Camphor is a waxy,
whiteWhite is a color, the perception of which is evoked by light that stimulates all three types of color sensitive cone cells in the human eye in nearly equal amounts and with high brightness compared to the surroundings. A white visual stimulation will be void of hue and grayness.White light can be...
or transparent
solidSolid is one of the three classical states of matter . It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a...
with a strong, aromatic odor. It is a
terpenoidThe terpenoids , sometimes called isoprenoids, are a large and diverse class of naturally occurring organic chemicals similar to terpenes, derived from five-carbon isoprene units assembled and modified in thousands of ways. Most are multicyclic structures that differ from one another not only in...
with the
chemical formulaA chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
CCarbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
10HHydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
16OOxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
. It is found in wood of the
camphor laurel (
Cinnamomum camphora), a large
evergreenIn botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...
tree found in Asia (particularly in
BorneoBorneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....
and
TaiwanTaiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
) and also of
Dryobalanops aromaticaDryobalanops is a genus of flowering plants and the genus of family Dipterocarpaceae. The name Dryobalanops is derived from Greek and describes the acorn-like nut. The genus has seven species, confined to the tropical forests of West Malesia...
, a giant of the Bornean forests. It also occurs in some other related trees in the laurel family, notably
Ocotea usambarensisOcotea usambarensis is a species of Ocotea , native to eastern Africa in Kenya, Tanzania, and locally in Uganda, where it occurs at 1600-2600 m altitude in high rainfall montane cloud forest...
. Dried
rosemaryRosemary, , is a woody, perennial herb with fragrant, evergreen, needle-like leaves and white, pink, purple or blue flowers, native to the Mediterranean region. It is a member of the mint family Lamiaceae, which includes many other herbs, and is one of two species in the genus Rosmarinus...
leaves (
Rosmarinus officinalis), in the mint family, contain up to 20% camphor. It can also be synthetically produced from oil of
turpentineTurpentine is a fluid obtained by the distillation of resin obtained from trees, mainly pine trees. It is composed of terpenes, mainly the monoterpenes alpha-pinene and beta-pinene...
. It is used for its scent, as an ingredient in cooking (mainly in
IndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
), as an embalming fluid, for medicinal purposes, and in religious ceremonies. A major source of camphor in Asia is camphor basil.
Norcamphor is a camphor derivative with the three methyl groups replaced by
hydrogenHydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
.
History
The word camphor derives from the French word , itself from Medieval
LatinLatin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
, from Arabic , from
SanskritSanskrit , is a historical Indo-Aryan language and the primary liturgical language of Hinduism, Jainism and Buddhism.Buddhism: besides Pali, see Buddhist Hybrid Sanskrit Today, it is listed as one of the 22 scheduled languages of India and is an official language of the state of Uttarakhand...
,
karpuura. Barus was the port on the western coast of the
IndonesiaIndonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
n island of
SumatraSumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...
where foreign traders would call to buy camphor, hence in
MalayMalay is a major language of the Austronesian family. It is the official language of Malaysia , Indonesia , Brunei and Singapore...
it became .
Camphor was known in Arabia in pre-Islamic times, as it is mentioned in the Quran 76:5 as a flavoring for drinks. In the 9th century, the Arab chemist,
Al-Kindi' , known as "the Philosopher of the Arabs", was a Muslim Arab philosopher, mathematician, physician, and musician. Al-Kindi was the first of the Muslim peripatetic philosophers, and is unanimously hailed as the "father of Islamic or Arabic philosophy" for his synthesis, adaptation and promotion...
(known as
Alkindus in Europe), provided the earliest recipe for the production of camphor in his
Kitab Kimiya' al-'Itr (
Book of the Chemistry of Perfume). By the 13th century, it was used in recipes everywhere in the Muslim world, ranging from main dishes such as
tharidTharid is a traditional Arabic dish made of pieces of bread in vegetable or meat broth. The dish is notable in that it has been mentioned in a number hadith attributed to the Prophet Mohammed.-External links:**...
and stew to desserts.
