Myrcene, or β-myrcene, is a

monoterpene Monoterpenes are a class of terpenes that consist of two isoprene units and have the molecular formula C10H16. Monoterpenes may be linear (acyclic) or contain rings (monocyclic and bicyclic). Modified terpenes, such as those containing oxygen funct ...

. A colorless oil, it occurs widely in

essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the o ...

s. It is produced mainly semi-synthetically from ''

Myrcia ''Myrcia'' is a genus of plants in the family Myrtaceae, containing about 765 species as of 2022. They are distributed in Central and South America, Mexico, and the Caribbean, with centers of diversity in the Brazilian Cerrado and Atlantic Forest ...

'', from which it gets its name. It is an intermediate in the production of several fragrances. α-Myrcene is the name for the

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

2-methyl-6-methylene-1,7-octadiene, which has not been found in nature.

Production

Myrcene is often produced commercially by the

pyrolysis The pyrolysis (or devolatilization) process is the thermal decomposition of materials at elevated temperatures, often in an inert atmosphere. It involves a change of chemical composition. The word is coined from the Greek-derived elements ''py ...

(400 °C) of β-

pinene Pinene is a collection of unsaturated bicyclic monoterpenes. Two geometric isomers of pinene are found in nature, α-pinene and β-pinene. Both are chiral. As the name suggests, pinenes are found in pines. Specifically, pinene is the major compo ...

, which is obtained from

turpentine Turpentine (which is also called spirit of turpentine, oil of turpentine, terebenthene, terebinthine and (colloquially) turps) is a fluid obtained by the distillation of resin harvested from living trees, mainly pines. Mainly used as a special ...

. It is rarely obtained directly from plants. Plants biosynthesize myrcene via geranyl pyrophosphate (GPP), which isomerizes into linalyl pyrophosphate. The release of the

pyrophosphate In chemistry, pyrophosphates are phosphorus oxyanions that contain two phosphorus atoms in a P–O–P linkage. A number of pyrophosphate salts exist, such as disodium pyrophosphate (Na2H2P2O7) and tetrasodium pyrophosphate (Na4P2O7), among other ...

(OPP) and a proton completes the conversion.

Occurrence

It could in principle be extracted from any number of plants, such as

verbena ''Verbena'' (), also known as vervain or verveine, is a genus in the family Verbenaceae. It contains about 150 species of annual and perennial herbaceous or semi-woody flowering plants. The majority of the species are native to the Americas a ...

wild thyme ''Thymus serpyllum'', known by the common names of Breckland thyme, Breckland wild thyme, wild thyme, creeping thyme, or elfin thyme, is a species of flowering plant in the mint family Lamiaceae, native to most of Europe and North Africa. It is ...

, the leaves of which contain up to 40% by weight of myrcene. Many other plants contain myrcene, sometimes in substantial amounts. Some of these include cannabis, hops, ''

Houttuynia ''Houttuynia'' is a genus of two species in the Saururaceae native to Southeast Asia. One species, '' H. cordata'', is widely cultivated as a culinary herb. The genus was originally described in 1783 by Carl Peter Thunberg when he formally d ...

'',

lemon grass ''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 s ...

mango A mango is an edible stone fruit produced by the tropical tree ''Mangifera indica''. It is believed to have originated in the region between northwestern Myanmar, Bangladesh, and northeastern India. ''M. indica'' has been cultivated in South a ...

, ''Myrcia'', West Indian bay tree, and

cardamom Cardamom (), sometimes cardamon or cardamum, is a spice made from the seeds of several plants in the genera ''Elettaria'' and ''Amomum'' in the family Zingiberaceae. Both genera are native to the Indian subcontinent and Indonesia. They are rec ...

. Of the several terpenes extracted from ''

Humulus lupulus ''Humulus lupulus'', the common hop or hops, is a species of flowering plant in the hemp family Cannabinaceae, native to Europe, western Asia and North America. It is a perennial, herbaceous climbing plant which sends up new shoots in early spr ...

'' (hops), the largest monoterpenes fraction is β-myrcene. One study of the chemical composition of the fragrance of ''

Cannabis sativa ''Cannabis sativa'' is an annual Herbaceous plant, herbaceous flowering plant indigenous to East Asia, Eastern Asia, but now of cosmopolitan distribution due to widespread cultivation. It has been cultivated throughout recorded history, used as ...

'' found β-myrcene to compose between 29.4% and 65.8% of the steam-distilled essential oil for the set of fiber and drug strains tested. Additionally, myrcene is thought to be the predominant terpene found in modern cannabis cultivars within North America. Interestingly, photo-oxidation of myrcene has been shown to rearrange the molecule into a novel terpene known as "hashishene" which is named for its abundance in hashish. It is found in the South African ''

Adenandra villosa ''Adenandra'' is a genus of evergreen shrubs of the family Rutaceae, commonly known as buchu (plural buchus). The genus is native to South Africa. The plants are related to the citrus family, and have oil glands in the leaves which give off a dis ...

'' (50%). & Brazilian ''

Schinus molle ''Schinus molle'' (Peruvian pepper, also known as American pepper, Peruvian peppertree, escobilla, false pepper, rosé pepper, molle del Peru, pepper tree, (Archived bWebCite peppercorn tree, California pepper tree, pirul (in Mexican Spanish s ...

'' (40%) Myrcene is also found in '' Myrcia cuprea''

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.: “ ...

