Linalool

Linalool
Skeletal formula
Ball-and-stick model
Names
Preferred IUPAC name
3,7-Dimethylocta-1,6-dien-3-ol
Other names
3,7-Dimethyl-1,6-octadien-3-ol, β-linalool, linalyl alcohol, linaloyl oxide, allo-ocimenol, coriandrol, Licareol
Identifiers
  • Compounds
  • (±)-linalool
  • (R): (−)-linalool
  • (S): (+)-linalool
3D model (JSmol)
3DMet
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.001.032 Edit this at Wikidata
KEGG
UNII
  • InChI=1S/C10H18O/c1-5-10(4,11)8-6-7-9(2)3/h5,7,11H,1,6,8H2,2-4H3 checkY
    Key: CDOSHBSSFJOMGT-UHFFFAOYSA-N checkY
  • InChI=1/C10H18O/c1-5-10(4,11)8-6-7-9(2)3/h5,7,11H,1,6,8H2,2-4H3
    Key: CDOSHBSSFJOMGT-UHFFFAOYAV
  • CC(O)(C=C)CCC=C(C)C
Properties
C10H18O
Molar mass 154.253 g·mol−1
Appearance Colorless oil
Density 0.858 to 0.868 g/cm3
Melting point < −20 °C (−4 °F; 253 K)
Boiling point 198 to 199 °C (388 to 390 °F; 471 to 472 K)
1.589 g/l
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
2
0
Flash point 55 °C (131 °F; 328 K)
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

Linalool (/lɪˈnæloʊɒl, laɪ-, -loʊoʊl, -ˈluːl/) refers to two enantiomers of a naturally occurring terpene alcohol found in many flowers and spice plants. Linalool has multiple commercial applications, the majority of which are based on its pleasant scent (floral, with a touch of spiciness). A colorless oil, linalool is classified as an acyclic monoterpenoid. In plants, it is a metabolite, a volatile oil component, an antimicrobial agent, and an aroma compound. Linalool has uses in manufacturing of soaps, fragrances, food additives as flavors, household products, and insecticides. Esters of linalool are referred to as linalyl, e.g. linalyl pyrophosphate, an isomer of geranyl pyrophosphate.

The word linalool is based on linaloe (a type of wood) and the suffix -ol. In food manufacturing, it may be called coriandrol.

Occurrence

(S)-(+)-linalool (left) and (R)-(–)-linalool (right)

Both enantiomeric forms are found in nature: (S)-linalool is found, for example, as a major constituent of the essential oils of coriander (Coriandrum sativum L.), cymbopogon (Cymbopogon martini var. martinii), and sweet orange (Citrus sinensis) flowers. (R)-linalool is present in lavender (Lavandula officinalis), bay laurel (Laurus nobilis), and sweet basil (Ocimum basilicum), among others.

Each enantiomer evokes distinct neural responses in humans, so each is classified as possessing distinct scents. (S)-(+)-Linalool is perceived as sweet, floral, petitgrain-like (odor threshold 7.4 ppb) and the (R)-form as more woody and lavender-like (odor threshold 0.8 ppb).

Over 200 species of plants produce linalool, notably from the families Lamiaceae (mint and other herbs), Lauraceae (laurels, cinnamon, rosewood), and Rutaceae (citrus fruits), but also birch trees and other plants, from tropical to boreal climate zones.

It was first synthesized in the laboratory of Leopold Ružička in 1919.

Biosynthesis

In higher plants linalool is formed by rearrangement of geranyl pyrophosphate (GPP). With the aid of linalool synthase (LIS), water attacks to form the chiral center. LIS appears to show a limonene synthase-type catalysis through a simplified "metal-cofactor-binding domain [where the majority] of the residues involved in substrate...binding [are] in the C-terminal part of the protein" suggesting stereoselectivity and the reasoning behind why some plants have varying levels of each enantiomer.

Linalool biosynthesis pathway. Abbreviations used: geranyl diphosphate synthase (GDS), pyrophosphate ester (OPP), isopentenyl pyrophosphate (IPP), dimethylallyl pyrophosphate (DMAPP), geranyl pyrophosphate (GPP). Stereogenic centers are indicated by an asterisk.

Odor and flavor

Linalool has complex odor and flavor properties. Its odor is similar to floral, spicy wood, somewhat resembling French lavender plants, bergamot oil or lily of the valley. It has a light, citrus-like flavor, sweet with a spicy tropical accent. Linalool is used as a scent in perfumed hygiene products and cleaning agents, including soaps, detergents, shampoos, and lotions. It exhibits antimicrobial and antifungal properties.

Chemical derivatives

Linalool is hydrogenated to give dihydro- and tetrahydrolinalool, which are fragrances that are more resilient toward oxidants, as might be found in household cleaning products. Linalyl acetate, a popular scent, is produced by esterification of linalool (as well as occurring naturally). Isomerization of linalool gives geraniol and nerol.

Safety

Linalool can be absorbed by inhalation of its aerosol and by oral intake or skin absorption, potentially causing irritation, pain and allergic reactions. Some 7% of people undergoing patch testing in Europe were found to be allergic to the oxidized form of linalool.

The US Food and Drug Administration (FDA) lists linalool in the Code of Federal Regulations under substances generally recognized as safe, synthetic flavoring substances and adjuvants.

See also


This page was last updated at 2024-02-16 14:43 UTC. Update now. View original page.

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