Terpineol

alpha-terpineol

Skeletal formula Skeletal formula Ball-and-stick model Ball-and-stick model
Names
IUPAC names p-Menth-1-en-8-ol 2-(4-Methylcyclohex-3-en-1-yl)propan-2-ol
Other names 2-(4-Methyl-1-cyclohex-3-enyl)propan-2-ol alpha-terpineol α-terpineol α,α,4-Trimethylcyclohex-3-ene-1-methanol Terpene alcohol
Identifiers
CAS Number	α: 98-55-5 checkY β: 138-87-4 γ: 586-81-2 4-: 562-74-3
3D model (JSmol)	α: Interactive image
Beilstein Reference	2325137
ChEBI	α: CHEBI:22469 checkY β: CHEBI:132899 γ: CHEBI:81151 4-: CHEBI:78884
ChEMBL	α: ChEMBL507795 ☒N 4-: ChEMBL507795
ChemSpider	α: 13850142 checkY β: 8418 γ: 10983 4-: 10756
ECHA InfoCard
EC Number	α: 202-680-6 β: 205-342-6 γ: 209-584-3 4-: 209-235-5
E number
KEGG	β: C17517 4-: C17073
PubChem CID	α: 17100 β: 8748 γ: 11467 4-: 11230
UNII	α: 21334LVV8W checkY γ: 5PH9U7XEWS
CompTox Dashboard (EPA)	α: {{#property:P3117}} 4-: DTXSID4044824
InChI InChI=1S/C10H18O/c1-8-4-6-9(7-5-8)10(2,3)11/h4,9,11H,5-7H2,1-3H3 checkY Key: WUOACPNHFRMFPN-UHFFFAOYSA-N checkY α: InChI=1/C10H18O/c1-8-4-6-9(7-5-8)10(2,3)11/h4,9,11H,5-7H2,1-3H3 Key: WUOACPNHFRMFPN-UHFFFAOYAL
SMILES α: C\C1=C\CC(CC1)C(O)(C)C
Properties
Chemical formula	C10H18O
Molar mass	154.253 g·mol−1
Appearance	Colorless liquid
Odor	Pleasant, lilac-like
Density	0.93 g/cm3
Melting point	−35.9 to −28.2 °C (−32.6 to −18.8 °F; 237.2 to 245.0 K) (mixture of isomers)
Boiling point	214–217 °C (417–423 °F; 487–490 K) (mixture of isomers)
Solubility in water	2.42 g/L
Magnetic susceptibility (χ)	−111.9·10−6 cm3/mol
Hazards
NFPA 704 (fire diamond)	2 1 0
Flash point	88 °C (190 °F; 361 K)
Safety data sheet (SDS)	External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). ☒N verify (what is checkY☒N ?) Infobox references

Terpineol is any of four isomeric monoterpenoids. Terpenoids are terpene that are modified by the addition of a functional group, in this case, an alcohol. Terpineols have been isolated from a variety of sources such as cardamom, cajuput oil, pine oil, and petitgrain oil. Four isomers exist: α-terpineol, β-terpineol, γ-terpineol, and terpinen-4-ol. β-Terpineol 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.

File:Terpineols.svg

Terpineols: alpha-, beta-, gamma-, and the 4-terpineol isomer

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 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:

File:Terpineolsynthesisfromlimonene.png

Terpineol synthesis from limonene

Limonene reacts with trifluoroacetic acid in a Markovnikov addition 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.

File:TerpeneVterpenoid.svg

Biosynthetic conversion of geranyl pyrophosphate to the terpenes α-pinene and β-pinene (right) and to α-terpineol (bottom left).

External links

• MSDS for alpha-terpineol
• Error creating thumbnail: File missing Media related to at Wikimedia Commons