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Terpineol

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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
3D model (JSmol)
Beilstein Reference 2325137
ChEBI
ChEMBL
ChemSpider
EC Number
  • α: 202-680-6
  • β: 205-342-6
  • γ: 209-584-3
  • 4-: 209-235-5
KEGG
PubChem CID
UNII
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C10H18O/c1-8-4-6-9(7-5-8)10(2,3)11/h4,9,11H,5-7H2,1-3H3Key: WUOACPNHFRMFPN-UHFFFAOYSA-N
  • α: InChI=1/C10H18O/c1-8-4-6-9(7-5-8)10(2,3)11/h4,9,11H,5-7H2,1-3H3Key: WUOACPNHFRMFPN-UHFFFAOYAL
SMILES
  • α: C\C1=C\CC(CC1)C(O)(C)C
Properties
Chemical formula C10H18O
Molar mass 154.253 g·mol
Appearance Colorless liquid
Odor Pleasant, lilac-like
Density 0.93 g/cm
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 cm/mol
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
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 , 100 kPa). ☒N verify (what is  ?) Infobox references
Chemical compound

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.

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:

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.

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

References

  1. ^ Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  2. The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (11th ed.). Merck. 1989. p. 9103. ISBN 091191028X.
  3. Yao, Shan-Shan; Guo, Wen-Fei; Lu, Yi; Jiang, Yuan-Xun (2005). "Flavor Characteristics of Lapsang Souchong and Smoked Lapsang Souchong, a Special Chinese Black Tea with Pine Smoking Process". Journal of Agricultural and Food Chemistry. 53 (22): 8688–93. doi:10.1021/jf058059i. PMID 16248572.
  4. Gscheidmeier, Manfred; Fleig, Helmut (June 15, 2000). "Turpentines, 16. Pine Oil". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a27_267. ISBN 978-3527306732.
  5. Yuasa, Yoshifumi; Yuasa, Yoko (2006). "A Practical Synthesis of d-α-Terpineol via Markovnikov Addition of d-Limonene Using Trifluoroacetic Acid". Organic Process Research & Development. 10 (6): 1231–1232. doi:10.1021/op068012d.
  6. Davis, Edward M.; Croteau, Rodney (2000). "Cyclization enzymes in the biosynthesis of monoterpenes, sesquiterpenes, and diterpenes". Biosynthesis. Vol. 209. pp. 53–95. doi:10.1007/3-540-48146-X_2. ISBN 978-3-540-66573-1. {{cite book}}: |journal= ignored (help)

External links

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