:Camphor

The word camphor derived in the 14th century from Old {{langx|fr|link=no|camphre}}, itself from Medieval {{langx|la|camfora}}, from {{langx|ar|كافور|kāfūr}}, perhaps through {{langx|sa|कर्पूर|karpūra}}, from {{langx|ta|கற்பூரம்|karpooram }} apparently from Austronesian {{langx|ms|kapur}} 'lime' (chalk).{{cite web |title=Camphor |url=https://www.etymonline.com/word/camphor |website=Online Etymology Dictionary |publisher=Douglas Harper |access-date=23 May 2021 |archive-date=23 May 2021 |archive-url=https://web.archive.org/web/20210523165548/https://www.etymonline.com/word/camphor |url-status=live }}

In Old Malay, camphor was called {{lang|ms|kapur barus}}, meaning "the chalk of Barus", referring to Barus, an ancient port near modern Sibolga on the western coast of Sumatra.{{cite journal|title = An Indian Ocean Port: Sources for the Earlier History of Barus | first =Jane |last =Drakard |journal= Archipel |year =1989 |volume =37 |pages = 53–82 |doi=10.3406/arch.1989.2562}} This port traded in camphor extracted from the Borneo camphor trees (Dryobalanops aromatica) that were abundant in the region.{{Cite journal|last=Laufer|first=Berthold|date=1919|title=SINO-IRANICA: Chinese Contributions to the History of Civilization in Ancient Iran|url=https://www.jstor.org/stable/29782155|journal=Publications of the Field Museum of Natural History. Anthropological Series|series=Publication. Field Museum of Natural History |volume=15|issue=3|pages=478–479|doi=10.5962/bhl.title.3538 |jstor=29782155 |issn=0894-8380|access-date=2022-01-22|archive-date=2020-11-17|archive-url=https://web.archive.org/web/20201117223750/https://www.jstor.org/stable/29782155|url-status=live}}

(+)-camphor has been produced as a forest product for centuries, condensed from the vapor given off by the roasting of wood chips cut from Camphora officinarum, and later by passing steam through the pulverized wood and condensing the vapors.{{cite encyclopedia | url = https://www.britannica.com/science/camphor | title = Camphor | publisher = | encyclopedia= britannica.com | access-date = 12 December 2018 | archive-date = 13 December 2018 | archive-url = https://web.archive.org/web/20181213114736/https://www.britannica.com/science/camphor | url-status = live }} By the early 19th century most camphor tree reserves had been depleted with the remaining large stands in Japan and Taiwan, with Taiwanese production greatly exceeding Japanese. Camphor was one of the primary resources extracted by Taiwan's colonial powers as well as one of the most lucrative. First the Chinese and then the Japanese established monopolies on Taiwanese camphor. In 1868, a British naval force sailed into Anping harbor and the local British representative demanded the end of the Chinese camphor monopoly. After the local imperial representative refused, the British bombarded the town and took the harbor. The "camphor regulations" negotiated between the two sides subsequently saw a brief end to the camphor monopoly.{{cite web |last1=Cheung |first1=Han |title=Taiwan in Time: The camphor dispute |url= https://www.taipeitimes.com/News/feat/archives/2020/11/15/2003746932 |publisher= | work= Taipei Times |access-date=14 November 2020 |archive-date=15 November 2020 |archive-url=https://web.archive.org/web/20201115175311/https://www.taipeitimes.com/News/feat/archives/2020/11/15/2003746932 |url-status=live }}

(-)-camphor occurs naturally in the essential oil of Matricaria plants. As a result, it's much rarer.

Camphor is 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 anhydride as the solvent and with catalysis by a strong acid, alpha-pinene is converted to isobornyl acetate. Hydrolysis of this ester gives isoborneol which can be oxidized to give racemic camphor.

