Terpineol

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title: "Terpineol" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["flavors", "monoterpenes", "alkenols", "cyclohexenes"] topic_path: "general/flavors" source: "https://en.wikipedia.org/wiki/Terpineol" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

| Verifiedfields = changed | Watchedfields = changed | verifiedrevid = 470602595 | Name = alpha-terpineol | ImageFileL1 = Terpineol alpha.svg | ImageNameL1 = Skeletal formula | ImageFileR1 = Alpha-terpineol-3D-balls.png | ImageNameR1 = Ball-and-stick model | ImageName = alpha-Terpineol | IUPACNames = p-Menth-1-en-8-ol 2-(4-Methylcyclohex-3-en-1-yl)propan-2-ol | OtherNames = 2-(4-Methyl-1-cyclohex-3-enyl)propan-2-ol alpha-terpineol α-terpineol α,α,4-Trimethylcyclohex-3-ene-1-methanol Terpene alcohol | Section1 = {{Chembox Identifiers | index_label = α | index1_label = β | index2_label = γ | index3_label = 4- | CASNo_Ref = | CASNo = 98-55-5 | CASNo1 = 138-87-4 | CASNo2 = 586-81-2 | CASNo3 = 562-74-3 | ChEBI_Ref = | ChEBI = 22469 | ChEBI1 = 132899 | ChEBI2 = 81151 | ChEBI3 = 78884 | Beilstein = 2325137 | ChemSpiderID_Ref = | ChemSpiderID = 13850142 | ChemSpiderID1 = 8418 | ChemSpiderID2 = 10983 | ChemSpiderID3 = 10756 | ChEMBL_Ref = | ChEMBL = 507795 | ChEMBL3 = 507795 | DTXSID3 = DTXSID4044824 | EC_number = 202-680-6 | EC_number1 =205-342-6 | EC_number2 = 209-584-3 | EC_number3 = 209-235-5 | KEGG1 = C17517 | KEGG3 = C17073 | PubChem = 17100 | PubChem1 = 8748 | PubChem2 = 11467 | PubChem3 = 11230 | UNII_Ref = | UNII = 21334LVV8W | UNII2 = 5PH9U7XEWS | InChI = 1/C10H18O/c1-8-4-6-9(7-5-8)10(2,3)11/h4,9,11H,5-7H2,1-3H3 | InChIKey = WUOACPNHFRMFPN-UHFFFAOYAL | StdInChI_Ref = | StdInChI = 1S/C10H18O/c1-8-4-6-9(7-5-8)10(2,3)11/h4,9,11H,5-7H2,1-3H3 | StdInChIKey_Ref = | StdInChIKey = WUOACPNHFRMFPN-UHFFFAOYSA-N | SMILES = C\C1=C\CC(CC1)C(O)(C)C | Section2 = {{Chembox Properties | C=10 | H=18 | O=1 | Density = 0.93g/cm3 | MeltingPtC = -35.9 to -28.2 | MeltingPt_notes = (mixture of isomers) | MeltingPt_ref = | BoilingPtC = 214–217 | BoilingPt_notes = (mixture of isomers) | BoilingPt_ref = | Solubility = 2.42g/L | Appearance = Colorless liquid |Odor = Pleasant, lilac-like | MagSus = −111.9·10−6cm3/mol | Section3 = {{Chembox Hazards | ExternalSDS = External MSDS | NFPA-H = 2 | NFPA-F = 1 | NFPA-R = 0 | NFPA-S = | HPhrases = | PPhrases = | GHS_ref = | FlashPtC = 88 | FlashPt_ref =

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|left|thumb|350x350px|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:

:[[Image:Terpineolsynthesisfromlimonene.png|thumb|left|400px|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|thumb|460px|left|Biosynthetic conversion of [[geranyl pyrophosphate]] to the terpenes [[Alpha-pinene|α-pinene]] and [[Beta-pinene|β-pinene]] (right) and to α-terpineol (bottom left).]]

References

References

  1. {{GESTIS
  2. {{Merck11th
  3. (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.
  4. (June 15, 2000). "Turpentines, 16. Pine Oil".
  5. (2006). "A Practical Synthesis of ''d''-α-Terpineol via Markovnikov Addition of ''d''-Limonene Using Trifluoroacetic Acid". Organic Process Research & Development.
  6. (2000). "Biosynthesis". Topics in Current Chemistry.

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flavorsmonoterpenesalkenolscyclohexenes