Linalool () refers to two

enantiomers In chemistry, an enantiomer ( /ɪˈnænti.əmər, ɛ-, -oʊ-/ ''ih-NAN-tee-ə-mər''; from Ancient Greek ἐνάντιος ''(enántios)'' 'opposite', and μέρος ''(méros)'' 'part') – also called optical isomer, antipode, or optical anti ...

of a naturally occurring

terpene Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n > 1. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. Terpenes ar ...

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...

found in many

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s and

spice A spice is a seed, fruit, root, bark, or other plant substance primarily used for flavoring or coloring food. Spices are distinguished from herbs, which are the leaves, flowers, or stems of plants used for flavoring or as a garnish. Spices a ...

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 In biochemistry, a metabolite is an intermediate or end product of metabolism. The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...

, a volatile oil component, an antimicrobial agent, and an aroma compound. Linalool has uses in manufacturing of soaps, fragrances,

food additive Food additives are substances added to food to preserve flavor or enhance taste, appearance, or other sensory qualities. Some additives have been used for centuries as part of an effort to preserve food, for example vinegar (pickling), salt (salt ...

s as flavors, household products, and

insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to b ...

Ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ar ...

s of linalool are referred to as linalyl, e.g. linalyl pyrophosphate, an isomer of

geranyl pyrophosphate Geranyl pyrophosphate (GPP), also known as geranyl diphosphate (GDP), is the pyrophosphate ester of the terpenoid geraniol. Its salts are colorless. It is a precursor to many natural products. Occurrence GPP is an intermediate in the isoprenoid ...

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

Occurrence

Linalool Enantiomers Structural Formulae

Both

enantiomer In chemistry, an enantiomer ( /ɪˈnænti.əmər, ɛ-, -oʊ-/ ''ih-NAN-tee-ə-mər''; from Ancient Greek ἐνάντιος ''(enántios)'' 'opposite', and μέρος ''(méros)'' 'part') – also called optical isomer, antipode, or optical ant ...

ic forms are found in nature: (''S'')-linalool is found, for example, as a major constituent of the essential oils of

coriander Coriander (;

('' Coriandrum sativum'' L.),

cymbopogon ''Cymbopogon'', also known as lemongrass, barbed wire grass, silky heads, Cochin grass, Malabar grass, oily heads, citronella grass or fever grass, is a genus of Asian, African, Australian, and tropical island plants in the grass family. Some ...

(''

Cymbopogon martini ''Cymbopogon martinii'' is a species of grass in the genus '' Cymbopogon'' (lemongrasses) native to India and Indochina, but widely cultivated in many places for its aromatic oil. It is best known by the common name palmarosa (''palm rose'') as i ...

'' var. ''martinii''), and sweet orange ('' Citrus sinensis'') flowers. (''R'')-linalool is present in lavender (''

Lavandula officinalis ''Lavandula angustifolia'', formerly ''L. officinalis'', is a flowering plant in the family Lamiaceae, native to the Mediterranean (Spain, France, Italy, Croatia etc.). Its common names include lavender, true lavender and English lavender (thoug ...

''), 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 Petitgrain () is an essential oil that is extracted from the leaves and green twigs of the bitter orange tree (''Citrus aurantium'' ssp. ''amara'') via steam distillation. It is also known as petitgrain bigarade. Etymology Petitgrain (Fr.: “ ...

-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 The Lamiaceae ( ) or Labiatae are a family of flowering plants commonly known as the mint, deadnettle or sage family. Many of the plants are aromatic in all parts and include widely used culinary herbs like basil, mint, rosemary, sage, savory ...

(

mint MiNT is Now TOS (MiNT) is a free software alternative operating system kernel for the Atari ST system and its successors. It is a multi-tasking alternative to TOS and MagiC. Together with the free system components fVDI device drivers, XaAES g ...

and other herbs),

Lauraceae Lauraceae, or the laurels, is a plant family that includes the true laurel and its closest relatives. This family comprises about 2850 known species in about 45 genera worldwide (Christenhusz & Byng 2016 ). They are dicotyledons, and occur ma ...

( laurels,

cinnamon Cinnamon is a spice obtained from the inner bark of several tree species from the genus ''Cinnamomum''. Cinnamon is used mainly as an aromatic condiment and flavouring additive in a wide variety of cuisines, sweet and savoury dishes, breakfa ...

