Linalool
Linalool refers to two enantiomers of a naturally occurring terpene alcohol found in many flowers and spice plants. Together with geraniol, nerol, and citronellol, linalool is one of the rose alcohols. Linalool has multiple commercial applications, the majority of which are based on its pleasant scent.
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 and the suffix . In food manufacturing, it may be called coriandrol.
Occurrence
Both enantiomeric forms are found in nature: -linalool is found, for example, as a major constituent of the essential oils of coriander, cymbopogon, and sweet orange flowers. -linalool is present in lavender, bay laurel, and sweet basil, among others.Each enantiomer evokes distinct neural responses in humans, so each is classified as possessing distinct scents. --Linalool is perceived as sweet, floral, petitgrain-like and the -form as more woody and lavender-like.
Over 200 species of plants produce linalool, notably from the families Lamiaceae, Lauraceae, and Rutaceae, but also birch trees and other plants, from tropical to boreal climate zones.
- Aniba rosaeodora
- Lavandula
- Cinnamomum tamala
- Cannabis sativa
- Basil
- Solidago
- Artemisia vulgaris
- Humulus lupulus
Production
Linalool is produced commercially from several terpenes and terpenoid precursors, which are often components of terpentine. 2-Pinanol, derived from pinene, gives linalool upon pyrolysis.Biosynthesis
In higher plants linalool is formed by rearrangement of geranyl pyrophosphate. With the aid of linalool synthase, water attacks to form the chiral center. LIS appears to show a limonene synthase-type catalysis through a simplified "metal-cofactor-binding domain of the residues involved in substrate...binding in the C-terminal part of the protein" suggesting stereoselectivity and the reasoning behind why some plants have varying levels of each enantiomer.File:Linalool_Biosynthesis.png|alt=|center|thumb|Linalool biosynthesis pathway. Abbreviations used: geranyl diphosphate synthase, pyrophosphate ester, isopentenyl pyrophosphate, dimethylallyl pyrophosphate, geranyl pyrophosphate. Stereogenic centers are indicated by an asterisk.|654x654px
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. 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 lists linalool in the Code of Federal Regulations under substances generally recognized as safe, synthetic flavoring substances and adjuvants.