A biological enzyme has been proposed for producing only the rare (-) or L-camphor. This EstB esterase from Burkholderia gladioli hydrolyzes only (+)-isobornyl acetate.{{cite journal |last1=Calderini |first1=Elia |last2=Drienovská |first2=Ivana |last3=Myrtollari |first3=Kamela |last4=Pressnig |first4=Michaela |last5=Sieber |first5=Volker |last6=Schwab |first6=Helmut |last7=Hofer |first7=Michael |last8=Kourist |first8=Robert |title=Simple Plug-In Synthetic Step for the Synthesis of (−)-Camphor from Renewable Starting Materials |journal=ChemBioChem |date=13 October 2021 |volume=22 |issue=20 |pages=2951–2956 |doi=10.1002/cbic.202100187|pmid=34033201 |pmc=8596451 }}

The reactions of camphor have been extensively examined. Some representative transformations include

• sulfonation:{{OrgSynth | title = D,L-10-Camphorsulfonic acid (Reychler's Acid) | first1 = Paul D.| last1= Bartlett | first2= L. H.| last2= Knox | doi = 10.15227/orgsyn.045.0012 | year = 1965 | volume = 45 | pages = 12}}

:File:10-CSA synthesis.png

• oxidation with selenium dioxide to camphorquinone .{{cite journal |doi=10.15227/orgsyn.079.0125|title=Camphorquinone and Camphorquinone Monoxime |journal=Organic Syntheses |year=2002 |volume=79 |page=125|first1=James D.|last1=White|first2=Duncan J.|last2=Wardrop|first3=Kurt F.|last3=Sundermann }}

:File:CamphorquinoneSynthesis.svg

Camphor can also be reduced to isoborneol using sodium borohydride. It can be converted to the alkene bornylene.{{cite journal|title=2-Bornene |journal=Organic Syntheses|page=6|year=1971|volume= 51|doi=10.15227/orgsyn.051.0066|first1=Robert H.|last1=Shapiro|first2=J. H.|last2=Duncan}}

File:Camphor_biosynthesis_en.svg

{{see also|Borneol#Biosynthesis|(+)-borneol dehydrogenase|(-)-borneol dehydrogenase}}

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.

The first significant manmade plastics were low-nitrogen (or "soluble") nitrocellulose (pyroxylin) plastics. In the early decades of the plastics industry, camphor was used in immense quantities{{rp|130}} as the plasticizer that creates celluloid from nitrocellulose, in nitrocellulose lacquers and other plastics and lacquers.

Camphor has been used for its scent, as an embalming fluid, as topical medication, as a manufacturing chemical, and in religious ceremonies.

File:Camphor Cubes.jpgCamphor has been used as a folk medicine over centuries, probably most commonly as a decongestant.{{cite book|title=Goodman and Gilman, Pharmacological Basis of Therapeutics, Macmillan 1965, p. 982-983|isbn=9780071468046|last1=Parker |first1=Keith |last2=Brunton |first2=Laurence |last3=Lazo |first3=John |last4=Buxton |first4=Iain |last5=Blumenthal |first5=Donald |date=September 2005 |publisher=McGraw-Hill Professional }} Camphor was used in ancient Sumatra to treat sprains, swellings, and inflammation.{{cite book |last=Miller |first=Charles |title=History of Sumatra : An account of Sumatra |page=121}} Camphor also was used for centuries in traditional Chinese medicine for various purposes. In Europe, camphor was used after the Black Death era.{{Cite journal |last1=Chen |first1=Weiyang |last2=Vermaak |first2=Ilze |last3=Viljoen |first3=Alvaro |date=10 May 2013 |title=Camphor—a fumigant during the Black Death and a coveted fragrant wood in ancient Egypt and Babylon—a review |journal=Molecules (Basel, Switzerland) |volume=18 |issue=5 |pages=5434–5454 |doi=10.3390/molecules18055434 |issn=1420-3049 |pmc=6270224 |pmid=23666009|doi-access=free }}

In the 20th century, camphor was used as an analeptic by injection,{{Cite journal |last=Wax |first=P. M. |date=1997 |title=Analeptic use in clinical toxicology: a historical appraisal |journal=Journal of Toxicology. Clinical Toxicology |volume=35 |issue=2 |pages=203–209 |doi=10.3109/15563659709001195 |issn=0731-3810 |pmid=9120893}} and to induce seizures in schizophrenic people in an attempt to treat psychosis.Bangen, Hans: Geschichte der medikamentösen Therapie der Schizophrenie. Berlin 1992, Page 51-55 {{ISBN|3-927408-82-4}}

Camphor has limited use in veterinary medicine by intramuscular injection to treat breathing difficulties in horses.{{cite web |title=Camphor injection (Canada) |url=https://www.drugs.com/vet/camphor-injection-can.html |publisher=Drugs.com |access-date=19 February 2020 |date=6 February 2020 |archive-date=27 July 2020 |archive-url=https://web.archive.org/web/20200727064923/https://www.drugs.com/vet/camphor-injection-can.html |url-status=live }}

