Editing Ethylene glycol (section)

== Production ==
===Industrial routes===
Ethylene glycol is produced from [[ethylene]] (ethene), via the intermediate [[ethylene oxide]]. Ethylene oxide reacts with [[water]] to produce ethylene glycol according to the [[chemical equation]]

: {{chem2|C_{2}H_{4}O + H_{2}O -> HO\sCH_{2}CH_{2}\sOH}}

This [[chemical reaction|reaction]] can be [[catalyst|catalyzed]] by either [[acid]]s or [[Base (chemistry)|bases]], or can occur at neutral [[pH]] under elevated temperatures. The highest yields of ethylene glycol occur at acidic or neutral pH with a large excess of water. Under these conditions, ethylene glycol yields of 90% can be achieved. The major byproducts are the oligomers [[diethylene glycol]], [[triethylene glycol]], and [[tetraethylene glycol]]. The separation of these oligomers and water is energy-intensive. World production of ethylene glycol was ~20&nbsp;Mt in 2010.<ref name="YueZhaoMa2012">{{cite journal |last1=Yue |first1=Hairong |last2=Zhao |first2=Yujun |last3=Ma |first3=Xinbin |last4=Gong |first4=Jinlong |title=Ethylene glycol: properties, synthesis, and applications |journal=Chemical Society Reviews |date=2012 |volume=41 |issue=11 |pages=4218–4244 |issn=0306-0012 |eissn=1460-4744 |doi=10.1039/c2cs15359a |pmid=22488259}}</ref>

A higher selectivity is achieved by the use of [[Royal Dutch Shell|Shell]]'s [[OMEGA process]]. In the OMEGA process, the ethylene oxide is first converted with [[carbon dioxide]] ({{CO2}}) to [[ethylene carbonate]]. This ring is then hydrolyzed with a base catalyst in a second step to produce mono-ethylene glycol in 98% selectivity.<ref>Scott D. Barnicki, "Synthetic Organic Chemicals", in ''Handbook of Industrial Chemistry and Biotechnology'' edited by James A. Kent, New York: Springer, 2012. 12th&nbsp;ed. {{ISBN|978-1-4614-4259-2}}.</ref> The carbon dioxide is released in this step again and can be fed back into the process circuit. The carbon dioxide comes in part from ethylene oxide production, where a part of the ethylene is completely [[oxidation|oxidized]].

Ethylene glycol is produced from [[carbon monoxide]] in countries with large coal reserves and less stringent environmental regulations. The oxidative carbonylation of methanol to [[dimethyl oxalate]] provides a promising approach to the production of {{chem|C|1}}-based ethylene glycol.<ref>{{cite web |url=http://www.chemsystems.com/reports/search/docs/prospectus/stmc10_coal_meg.pdf |title=Coal to MEG, Changing the Rules of the Game |website=Nexant/Chemsystems |access-date=2016-08-08 |url-status=dead |archive-url=https://web.archive.org/web/20110714135349/http://www.chemsystems.com/reports/search/docs/prospectus/stmc10_coal_meg.pdf |archive-date=July 14, 2011}} (PDF; 5.4&nbsp;MB), 2011 Prospectus.</ref> Dimethyl oxalate can be converted into ethylene glycol in high yields (94.7%)<ref>{{cite patent |country=EP |number=046 983 |status= |title=Process for continuously preparing ethylene glycol |pubdate= |gdate= |fdate=1982-03-10 |pridate= |inventor = |invent1=S. Tahara et al. |assign1=Ube Industries}} and H. T. Teunissen and C. J. Elsevier, ''Ruthenium catalyzed hydrogenation of dimethyl oxalate to ethylene glycol'', J. Chem. Soc., Chem. Commun., 1997, 667–668), {{DOI|10.1039/A700862G}}.</ref> by [[hydrogenation]] with a copper catalyst:<ref>S. Zhang et al., ''Highly-Dispersed Copper-Based Catalysts from Cu–Zn–Al Layered Double Hydroxide Precursor for Gas-Phase Hydrogenation of Dimethyl Oxalate to Ethylene Glycol'', Catalysis Letters, Sept. 2012, '''142''' (9), 1121–1127, {{DOI|10.1007/s10562-012-0871-8}}.</ref>

[[File:MEG ex CO.svg|center]]