Already in the 19th century, it was known that with nitric acid, camphor could be oxidized into
camphoric acidCamphoric acid, C10H16O4 or in Latin form Acidum camphoricum, is a white crystallisable substance obtained from the oxidation of camphor, it exists in three optically different forms; dextrorotatory one is obtained by the oxidation of dextrorotatory camphor and used in...
. Haller and Blanc published a semisynthesis of camphor from camphoric acid, which, although demonstrating its structure, would not prove it. The first complete
total synthesisIn organic chemistry, a total synthesis is, in principle, the complete chemical synthesis of complex organic molecules from simpler pieces, usually without the aid of biological processes. In practice, these simpler pieces are commercially available in bulk and semi-bulk quantities, and are often...
for camphoric acid was published by
Gustaf KomppaGustaf Komppa was a Finnish chemist best known for a world-first in commercializing total synthesis, that of camphor in 1903....
in 1903. Its starting materials were
diethyl oxalateOxalate , is the dianion with formula C2O42− also written 22−. Either name is often used for derivatives, such as disodium oxalate, 2C2O42−, or an ester of oxalic acid Oxalate (IUPAC: ethanedioate), is the dianion with formula C2O42− also written (COO)22−. Either...
and 3,3-dimethylpentanoic acid, which reacted by
Claisen condensationThe Claisen condensation is a carbon–carbon bond forming reaction that occurs between two esters or one ester and another carbonyl compound in the presence of a strong base, resulting in a β-keto ester or a β-diketone...
to give diketocamphoric acid. Methylation with methyl iodide and a complicated reduction procedure produced camphoric acid.
William PerkinSir William Henry Perkin, FRS was an English chemist best known for his discovery, at the age of 18, of the first aniline dye, mauveine.-Early years:...
published another synthesis a short time later. Previously, some organic compounds (such as
ureaUrea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
) had been synthesized in the laboratory as a
proof of conceptA proof of concept or a proof of principle is a realization of a certain method or idea to demonstrate its feasibility, or a demonstration in principle, whose purpose is to verify that some concept or theory that has the potential of being used...
, but camphor was a scarce natural product with a worldwide demand. Komppa realized this and began industrial production of camphor in Tainionkoski,
FinlandFinland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...
, in 1907.
Production
Camphor can be produced from
alpha-pineneα-Pinene is an organic compound of the terpene class, one of two isomers of pinene. It is an alkene and it contains a reactive four-membered ring. It is found in the oils of many species of many coniferous trees, notably the pine. It is also found in the essential oil of rosemary...
, which is abundant in the oils of coniferous trees and can be distilled from
turpentineTurpentine is a fluid obtained by the distillation of resin obtained from trees, mainly pine trees. It is composed of terpenes, mainly the monoterpenes alpha-pinene and beta-pinene...
produced as a side product of chemical pulping. With acetic acid as the solvent and with catalysis by a strong acid, alpha-pinene readily
rearrangesA rearrangement reaction is a broad class of organic reactions where the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. Often a substituent moves from one atom to another atom in the same molecule...
into
campheneCamphene is bicyclic monoterpene. It is nearly insoluble in water, but very soluble in common organic solvents. It volatilizes readily at room temperature and has a pungent smell. It is a minor constituent of many essential oils such as turpentine, cypress oil, camphor oil, citronella oil,...
, which in turn undergoes
Wagner-Meerwein rearrangementA Wagner–Meerwein rearrangement is a class of carbocation 1,2-rearrangement reactions in which a hydrogen, alkyl or aryl group migrates from one carbon to a neighboring carbon.Several reviews have been published....
into the isobornyl cation, which is captured by acetate to give isobornyl acetate. Hydrolysis into isoborneol followed by oxidation gives camphor.
Biosynthesis
In
biosynthesisBiosynthesis is an enzyme-catalyzed process in cells of living organisms by which substrates are converted to more complex products. The biosynthesis process often consists of several enzymatic steps in which the product of one step is used as substrate in the following step...
, camphor is produced from
geranyl pyrophosphateGeranyl pyrophosphate is an intermediate in the HMG-CoA reductase pathway used by organisms in the biosynthesis of farnesyl pyrophosphate, geranylgeranyl pyrophosphate, cholesterol, terpenes and terpenoids....