Camphor is commonly applied as a topical medication as a skin cream or ointment to relieve itching from insect bites, minor skin irritation, or joint pain. It is absorbed in the skin epidermis,{{cite web |title=Camphor cream and ointment |url=https://www.drugs.com/cdi/camphor-cream-and-ointment.html |publisher=Drugs.com |access-date=19 February 2020 |date=25 August 2019 |archive-date=3 May 2021 |archive-url=https://web.archive.org/web/20210503034409/https://www.drugs.com/cdi/camphor-cream-and-ointment.html |url-status=live }} where it stimulates nerve endings sensitive to heat and cold, producing a warm sensation when vigorously applied, or a cool sensation when applied gently, indicating its properties as a counterirritant. The action on nerve endings also induces a slight local analgesia.{{cite book| title=Bonica's Management of Pain|isbn=9780781768276|publisher=Wolters Kluwer - Lippincott Williams & Wilkins|year=2009|location=Philadelphia, Baltimore|edition=4th|pages=29}}

Camphor is also used via an aerosol, typically by steam inhalation, sometimes in the form of branded nasal inhaler sticks, to inhibit coughing and relieve upper airway congestion due to the common cold.{{Cite web |title=Camphor Inhalation Liquid: Indications, Side Effects, Warnings |url=https://www.drugs.com/cdi/camphor-inhalation-liquid.html |access-date=2022-10-28 |website=Drugs.com |language=en}} However, the clinical efficacy of these remedies is challenged.{{Cite journal |last1=Burrow |first1=A. |last2=Eccles |first2=R |last3=Jones |first3=AS |date=July 1983 |title=The effects of camphor, eucalyptus and menthol vapour on nasal resistance to airflow and nasal sensation |journal=Acta Oto-Laryngologica |volume=96 |issue=1–2 |pages=157–161 |doi=10.3109/00016488309132886 |issn=0001-6489 |pmid=6613544}}

Camphor is used by marksmen to blacken the front and rear sights of rifles to prevent the sights from reflecting.[some marksmen] "always blackened their sights by using a small piece of camphor."Chapel, Charles Edward, "The Boy's Book of Rifles, " Coward-McCann, Inc., New York, Copyright 1948, page 96. This is done by setting light to a small amount of camphor, which burns at a relatively low temperature, and using the soot rising from the flame to deposit a coating on a surface held above it. Historically, this soot blackening was also used to coat barograph record charts. A barracks-room rumour possibly derived from an older rumour about saltpetre{{cite web | url=https://www.straightdope.com/21341904/does-saltpeter-suppress-male-ardor | title=Does saltpeter suppress male ardor? | date=16 June 1989 }}{{cite web | url=https://www.militarytimes.com/off-duty/military-culture/2021/09/22/saltpeter-for-sex-drives-and-the-urban-legend-of-the-militarys-libido-manipulation/ | title=Saltpeter for sex drives, and the urban legend of the military's libido manipulation | date=22 September 2021 }} holds that soldiers in the Islamic Republic of Iran are dosed with camphor in their daily meals in order to repress their libido and prevent homosexual incidents.{{Cite news |title=Camphor during military service |work=سرباز مشاور |date=May 2024 |url=https://sarbazmoshaver.com/%DA%A9%D8%A7%D9%81%D9%88%D8%B1-%D8%AF%D8%B1-%D8%B3%D8%B1%D8%A8%D8%A7%D8%B2%DB%8C-%D9%86%D8%AD%D9%88%D9%87-%D8%AE%D9%88%D8%B1%D8%A7%D9%86%D8%AF%D9%86-%D9%88-%D8%B9%D9%88%D8%A7%D8%B1%D8%B6-%D8%A2%D9%86/ |language=fa}}

Camphor is believed to be toxic to insects and is thus sometimes used as a repellent.The Housekeeper's Almanac, or, the Young Wife's Oracle! for 1840!. No. 134. New-York: Elton, 1840. Print. 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. The smoke of camphor crystal or camphor incense sticks can be used as an environmentally-friendly mosquito repellent.{{Cite book

|publisher = APH Publishing

|isbn = 978-8-176-48135-9

|last = Ghosh

|first = G.K.

