Phellandrene

Phellandrene

Phellandrene

Chemical compound

Phellandrenes are 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 diethyl ether.

Quick Facts Names, Identifiers ...

α-Phellandrene was named after Eucalyptus phellandra, now called Eucalyptus radiata, from which it can be isolated.[2] It is also a constituent of the essential oil of Eucalyptus dives.[3] β-Phellandrene has been isolated from the oil of water fennel and Canada balsam oil.

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.

The α-phellandrene isomer can form hazardous and explosive peroxides on contact with air at elevated temperatures.[4]

Biosynthesis

The biosynthesis of phellandrene begins with dimethylallyl pyrophosphate and isopentenyl pyrophosphate condensing in an SN1 reaction to form geranyl pyrophosphate. The resultant monoterpene undergoes cyclization to form a menthyl cationic species. A hydride shift then forms an allylic carbocation. Finally, an elimination reaction occurs at one of two positions, yielding either α-phellandrene or β-phellandrene.[5]

References

  1. [1]
    The Merck Index, 12th Edition, 7340, 7341
  2. [2]
    Jacobs, S.W.L., Pickard, J., Plants of New South Wales, 1981, ISBN 0-7240-1978-2.
  3. [3]
    Boland, D. J., Brophy, J. J., and A. P. N. House, Eucalyptus Leaf Oils, 1991, ISBN 0-909605-69-6.
  4. [4]
    Urben, Peter (2007). Bretherick's Handobook of Reactive Chemical Hazards. Vol. 1 (7 ed.). Butterworth-Heinemann. p. 1154.
  5. [5]
    Dewick, Paul M. (9 March 2009). Medicinal natural products : a biosynthetic approach (3rd ed.). Chichester, West Sussex, United Kingdom. ISBN 9780470741689. OCLC 259265604.{{cite book}}: CS1 maint: location missing publisher (link)
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