View source for Ethylene

{{Short description|1=Hydrocarbon compound (H2C=CH2)}}
{{Redirect-distinguish|Ethene|Ethane|Ethyne}}
{{Chembox
| Watchedfields  = changed
| verifiedrevid  = 477167214
| ImageFile      = Ethylene-CRC-MW-dimensions-2D-Vector.svg
| ImageSize      = 160px
| ImageClass     = skin-invert-image
| ImageFileL1    = Ethylene-CRC-MW-3D-balls.png
| ImageFileR1    = Ethylene-3D-vdW.png
| PIN            = Ethene<ref>{{Cite web|url=https://pubchem.ncbi.nlm.nih.gov/compound/6325#section=IUPAC-Name&fullscreen=true|title=Ethylene|access-date=2021-05-27|archive-date=2023-10-08|archive-url=https://web.archive.org/web/20231008084336/https://pubchem.ncbi.nlm.nih.gov/compound/6325#section=IUPAC-Name&fullscreen=true|url-status=live}}</ref>
| SystematicName = Ethene
| OtherNames     = Refrigerant R-1150
| Section1       = {{Chembox Identifiers
| Beilstein = 1730731
| CASNo = 74-85-1
| CASNo_Ref = {{cascite|correct|CAS}}
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 18153
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 117822
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 6085
| EC_number = 200-815-3
| Gmelin = 214
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = C06547
| PubChem = 6325
| RTECS = KU5340000
| UNNumber = 1962 1038
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 91GW059KN7
| SMILES = C=C
| InChI=1/C2H4/c1-2/h1-2H2
| InChIKey = VGGSQFUCUMXWEO-UHFFFAOYAE
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C2H4/c1-2/h1-2H2
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = VGGSQFUCUMXWEO-UHFFFAOYSA-N
  }}
| Section2       = {{Chembox Properties
| Formula = {{chem|C|2|H|4}}
| C = 2| H = 4 <!-- calculate molar mass -->
| Appearance = colourless gas
| Density = 1.178&nbsp;kg/m<sup>3</sup> at 15&nbsp;°C, gas<ref name="GESTIS">{{GESTIS|ZVG=12710|Name=Ethylene|Date=25 October 2007}}</ref>
| MeltingPtC = -169.2
| BoilingPtC = -103.7
| Solubility = 131&nbsp;mg/L (25&nbsp;°C);<ref name="JPhysChem1966">{{cite journal |title=Solubility in Water of Paraffin, Cycloparaffin, Olefin, Acetylene, Cycloolefin, and Aromatic Hydrocarbons |journal=Journal of Physical Chemistry |date=1966 |author=McAuliffe, C. |volume=70 |number=4 |pages=1267–1275 |doi=10.1021/j100876a049 |bibcode=1966JPhCh..70.1267M }}</ref> 2.9&nbsp;mg/L<ref name="neilands">Neiland, O. Ya. (1990) ''Органическая химия: Учебник для хим. спец. вузов''. Moscow. Vysshaya Shkola. p. 128.</ref>
| Solubility1 = 4.22&nbsp;mg/L<ref name="neilands" />
| Solvent1 = ethanol
| Solubility2 = good<ref name="neilands" />
| Solvent2 = diethyl ether
| pKa = 44
| ConjugateAcid = [[Ethenium]]
| MagSus = −15.30·10<sup>−6</sup> cm<sup>3</sup>/mol
| Viscosity = 10.28 μPa·s<ref name="Kestin1977">{{cite journal |title=The viscosity of five gaseous hydrocarbons |journal=The Journal of Chemical Physics |date=1977 |vauthors=Kestin J, Khalifa HE, Wakeham WA |volume=66 |issue=3 |pages=1132–1134 |doi=10.1063/1.434048 |bibcode=1977JChPh..66.1132K}}</ref>  
}}
| Section3       = {{Chembox Structure
| MolShape = D<sub>2h</sub>
| Dipole = zero
  }}
| Section4       = {{Chembox Thermochemistry
| DeltaHf = +52.47 kJ/mol
| DeltaHc =
| Entropy = 219.32 J·K<sup>−1</sup>·mol<sup>−1</sup>
| HeatCapacity =
  }}
| Section7       = {{Chembox Hazards
| ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics0475.htm ICSC 0475]
| GHSPictograms = {{GHS02}}{{GHS07}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|220|336}}
| PPhrases = {{P-phrases|210|261|271|304+340|312|377|381|403|403+233|405|501}}
| NFPA-H = 2
| NFPA-F = 4
| NFPA-R = 2
| NFPA-S =
| FlashPtC = −136
| AutoignitionPtC = 542.8
  }}<ref>[http://cameochemicals.noaa.gov/chemical/8655 ETHYLENE | CAMEO Chemicals | NOAA] {{Webarchive|url=https://web.archive.org/web/20150402200815/http://cameochemicals.noaa.gov/chemical/8655 |date=2015-04-02 }}. Cameochemicals.noaa.gov. Retrieved on 2016-04-24.</ref>
| Section8       = {{Chembox Related
| OtherFunction =
| OtherFunction_label =
| OtherCompounds = [[Ethane]]<br />[[Acetylene]] <br />[[Propene]]
  }}
}}

