Linalool

Linalool (IPA: /lɪˈnæloʊɒl/) is a naturally-occurring terpene alcohol chemical found in many flowers and spice plants with many commercial applications, the majority of which are based on its pleasant scent (floral, with a touch of spiciness). It has other names such as β-linalool, linalyl alcohol, linaloyl oxide, p-linalool, allo-ocimenol and 2,6-dimethyl-2,7-octadien-6-ol.

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In nature

Over 200 species of plants produce linalool, mainly from the families Lamiaceae (mints, scented herbs), Lauraceae (laurels, cinnamon, rosewood) and Rutaceae (citrus fruits), but also birch trees and other plants, from tropical to boreal climate zones. It was also found in some fungi.

Enantiomers

Linalool has a chiral center at C₃ and therefore two stereoisomers: licareol is (S)-(+)-linalool with CAS No. 126–90–9 (PubChem 67179) and coriandrol is (R)-(–)-linalool with CAS No. 126–91–0 (PubChem 13562).

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. family Apiaceae) seed, palmarosa [Cymbopogon martinii var martinii (Roxb.) Wats., family Poaceae], and sweet orange (Citrus sinensis Osbeck, family Rutaceae) flowers. R-linalool is present in lavender (Lavandula officinalis Chaix, family Lamiaceae), laurel (Laurus nobilis, family Lauraceae), and sweet basil (Ocimum basilicum, family Lamiaceae), among others.

Each enantiomer evokes different neural responses in humans, and therefore are anthropophilically classified as possessing distinct scents. 3S-(+)-linalool is perceived as sweet, floral, petitgrain-like (odour threshold 7.4 ppb) and the 3R-form as more woody and lavender-like (odour threshold 0.8 ppb)

Biosynthesis

In higher plants linalool as other monoterpenoids is produced from isopentenyl pyrophosphate via the universal isoprenoid intermediate geranyl pyrophosphate, through a class of membrane-bound enzymes named monoterpene synthases. One of these, linalool synthase (LIS), has been reported to produce (S)-linalool in several floral tissues.

Uses

In addition to its use as a scent in domestic products such as soap, detergent, shampoo, and lotion, linalool is also used as a chemical intermediate. One common downstream product of linalool is Vitamin E.

Safety information

Linalool should be avoided by people with perfume allergy^[1].

References

Notes

1. ^ Survey and health assessment of chemical substances in massage oils

General references

• Casabianca H, Graff JB, Faugier V, Fleig F, Grenier C (1997) Enantiomeric distribution studies of linalool and linalyl acetate. A powerful tool for authenticity control of essential oils. HRC J High Res Chrom 21:107-112

• Lewinshon E, Schalechet F, Wilkinson J, Matsui K, Tadmor Y, Nam K, Amar O, Lastochkin E, Larkov O, Ravid U, Hiatt W, Gepstein S, Pichersky E (2001) Enhanced levels of the aroma and flavor compound S-linalool by metabolic engineering of the terpenoid pathway in tomato fruits. Plant Physiol 127:1256–1265

• Raguso RA, Pichersky E (1999) A day in the life of a linalool molecule: chemical communication in a plant-pollinator system. Part 1: linalool biosynthesis in flowering plants. Plant Species Biol 14:95-120