|title = Biopesticide and Integrated Pest Management

|year = 2000}}

Recent studies have indicated that camphor essential oil can be used as an effective fumigant against red fire ants, as it affects the attacking, climbing, and feeding behavior of major and minor workers.{{Cite journal

|vauthors = Fu JT, Tang L, Li WS, Wang K, Cheng DM, Zhang ZX

|title = Carbon Nanotubes from Camphor: An Environment-Friendly Nanotechnology

|journal = J Insect Sci

|volume = 15

|issue = 1

|pages = 129

|year=2015|doi = 10.1093/jisesa/iev112

|pmid = 26392574

|pmc = 4664941

}}

Camphor is also used as an antimicrobial substance. In embalming, camphor oil was one of the ingredients used by ancient Egyptians for mummification.{{cite web|url=https://www.newscientist.com/article/dn1475-mummymaking-complexity-revealed.html#.VKVwGMksoow|title=Mummy-making complexity revealed|access-date=3 July 2018|archive-date=18 May 2015|archive-url=https://web.archive.org/web/20150518073513/http://www.newscientist.com/article/dn1475-mummymaking-complexity-revealed.html#.VKVwGMksoow|url-status=live}}

In the ancient Arab world, camphor was a common perfume ingredient.{{Cite book

|publisher = Springer Netherlands

|isbn = 978-9-401-12296-2

|last = Groom

|first = N.

|title = The Perfume Handbook

|year = 2012

}} The Chinese referred to the best camphor as "dragon's brain perfume", due to its "pungent and portentous aroma" and "centuries of uncertainty over its provenance and mode of origin".{{Cite book

|publisher = Brill

|isbn = 978-9-004-10983-4

|last = Donkin

|first = R. A.

|title = Dragon's Brain Perfume: An Historical Geography of Camphor

|year = 1999}}

One of the earliest known recipes for ice cream dating to the Tang dynasty includes camphor as an ingredient.{{cite book |last=Clarke |first=Chris |title=Science of Ice Cream |year=2004 |url=https://archive.org/details/scienceicecream00clar_002 |url-access=limited |publisher=Royal Society of chemistry |page=[https://archive.org/details/scienceicecream00clar_002/page/n21 4]}} It was used to flavor leavened bread in ancient Egypt.{{cite book |last1=Muller |first1=H. G. |title=Baking and bakeries |date=1986 |publisher=Shire Publications |isbn=9780852638019 |page=7}} 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 Kitab al-Ṭabikh compiled by ibn Sayyār al-Warrāq in the 10th century.{{Cite book

| publisher = Brill

| series = Islamic History and Civilization, 70

| isbn = 978-0-415-35059-4

| last = Nasrallah

| first = Nawal

| title = Annals of the Caliphs' Kitchens: Ibn Sayyâr al-Warrâq's Tenth-century Baghdadi Cookbook

| location = Leiden, The Netherlands

| year = 2007

}} It also was used in sweet and savory dishes in the Ni'matnama, according to a book written in the late 15th century for the sultans of Mandu.{{Cite book

| publisher = Routledge

| series = Routledge Studies in South Asia

| isbn = 978-0-415-35059-4

| last = Titley

| first = Norah M.

| title = The Ni'matnama Manuscript of the Sultans of Mandu: The Sultan's Book of Delights

| location = London, UK

| year = 2004

}} It is a main constituent of a spice known as "edible camphor" (or kapur), which may be used in traditional South Indian desserts like Payasam and Chakkarai Pongal.{{Cite web |title=5 Unique Culinary Uses Of Edible Camphor To Add To Your Diet |url=https://food.ndtv.com/food-drinks/5-interesting-culinary-uses-of-edible-camphor-you-must-know-1826287 |access-date=2023-01-01 |website=NDTV Food |language=en}}

Camphor is widely used in Hindu religious ceremonies. Aarti is performed after placing it on a stand and setting fire to it usually as the last step of puja or devotional worship ritual to one or more deities.{{cite book|title=The book of Hindu festivals and ceremonies|last=Bahadur|first=Om Lata|isbn=978-81-86112-23-6|publisher=UBS Publishers Distributors ltd.|year=1996|location=New Delhi|edition=3rd|pages=[https://archive.org/details/bookofhindufesti0000baha/page/172 172–3]|url=https://archive.org/details/bookofhindufesti0000baha/page/172}}{{dead link|date=January 2023}} Camphor is mentioned in the Quran as being the fragrance of wine given to believers in heaven.Quran 76:5 pg 578