'''Ethylene''' ([[IUPAC]] name: '''ethene''') is a [[hydrocarbon]] which has the formula {{chem2|C2H4}} or {{chem2|H2C\dCH2}}. It is a colourless, [[flammable]] gas with a faint "sweet and [[musk]]y" odour when pure.<ref name=UllmannEthylene/> It is the simplest [[alkene]] (a hydrocarbon with [[carbon–carbon bond|carbon–carbon]] [[double bond]]s).

Ethylene is widely used in the chemical industry, and its worldwide production (over 225 million [[tonne]]s in 2022)<ref>{{cite web |title=Decarbonization approaches for ethylene production: comparative techno-economic and life-cycle analysis |url=https://pubs.rsc.org/en/content/articlehtml/2025/gc/d4gc04538f#:~:text=3%2C4,Japan%2C%20Germany%2C%20and%20Canada. |website=Royal Society of Chemistry |publisher=Royal Society of Chemistry |access-date=13 November 2025}}</ref> exceeds that of any other [[organic compound]].<ref name="cenews">{{cite journal |title=Production: Growth is the Norm |journal=Chemical and Engineering News |volume=84 |issue=28 |pages=59–236 |date=July 10, 2006 |doi=10.1021/cen-v084n034.p059}}</ref><ref name="Technology Economics Program">{{cite book |url=http://www.slideshare.net/intratec/propylene-production-from-methanol |title=Propylene Production from Methanol |publisher=Intratec |isbn=978-0-615-64811-8 |date=2012-05-31 |access-date=2012-09-17 |archive-date=2016-03-04 |archive-url=https://web.archive.org/web/20160304063136/http://www.slideshare.net/intratec/propylene-production-from-methanol |url-status=live }}</ref> Much of this production goes toward creating [[polyethylene]], which is a widely used [[plastic]] containing [[polymer]] chains of ethylene units in various chain lengths. Production [[greenhouse gas emissions|emits greenhouse gases]], including [[methane]] from [[feedstock]] production and [[carbon dioxide]] from any non-[[sustainable energy]] used.

Ethylene is also an important natural [[plant hormone]] and is used in agriculture to induce [[ripening]] of [[fruit]]s.<ref name="Wang_2002">{{cite journal |vauthors=Wang KL, Li H, Ecker JR |title=Ethylene biosynthesis and signaling networks |journal=[[The Plant Cell]] |volume=14 |issue=Suppl |pages=S131-151 |year=2002 |pmid=12045274 |pmc=151252 |doi=10.1105/tpc.001768|bibcode=2002PlanC..14S.131W }}</ref> The [[hydrate]] of ethylene is [[ethanol]].

==Structure and properties==
[[Image:Dewar-Chatt-Duncanson model.png|thumb|260 px|left|Orbital description of bonding between ethylene and a transition metal]]
This [[hydrocarbon]] has four [[hydrogen]] [[atom]]s bound to a pair of [[carbon]] atoms that are connected by a [[double bond]]. All six atoms that comprise ethylene are [[coplanar]]. The H-C-H [[angle]] is 117.4°, close to the 120° for ideal sp² [[hybridization (chemistry)|hybridized]] carbon. The molecule is also relatively weak: rotation about the C-C bond is a very low energy process that requires breaking the [[Pi bond|π-bond]] by supplying heat at 50&nbsp;°C.{{Citation needed|date=January 2021}}

The [[Pi bond|π-bond]] in the ethylene molecule is responsible for its useful reactivity. The double bond is a region of high [[electron density]], thus it is susceptible to attack by [[electrophiles]]. Many reactions of ethylene are catalyzed by transition metals, which bind temporarily to the ethylene using both the π and π* orbitals.{{Citation needed|date=January 2021}}

