Camphor

Camphor[1][2]

(R)- (left) and (S)-camphor
Names
IUPAC name
1,7,7-Trimethylbicyclo[2.2.1]heptan-2-one
Other names
2-Bornanone; Bornan-2-one; 2-Camphanone; Formosa
Identifiers
3D model (JSmol)
3DMet B04902
1907611
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.000.860
EC Number 200-945-0
83275
KEGG
MeSH Camphor
RTECS number EX1225000
UNII
UN number 2717
Properties
C10H16O
Molar mass 152.24 g·mol−1
Appearance White, translucent crystals
Odor Fragrant and penetrating
Density 0.992 g·cm−3
Melting point 175–177 °C (347–351 °F; 448–450 K)
Boiling point 209 °C (408 °F; 482 K)
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)
+44.1°
−103×10−6 cm3/mol
Pharmacology
C01EB02 (WHO)
Hazards
F Xn
R-phrases (outdated) R11 R22 R36/37/38
S-phrases (outdated) S16 S26
NFPA 704
Flammability code 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g., diesel fuelHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
2
2
0
Flash point 54 °C (129 °F; 327 K)
466 °C (871 °F; 739 K)
Explosive limits 0.6–3.5%[3]
Lethal dose or concentration (LD, LC):
1310 mg/kg (oral, mouse)[4]
800 mg/kg (dog, oral)
2000 mg/kg (rabbit, oral)[4]
400 mg/m3 (mouse, 3 hr)[4]
US health exposure limits (NIOSH):
PEL (Permissible)
 TWA 2 mg/m3[3]
REL (Recommended)
 TWA 2 mg/m3[3]
IDLH (Immediate danger)
 200 mg/m3[3]
Related compounds
Related Ketones
 Fenchone, Thujone
Related compounds
 Camphene, Pinene, Borneol, Isoborneol, Camphorsulfonic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is ☑Y☒N ?)
Infobox references

Camphor (/ˈkæmfər/) is a waxy, flammable, transparent solid with a strong aroma.[5] It is a terpenoid with the chemical formula C10H16O. It is found in the wood of the camphor laurel (Cinnamomum camphora), a large evergreen tree found in Asia (particularly in Sumatra and Borneo islands, Indonesia) and also of the unrelated kapur tree, a tall timber tree from the same region. It also occurs in some other related trees in the laurel family, notably Ocotea usambarensis. The oil in rosemary leaves (Rosmarinus officinalis), in the mint family, contains 10 to 20% camphor,[6] while camphorweed (Heterotheca) only contains some 5%.[7] Camphor 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 (the parent of African blue basil).

The molecule has two possible enantiomers as shown in the structural diagrams. The structure on the left is the naturally occurring (R)-form, while its mirror image shown on the right is the (S)-form.

Etymology

The word camphor derives from the French word camphre, itself from Medieval Latin camfora, from Arabic kāfūr, from Sanskrit karpūraḥ (कर्पूरः), from Austroasiatic languages - Khmer kāpōr / kapū, Mon khapuiw, ultimately from an Austronesian source - Malay kapur.[8] Camphor was not known in India during the Vedic period since there are no references to this product. However, Suśruta and later kāvya literature mention this word. In Old Malay it is known as kapur Barus, which means "the chalk of Barus". Barus was the name of an ancient port located near modern Sibolga city on the western coast of Sumatra island.[9] This port traded in camphor extracted from laurel trees (Cinnamonum camphora) that were abundant in the region. Even now, the local tribespeople and Indonesians in general refer to aromatic naphthalene balls and moth balls as kapur Barus.

