camphor

This article needs attention from an expert on the subject. See the talk page for details. WikiProject Chemicals may be able to help recruit an expert. (December 2011)

Camphor[1][2]
IUPAC name 1,7,7-Trimethylbicyclo[2.2.1]heptan-2-one
Systematic name 1,7,7-Trimethylbicyclo[2.2.1]heptan-2-one
Other names 2-Bornanone; Bornan-2-one; 2-Camphanone; Formosa
Identifiers
CAS number	76-22-2 Y, 464-49-3 (R) Y, 464-48-2 (S) Y
PubChem	2537, 9543187 (R), 10050 (S)
ChemSpider	2441 Y, 7822160 (R) Y, 9655 (S) Y
UNII	5TJD82A1ET Y
EC number	200-945-0
UN number	2717
DrugBank	DB01744
KEGG	D00098 Y
MeSH	Camphor
ChEBI	CHEBI:36773 Y
ChEMBL	CHEMBL15768 Y
IUPHAR ligand	2422
RTECS number	EX1225000
ATC code	C01EB02
Beilstein Reference	1907611
Gmelin Reference	83275
3DMet	B04729
Jmol-3D images	Image 1 Image 2
SMILES CC1(C)C2CCC1(C)C(=O)C2 O=C1CC2CCC1(C)C2(C)C
InChI InChI=1S/C10H16O/c1-9(2)7-4-5-10(9,3)8(11)6-7/h7H,4-6H2,1-3H3 Y Key: DSSYKIVIOFKYAU-UHFFFAOYSA-N Y InChI=1/C10H16O/c1-9(2)7-4-5-10(9,3)8(11)6-7/h7H,4-6H2,1-3H3 Key: DSSYKIVIOFKYAU-UHFFFAOYAK
Properties
Molecular formula	C10H16O
Molar mass	152.23 g mol−1
Exact mass	152.120115134 g mol−1
Appearance	White, translucent crystals
Density	0.990 g cm−3
Melting point	175-177 °C, 448-450 K, 347-351 °F
Boiling point	204 °C, 477 K, 399 °F
Solubility in water	1.2 g dm−3
Solubility in acetone	~2500 g dm−3
Solubility in acetic acid	~2000 g dm−3
Solubility in diethyl ether	~2000 g dm−3
Solubility in chloroform	~1000 g dm−3
Solubility in ethanol	~1000 g dm−3
log P	2.089
Vapor pressure	4 mmHg (at 70 °C)
Chiral rotation [α]D	+44.1°
Hazards
EU classification	F Xn
R-phrases	R11 R22 R36/37/38
S-phrases	S16 S26
NFPA 704	2 2 0
Flash point	64 °C
Explosive limits	3.5%
Related compounds
Related Ketones	Fenchone, Thujone
Related compounds	Camphene, Pinene, Borneol, Isoborneol, Camphorsulfonic acid
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

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) and also of Dryobalanops aromatica, a giant of the Bornean forests. It also occurs in some other related trees in the laurel family, notably Ocotea usambarensis. Dried rosemary leaves (Rosmarinus officinalis), in the mint family, contain up to 20% camphor. 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, 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 hydrogen.

History

The word camphor derives from the French word camphre, itself from Medieval Latin camfora, from Arabic kafur, from Sanskrit, karpuura.^[4] Barus was the port on the western coast of the Indonesian island of Sumatra where foreign traders would call to buy camphor, hence in Malay it became kapur Barus. 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).^{[citation needed]} By the 13th century, it was used in recipes everywhere in the Muslim world, ranging from main dishes such as tharid and stew to desserts.^[5]

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

A sample of sublimed camphor

Camphor can be produced from alpha-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, alpha-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.

Reactions

Typical camphor reactions are

• bromination,

• oxidation with nitric acid,

• conversion to isonitrosocamphor.

Camphor can also be reduced to isoborneol using sodium borohydride.

In 2007, carbon nanotubes were successfully synthesized using camphor in chemical vapor deposition process.^[6]

Uses

Modern uses include camphor as a plasticizer for nitrocellulose (see Celluloid), 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.^[7]

Camphor crystals are also used to prevent damage to insect collections by other small insects, also as a cough suppressant. 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.^[8]

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 cream in China during the Tang dynasty (AD 618–907).^{[citation needed]} It was used in a wide variety of both savory and sweet dishes in medieval Arabic language cookbooks, such as al-Kitab al-Ṭabikh compiled by ibn Sayyâr al-Warrâq in the 10th century,^[9] and an anonymous Andalusian cookbook of the 13th century.^[10] 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.^[11]

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 Tamil: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 menthol, and acts as slight local anesthetic and antimicrobial substance. There are anti-itch gels 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. Although touted as a cough suppressant, it has no effects on respiratory tract function. A recent publication in Pediatrics suggests the topical application of VapoRub may improve symptoms of colds and sleep quality when compared to a control.^[12]

Camphor may also be administered orally in small quantities (50 mg) for minor heart symptoms and fatigue.^[13] Through much of the 1900s this was sold under the trade name Musterole; production ceased in the 1990s.

In the 18th century, camphor was used by Auenbrugger in the treatment of mania.^[14]

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 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^[when?], 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 aarti. 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, camphor is poisonous when ingested and can cause seizures, confusion, irritability, and neuromuscular hyperactivity. In extreme cases, even topical application of camphor may lead to hepatotoxicity.^{[15] [16]} 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.^[17]

In 1980, the U.S. 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 (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.

See also

• 1,4-Dichlorobenzene
• Citral
• Eucalyptol
• Lavender
• Vaporizer

References

External links

Wikimedia Commons has media related to: Camphor

• Camphor Evidence-based Monograph from Natural Medicines Comprehensive Database
• INCHEM at IPCS (International Programme on Chemical Safety)