Borneol is a

bicyclic In chemistry, a bicyclic molecule () is a molecule that features two joined rings. Bicyclic structures occur widely, for example in many biologically important molecules like α-thujene and camphor. A bicyclic compound can be carbocyclic (all ...

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

and a

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 ...

derivative. The

hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydrox ...

group in this compound is placed in an '' endo'' position. The exo diastereomer is called isoborneol. Being chiral, borneol exists as

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 anti ...

s, both of which are found in nature.

Reactions

Borneol is

oxidized Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...

to the

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double b ...

(

camphor Camphor () is a waxy, colorless solid with a strong aroma. It is classified as a terpenoid and a cyclic ketone. It is found in the wood of the camphor laurel (''Cinnamomum camphora''), a large evergreen tree found in East Asia; and in the k ...

Occurrence

The compound was named in 1842 by the French chemist

Charles Frédéric Gerhardt Charles Frédéric Gerhardt (21 August 1816 – 19 August 1856) was a French chemist, born in Alsace and active in Paris, Montpellier, and his native Strasbourg. Biography He was born in Strasbourg, which is where he attended the gymnasium (an a ...

. Borneol can be found in several species of ''

Heterotheca ''Heterotheca'', (common names goldenasters, camphorweed, or telegraph weed) are North American plants in the family Asteraceae. Etymology ''Heterotheca'' comes from Ancient Greek "other, different" and "case, chest", and refers to the fact ...

'', '' Artemisia'', ''Rosmarinus officinalis'' (

rosemary ''Salvia rosmarinus'' (), commonly known as rosemary, is a shrub with fragrant, evergreen, needle-like leaves and white, pink, purple, or blue flowers, native plant, native to the Mediterranean Region, Mediterranean region. Until 2017, it was kn ...

) ''

Dipterocarpaceae Dipterocarpaceae is a family of 16 genera and about 695 known species of mainly tropical lowland rainforest trees. The family name, from the type genus ''Dipterocarpus'', is derived from Greek (''di'' = two, ''pteron'' = wing and ''karpos'' = fru ...

'', ''

Blumea balsamifera ''Blumea balsamifera'' is a flowering plant belonging to the genus ''Blumea'' of the family Asteraceae. It is also known as Ngai camphor and sambong (also sembung). Description In the Philippines, where it is most commonly known as sambong, ''B ...

'' and ''

Kaempferia galanga ''Kaempferia galanga'', commonly known as kencur, aromatic ginger, sand ginger, cutcherry, is a monocotyledonous plant in the ginger family, and one of four plants called galangal. It is found primarily in open areas in Indonesia, southern C ...

''. It is one of the chemical compounds found in

castoreum Castoreum is a yellowish exudate from the castor sacs of mature beavers. Beavers use castoreum in combination with urine to scent mark their territory. Both beaver sexes have a pair of castor sacs and a pair of anal glands, located in two cavities ...

. This compound is gathered from the beaver's plant food.

Synthesis

Borneol can be synthesized by reduction of

by the

Meerwein–Ponndorf–Verley reduction The Meerwein–Ponndorf–Verley (MPV) reduction in organic chemistry is the reduction of ketones and aldehydes to their corresponding alcohols utilizing aluminium alkoxide catalysis in the presence of a sacrificial alcohol. The advantages of th ...

(a reversible process). Reduction of camphor with

sodium borohydride Sodium borohydride, also known as sodium tetrahydridoborate and sodium tetrahydroborate, is an inorganic compound with the formula Na BH4. This white solid, usually encountered as an aqueous basic solution, is a reducing agent that finds applica ...

(fast and irreversible) gives instead the

diastereomer In stereochemistry, diastereomers (sometimes called diastereoisomers) are a type of stereoisomer. Diastereomers are defined as non-mirror image, non-identical stereoisomers. Hence, they occur when two or more stereoisomers of a compound have di ...

isoborneol. :

Uses

Whereas ''d''-borneol was the

that used to be the most readily available commercially, the more commercially available enantiomer now is ''l''-borneol, which also occurs in nature. Borneol from ''

Dipterocarpus '' D. retusus'' in Köhler ''Dipterocarpus'' is a genus of flowering plants and the type genus of family Dipterocarpaceae. ''Dipterocarpus'' is the third-largest and most diverse genus among the Dipterocarpaceae. The species are well known for ...

'' spp. is used in

traditional Chinese medicine Traditional Chinese medicine (TCM) is an alternative medical practice drawn from traditional medicine in China. It has been described as "fraught with pseudoscience", with the majority of its treatments having no logical mechanism of acti ...

. An early description is found in the

Bencao Gangmu The ''Bencao gangmu'', known in English as the ''Compendium of Materia Medica'' or ''Great Pharmacopoeia'', is an encyclopedic gathering of medicine, natural history, and Chinese herbology compiled and edited by Li Shizhen and published in the ...

. Borneol is a component of many

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 and it is a natural

insect repellent An insect repellent (also commonly called "bug spray") is a substance applied to skin, clothing, or other surfaces to discourage insects (and arthropods in general) from landing or climbing on that surface. Insect repellents help prevent and cont ...

. It also generates a

TRPM8 Transient receptor potential cation channel subfamily M (melastatin) member 8 (TRPM8), also known as the cold and menthol receptor 1 (CMR1), is a protein that in humans is encoded by the ''TRPM8'' gene. The TRPM8 channel is the primary molecular ...

-mediated cooling sensation similar to

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 ...

. Laevo-borneol is used in perfumery. It has a balsamic odour type with pine, woody and camphoraceous facets.

Toxicology

Borneol may cause eye, skin, and respiratory irritation; it is harmful if swallowed. Acute exposure may cause headache, nausea, vomiting, dizziness, lightheadedness, and syncope. Exposure to higher levels or over a longer period of time may cause restlessness, difficulty concentrating, irritability, and seizures.HAZARDOUS SUBSTANCE FACT SHEET
/ref>

Skin Irritation

Borneol has been shown to have little to no irritation effect when applied to the human skin at doses used in fine fragrance formulation. Skin exposure can lead to sensitization and a future

allergic reaction 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 derm ...

even to small quantities.

Derivatives

The bornyl group is a univalent radical C₁₀H₁₇ derived from borneol by removal of hydroxyl and is also known as 2-bornyl. Isobornyl is the univalent radical C₁₀H₁₇ that is derived from isoborneol. The

structural isomer In chemistry, a structural isomer (or constitutional isomer in the IUPAC nomenclature) of a compound is another compound whose molecule has the same number of atoms of each element, but with logically distinct bonds between them. The term meta ...

fenchol Fenchol or 1,3,3-trimethyl-2-norbornanol is a monoterpenoid and an isomer of borneol. It is a colorless or white solid. It occurs widely in nature. The naturally occurring enantiomere (1''R'')-endo-(+)-fenchol is used extensively in perfumery. ...

is also a widely used compound derived from certain

Bornyl acetate Bornyl acetate is a chemical compound. Its molecular formula is C12H20O2 and its molecular weight is 196.29 g/mol. It is the acetate ester of borneol. It is used as a food additive, flavouring agent, and odour agent. It is a component of the es ...

is the

acetate An acetate is a salt formed by the combination of acetic acid with a base (e.g. alkaline, earthy, metallic, nonmetallic or radical base). "Acetate" also describes the conjugate base or ion (specifically, the negatively charged ion called ...

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 ...

of borneol.

Notes and references

External links

NIST datasheet including full spectroscopic data

{{GABAAR PAMs Secondary alcohols Monoterpenes GABAA receptor positive allosteric modulators Bicyclic compounds Cyclopentanes