Production

A sample of sublimed camphor

Camphor was produced as a forest product for millennia, condensed from the vapor given off by the roasting of wood chips cut from the relevant trees. When its uses in the nascent chemical industries (discussed below) greatly increased the volume of demand in the late 19th century, potential for changes in supply and in price followed. In 1911 Robert Kennedy Duncan, an industrial chemist and educator, related that the Imperial Japanese government had recently (1907–1908) tried to monopolize the production of natural camphor as a forest product in Asia but that the monopoly was prevented by the development of the total synthesis alternatives,[10] which began in "purely academic and wholly uncommercial"[10] form with Gustav Komppa's first report "but it sealed the fate of the Japanese monopoly […] For no sooner was it accomplished than it excited the attention of a new army of investigators—the industrial chemists. The patent offices of the world were soon crowded with alleged commercial syntheses of camphor, and of the favored processes companies were formed to exploit them, factories resulted, and in the incredibly short time of two years after its academic synthesis artificial camphor, every whit as good as the natural product, entered the markets of the world […]."[10]:133–134 "...And yet artificial camphor does not—and cannot—displace the natural product to an extent sufficient to ruin the camphor-growing industry. Its sole present and probable future function is to act as a permanent check to monopolization, to act as a balance-wheel to regulate prices within reasonable limits." This ongoing check on price growth was confirmed in 1942 in a monograph on DuPont's history, where William S. Dutton said, "Indispensable in the manufacture of pyroxylin plastics, natural camphor imported from Formosa and selling normally for about 50 cents a pound, reached the high price of $3.75 in 1918 [amid the global trade disruption and high explosives demand that World War I created]. The organic chemists at [DuPont] replied by synthesizing camphor from the turpentine of Southern pine stumps, with the result that the price of industrial camphor sold in carload lots in 1939 was between 32 cents and 35 cents a pound."[11]:293

The background of Gustaf Komppa's synthesis was as follows. In the 19th century, it was known that nitric acid oxidizes camphor into camphoric acid. Haller and Blanc published a semisynthesis of camphor from camphoric acid. Although they demonstrated its structure, they were unable to prove it. The first complete total synthesis of camphoric acid was published by Komppa in 1903. Its inputs were diethyl oxalate and 3,3-dimethylpentanoic acid, which reacted by Claisen condensation to yield 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. He began industrial production of camphor in Tainionkoski, Finland, in 1907 (with plenty of competition, as Kennedy Duncan reported).

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 racemic camphor. By contrast, camphor occurs naturally as D-camphor, the (R)-enantiomer.

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

  • conversion to isonitrosocamphor.

Camphor can also be reduced to isoborneol using sodium borohydride.

In 1998, K. Chakrabarti and coworkers from the Indian Association for the Cultivation of Science, Kolkata, prepared diamond thin film using camphor as the precursor for chemical vapor deposition.[12]

In 2007, carbon nanotubes were successfully synthesized using camphor in chemical vapor deposition process.[13]

Physical uses

The sublimating capability of camphor gives it several uses.

Explosives

Camphor is used as a plasticizer for nitrocellulose, an ingredient for fireworks and explosive munitions. During the late 19th Century, as Western manufacturers developed machine guns and other rapid fire ordnance, it became imperative to reduce the smoke that covered battlefields so that haze obscured hidden gun emplacements could be revealed. Camphor was an essential component in the production of smokeless gunpowder. Also, the new smokeless powder did not foul the weapons as much as conventional gunpowder.[14]

Nitrocellulose plastics

Closely related chemically to the explosives uses are the uses in nitrocellulose plastics (pyroxylin plastics). In the early decades of the plastics industry, camphor was used in "immense quantities"[10]:130 (that is, by the carload) in the making of such plastics, including celluloid and pyroxylin lacquers, and of explosives. It was in this connection that the development of a synthetic source became economically important, as discussed above.

Pest deterrent and preservative

Camphor is believed to be toxic to insects and is thus sometimes used as a repellent.[15] Camphor is used as an alternative to mothballs. Camphor crystals are sometimes used to prevent damage to insect collections by other small insects. It is kept in clothes used on special occasions and festivals, and also in cupboard corners as a cockroach repellent.

