Editing Acetylene (section)

==Applications==
===Welding===
Approximately 20% of acetylene is supplied by the [[Industrial gas|industrial gases industry]] for [[oxyacetylene]] [[gas welding]] and [[Oxy-fuel welding and cutting|cutting]] due to the high temperature of the flame. Combustion of acetylene with oxygen produces a flame of over {{convert|3600|K|C F}}, releasing 11.8&nbsp;[[Kilojoule|kJ]]/g. Oxygen with acetylene is the hottest burning common gas mixture.<ref name=Linde2013>{{cite web |url=http://www.linde-gas.com/en/products_and_supply/gases_fuel/acetylene.html |title=Acetylene |access-date=2013-11-30 |publisher=Linde |website=Products and Supply > Fuel Gases |archive-date=12 January 2018 |archive-url=https://web.archive.org/web/20180112184128/http://www.linde-gas.com/en/products_and_supply/gases_fuel/acetylene.html |url-status=live }}</ref> Acetylene is the third-hottest natural chemical flame after [[dicyanoacetylene]]'s {{convert|5260|K|C F}} and [[cyanogen]] at {{convert|4798|K|C F}}. [[Oxy-fuel welding and cutting|Oxy-acetylene welding]] was a popular welding process in previous decades. The development and advantages of [[arc welding|arc-based welding processes]] have made oxy-fuel welding nearly extinct for many applications. Acetylene usage for welding has dropped significantly. On the other hand, oxy-acetylene welding ''equipment'' is quite versatile – not only because the torch is preferred for some sorts of iron or steel welding (as in certain artistic applications), but also because it lends itself easily to brazing, braze-welding, metal heating (for annealing or tempering, bending or forming), the loosening of corroded nuts and bolts, and other applications. [[Bell Canada]] cable-repair technicians still use portable acetylene-fuelled torch kits as a [[soldering]] tool for sealing lead sleeve splices in [[manhole]]s and in some aerial locations. Oxyacetylene welding may also be used in areas where electricity is not readily accessible. Oxyacetylene cutting is used in many metal fabrication shops. For use in welding and cutting, the working pressures must be controlled by a regulator, since above {{convert|15|psi|abbr=on}}, if subjected to a shockwave (caused, for example, by a [[flashback (welding)|flashback]]), acetylene [[decompose]]s explosively into [[hydrogen]] and [[carbon]].<ref>[http://www.esabna.com/euweb/oxy_handbook/589oxy3_3.htm ESAB Oxy-acetylene welding handbook – Acetylene properties] {{Webarchive|url=https://web.archive.org/web/20200510192947/https://www.esabna.com/euweb/oxy_handbook/589oxy3_3.htm |date=10 May 2020 }}.</ref>

[[File:Laskarbit.jpg|thumb|200px|Acetylene fuel container/burner as used in the island of [[Bali]]]]

===Chemicals===
Acetylene is useful for many processes, but few are conducted on a commercial scale.<ref name=trot>{{cite journal |doi=10.1021/cr400357r |title=Catalytic Reactions of Acetylene: A Feedstock for the Chemical Industry Revisited |date=2014 |last1=Trotuş |first1=Ioan-Teodor |last2=Zimmermann |first2=Tobias |last3=Schüth |first3=Ferdi |journal=Chemical Reviews |volume=114 |issue=3 |pages=1761–1782 |pmid=24228942 |doi-access=free }}</ref>

