|Preferred IUPAC name
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||154.253 g·mol−1|
|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)|
|NFPA 704 (fire diamond)|
|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).
|what is ?)(|
Linalool (/ -, - , - /,) refers to two enantiomers of a naturally occurring terpene alcohol found in many flowers and spice plants. These have multiple commercial applications, the majority of which are based on its pleasant scent (floral, with a touch of spiciness).
The word linalool is based on linaloe (a type of wood) and the suffix -ol. It has other names such as β-linalool, linalyl alcohol, linaloyl oxide, allo-ocimenol, and 3,7-dimethyl-1,6-octadien-3-ol.
Over 200 species of plants produce linalool, mainly 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, including fungi.
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 different neural responses in humans, so are 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).
In higher plants, linalool, is an acyclic monoterpenoid. Like the majority of monoterpenes, it starts at the condensation of dimethylallyl diphosphate (DMAPP) and isopentenyl diphosphate (IPP) to form 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.
In addition, linalool is used by pest professionals as a flea, fruit fly, and cockroach insecticide. It can also be used as a method of pest control for codling moths. Linalool creates a synergistic effect with the codling moth's pheromone called codlemone, which increases attraction of males.
Linalool is used in some mosquito-repellent products; however, the EPA notes that "a preliminary screen of labels for products containing [l]inalool (as the sole active ingredient) indicates that efficacy data on file with the Agency may not support certain claims to repel mosquitos."
Plants that contain linalool
- Cinnamomum tamala
- Artemisia vulgaris (mugwort)
- Humulus lupulus
Safety and potential toxicity
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.
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