Camphor is also used as an antimicrobial substance. In embalming, camphor oil was one of the ingredients used by ancient Egyptians for mummification.[16]

Solid camphor releases fumes that form a rust-preventative coating and is therefore stored in tool chests to protect tools against rust.[17]

Culinary uses

In ancient and medieval Europe, camphor was used as an ingredient in sweets. 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,[18] and an anonymous Andalusian cookbook of the 13th century.[19] It also appears in sweet and savory dishes in the Ni'matnama, a book written in the late 15th century for the sultans of Mandu.[20] An early international trade in it made camphor widely known throughout Arabia in pre-Islamic times, as it is mentioned in the Quran 76:5 as a flavoring for drinks.[21] 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.[19]

An alcohol analog of camphor also known as isoborneol currently is used in Asia as a flavoring, mostly for sweets. In India it is widely used in cooking, mainly for dessert dishes, and is known as kachha karpooram or "pachha karpoora" ("crude/raw camphor"), in (Telugu:పచ్చ కర్పూరo), (Tamil:பச்சைக் கற்பூரம்), (Kannada:ಪಚ್ಚ ಕರ್ಪೂರ), and is available in Indian grocery stores where it is labeled as "edible camphor".

Medicinal uses

Physiology

Camphor is readily absorbed through the skin, where it stimulates nerve endings sensitive to heat and cold, producing a warm sensation when vigorously applied, or a cool sensation when applied gently.[22][23][24] These effects are particularly noticeable in the lungs and airways if camphor is inhaled as an aerosol.[22] The action on nerve endings also induces a slight local analgesia.[25]

The sensation of heat that camphor produces on the skin is presumably due to activation of the ion channels TRPV3 and TRPV1, while the cool sensation due to activation of TRPM8.[26][27][28]

The global effects on the body include tachycardia (increased heart rate), vasodilation in skin (flushing), slower breathing, reduced appetite, and increased secretions and excretions such as perspiration and urination. [29]

Camphor is toxic in large doses. It produces symptoms of irritability, disorientation, lethargy, muscle spasms, vomiting, abdominal cramps, convulsions, and seizures.[30][31][32] 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.[33]

Traditional uses

Camphor has been used in traditional medicine from time immemorial in countries where it was native. It was probably the odor of the substance and its decongestant effect that led to its use in medicine.[22]

Camphor was used in ancient Sumatra to treat sprains, swellings, and inflammation.[34]

It has long been used as a medical substance in ancient India, where it generally goes by the name karpūra. It has been described in the 7th-century Āyurvedic work Mādhavacikitsā as being an effective drug used for the treatment of fever. The plant has also been named hima and has been identified with the plant Cinnamomum camphora. According to the Vaidyaka-śabda-sindhu, it is one of the “five flavours” used in betel-chewing, where it is also referred to as candrabhasma (‘moon powder’).

Camphor also was used for centuries in Chinese medicine for a variety of purposes.[22]

Modern uses

Camphor was a component of paregoric, an opium/camphor tincture developed in the 18th century. Paregoric was used in various formulations for hundreds of years. It was a household remedy in the 18th and 19th centuries when it was widely used to control diarrhea in adults and children, as an expectorant and cough medicine, to calm fretful children, and to rub on the gums to counteract the pain from teething. Its use declined in the 20th century after the regulation of opium.

Also in the 18th century, camphor was used by Auenbrugger in the treatment of mania, paradoxically by inducing seizures.[35]

Based on Hahnemann's writings, camphor (dissolved in alcohol) was successfully used in the 19th century to treat the 1854-1855 cholera epidemics in Naples.[36]

In the 20th century, camphor was administered orally in small quantities (50 mg) for minor heart symptoms and fatigue.[37] This preparation was sold under the trade name Musterole; production ceased in the 1990s.

Today the main use of camphor is as a cough suppressant[38] and as a decongestant.[38] It is an active ingredient (along with menthol) in vapor-steam decongestant products, such as Vicks VapoRub.

Regulation

In 1980, the US Food and Drug Administration set a limit of 11% allowable camphor in consumer products, and 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.