One of the major chemical applications is [[ethynylation]] of formaldehyde.<ref name="Ullmann" /> 
Acetylene adds to [[Aldehyde|aldehydes]] and [[Ketone|ketones]] to form α-ethynyl alcohols:
:[[File:Reppe-chemistry-endiol-V1.svg|300px]]
The reaction gives [[1,4-Butynediol|butynediol]], with [[propargyl alcohol]] as the by-product. [[Copper(I) acetylide|Copper acetylide]] is used as the catalyst.<ref>{{Citation |last1=Gräfje |first1=Heinz |title=Butanediols, Butenediol, and Butynediol |date=2000-06-15 |url=https://onlinelibrary.wiley.com/doi/10.1002/14356007.a04_455 |encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry |pages=a04_455 |editor-last=Wiley-VCH Verlag GmbH & Co. KGaA |place=Weinheim, Germany |publisher=Wiley-VCH Verlag GmbH & Co. KGaA |language=en |doi=10.1002/14356007.a04_455 |isbn=978-3-527-30673-2 |access-date=2022-03-03 |last2=Körnig |first2=Wolfgang |last3=Weitz |first3=Hans-Martin |last4=Reiß |first4=Wolfgang |last5=Steffan |first5=Guido |last6=Diehl |first6=Herbert |last7=Bosche |first7=Horst |last8=Schneider |first8=Kurt |last9=Kieczka |first9=Heinz |s2cid=178601434 |archive-date=19 March 2022 |archive-url=https://web.archive.org/web/20220319160632/https://onlinelibrary.wiley.com/doi/10.1002/14356007.a04_455 |url-status=live }}</ref><ref>{{Citation |last1=Falbe |first1=Jürgen |title=Alcohols, Aliphatic |date=2000-06-15 |url=https://onlinelibrary.wiley.com/doi/10.1002/14356007.a01_279 |encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry |pages=a01_279 |editor-last=Wiley-VCH Verlag GmbH & Co. KGaA |place=Weinheim, Germany |publisher=Wiley-VCH Verlag GmbH & Co. KGaA |language=en |doi=10.1002/14356007.a01_279 |isbn=978-3-527-30673-2 |access-date=2022-03-03 |last2=Bahrmann |first2=Helmut |last3=Lipps |first3=Wolfgang |last4=Mayer |first4=Dieter |archive-date=9 March 2022 |archive-url=https://web.archive.org/web/20220309153410/https://onlinelibrary.wiley.com/doi/10.1002/14356007.a01_279 |url-status=live}}</ref>

In addition to ethynylation, acetylene reacts with [[carbon monoxide]], acetylene reacts to give [[acrylic acid]], or acrylic esters.  Metal catalysts are required. These derivatives form products such as [[acrylic fiber]]s, [[Acrylic glass|glass]]es, [[Acrylic paint|paint]]s, [[Acrylic resin|resin]]s, and [[Acrylate polymer|polymer]]s. Except in China, use of acetylene as a chemical feedstock has declined by 70% from 1965 to 2007 owing to cost and environmental considerations.<ref>{{cite journal|author1=Takashi Ohara|author2=Takahisa Sato|author3=Noboru Shimizu|author4=Günter Prescher|author5=Helmut Schwind|author6=Otto Weiberg|author7=Klaus Marten|author8=Helmut Greim|title=Acrylic Acid and Derivatives|journal=Ullmann's Encyclopedia of Industrial Chemistry|year=2003|page=7|doi=10.1002/14356007.a01_161.pub2|isbn=3527306730 }}</ref>  In China, acetylene is a major precursor to [[vinyl chloride]].<ref name=trot/>

===Historical uses===
Prior to the widespread use of petrochemicals, coal-derived acetylene was a building block for several industrial chemicals.  Thus acetylene can be hydrated to give [[acetaldehyde]], which in turn can be oxidized to acetic acid.  Processes leading to acrylates were also commercialized. Almost all of these processes became obsolete with the availability of petroleum-derived ethylene and propylene.<ref>{{cite journal |doi=10.1021/cr400276u |title=Production of Acetylene and Acetylene-based Chemicals from Coal |date=2014 |last1=Schobert |first1=Harold |journal=Chemical Reviews |volume=114 |issue=3 |pages=1743–1760 |pmid=24256089 }}</ref>

===Niche applications===
In 1881, the Russian chemist Mikhail Kucherov<ref>{{Cite journal|doi=10.1002/cber.188101401320|title=Ueber eine neue Methode direkter Addition von Wasser (Hydratation) an die Kohlenwasserstoffe der Acetylenreihe|year=1881|last1=Kutscheroff|first1=M.|journal=Berichte der Deutschen Chemischen Gesellschaft|volume=14|pages=1540–1542|url=https://zenodo.org/record/1425226|access-date=9 September 2019|archive-date=2 December 2020|archive-url=https://web.archive.org/web/20201202225306/https://zenodo.org/record/1425226|url-status=live}}</ref> described the [[Hydration reaction|hydration]] of acetylene to [[acetaldehyde]] using catalysts such as [[mercury(II) bromide]]. Before the advent of the [[Wacker process]], this reaction was conducted on an industrial scale.<ref>{{cite journal | title = Hydration of Acetylene: A 125th Anniversary | author1 = Dmitry A. Ponomarev | author2 = Sergey M. Shevchenko | journal = [[J. Chem. Educ.]] | volume = 84 | issue = 10 | year = 2007 | page = 1725 | url = http://jchemed.chem.wisc.edu/HS/Journal/Issues/2007/OctACS/ACSSub/p1725.pdf | doi = 10.1021/ed084p1725 | bibcode = 2007JChEd..84.1725P | access-date = 18 February 2009 | archive-date = 11 June 2011 | archive-url = https://web.archive.org/web/20110611190527/http://jchemed.chem.wisc.edu/HS/Journal/Issues/2007/OctACS/ACSSub/p1725.pdf | url-status = live }}</ref>