, via cyclisation of
linaloyl pyrophosphate to
bornylBorneol is a bicyclic organic compound and a terpene. The hydroxyl group in this compound is placed in an endo position.Borneol is easily oxidized to the ketone yielding camphor. One historical name for borneol is Borneo camphor which explains the name. Borneol can be synthesized by reduction of...
pyrophosphate, followed by hydrolysis to
borneolBorneol is a bicyclic organic compound and a terpene. The hydroxyl group in this compound is placed in an endo position.Borneol is easily oxidized to the ketone yielding camphor. One historical name for borneol is Borneo camphor which explains the name. Borneol can be synthesized by reduction of...
and oxidation to camphor.
Reactions
Typical camphor reactions are
- oxidation with nitric acid
Nitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosive and toxic strong acid.Colorless when pure, older samples tend to acquire a yellow cast due to the accumulation of oxides of nitrogen. If the solution contains more than 86% nitric acid, it is referred to as fuming...
,
- conversion to isonitrosocamphor.
Camphor can also be reduced to isoborneol using
sodium borohydrideSodium borohydride, also known as sodium tetrahydridoborate, is an inorganic compound with the formula NaBH4. This white solid, usually encountered as a powder, is a versatile reducing agent that finds wide application in chemistry, both in the laboratory and on a technical scale. Large amounts are...
.
In 2007, carbon nanotubes were successfully synthesized using camphor in
chemical vapor depositionChemical vapor deposition is a chemical process used to produce high-purity, high-performance solid materials. The process is often used in the semiconductor industry to produce thin films. In a typical CVD process, the wafer is exposed to one or more volatile precursors, which react and/or...
process.
Uses
Modern uses include camphor as a plasticizer for
nitrocelluloseNitrocellulose is a highly flammable compound formed by nitrating cellulose through exposure to nitric acid or another powerful nitrating agent. When used as a propellant or low-order explosive, it is also known as guncotton...
(see
CelluloidCelluloid is the name of a class of compounds created from nitrocellulose and camphor, plus dyes and other agents. Generally regarded to be the first thermoplastic, it was first created as Parkesine in 1862 and as Xylonite in 1869, before being registered as Celluloid in 1870. Celluloid is...
), as a
moth repellentMothballs are small balls of chemical pesticide and deodorant used when storing clothing and other articles susceptible to damage from mold or moth larvae ....
, as an antimicrobial substance, in embalming, and in
fireworksFireworks are a class of explosive pyrotechnic devices used for aesthetic and entertainment purposes. The most common use of a firework is as part of a fireworks display. A fireworks event is a display of the effects produced by firework devices...
. Solid camphor releases fumes that form a
rustRust is a general term for a series of iron oxides. In colloquial usage, the term is applied to red oxides, formed by the reaction of iron and oxygen in the presence of water or air moisture...
-preventative coating, and is therefore stored in tool chests to protect tools against rust.
Camphor crystals are also used to prevent damage to
insect collectionsInsect collecting is the collection of insects for hobby, scientific study or profit. Historically insect collecting has been widespread and a very popular educational hobby. Insect collecting has left traces in European cultural history, literature and songs Insect collecting is the collection of...
by other small insects. Some folk remedies state camphor will deter snakes and other reptiles due to its strong odor. Similarly, camphor is believed to be toxic to insects and is thus sometimes used as a repellent.
Culinary
In ancient and medieval Europe, camphor was used as an ingredient in sweets. It was also used as a flavoring in confections resembling
ice creamIce cream is a frozen dessert usually made from dairy products, such as milk and cream, and often combined with fruits or other ingredients and flavours. Most varieties contain sugar, although some are made with other sweeteners...
in
ChinaChinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
during the
Tang dynastyThe Tang Dynasty was an imperial dynasty of China preceded by the Sui Dynasty and followed by the Five Dynasties and Ten Kingdoms Period. It was founded by the Li family, who seized power during the decline and collapse of the Sui Empire...
