Camphor

Camphor is a waxy, white or transparent solid with a strong, aromatic odor.^[3] 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.

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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 meaning "Barus chalk". In fact Malay traders from whom Indian and Middle East merchants would buy camphor called it kapur, "chalk" because of its white colour [1]. 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 karpoor is used to denote Camphore. A South-Indian adaptation of this word, karpooram, has been used for camphor in many South-Indian/Dravidian languages (like Telugu, Tamil, Kannada and Malayalam).

Camphor was first synthesized by Gustaf Komppa in 1903. 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. The synthesis was the first industrial total synthesis, when Komppa began industrial production in Tainionkoski, Finland, in 1907.

Norcamphor is a camphor derivative with the three methyl groups replaced by hydrogen.

Other substances deriving from trees are sometimes wrongly sold as camphor.

Camphor Trees are widely found in very deep jungles of Western Ghats of Tamil Nadu and Kerala states in South India.

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.^[4] 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. A form of anti-itch gel currently on the market uses camphor as its 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.^[5]

In the 17th Century, it was used by Auenbrugger in the treatment of mania.^{[citation needed]}

It is also believed 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.^{[citation needed]}

Camphor is also used in the Mahashiva ratri celebrations of Shiva, the Hindu god of destruction of evil. Its natural pitch substance burns cool without leaving an ash residue, which symbolizes the consciousness.

Recently, carbon nanotubes were successfully synthesized using camphor in chemical vapor deposition process.^[6]

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 flavouring in confections resembling ice cream in China during the Tang dynasty (A.D. 618-907).^{[citation needed]} Camphor is widely used in cooking (mainly for desert dishes) in India where it is known as Pachha Karpooram (literally meaning "green camphor" though "Pachha" in Tamil can also be translated to mean "raw" which is "Pachha Karpooram's" intended meaning). It is widely available at Indian grocery stores and is labeled as "Edible Camphor." In Hindu poojas 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."

Toxicology

In larger quantities, it is poisonous when ingested and can cause seizures, confusion, irritability, and neuromuscular hyperactivity. 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 liniment (but "white camphor essential oil" 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:

• bromination

• oxidation with nitric acid

• conversion to isonitrosocamphor

Camphor can also be reduced to isoborneol using sodium borohydride.

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.

References

1. ^ The Merck Index, 7th edition, Merk & Co, Rahway, New Jersey, USA, 1960
2. ^ Handbook of Chemistry and Physics, CRC Press, Ann Arbor, Michigan
3. ^ J. Mann, R. S. Davidson, J. B. Hobbs, D. V. Banthorpe, J. B. Harborne, Natural Products, pp. 309-311, Addison Wesley Longman Ltd., Harlow, UK, 1994. ISBN 0-582-06009-5
4. ^ Tips for Cabinet Making Shops
5. ^ National Agency for Medicines
6. ^ Mukul Kumar, Yoshinori Ando, Carbon Nanotubes from Camphor: An Environment-Friendly Nanotechnology, Journal of Physics: Conference Series 61 (2007) 643–646