Terpineol
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Names | |||
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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 | |||
3D model (JSmol)
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2325137 | |||
ChEBI |
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ChEMBL |
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ChemSpider | |||
EC Number |
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KEGG | |||
PubChem CID
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UNII |
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CompTox Dashboard (EPA)
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Properties | |||
C10H18O | |||
Molar mass | 154.253 g·mol−1 | ||
Appearance | Colorless liquid[1] | ||
Density | 0.93 g/cm3[1] | ||
Melting point | −35.9 to −28.2 °C (−32.6 to −18.8 °F; 237.2 to 245.0 K)[1] (mixture of isomers) | ||
Boiling point | 214–217 °C (417–423 °F; 487–490 K)[1] (mixture of isomers) | ||
2.42 g/L[1] | |||
−111.9·10−6 cm3/mol | |||
Hazards | |||
NFPA 704 (fire diamond) | |||
Flash point | 88 °C (190 °F; 361 K)[1] | ||
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).
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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.[2] 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 constituents of lapsang souchong tea; the α-terpineol originates in the pine smoke used to dry the tea.[3] (+)-α-terpineol is a chemical constituent of skullcap.
Synthesis and biosynthesis
[edit]Although it is naturally occurring, terpineol is commonly manufactured from alpha-pinene, which is hydrated in the presence of sulfuric acid.[4]
An alternative route starts from limonene:[5]
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.
References
[edit]- ^ a b c d e f Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
- ^ Merck Index, 11th Edition, 9103
- ^ Shan-Shan Yao; Wen-Fei Guo; Yi Lu; Yuan-Xun Jiang (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.
- ^ 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.
- ^ 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.
- ^ 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.
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External links
[edit]- MSDS for alpha-terpineol
- Media related to Terpineols at Wikimedia Commons