Being a simple molecule, ethylene is spectroscopically simple. Its UV-vis [[Spectroscopy|spectrum]] is still used as a test of theoretical methods.<ref name=NIST_Webbook>{{cite web |title=Ethylene:UV/Visible Spectrum |work=NIST Webbook |url=http://webbook.nist.gov/cgi/cbook.cgi?ID=C74851&Units=SI&Mask=400#UV-Vis-Spec |access-date=2006-09-27 |archive-date=2017-01-19 |archive-url=https://web.archive.org/web/20170119013204/http://webbook.nist.gov/cgi/cbook.cgi?ID=C74851&Units=SI&Mask=400#UV-Vis-Spec |url-status=live }}</ref>

==Uses==
[[File:Uses_of_Ethene.tif|thumb|left|Diagram of uses of ethene]]
Major industrial reactions of ethylene include in order of scale: 1) [[polymerization]], 2) [[oxidation]], 3) [[halogenation]] and [[hydrohalogenation]], 4) [[alkylation]], 5) [[Hydration reaction|hydration]], 6) [[oligomerization]], and 7) [[hydroformylation]]. In the [[United States]] and [[Europe]], approximately 90% of ethylene is used to produce [[ethylene oxide]], [[ethylene dichloride]], [[ethylbenzene]] and [[polyethylene]].<ref name="inchem">{{cite web |url=http://www.inchem.org/documents/sids/sids/74851.pdf |title=OECD SIDS Initial Assessment Profile — Ethylene |publisher=inchem.org |access-date=2008-05-21 |archive-url=https://web.archive.org/web/20150924051942/http://www.inchem.org/documents/sids/sids/74851.pdf |archive-date=2015-09-24 |url-status=dead}}</ref> Most of the reactions with ethylene are [[electrophilic addition]].{{Citation needed|date=January 2021}}

[[Image:C2H4uses.png|thumb|520 px|left|Main industrial uses of ethylene. Clockwise from the upper right: its conversions to [[ethylene oxide]], precursor to [[ethylene glycol]]; to [[ethylbenzene]], precursor to [[styrene]]; to various kinds of [[polyethylene]]; to [[ethylene dichloride]], precursor to [[vinyl chloride]].]]
{{clear|left}}

===Polymerization===
{{See also|Ziegler–Natta catalyst|Polyethylene}}
Polyethylene production uses more than half of the world's ethylene supply. Polyethylene, also called ''polyethene'' and ''polythene'', is the world's most widely used plastic. It is primarily used to make films in [[packaging]], [[carrier bags]] and trash [[bin bag|liners]]. Linear [[alpha-olefins]], produced by [[oligomerization]] (formation of short-chain molecules) are used as [[precursor (chemistry)|precursors]], [[detergents]], [[plasticisers]], [[synthetic lubricants]], additives, and also as co-monomers in the production of polyethylenes.<ref name="inchem" />

===Oxidation===
Ethylene is [[oxidation|oxidized]] to produce [[ethylene oxide]], a key raw material in the production of [[surfactant]]s and [[detergent]]s by [[ethoxylation]]. Ethylene oxide is also hydrolyzed to produce [[ethylene glycol]], widely used as an automotive antifreeze as well as higher molecular weight glycols, [[glycol ethers]], and [[polyethylene terephthalate]].<ref>{{Cite web|title=Ethylene Glycol: Systemic Agent|url=https://www.cdc.gov/niosh/ershdb/emergencyresponsecard_29750031.html|website=Center for Disease Control|date=20 October 2021|access-date=20 February 2022|archive-date=26 December 2017|archive-url=https://web.archive.org/web/20171226021019/https://www.cdc.gov/niosh/ershdb/EmergencyResponseCard_29750031.html|url-status=live}}</ref><ref>{{Cite web|title=Ethylene Glycol|url=https://www.sciencedirect.com/topics/engineering/ethylene-glycol|website=Science Direct|access-date=2022-02-20|archive-date=2022-02-20|archive-url=https://web.archive.org/web/20220220235304/https://www.sciencedirect.com/topics/engineering/ethylene-glycol|url-status=live}}</ref>