Hindu religious ceremonies

Camphor is widely used in Hindu religious ceremonies. It is put on a stand called 'karpur dāni' in India. Aarti is performed after setting fire to it usually as the last step of puja.[39]

See also

References

  1. ↑ The Merck Index, 7th edition, Merck & Co., Rahway, New Jersey, USA, 1960
  2. ↑ Handbook of Chemistry and Physics, CRC Press, Ann Arbor, Michigan, USA
  3. 1 2 3 4 "NIOSH Pocket Guide to Chemical Hazards #0096". National Institute for Occupational Safety and Health (NIOSH).
  4. 1 2 3 "Camphor (synthetic)". National Institute for Occupational Safety and Health (NIOSH). 4 December 2014. Retrieved 19 February 2015.
  5. ↑ Mann JC, Hobbs JB, Banthorpe DV, Harborne JB (1994). Natural products: their chemistry and biological significance. Harlow, Essex, England: Longman Scientific & Technical. pp. 309–11. ISBN 0-582-06009-5.
  6. ↑ "Rosemary". Drugs.com. Retrieved 23 July 2016.
  7. ↑ Lincoln, D.E., B.M. Lawrence. 1984. The volatile constituents of camphorweed, Heterotheca subaxillaris. Phytochemistry 23(4):933-934
  8. ↑ Camphor at the Online Etymology Dictionary
  9. ↑ Drakard, Jane (1989). "An Indian Ocean Port: Sources for the Earlier History of Barus". Archipel. 37: 53–82. doi:10.3406/arch.1989.2562. Retrieved 9 October 2015.
  10. 1 2 3 4 Kennedy Duncan, Robert (1911), "Camphor: An Industry Revolutionized", Some Chemical Problems of Today, Harper and Brothers, LCCN 11026192.
  11. ↑ Dutton, William S. (1942), Du Pont: One Hundred and Forty Years, Charles Scribner's Sons, LCCN 42011897.
  12. ↑ Chakrabarti K, Chakrabarti R, Chattopadhyay KK, Chaudhuri S, Pal AK (1998). "Nano-diamond films produced from CVD of camphor". Diam Relat Mater. 7 (6): 845–52. Bibcode:1998DRM.....7..845C. doi:10.1016/S0925-9635(97)00312-9.
  13. ↑ Kumar M, Ando Y (2007). "Carbon Nanotubes from Camphor: An Environment-Friendly Nanotechnology". J Phys Conf Ser. 61: 643–6. Bibcode:2007JPhCS..61..643K. doi:10.1088/1742-6596/61/1/129.
  14. ↑ Rubinstein, M. A. 2015, Taiwan: A New History, London: Routledge. ISBN 1317459075
  15. ↑ The Housekeeper's Almanac, or, the Young Wife's Oracle! for 1840!. No. 134. New-York: Elton, 1840. Print.
  16. ↑ "Mummy-making complexity revealed". Retrieved 3 July 2018.
  17. ↑ Inc., Shopsmith,. "Tips For Cabinet Making Shops". www.cabinetshoptips.com. Retrieved 3 July 2018.
  18. ↑ Nasrallah, Nawal (2007). Annals of the Caliphs' Kitchens: Ibn Sayyâr al-Warrâq's Tenth-century Baghdadi Cookbook. Islamic History and Civilization, 70. Leiden, The Netherlands: Brill. ISBN 978-0-415-35059-4.
  19. 1 2 "Andalusian Cookbook: Table of Contents". www.daviddfriedman.com. Retrieved 3 July 2018.
  20. ↑ Titley, Norah M. (2004). The Ni'matnama Manuscript of the Sultans of Mandu: The Sultan's Book of Delights. Routledge Studies in South Asia. London, UK: Routledge. ISBN 978-0-415-35059-4.
  21. ↑ [Quran 76:5]
  22. 1 2 3 4 Goodman and Gilman, Pharmacological basis of therapeutics, Macmillan 1965, p. 982-983.
  23. ↑ Green, B. G. (1990). "Sensory characteristics of camphor". The Journal of Investigative Dermatology. 94 (5): 662–6. doi:10.1111/1523-1747.ep12876242. PMID 2324522.
