Verbenol (2-pine-4-ol) is a group of stereoisomeric
bicyclic
In chemistry, a bicyclic molecule () is a molecule that features two joined rings. Bicyclic structures occur widely, for example in many biologically important molecules like α-thujene and camphor. A bicyclic compound can be carbocyclic (all o ...
monoterpene
Monoterpenes are a class of terpenes that consist of two isoprene units and have the molecular formula C10H16. Monoterpenes may be linear (acyclic) or contain rings (monocyclic and bicyclic). Modified terpenes, such as those containing oxygen funct ...
alcohols
In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl () functional group bound to a saturated carbon atom. The term ''alcohol'' originally referred to the primary alcohol ethanol (ethyl alcohol), which is ...
. These compounds have been found to be active components of insect
pheromones
A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...
and
essential oils
An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the o ...
.
Isomers
Four stereoisomers of verbenol are known. For the ''cis'' isomer, the two
methyl group
In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula . In formulas, the group is often abbreviated as Me. This hydrocarbon group occurs in many ...
s (-CH
3) are on the same side of the carbon ring as the
hydroxy group
In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...
(-OH), and for the ''trans'' isomer, they are on the opposite sides. Again, there are
enantiomer
In chemistry, an enantiomer ( /ɪˈnænti.əmər, ɛ-, -oʊ-/ ''ih-NAN-tee-ə-mər''; from Ancient Greek ἐνάντιος ''(enántios)'' 'opposite', and μέρος ''(méros)'' 'part') – also called optical isomer, antipode, or optical ant ...
s of each form that exhibit
optical activity
Optical rotation, also known as polarization rotation or circular birefringence, is the rotation of the orientation of the plane of polarization about the optical axis of linearly polarized light as it travels through certain materials. Circul ...
, that is, turn the plane of linearly polarized light as it passes through the substance or its solution.
''trans''-Verbenol is a
mountain pine beetle
The mountain pine beetle (''Dendroctonus ponderosae'') is a species of bark beetle native to the forests of western North America from Mexico to central British Columbia. It has a hard black exoskeleton, and measures approximately , about the siz ...
pheromone that attracts insects to a tree.
''cis''-Verbenol is an aggregation pheromone of ''Ips'' typographus and ''Dendroctonus ponderosae'' Hopkins.
Enantiomeric composition
Typically, verbenol and related cyclic monoterpenes are available as non‐racemic mixtures of their enantiomers. There are methods to increase
enantiomeric excess
In stereochemistry, enantiomeric excess (ee) is a measurement of purity used for chiral substances. It reflects the degree to which a sample contains one enantiomer in greater amounts than the other. A racemic mixture has an ee of 0%, while a sin ...
(optical purity) of verbenol and to isolate individual enantiomers.
[Mori, Kenji et al. Synthesis of Optically Pure (1S, 4S, 5S)-2-Pinen-4-ol (cis-Verbenol) and Its Antipode, the Pheromone of Ips Bark Beetles. https://doi.org/10.1080/00021369.1976.10862248]
References
{{Reflist
Pheromones
Bicyclic compounds
Monoterpenes