{{Main|Wacker process}}

Ethylene oxidation in the presence of a  palladium catalyst can form [[acetaldehyde]]. This conversion remains a major industrial process (10M kg/y).<ref>{{cite book |vauthors=Elschenbroich C, Salzer A |title=Organometallics: A Concise Introduction |edition=2nd |publisher=Wiley-VCH |location=Weinheim |year=2006 |isbn=978-3-527-28165-7 }}</ref> The process proceeds via the initial complexation of ethylene to a Pd(II) center.{{Citation needed|date=January 2021}}

===Halogenation and hydrohalogenation===
Major intermediates from the [[halogenation]] and [[hydrohalogenation]] of ethylene include [[ethylene dichloride]], [[ethyl chloride]], and [[ethylene dibromide]]. The addition of chlorine entails "[[oxychlorination]]", i.e. chlorine itself is not used. Some products derived from this group are [[polyvinyl chloride]], [[trichloroethylene]], [[perchloroethylene]], [[methyl chloroform]], [[polyvinylidene chloride]] and [[copolymer]]s, and [[ethyl bromide]].<ref name=Keystone/>

===Alkylation===
Major chemical intermediates from the [[alkylation]] with ethylene is [[ethylbenzene]], precursor to [[styrene]]. Styrene is used principally in [[polystyrene]] for packaging and insulation, as well as in [[styrene-butadiene]] rubber for tires and footwear. On a smaller scale, [[ethyltoluene]], ethylanilines, 1,4-hexadiene, and [[aluminium]] alkyls. Products of these intermediates include [[polystyrene]], [[Saturated and unsaturated compounds|unsaturated]] [[polyester]]s and ethylene-propylene [[copolymer|terpolymers]].<ref name=Keystone/>

===Oxo reaction===
The [[hydroformylation]] (oxo reaction) of ethylene results in [[propionaldehyde]], a precursor to [[propionic acid]] and [[n-propyl alcohol]].<ref name=Keystone/>

===Hydration===
Ethylene has long represented the major non-fermentative precursor to [[ethanol]]. The original method entailed its conversion to [[diethyl sulfate]], followed by hydrolysis. The main method practiced since the mid-1990s is the direct hydration of ethylene catalyzed by [[solid acid catalyst]]s:<ref>{{cite book |vauthors=Kosaric N, Duvnjak Z, Farkas A, Sahm H, Bringer-Meyer S, Goebel O, Mayer D |chapter=Ethanol |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2011 |pages=1–72 |publisher=Wiley-VCH |location=Weinheim |doi=10.1002/14356007.a09_587.pub2 |isbn=9783527306732}}</ref>
:C<sub>2</sub>H<sub>4</sub>  +  H<sub>2</sub>O  →    CH<sub>3</sub>CH<sub>2</sub>OH

===Dimerization to butenes===
Ethylene is [[dimer (chemistry)|dimerized]] by [[hydrovinylation]] to give ''n''-butenes using processes licensed by Lummus or [[French Institute of Petroleum|IFP]]. The Lummus process produces mixed ''n''-butenes (primarily [[2-butene]]s) while the IFP process produces [[1-butene]]. 1-Butene is used as a [[comonomer]] in the production of certain kinds of [[polyethylene]].<ref>{{Cite web|title=1-Butene - Major Uses |url=https://webwiser.nlm.nih.gov/substance?substanceId=474&identifier=1-Butene&identifierType=name&menuItemId=22&catId=24|access-date=2021-11-16|website=WISER |language=en |url-status=dead |archive-url=https://web.archive.org/web/20211116165807/https://webwiser.nlm.nih.gov/substance?substanceId=474&identifier=1-Butene&identifierType=name&menuItemId=22&catId=24 |archive-date= Nov 16, 2021 }}</ref>

