Terpineol is any of four isomeric monoterpenoids. Terpenoids are terpene that are modified by the addition of a

functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the r ...

, in this case, an alcohol. Terpineols have been isolated from a variety of sources such as

cardamom Cardamom (), sometimes cardamon or cardamum, is a spice made from the seeds of several plants in the genera '' Elettaria'' and '' Amomum'' in the family Zingiberaceae. Both genera are native to the Indian subcontinent and Indonesia. They ar ...

, cajuput oil, pine oil, and

petitgrain Petitgrain () is an essential oil that is extracted from the leaves and green twigs of the bitter orange tree (''Citrus aurantium'' ssp. ''amara'') via steam distillation. It is also known as petitgrain bigarade. Etymology Petitgrain (Fr.: “ ...

oil. Four isomers exist: α-, β-, γ-terpineol, and terpinen-4-ol. β- and γ-terpineol differ only by the location of the double bond. Terpineol is usually a mixture of these isomers with α-terpineol as the major constituent. : Terpineol has a pleasant odor similar to lilac and is a common ingredient in perfumes, cosmetics, and flavors. α-Terpineol is one of the two most abundant

aroma An odor (American English) or odour (Commonwealth English; see spelling differences) is caused by one or more volatilized chemical compounds that are generally found in low concentrations that humans and animals can perceive via their sens ...

constituents of lapsang souchong tea; the α-terpineol originates in the pine smoke used to dry the tea. (+)-α-terpineol is a chemical constituent of skullcap.

Synthesis and biosynthesis

Although it is naturally occurring, terpineol is commonly manufactured from alpha-pinene, which is hydrated in the presence of sulfuric acid. An alternative route starts from limonene: : Limonene reacts with

trifluoroacetic acid Trifluoroacetic acid (TFA) is an organofluorine compound with the chemical formula CF3CO2H. It is a structural analogue of acetic acid with all three of the acetyl group's hydrogen atoms replaced by fluorine atoms and is a colorless liquid with ...

in a

Markovnikov addition In organic chemistry, Markovnikov's rule or Markownikoff's rule describes the outcome of some addition reactions. The rule was formulated by Russian chemist Vladimir Markovnikov in 1870. Explanation The rule states that with the addition of a pr ...

to a trifluoroacetate intermediate, which is easily hydrolyzed with sodium hydroxide to α-terpineol with 7% selectivity. Side-products are β-terpineol in a mixture of the ''cis'' isomer, the ''trans'' isomer, and 4-terpineol. The biosynthesis of α-terpineol proceeds from geranyl pyrophosphate, which releases pyrophosphate to give the terpinyl cation. This carbocation is the precursor to many terpenes and terpenoids. Its hydrolysis gives terpineol. : TerpeneVterpenoid

References

External links

MSDS for alpha-terpineol
* {{Authority control Flavors Monoterpenes Alkenols Cyclohexenes