in both its optical isomer forms (dextrorotatory and laevorotatory).
The right-handed body is existed in cinnamon oil, ginger oil, elemi oil, cumin oil and other plants. The left-handed body is existed in eucalyptus oil, star anise oil, gump couch oil, laurel oil, pepper oil and other plants.
Phellandrene is the name for a pair of organic compounds that have a similar molecular structure and similar chemical properties. α-Phellandrene and β-phellandrene are cyclic monoterpenes and are double-bond isomers.
In α-phellandrene, both double bonds are endocyclic and in β-phellandrene, one of them is exocyclic. Both are insoluble in water, but miscible with ether.
The phellandrenes are used in fragrances because of their pleasing aromas. The odor of β-phellandrene has been described as peppery-minty and slightly citrusy.It is colorless to light yellow oily liquid with peppermint aroma. Right-handed body exists in cinnamon oil, ginger oil, elemi oil, cumin oil etc. Left-handed body exists in eucalyptus oil, star anise oil, gump couch oil, laurel oil, pepper oil, etc.
α-Phellandrene was named after Eucalyptus phellandra, now called Eucalyptus radiata, from which it can be isolated. It is also a constituent of the essential oil of Eucalyptus dives.
Limonene is present in citrus essential oils, where its content can reach up to 90%. (−)-Limonene naturally occurs in pine needle oil, turpentine, cajuput oil, and other essential oils. It is a liquid with an orange-like aroma and is obtained by fractionation from terpenes in orange oil.
Limonene has optical isomers, including L-limonene, R-limonene, and the racemic isomer dipentene.
In flavor formulations for personal care products, the content of limonene can be as high as 30%. Limonene is also mainly used as an intermediate in the synthesis of bergamyl esters, carvone, p-cymene, tonalide, and fantolide.