(up to 48%),

bay leaf The bay leaf is an aromatic leaf commonly used in cooking. It can be used whole, either dried or fresh, in which case it is removed from the dish before consumption, or less commonly used in ground form. It may come from several species of tr ...

juniper berry A juniper berry is the female seed cone produced by the various species of junipers. It is not a true berry, but a cone with unusually fleshy and merged scales, which gives it a berry-like appearance. The cones from a handful of species, especial ...

cannabis ''Cannabis'' () is a genus of flowering plants in the family Cannabaceae. The number of species within the genus is disputed. Three species may be recognized: ''Cannabis sativa'', '' C. indica'', and '' C. ruderalis''. Alternatively ...

, and

hops Hops are the flowers (also called seed cones or strobiles) of the hop plant ''Humulus lupulus'', a member of the Cannabaceae family of flowering plants. They are used primarily as a bittering, flavouring, and stability agent in beer, to whi ...

Use in fragrance and flavor industries

Myrcene is an intermediate used in the

perfumery 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 ...

industry. It has a pleasant odor but is rarely used directly. It is also unstable in air, tending to

polymer A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

ize. Samples are stabilized by the addition of alkylphenols or

tocopherol Tocopherols (; TCP) are a class of organic chemical compounds (more precisely, various methylated phenols), many of which have vitamin E activity. Because the vitamin activity was first identified in 1936 from a dietary fertility factor in rats, i ...

. It is thus more highly valued as an intermediate for the preparation of flavor and fragrance chemicals, such as

menthol Menthol is an organic compound, more specifically a monoterpenoid, made synthetically or obtained from the oils of corn mint, peppermint, or other mints. It is a waxy, clear or white crystalline substance, which is solid at room temperature and ...

citral Citral is an acyclic monoterpene aldehyde, and being a monoterpene, it is made of two isoprene units. Citral is a collective term which covers two geometric isomers that have their own separate names; the ''E''-isomer is named geranial (''trans ...

citronellol Citronellol, or dihydrogeraniol, is a natural acyclic monoterpenoid. Both enantiomers occur in nature. (+)-Citronellol, which is found in citronella oils, including ''Cymbopogon nardus'' (50%), is the more common isomer. (−)-Citronellol is w ...

citronellal Citronellal or rhodinal ( C10 H18 O) is a monoterpenoid aldehyde, the main component in the mixture of terpenoid chemical compounds that give citronella oil its distinctive lemon scent. Citronellal is a main isolate in distilled oils from the pl ...

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 ...

nerol Nerol is a monoterpenoid alcohol found in many essential oils such as lemongrass and hops. It was originally isolated from neroli oil, hence its name. This colourless liquid is used in perfumery. Like geraniol, nerol has a sweet rose odor but it i ...

, and

linalool Linalool () 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 ...

. Myrcene is converted to

myrcenol Myrcenol is an organic compound, specifically a terpenoid. It is most notable as one of the fragrant components of lavender oil. It is also found in the hop plant (''Humulus lupulus''). E-Myrcenol acts also as a pheromone for bark beetles. Role ...

, another fragrance found in

lavender ''Lavandula'' (common name lavender) is a genus of 47 known species of flowering plants in the mint family, Lamiaceae. It is native to the Old World and is found in Cape Verde and the Canary Islands, and from Europe across to northern and easte ...

, via

hydroamination In organic chemistry, hydroamination is the addition of an bond of an amine across a carbon-carbon multiple bond of an alkene, alkyne, diene, or allene. In the ideal case, hydroamination is atom economical and green. Amines are common in fine-c ...

of the 1,3-diene by diethylamine followed by hydrolysis and

palladium Palladium is a chemical element with the symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by the English chemist William Hyde Wollaston. He named it after the asteroid Pallas, which was itself na ...

-catalyzed removal of the

amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituen ...

. Both myrcene and myrcenol undergo Diels-Alder reactions with several dienophiles such as

acrolein Acrolein (systematic name: propenal) is the simplest unsaturated aldehyde. It is a colorless liquid with a piercing, acrid smell. The smell of burnt fat (as when cooking oil is heated to its smoke point) is caused by glycerol in the burning fa ...

to give

cyclohexene Cyclohexene is a hydrocarbon with the formula C6H10. This cycloalkene is a colorless liquid with a sharp smell. It is an intermediate in various industrial processes. Cyclohexene is not very stable upon long term storage with exposure to light an ...

derivatives that are also useful fragrances, for instance

Lyral Hydroxymethylpentylcyclohexenecarboxaldehyde is a synthetic fragrance known by the trade names Lyral, Kovanol, Mugonal, Landolal. It is found in some soaps, eau de toilettes, aftershaves and deodorant A deodorant is a substance applied to the ...

. Myrcene also contributes a peppery and balsam aroma in beer. As of October 2018, the

U.S. FDA The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food s ...

withdrew authorization for the use of myrcene as a synthetic flavoring substance for use in food, without regard to its continuing stance that this substance does not pose a risk to public health under the conditions of its intended use.

Health and safety

In 2015, beta-myrcene was added to California's Prop 65 list of chemicals known to the state of California to cause cancer or reproductive harm.

References

{{reflist Flavors Polyenes Perfume ingredients Monoterpenes

Production

Occurrence

Use in fragrance and flavor industries

Health and safety

See also

References