  24. ↑ Kotaka, T.; Kimura, S.; Kashiwayanagi, M.; Iwamoto, J. (2014). "Camphor induces cold and warm sensations with increases in skin and muscle blood flow in human". Biological and Pharmaceutical Bulletin. 37 (12): 1913–8. doi:10.1248/bpb.b14-00442. PMID 25451841.
  25. ↑ Bonica's Management of Pain (4th ed.). Philadelphia, Baltimore: Wolters Kluwer - Lippincott Williams & Wilkins. 2009. p. 29. ISBN 9780781768276.
  26. ↑ Moqrich, A.; Hwang, S. W.; Earley, T. J.; Petrus, M. J.; Murray, A. N.; Spencer, K. S. R.; Andahazy, M.; Story, G. M.; Patapoutian, A. (2005). "Impaired Thermosensation in Mice Lacking TRPV3, a Heat and Camphor Sensor in the Skin". Science. 307 (5714): 1468–72. Bibcode:2005Sci...307.1468M. doi:10.1126/science.1108609. PMID 15746429.
  27. ↑ Xu, H.; Blair, N. T.; Clampham, D. E. (2005). "Camphor activates and strongly desensitizes the transient receptor potential vanilloid subtype 1 channel in a vanilloid-independent mechanism". The Journal of Neuroscience. 25 (39): 8924–37. doi:10.1523/JNEUROSCI.2574-05.2005. PMID 16192383.
  28. ↑ Selescu, T.; Ciobanu, A. C.; Dobre, C.; Babes, A. (2013). "Camphor activates and sensitizes transient receptor potential melastatin 8 (TRPM8) to cooling and icilin". Chemical Senses. 38 (7): 563–75. doi:10.1093/chemse/bjt027. PMID 23828908.
  29. ↑ Church, John (1797). An inaugural dissertation on camphor: submitted to the examination of the Rev. John Ewing, S.S.T.P. provost ; the trustees & medical faculty of the University of Pennsylvania, on the 12th of May, 1797 ; for the degree of Doctor of Medicine. University of Philadelphia: Printed by John Thompson. Retrieved January 18, 2013.
  30. ↑ "Camphor overdose". Medline. NIH. Retrieved January 19, 2012.
  31. ↑ Martin D, Valdez J, Boren J, Mayersohn M (Oct 2004). "Dermal absorption of camphor, menthol, and methyl salicylate in humans". Journal of Clinical Pharmacology. 44 (10): 1151–7. doi:10.1177/0091270004268409. PMID 15342616.
  32. ↑ Uc A, Bishop WP, Sanders KD (Jun 2000). "Camphor hepatotoxicity". Southern Medical Journal. 93 (6): 596–8. doi:10.1097/00007611-200006000-00011. PMID 10881777.
  33. ↑ "Poisons Information Monograph: Camphor". International Programme on Chemical Safety.
  34. ↑ Miller, Charles. History of Sumatra : An account of Sumatra. p. 121.
  35. ↑ Pearce, J.M.S. (2008). "Leopold Auenbrugger: Camphor-Induced Epilepsy – Remedy for Manic Psychosis". European Neurology. 59 (1–2): 105–7. doi:10.1159/000109581. PMID 17934285.
  36. ↑ Bayes (1866). "Cholera, as Treated by Dr. Rubini". The American Homoeopathic Review. 6 (11–12): 401–3.
  37. ↑ Lääketietokeskus. Lääkevalmisteet Pharmaca Fennica 1996, p. 814.
  38. 1 2 "Camphor Inhalation Liquid: Indications, Side Effects, Warnings - Drugs.com". Retrieved 3 July 2018.
  39. ↑ Bahadur, Om Lata (1996). The book of Hindu festivals and ceremonies (3rd ed.). New Delhi: UBS Publishers Distributors ltd. pp. 172–3. ISBN 81-86112-23-5.
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