===Fruit and flowering===
{{main|Ethylene (plant hormone)}}

Ethylene is a hormone that affects the ripening and flowering of many plants.  It is widely used to control freshness in [[horticulture]] and [[fruit]]s.<ref>{{Cite book|last1=Arshad|first1=Muhammad|title=Ethylene|last2=Frankenberger|first2=William |url=https://books.google.com/books?id=7U-4TU0ryoAC&pg=PA289 |publisher=Springer|year=2002|isbn=978-0-306-46666-3|location=Boston, MA|pages=289}}</ref>  The scrubbing of naturally occurring ethylene delays ripening.<ref>{{Cite book |last1=Melton |first1=Laurence |first2=Fereidoon |last2=Shahidi |first3=Peter |last3=Varelis |title=Encyclopedia of Food Chemistry |url=https://books.google.com/books?id=MTV8DwAAQBAJ&pg=PA114 |publisher=Elsevier |year=2019 |isbn=978-0-12-814045-1 |location=Netherlands |pages=114}}</ref> Adsorption of ethylene by nets coated in [[titanium dioxide]] gel has also been shown to be effective.<ref>{{cite journal | title = Gelatin-TiO2-coated expanded polyethylene foam nets as ethylene scavengers for fruit postharvest application | first1 = J. | last1 = de Matos Fonseca | first2 = N.Y.L | last2 = Pabón | first3 = L.G | last3 = Nandi | journal = Postharvest Biology and Technology | date = 2021 | volume = 180 | article-number = 111602 | doi = 10.1016/j.postharvbio.2021.111602}}</ref>

===Niche uses===
An example of a niche use is as an [[anesthesiology|anesthetic agent]] (in an 85% ethylene/15% oxygen ratio).<ref>{{cite journal |vauthors=Trout HH |title=Blood Changes Under Ethylene Anæsthesia |journal=Annals of Surgery |volume=86 |issue=2 |pages=260–7 |date=August 1927 |pmid=17865725 |pmc=1399426 |doi=10.1097/00000658-192708000-00013}}</ref> It is also used as a refrigerant gas for low temperature applications under the name R-1150.<ref>{{Cite web |date=April 2015 |title=R-1150 ETHYLENE Safety Data Sheet |url=https://www.arma.org.au/wp-content/uploads/2017/02/SDS-R1150-Ethylene.pdf |access-date=1 July 2023 |website=Australian Refrigeration Mechanics Association |archive-date=1 July 2023 |archive-url=https://web.archive.org/web/20230701104846/https://www.arma.org.au/wp-content/uploads/2017/02/SDS-R1150-Ethylene.pdf |url-status=live }}</ref>

==Production==
Global ethylene production was 107 million tonnes in 2005,<ref name="cenews"/> 109 million tonnes in 2006,<ref>Nattrass, L and Higson, A (22 July 2010) [http://www.nnfcc.co.uk/publications/nnfcc-renewable-chemicals-factsheet-ethanol NNFCC Renewable Chemicals Factsheet: Ethanol] {{Webarchive|url=https://archive.today/20120905034212/http://www.nnfcc.co.uk/publications/nnfcc-renewable-chemicals-factsheet-ethanol |date=2012-09-05 }}. [[National Non-Food Crops Centre]]</ref> 138 million tonnes in 2010, and 141 million tonnes in 2011.<ref>{{cite journal |last=True |first=Warren R. |name-list-style=vanc |journal=[[Oil & Gas Journal]] |year=2012 |volume=110 |issue=7 |url=http://www.ogj.com/articles/print/vol-110/issue-07/special-report-ethylene-report/global-ethylene-capacity.html |title=Global ethylene capacity poised for major expansion |pages=90–95 |access-date=2016-05-06 |archive-date=2016-06-04 |archive-url=https://web.archive.org/web/20160604011302/http://www.ogj.com/articles/print/vol-110/issue-07/special-report-ethylene-report/global-ethylene-capacity.html |url-status=live }}</ref> By 2013, ethylene was produced by at least 117 companies in 32 countries. To meet the ever-increasing demand for ethylene, sharp increases in production facilities are added globally, particularly in the [[Mideast]] and in [[China]].<ref name="Ceresana">{{cite web |url=http://www.ceresana.com/en/market-studies/chemicals/ethylene/ |title=Market Study: Ethylene (2nd edition), Ceresana, November 2014 |publisher=ceresana.com |access-date=2015-02-03 |archive-date=2015-03-07 |archive-url=https://web.archive.org/web/20150307115926/http://www.ceresana.com/en/market-studies/chemicals/ethylene/ |url-status=live }}</ref> Production [[greenhouse gas emissions|emits greenhouse gas]], namely significant amounts of carbon dioxide.<ref>{{Cite journal |last1=Mynko |first1=Oleksii |last2=Amghizar |first2=Ismaël |last3=Brown |first3=David J. |last4=Chen |first4=Lin |last5=Marin |first5=Guy B. |last6=de Alvarenga |first6=Rodrigo Freitas |last7=Uslu |first7=Didem Civancik |last8=Dewulf |first8=Jo |last9=Van Geem |first9=Kevin M. |date=2022-08-15 |title=Reducing CO<sub>2</sub> emissions of existing ethylene plants: Evaluation of different revamp strategies to reduce global CO<sub>2</sub> emission by 100 million tonnes |url=https://www.sciencedirect.com/science/article/pii/S0959652622017334 |journal=Journal of Cleaner Production |language=en |volume=362 |article-number=132127 |doi=10.1016/j.jclepro.2022.132127 |bibcode=2022JCPro.36232127M |hdl=1854/LU-8760240 |s2cid=248838079 |issn=0959-6526|hdl-access=free }}</ref>