(AD 618–907). It was used in a wide variety of both savory and sweet dishes in medieval
Arabic languageArabic is a name applied to the descendants of the Classical Arabic language of the 6th century AD, used most prominently in the Quran, the Islamic Holy Book...
cookbooks, such as
al-Kitab al-Ṭabikh compiled by
ibn Sayyâr al-WarrâqAbu Muhammad al-Muzaffar ibn Nasr ibn Sayyār al-Warrāq of Baghdad was the compiler of a tenth-century cookbook, al-Kitab al-Ṭabīḫ . This is the earliest known Arabic cookbook.-References:...
in the 10th century, and an anonymous
AndalusiaAndalusia is the most populous and the second largest in area of the autonomous communities of Spain. The Andalusian autonomous community is officially recognised as a nationality of Spain. The territory is divided into eight provinces: Huelva, Seville, Cádiz, Córdoba, Málaga, Jaén, Granada and...
n cookbook of the 13th century.
It also appears in sweet and savory dishes in a book written in the late 15th century for the sultans of Mandu, the
Ni'matnama.
Currently, camphor is used as a flavoring, mostly for sweets, in Asia. It is widely used in cooking, mainly for dessert dishes, in India where it is known as
kachha karpooram ("crude/raw camphor"), in
TamilTamil is a Dravidian language spoken predominantly by Tamil people of the Indian subcontinent. It has official status in the Indian state of Tamil Nadu and in the Indian union territory of Pondicherry. Tamil is also an official language of Sri Lanka and Singapore...
:பச்சைக் கற்பூரம்), and is available in Indian grocery stores where it is labeled as "Edible Camphor". But in Tamil,
rasak karpooram is entirely different and toxic.
Medicinal
Camphor is readily absorbed through the skin and produces a feeling of cooling similar to that of
mentholMenthol is an organic compound made synthetically or obtained from peppermint or other mint oils. It is a waxy, crystalline substance, clear or white in color, which is solid at room temperature and melts slightly above. The main form of menthol occurring in nature is -menthol, which is assigned...
, and acts as slight local anesthetic and
antimicrobialAn anti-microbial is a substance that kills or inhibits the growth of microorganisms such as bacteria, fungi, or protozoans. Antimicrobial drugs either kill microbes or prevent the growth of microbes...
substance. There are
anti-itch gelsAntipruritics, also known as anti-itch drugs, are medications that inhibit the itching that is often associated with sunburns, allergic reactions, eczema, psoriasis, chickenpox, fungal infections, insect bites and stings like those from mosquitoes, fleas, and mites, and contact dermatitis and...
and cooling gels with camphor as the
active ingredientAn active ingredient is the substance of a pharmaceutical drug or a pharmaceutical ingredient and bulk active in medicine; in pesticide formulations active substance may be used. Some medications and pesticide products may contain more than one active ingredient...
. Camphor is an active ingredient (along with menthol) in vapor-steam products, such as
VicksVicks is a line of over-the-counter medications owned by the American company Procter & Gamble. Vicks manufactures NyQuil and its sister medication, DayQuil. The Vicks brand also produces Formula 44 cough medicines, cough drops, VapoRub, and a number of inhaled breathing treatments...
VapoRub. Although touted as a cough suppressant, it has no effects on respiratory tract function. A recent publication in
PediatricsPediatrics is an official peer-reviewed journal of the American Academy of Pediatrics. In the inaugural January 1948 issue, the journal's first editor, Hugh McCulloch, articulated the journal's vision: "The content of the journal is... intended to encompass the needs of the whole child in his...
suggests the topical application of VapoRub may improve symptoms of colds and sleep quality when compared to a control.
Camphor may also be administered orally in small quantities (50 mg) for minor heart symptoms and fatigue. Through much of the 1900s this was sold by the trade name Musterole, production ceased in the 1990's.
In the 18th century, camphor was used by
AuenbruggerJosef Leopold Auenbrugger or Leopold von Auenbrugg , Austrian physician who invented percussion as a diagnostic technique. On the strength of this discovery, he is considered one of the founders of modern medicine.-Biography:Auenbrugger was a native of Graz in Styria, an Austrian province...
in the treatment of
maniaMania, the presence of which is a criterion for certain psychiatric diagnoses, is a state of abnormally elevated or irritable mood, arousal, and/ or energy levels. In a sense, it is the opposite of depression...