Applied on skin, camphor may cause allergic reactions in some people; when ingested by mouth, camphor cream or ointment is poisonous. In high ingested doses, camphor produces symptoms of irritability, disorientation, lethargy, muscle spasms, vomiting, abdominal cramps, convulsions, and seizures.{{Cite web | title = Camphor overdose | url = https://www.nlm.nih.gov/medlineplus/ency/article/002566.htm | publisher = MedlinePlus, National Library of Medicine, US National Institutes of Health | date = 12 January 2019 | access-date = 19 February 2020 | archive-date = 5 July 2016 | archive-url = https://web.archive.org/web/20160705120523/https://www.nlm.nih.gov/medlineplus/ency/article/002566.htm | url-status = live }} Lethal doses by ingestion in adults are in the range 50–500 mg/kg (orally). Generally, ingestion of two grams causes serious toxicity and four grams is potentially lethal.{{cite web | publisher = International Programme on Chemical Safety | title = Poisons Information Monograph: Camphor | url = http://www.inchem.org/documents/pims/pharm/camphor.htm | access-date = 12 December 2008 | archive-date = 2021-02-11 | archive-url = https://web.archive.org/web/20210211082914/http://www.inchem.org/documents/pims/pharm/camphor.htm | url-status = live }}

Airborne camphor may be toxic if respired by humans. The permissible exposure limit (PEL) for camphor in ambient air is 2 mg/m³ at exposure time (TWA) not more than 8 hours. 200 mg/m³ is considered a very dangerous concentration (IDLH).{{Cite web |title=CAMPHOR {{!}} Occupational Safety and Health Administration |url=https://www.osha.gov/chemicaldata/612 |access-date=2022-11-29 |website=www.osha.gov}}

When its use 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,{{Citation |last=Kennedy Duncan |first=Robert |year=1911 |title=Some Chemical Problems of Today |chapter=Camphor: An Industry Revolutionized |publisher=Harper and Brothers |chapter-url=https://books.google.com/books?id=JBVDAAAAIAAJ&pg=PA128 |lccn=11026192 |postscript=. |access-date=2018-01-17 |archive-date=2020-07-27 |archive-url=https://web.archive.org/web/20200727161621/https://books.google.com/books?id=JBVDAAAAIAAJ&pg=PA128 |url-status=live }} which began in "purely academic and wholly uncommercial" form with Gustav Komppa's first report:

{{Blockquote|"{{Omission}} but it sealed the fate of the Japanese monopoly {{Omission}} 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 {{Omission}} 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."{{rp|133–134}}}}

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 US 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."{{Citation |last=Dutton |first=William S. |year=1942 |title=Du Pont: One Hundred and Forty Years |publisher=Charles Scribner's Sons |url=https://books.google.com/books?id=WEtZAAAAYAAJ |lccn=42011897 |postscript=. |access-date=2018-01-17 |archive-date=2020-08-04 |archive-url=https://web.archive.org/web/20200804134517/https://books.google.com/books?id=WEtZAAAAYAAJ |url-status=live }}{{rp|293}}

{{Anchor|Komppa 1903}} 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, and began industrial production of camphor in Tainionkoski, Finland, in 1907 (with plenty of competition, as Kennedy Duncan reported).{{citation needed|date=June 2022}}

A different way of synthesis was developed at the same time by Dr. Karl Stephan from Chemische Fabrik auf Actien. This chemist, who had patented a route to synthesize camphene in 1902, found out that borneol or isoborneol could easily be oxidized with permanganate in benzene solution with unprecedentedly high yields of 95+%, and patented it in 1903.{{Cite patent|country=CA|number=84302A|title=Process of making camphor|pubdate=|gdate=}}; {{Cite patent|country=AT|number=21683B|title=Verfahren zur Darstellung von Kampfer}} The process was efficient enough to compete with natural camphor, and Japan was forced to lower prices in 1907, but the German company still increased its production, reaching 623 tons in 1913, only to be interrupted by the First World War.{{Cite web |title=The Raw Materials of Celluloid Film: Wartime Economy, Educational Animation, and Film's Plasticity |url=https://film-history.org/issues/text/raw-materials-celluloid-film |access-date=2024-06-10 |website=film-history.org |language=en}}

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

{{Reflist|30em}}

{{EB1911 poster|Camphors}}

• [http://www.inchem.org/documents/pims/pharm/camphor.htm INCHEM] at IPCS (International Programme on Chemical Safety)
• [https://www.cdc.gov/niosh/npg/npgd0096.html NIOSH Pocket Guide to Chemical Hazards – Camphor] at Centers for Disease Control and Prevention

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