===Industrial process===
Ethylene is produced by several methods in the [[petrochemical industry]]. A primary method is [[steam cracking]] (SC) where hydrocarbons and steam are heated to 750–950&nbsp;°C. This process converts large hydrocarbons into smaller ones and introduces unsaturation. When [[ethane]] is the feedstock, ethylene is the product. Ethylene is separated from the resulting mixture by repeated [[compression (physical)|compression]] and [[distillation]].<ref name=Keystone>{{cite book |vauthors=Kniel L, Winter O, Stork K |title=Ethylene, keystone to the petrochemical industry |year=1980 |publisher=M. Dekker |location=New York |isbn=978-0-8247-6914-7 }}</ref> In Europe and Asia, ethylene is obtained mainly from cracking naphtha, gasoil and condensates with the coproduction of propylene, C4 olefins and aromatics (pyrolysis gasoline).<ref>{{cite web |url=https://www.icis.com/explore/resources/news/2007/11/05/9075778/ethylene-production-and-manufacturing-process |title=Ethylene Production and Manufacturing Process |website=Icis |access-date=2019-07-29 |archive-date=2019-07-29 |archive-url=https://web.archive.org/web/20190729165959/https://www.icis.com/explore/resources/news/2007/11/05/9075778/ethylene-production-and-manufacturing-process |url-status=live }}</ref> Other procedures employed for the production of ethylene include [[Fischer-Tropsch synthesis]] and [[methanol-to-olefin]]s (MTO).<ref>{{cite journal |title=New Trends in Olefin Production |vauthors=Amghizar I, Vandewalle LA, Van Geem KM, Marin GB |doi=10.1016/J.ENG.2017.02.006 |journal=Engineering |year=2017 |volume=3 |issue=2 |pages=171–178 |doi-access=free|bibcode=2017Engin...3..171A }}</ref>

===Laboratory synthesis===
Although of great value industrially, ethylene is rarely synthesized in the laboratory and is ordinarily purchased.<ref>{{cite book |vauthors=Crimmins MT, Kim-Meade AS |chapter=Ethylene |editor=Paquette, L. |title=Encyclopedia of Reagents for Organic Synthesis |publisher=Wiley |location=New York |year=2001 |doi=10.1002/047084289X.re066 |isbn=0471936235}}</ref> It can be produced via dehydration of [[ethanol]] with [[sulfuric acid]] or in the gas phase with [[aluminium oxide]] or [[activated alumina]].<ref>{{cite book |title=Practical Organic Chemistry (preparation 4) |last=Cohen |first=Julius B. |name-list-style=vanc |publisher=Macmillan |year=1930}}</ref>

===Biosynthesis===
Ethylene is produced from [[methionine]] in nature.  The immediate precursor is [[1-Aminocyclopropane-1-carboxylic acid|1-aminocyclopropane-1-carboxylic acid]].<ref name=Yang_1984>{{cite journal | vauthors = Yang SF, Hoffman NE | title = Ethylene biosynthesis and its regulation in higher plants | journal = Annu. Rev. Plant Physiol. | volume = 35 | pages = 155–89 | year = 1984 | doi = 10.1146/annurev.pp.35.060184.001103}}</ref>