.
Hindu religious ceremonies
Camphor is widely used in Hindu religious ceremonies. Hindus worship a holy flame by burning camphor, which forms an important part of many religious ceremonies. Camphor is used in the Mahashivratri celebrations of
ShivaShiva is a major Hindu deity, and is the destroyer god or transformer among the Trimurti, the Hindu Trinity of the primary aspects of the divine. God Shiva is a yogi who has notice of everything that happens in the world and is the main aspect of life. Yet one with great power lives a life of a...
, the Hindu god of destruction and (re)creation. As a natural pitch substance, it burns cool without leaving an ash residue, which symbolizes consciousness. Of late, most temples in southern India have stopped lighting camphor in the main Sanctum Sanctorum because of the heavy carbon deposits it produces; however, open areas still burn it.
In Hindu
pujas and ceremonies, camphor is burned in a ceremonial spoon for performing
aartiAarti , also spelled arathi, aarthi is a Hindu religious ritual of worship, a form of puja, in which light from wicks soaked in ghee or camphor is offered to one or more deities...
. This type of camphor, the processed white crystalline kind, is also sold at Indian grocery stores. It is not suitable for cooking, however, and is hazardous to health if eaten.
Toxicology
In larger quantities, it is poisonous when ingested and can cause seizures, confusion, irritability, and neuromuscular
hyperactivity. In extreme cases, even topical application of camphor may lead to
hepatotoxicityHepatotoxicity implies chemical-driven liver damage.The liver plays a central role in transforming and clearing chemicals and is susceptible to the toxicity from these agents. Certain medicinal agents, when taken in overdoses and sometimes even when introduced within therapeutic ranges, may injure...
.
Lethal doses in adults are in the range 50–500 mg/kg (orally). Generally, two grams cause serious toxicity and four grams are potentially lethal.
In 1980, the
U.S.The United States of America is a federal constitutional republic comprising fifty states and a federal district...
Food and Drug AdministrationThe Food and Drug Administration is an agency of the United States Department of Health and Human Services, one of the United States federal executive departments...
set a limit of 11% allowable camphor in consumer products, and totally banned products labeled as camphorated oil, camphor oil, camphor
linimentLiniment , from the Latin linere, to anoint, is a medicated topical preparation for application to the skin. Preparations of this type are also called balm...
, and camphorated liniment (except "white camphor
essential oilAn essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants. Essential oils are also known as volatile oils, ethereal oils or aetherolea, or simply as the "oil of" the plant from which they were extracted, such as oil of clove...
", which contains no significant amount of camphor). Since alternative treatments exist, medicinal use of camphor is discouraged by the FDA, except for skin-related uses, such as medicated powders, which contain only small amounts of camphor.
See also
- 1,4-Dichlorobenzene
1,4-Dichlorobenzene is an organic compound with the formula C6H4Cl2. This colorless solid has a strong odor. It consists of two chlorine atoms substituted at opposing sites on a benzene ring. p-DCB is used a pesticide and a deodorant, most familiarly in mothballs in which it is a replacement for...
- Citral
Citral, or 3,7-dimethyl-2,6-octadienal or lemonal, is either of, or a mixture of, a pair of terpenoids with the molecular formula C10H16O. The two compounds are double bond isomers. The E-isomer is known as geranial or citral A...
- Eucalyptol
Eucalyptol is a natural organic compound which is a colorless liquid. It is a cyclic ether and a monoterpenoid.Eucalyptol is also known by a variety of synonyms: 1,8-cineol, 1,8-cineole, limonene oxide, cajeputol, 1,8-epoxy-p-menthane, 1,8-oxido-p-menthane, eucalyptol, eucalyptole,...
- Lavender
The lavenders are a genus of 39 species of flowering plants in the mint family, Lamiaceae. An Old World genus, distributed from Macaronesia across Africa, the Mediterranean, South-West Asia, Arabia, Western Iran and South-East India...
- Vaporizer
A vaporizer or vapouriser is a device used to extract for inhalation the active ingredients of plant material, commonly cannabis, tobacco, or other herbs or blends....
External links