Because the methanol is recycled, only carbon monoxide, hydrogen, and oxygen are consumed. One plant with a production capacity of {{val|200000|u=tons}} of ethylene glycol per year is in [[Inner Mongolia]], and a second plant in the Chinese province of [[Henan]] with a capacity of {{val|250000|u=tons per year}} was scheduled for 2012.<ref>{{Cite web |url=http://www.icis.com/resources/news/2012/01/30/9527520/china-s-coal-based-chemicals-are-a-trade-off/ |title=China's coal-based chemicals are a trade-off |author=Clay Boswell |date=30 Jan 2012 |publisher=Independent Commodity Intelligence Services}}</ref> {{As of|2015}}, four plants in China with a capacity of {{val|200000|u=t/a}} each were operating, with at least 17 more to follow.<ref>{{Cite book |url=https://books.google.com/books?id=EPCeBgAAQBAJ&q=meg+china+synthesis+gas&pg=PA15 |title=Industrial Coal Gasification Technologies Covering Baseline and High-Ash Coal |isbn=978-3-527-33690-6 |last1=Gräbner |first1=Martin |date=2014-11-24 |publisher=John Wiley & Sons}}</ref>

===Biological routes===
Ethylene glycol can be produced by recycling its polymeric derivatives, such as [[polyethylene terephthalate]].<ref>{{cite journal |doi=10.1021/acs.chemrev.2c00644 |title=Enzymes' Power for Plastics Degradation |date=2023 |last1=Tournier |first1=Vincent |last2=Duquesne |first2=Sophie |last3=Guillamot |first3=Frédérique |last4=Cramail |first4=Henri |last5=Taton |first5=Daniel |last6=Marty |first6=Alain |last7=André |first7=Isabelle |journal=Chemical Reviews |volume=123 |issue=9 |pages=5612–5701 |pmid=36916764 |url=https://hal.science/hal-04150645/file/Andre_Chemical_Reviews_HAL.pdf }}</ref>

=== Historical routes ===
According to most sources, French chemist [[Charles-Adolphe Wurtz]] (1817–1884) first prepared ethylene glycol in 1856.<ref>{{cite journal | author = Adolphe Wurtz | author-link = Charles-Adolphe Wurtz | date = 1856 | url = http://gallica.bnf.fr/ark:/12148/bpt6k3000k/f203.image | title = Sur le glycol ou alcool diatomique |trans-title=On glycol or dibasic alcohol | journal = Comptes Rendus | volume = 43 | pages = 199–204}}</ref>  He first treated "ethylene iodide" ([[1,2-Diiodoethane]]) with silver acetate and then hydrolyzed the resultant "ethylene diacetate" with [[potassium hydroxide]]. Wurtz named his new compound "glycol" because it shared qualities with both [[ethyl alcohol]] (with one hydroxyl group) and [[glycerin]] (with three hydroxyl groups).<ref>Wurtz (1856), page 200: ''"… je propose de le nommer ''glycol'', parce qu'il se rapproche à la fois, par ses propriétés, de l'alcool proprement dit et de la glycérin, entre lesquels il se trouve placé."'' ( … I propose to call it ''glycol'' because, by its properties, it is simultaneously close to [ethyl] alcohol properly called and glycerin, between which it is placed.)</ref> In 1859, Wurtz prepared ethylene glycol via the [[Hydration reaction|hydration]] of [[ethylene oxide]].<ref>Ad. Wurtz (1859) [http://gallica.bnf.fr/ark:/12148/bpt6k3006f/f815.item.r=.zoom "Synthèse du glycol avec l'oxyde d'éthylène et l'eau"] (Synthesis of glycol from ethylene oxide and water), ''Comptes rendus'', '''49''' :  813–815.</ref> There appears to have been no commercial manufacture or application of ethylene glycol prior to [[World War I]], when it was synthesized from [[ethylene dichloride]] in Germany and used as a substitute for [[glycerol]] in the [[explosives]] industry.

In the United States, semicommercial production of ethylene glycol via [[ethylene chlorohydrin]] started in 1917. The first large-scale commercial glycol plant was erected in 1925 at [[South Charleston, West Virginia]], by Carbide and Carbon Chemicals Co. (now [[Union Carbide]] Corp.). By 1929, ethylene glycol was being used by almost all [[dynamite]] manufacturers. In 1937, Carbide started up the first plant based on Lefort's process for vapor-phase oxidation of ethylene to ethylene oxide. Carbide maintained a monopoly on the direct oxidation process until 1953 when the Scientific Design process was commercialized and offered for licensing.