, rosewood), and Rutaceae ( citrus fruits), but also

birch trees A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech-oak family Fagaceae. The genus ''Betula'' contains 3 ...

and other plants, from

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

boreal climate The subarctic climate (also called subpolar climate, or boreal climate) is a climate with long, cold (often very cold) winters, and short, warm to cool summers. It is found on large landmasses, often away from the moderating effects of an ocean, ge ...

zones. * '' Lavandula'' * ''

Cinnamomum tamala ''Cinnamomum tamala'', Indian bay leaf'','' also known as tejpat'', ''tejapatta'','' Malabar leaf, Indian bark, Indian cassia, or malabathrum, is a tree in the family Lauraceae that is native to India, Bangladesh, Nepal, Bhutan, and China. It c ...

'' * '' Cannabis sativa'' * '' Basil'' * '' Solidago'' * ''

Artemisia vulgaris ''Artemisia vulgaris'', the common mugwort, is a species of flowering plant in the daisy family Asteraceae. It is one of several species in the genus ''Artemisia'' commonly known as mugwort, although ''Artemisia vulgaris'' is the species most ...

'' (mugwort) * '' Humulus lupulus'' It was first synthesized in the laboratory of Leopold Ružička in 1919.Albert Eschenmoser: "Leopold Ruzicka - From the Isoprene Rule to the Question of Life's Origin" CHIMIA 44 (1990)

Biosynthesis

higher plants Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They al ...

linalool is formed by rearrangement of

(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 here the majorityof the residues involved in substrate...binding rein the C-terminal part of the protein" suggesting stereoselectivity and the reasoning behind why some plants have varying levels of each enantiomer. Linalool_Biosynthesis

Odor and flavor

Linalool has complex

odor An odor (American English) or odour (English in the Commonwealth of Nations, Commonwealth English; American and British English spelling differences#-our, -or, see spelling differences) is caused by one or more volatilized chemical compounds ...

and flavor properties. Its odor is similar to floral, spicy wood, somewhat resembling

French lavender French lavender may refer to at least two species of plants in the genus ''Lavandula'': *''Lavandula dentata ''Lavandula dentata'', ''Lavanda de la brecha (Spain)'', fringed lavender or French lavender, is a species of flowering plant in the ...

plants,

bergamot oil Bergamot essential oil is a cold-pressed essential oil produced by cells inside the rind of a bergamot orange fruit. It is a common flavoring and top note in perfumes. The scent of bergamot essential oil is similar to a sweet light orange peel oi ...

lily of the valley Lily of the valley (''Convallaria majalis'' (), sometimes written lily-of-the-valley, is a woodland flowering plant with sweetly scented, pendent, bell-shaped white flowers borne in sprays in spring. It is native throughout the cool temperate No ...

. It has a light, citrus-like flavor, sweet with a spicy tropical accent. Linalool is used as a scent in 60% to 80% of

perfume Perfume (, ; french: parfum) is a mixture of fragrant essential oils or aroma compounds (fragrances), fixatives and solvents, usually in liquid form, used to give the human body, animals, food, objects, and living-spaces an agreeable scent. Th ...

d hygiene products and cleaning agents, including

soap Soap is a salt of a fatty acid used in a variety of cleansing and lubricating products. In a domestic setting, soaps are surfactants usually used for washing, bathing, and other types of housekeeping. In industrial settings, soaps are use ...

detergent A detergent is a surfactant or a mixture of surfactants with cleansing properties when in dilute solutions. There are a large variety of detergents, a common family being the alkylbenzene sulfonates, which are soap-like compounds that are more ...

shampoo Shampoo () is a hair care product, typically in the form of a viscous liquid, that is used for cleaning hair. Less commonly, shampoo is available in solid bar format. Shampoo is used by applying it to wet hair, massaging the product into the ...

s, 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 Linalyl acetate, an organic compound, is the acetate ester of linalool. phytochemical found in many flowers and spice plants. It is one of the principal components of the essential oils of bergamot and lavender. It often occurs together with ...

, a popular scent, is produced by esterification of linalool (as well as occurring naturally). Isomerization of linalool gives

geraniol Geraniol is a monoterpenoid and an alcohol. It is the primary component of citronella oil and is a primary component of rose oil, palmarosa oil. It is a colorless oil, although commercial samples can appear yellow. It has low solubility in water ...

and nerol.

Safety and potential toxicity

Linalool can be absorbed by inhalation of its

aerosol An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be natural or Human impact on the environment, anthropogenic. Examples of natural aerosols are fog o ...

and by oral intake or skin absorption, potentially causing irritation, pain and

allergic Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derma ...

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.

References

External links

Comprehensive data sheet
* {{Transient receptor potential channel modulators Flavors Tertiary alcohols Plant toxin insecticides Alkene derivatives Monoterpenes Perfume ingredients