α-Pinene is an organic compound belonging to the terpene class, notable as one of the two isomers of pinene, with the other being β-pinene. It is an alkene that features a reactive four-membered ring, predominantly found in the oils of coniferous trees, especially pines, and also in the essential oil of rosemary (Rosmarinus officinalis) and Satureja myrtifolia. α-Pinene exists in nature in both of its enantiomers; the (1S,5S)- or (−)-α-pinene variant is more commonly found in European pines, while the (1R,5R)- or (+)-α-pinene variant is prevalent in North America. The racemic mixture of these enantiomers is present in certain oils like eucalyptus oil and orange peel oil, highlighting its widespread occurrence and significance in various natural sources.
Reactivity
- Commercially important derivatives of alpha-pinene are linalool, geraniol, nerol, a-terpineol, and camphene.
- Alpha-pinene is reactive due to the presence of the four-membered ring adjacent to the alkene.
- The compound is prone to skeletal rearrangements such as the Wagner–Meerwein rearrangement.
- Acids typically lead to rearranged products.
- Under aerobic oxidation conditions, the main oxidation products are pinene oxide, verbenyl hydroperoxide, verbenol, and verbenone.
Atmospheric Role
- Monoterpenes, including alpha-pinene, are emitted in substantial amounts by vegetation.
- In the atmosphere, alpha-pinene undergoes reactions with ozone, the hydroxyl radical, or the NO radical.
- These reactions lead to low-volatility species that partly condense on existing aerosols, generating secondary organic aerosols.
- Identified products of alpha-pinene include pinonaldehyde, norpinonaldehyde, pinic acid, pinonic acid, and pinalic acid.
Properties and Usage
- Alpha-pinene is highly bioavailable, with 60% human pulmonary uptake and rapid metabolism or redistribution.
- It is an anti-inflammatory via PGE1 and likely antimicrobial.
- Alpha-pinene acts as an acetylcholinesterase inhibitor, aiding memory.
- It is a positive modulator of GABAA receptors, acting at the benzodiazepine binding site.
- Alpha-pinene forms the biosynthetic base for CB2 ligands and is found in cannabis plants.
Chemical Compound
- Alpha-pinene is an organic compound of the terpene class and one of the two isomers of pinene.
- It contains a reactive four-membered ring and is found in the oils of many coniferous trees.
- Both enantiomers of alpha-pinene are known in nature, with different common occurrences in European and North American pines.
- Commercially, alpha-pinene derivatives include terpineol, ethyl ether, and acetate products.
- It serves as a biosynthetic base for CB2 ligands and contributes to the unique odor profiles of cannabis strains.
References
- Simonsen, J. L. (1957). The Terpenes.
- Zebib, Bachar; Beyrouthy, Marc El; Sarfi, Carl; Merah, Othmane (2015). Chemical Composition of the Essential Oil of Satureja myrtifolia.
- Sell, Charles S. (2006). Terpenoids.
- Richter, G. H. (1945). Textbook of Organic Chemistry.
- Neuenschwander, U. (2010). Mechanism of the Aerobic Oxidation of α-Pinene.
α-Pinene Data Sources
| Reference | URL |
|---|---|
| Glossary | https:/glossary/α-pinene |
| Wikipedia | https://en.wikipedia.org/wiki/Α-Pinene |
| Wikidata | https://www.wikidata.org/wiki/Q300852 |
| Knowledge Graph | https://www.google.com/search?kgmid=/m/09_118 |
| DBPedia | http://dbpedia.org/resource/Α-Pinene |
| Product Ontology | http://www.productontology.org/id/Α-Pinene |