Camphor
is a waxy, white or transparent solid with a strong, aromatic odor. [1] It is a terpenoid with the chemical formula C10H16O. It is found in wood of the camphor laurel
(Cinnamomum camphora
), a large evergreen tree found in Asia (particularly in Borneo and Taiwan, hence its alternate name). It also occurs in some other related trees in the laurel family, notably Ocotea usambarensis
. It can also be synthetically produced from oil of turpentine. It is used for its scent, as an ingredient in cooking (mainly in India), as an embalming fluid, in religious ceremonies and for medicinal purposes. A major source of camphor in Asia is camphor basil.
Norcamphor
is a camphor derivative with the three methyl groups replaced by hydrogen.
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CAMPHOR TICKETS
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History
The word camphor derives from the French word
camphre
, itself from
Medieval Latin camfora
, from
Arabic kafur
, from
Malay kapur Barus
.
[2] Barus was the port on the western coast of the
Indonesian island of
Sumatra where foreign traders would call to buy camphor. In the Indian language
Sanskrit, the word for camphor is
karpoor
. A South-Indian adaptation of this word,
karpooram
, is found in many South-Indian/
Dravidian languages (like
Telugu,
Tamil,
Kannada, and
Malayalam).
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
Alkindus
in Europe), provided the earliest recipe for the production of camphor in his
Kitab Kimiya' al-'Itr
(
Book of the Chemistry of Perfume
).
[3]. By the 13th century, it was used in recipes everywhere in the Muslim world, randing from main dishes such as
tharid, stew, and desserts
[4].
Already in the 19th century, it was known that with nitric acid, camphor could be oxidized into
camphoric acid. Haller and Blanc published a semisynthesis of camphor from camphoric acid, which, although demonstrating its structure, would not prove it. The first complete
total synthesis for camphoric acid was published by
Gustaf Komppa in 1903. Its starting materials were
diethyl oxalate and
3,3-dimethylpentanoic acid, which reacted by
Claisen condensation to give diketocamphoric acid. Methylation with methyl iodide and a complicated reduction procedure produced camphoric acid.
William Perkin published another synthesis a short time later. Previously, some organic compounds (such as
urea) had been synthesized in the laboratory as a
proof of concept, but camphor was a scarce natural product with a worldwide demand. Komppa realized this and began industrial production of camphor in
Tainionkoski,
Finland, in 1907.
Production
Camphor can be produced from
a-pinene, which is abundant in the oils of coniferous trees and can be distilled from
turpentine produced as a side product of
chemical pulping. With acetic acid as the solvent and with catalysis by a strong acid,
a-pinene readily
rearranges into
camphene, which in turn undergoes
Wagner-Meerwein rearrangement into the isobornyl cation, which is captured by acetate to give
isobornyl acetate. Hydrolysis into
isoborneol followed by oxidation gives camphor.
Biosynthesis
In
biosynthesis camphor is produced from
geranyl pyrophosphate, via cyclisation of
linaloyl pyrophosphate to
bornyl pyrophosphate, followed by hydrolysis to
borneol and oxidation to camphor.
Uses
Modern uses include as a plasticizer for
nitrocellulose, as a
moth repellent, as an antimicrobial substance, in embalming, and in
fireworks. Solid camphor releases fumes that form a
rust-preventative coating and is therefore stored in tool chests to protect tools against rust.
[5] Camphor crystals are also used to prevent damage to
insect collections by other small insects.
It is also used in
medicine. Camphor is readily absorbed through the skin and produces a feeling of cooling similar to that of
menthol and acts as slight local
anesthetic and
antimicrobial substance. There are
anti-itch gel and
cooling gels with camphor as the
active ingredient. Camphor is an active ingredient (along with menthol) in vapor-steam products, such as
Vicks VapoRub, and it is effective as a cough suppressant. It may also be administered orally in small quantities (50 mg) for minor heart symptoms and fatigue.
[6]
In the 18th century, it was used by
Auenbrugger in the treatment of
mania [7].
It is also believed
[by whom?] that 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.
Camphor is widely used in Hindu religious ceremonies. Hindus worship by lighting a holy flame by burning camphor which forms the most important part of many religious ceremonies. Camphor is used in the Mahashivratri celebrations of Shiva, 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 Sanctorium due to heavy deposits of carbon; however, open areas do use camphor.
It is also found in clarifying masks used for skin.
Recently,
carbon nanotubes were successfully synthesized using camphor in
chemical vapor deposition process.
[8]
Other substances deriving from trees are sometimes wrongly sold as camphor.
Culinary
Currently, camphor is mostly used as a flavoring for sweets in Asia. In ancient and medieval Europe it was widely used as ingredient for sweets but it is now mainly used for medicinal purposes. Camphor was used as a flavoring in confections resembling
ice cream in
China during the
Tang dynasty (AD 618–907). Camphor is widely used in cooking (mainly for dessert dishes) in India where it is known as
Kachha(raw/crude) Karpooram
("crude camphor" in
Tamil:??????? ????????). It is widely available at Indian grocery stores and is labeled as "Edible Camphor". In Hindu
pujas and ceremonies, camphor is burned in a ceremonial spoon for performing
aarti. This type of camphor is also sold at Indian grocery stores but it is not suitable for cooking. The only type that should be used for food are those which are labeled as "Edible Camphor".
Medicinal
Camphor is used in several cough preparations such as
Vicks and
Buckley's as a cough suppressant and topical analgesic.
Toxicology
In larger quantities, it is
poisonous when ingested and can cause seizures, confusion, irritability, and
neuromuscular hyperactivity. Despite the rather low skin absorption it may still lead to
hepatotoxicity in extreme cases.
[9]
[10] Lethal doses in adults are in the range 50–500 mg/kg (orally). Generally, 2 g causes serious toxicity and 4 g is potentially lethal.
In 1980, the
United States Food and Drug Administration set a limit of 11% allowable camphor in consumer products and totally banned products labeled as camphorated oil, camphor oil, camphor
liniment, and camphorated linament (except "white camphor
essential oil", 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.
Reactions
Typical camphor reactions are
:
- oxidation with nitric acid,
:
- conversion to isonitrosocamphor.
:
Camphor can also be reduced to
isoborneol using
sodium borohydride.
See also
- 1,4-Dichlorobenzene
- Cinnamomum camphora
- Citral
- Eucalyptol
- Lavender
- List of the consumer products
- Menthol
- Vaporizer
References
- Natural products: their chemistry and biological significance
- http://www.etymonline.com/index.php?search=camphor
- Al-Kindi, FSTC
- Anonymous Andalusian cookbook from the 13th century
- Tips for Cabinet Making Shops
- National Agency for Medicines
- Leopold Auenbrugger: camphor-induced epilepsy - remedy for manic psychosis
- Carbon Nanotubes from Camphor: An Environment-Friendly Nanotechnology
- Dermal absorption of camphor, menthol, and methyl salicylate in humans
- Camphor hepatotoxicity