The [[polymerization]] of acetylene with [[Ziegler–Natta catalyst]]s produces [[polyacetylene]] films. Polyacetylene, a chain of CH centres with alternating single and double bonds, was one of the first discovered [[organic semiconductor]]s. Its reaction with [[iodine]] produces a highly electrically conducting material. Although such materials are not useful, these discoveries led to the developments of [[organic semiconductor]]s, as recognized by the [[Nobel Prize in Chemistry]] in 2000 to [[Alan J. Heeger]], [[Alan G MacDiarmid]], and [[Hideki Shirakawa]].<ref name=Ullmann/>

In the 1920s, pure acetylene was experimentally used as an [[inhalation anesthetic]].<ref>{{cite encyclopedia |year=1930 |title=Acetylene in medicine|encyclopedia=[[Encyclopaedia Britannica]] |edition=14|volume=1|page=119 |author=William Stanley Sykes |author-link=William Stanley Sykes |language=en}}</ref>

Acetylene is sometimes used for [[carburization]] (that is, hardening) of steel when the object is too large to fit into a furnace.<ref name=BOC2006>{{cite web |url=http://boc.com/products_and_services/by_product/acetylene/index.asp |title=Acetylene |publisher=BOC |website=Products and Services |archive-url=https://web.archive.org/web/20060517074022/http://boc.com/products_and_services/by_product/acetylene/index.asp |archive-date=2006-05-17 }}</ref>

Acetylene is used to volatilize carbon in [[radiocarbon dating]]. The carbonaceous material in an archeological sample is treated with [[lithium]] metal in a small specialized research furnace to form [[lithium carbide]] (also known as lithium acetylide). The carbide can then be reacted with water, as usual, to form acetylene gas to feed into a [[mass spectrometer]] to measure the isotopic ratio of carbon-14 to carbon-12.<ref>{{cite journal|last=Geyh, Mebus|title=Radiocarbon dating problems using acetylene as counting gas|journal=Radiocarbon|year=1990|volume=32|issue=3|pages=321–324|doi=10.2458/azu_js_rc.32.1278|url=https://journals.uair.arizona.edu/index.php/radiocarbon/article/view/1278/1283|access-date=2013-12-26|archive-date=26 December 2013|archive-url=https://web.archive.org/web/20131226194553/https://journals.uair.arizona.edu/index.php/radiocarbon/article/view/1278/1283|url-status=live|doi-access=free}}</ref>

Acetylene combustion produces a strong, bright light and the ubiquity of [[Carbide lamp|carbide lamps]] drove much acetylene commercialization in the early 20th century. Common applications included coastal [[Lighthouse|lighthouses]],<ref>{{Cite web|title=Lighthouse Lamps Through Time by Thomas Tag {{!}} US Lighthouse Society|url=http://uslhs.org/lighthouse-lamps-through-time|access-date=2017-02-24|website=uslhs.org|language=en|archive-date=25 February 2017|archive-url=https://web.archive.org/web/20170225130406/http://uslhs.org/lighthouse-lamps-through-time|url-status=live}}</ref> [[Street light|street lights]],
<ref name="Myers">{{Cite book|last=Myers|first=Richard L.|url=https://books.google.com/books?id=0AnJU-hralEC|title=The 100 Most Important Chemical Compounds: A Reference Guide|date=2007|publisher=ABC-CLIO|isbn=978-0-313-33758-1|language=en|pages=7-9|access-date=21 November 2015|archive-date=17 June 2016|archive-url=https://web.archive.org/web/20160617093705/https://books.google.com/books?id=0AnJU-hralEC|url-status=live}}</ref> and [[Headlamp|automobile]]<ref>Grainger, D., (2001). By cars' early light: A short history of the headlamp: 1900s lights bore port and starboard red and green lenses. National Post. [Toronto Edition] DT7.</ref> and [[Miner's helmet|mining]] [[Headlamp (outdoor)|headlamps]].<ref name="Thorpe-2005">{{cite book|last=Thorpe|first=Dave|title=Carbide Light: The Last Flame in American Mines|publisher=Bergamot Publishing|year=2005|isbn=978-0976090526}}</ref> In most of these applications, direct combustion is a [[fire hazard]], and so acetylene has been replaced, first by [[Incandescent light bulb|incandescent lighting]] and many years later by low-power/high-lumen LEDs. Nevertheless, acetylene lamps remain in limited use in remote or otherwise inaccessible areas and in countries with a weak or unreliable central [[Electrical grid|electric grid]].<ref name="Thorpe-2005"/>