==Ligand==
[[file:Rh2Cl2 C2H4 4.svg|thumb|right|[[Chlorobis(ethylene)rhodium dimer]] is a well-studied complex of ethylene.<ref>{{cite book|chapter=chlorobis(ethylene)rhodium(I) dimer
|author=Neely, Jamie M.
|title=E-EROS Encyclopedia of Reagents for Organic Synthesis|year=2014|pages=1–6|doi=10.1002/047084289X.rn01715|isbn=9780470842898
}}</ref>]]
Ethylene is a fundamental [[ligand]] in [[transition metal alkene complexes]]. One of the first organometallic compounds, [[Zeise's salt]] is a complex of ethylene. Useful reagents containing ethylene include Pt(PPh<sub>3</sub>)<sub>2</sub>(C<sub>2</sub>H<sub>4</sub>) and Rh<sub>2</sub>Cl<sub>2</sub>(C<sub>2</sub>H<sub>4</sub>)<sub>4</sub>. The Rh-catalysed [[hydroformylation]] of ethylene is conducted on an industrial scale to provide [[propionaldehyde]].<ref>{{Cite book |url=https://onlinelibrary.wiley.com/doi/book/10.1002/14356007 |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2003-03-11 |publisher=Wiley |isbn=978-3-527-30385-4 |editor-last=Wiley-VCH |edition=1 |language=en |doi=10.1002/14356007.a22_157.pub3 |access-date=2023-10-17 |archive-date=2018-03-05 |archive-url=https://web.archive.org/web/20180305044518/http://onlinelibrary.wiley.com/book/10.1002/14356007 |url-status=live }}</ref>

==History==
Some geologists and scholars believe that the famous Greek Oracle at [[Delphi]] (the [[Pythia]]) went into her trance-like state as an effect of ethylene rising from ground faults.<ref name=Roach>{{cite magazine |title=Delphic Oracle's Lips May Have Been Loosened by Gas Vapors |first=John |last=Roach |name-list-style=vanc |magazine=[[National Geographic]] |date=2001-08-14 |url=http://news.nationalgeographic.com/news/2001/08/0814_delphioracle.html |archive-url=https://web.archive.org/web/20010924070805/http://news.nationalgeographic.com/news/2001/08/0814_delphioracle.html |url-status=dead |archive-date=September 24, 2001 |access-date=March 8, 2007}}</ref>

Ethylene appears to have been discovered by [[Johann Joachim Becher]], who obtained it by heating [[ethanol]] with sulfuric acid;<ref>{{cite book |first1=Henry Enfield |last1=Roscoe |first2=Carl |last2=Schorlemmer |name-list-style=vanc |title=A treatise on chemistry |url=https://books.google.com/books?id=o7gtAAAAYAAJ |year=1878 |publisher=D. Appleton |page=611 |volume=1}}</ref> he mentioned the gas in his ''Physica Subterranea'' (1669).<ref>{{cite book |first=James Campbell |last=Brown |name-list-style=vanc |title=A History of Chemistry: From the Earliest Times Till the Present Day |url=https://books.google.com/books?id=pEhCyILvi8cC |date=July 2006 |publisher=Kessinger |isbn=978-1-4286-3831-0 |page=225}}</ref> [[Joseph Priestley]] also mentions the gas in his ''Experiments and observations relating to the various branches of natural philosophy: with a continuation of the observations on air'' (1779), where he reports that [[Jan Ingenhousz]] saw ethylene synthesized in the same way by a Mr. Enée in Amsterdam in 1777 and that Ingenhousz subsequently produced the gas himself.<ref>Appendix, §VIII, pp. 474 ff., [https://archive.org/stream/experimentsobser00prie#page/474/mode/2up ''Experiments and observations relating to the various branches of natural philosophy: with a continuation of the observations on air''], Joseph Priestley, London: printed for J. Johnson, 1779, vol. 1.</ref> The properties of ethylene were studied in 1795 by four [[Netherlands|Dutch]] chemists, Johann Rudolph Deimann, Adrien Paets van Troostwyck, Anthoni Lauwerenburgh and Nicolas Bondt, who found that it differed from [[hydrogen]] gas and that it contained both carbon and hydrogen.<ref>{{harvnb|Roscoe|Schorlemmer|1878|p=612}}</ref> This group also discovered that ethylene could be combined with [[chlorine]] to produce the ''Dutch oil'', [[1,2-Dichloroethane|1,2-dichloroethane]]; this discovery gave ethylene the name used for it at that time, ''olefiant gas'' (oil-making gas.)<ref>{{harvnb|Roscoe|Schorlemmer|1878|p=613}}<br/>{{cite book |first=William |last=Gregory | name-list-style = vanc |title=Handbook of organic chemistry |url=https://archive.org/details/handbookorganic00greggoog |year=1857 |publisher=A.S. Barnes & Co. |page=[https://archive.org/details/handbookorganic00greggoog/page/n167 157] |edition=4th American}}</ref> The term olefiant gas is in turn the etymological origin of the modern word "olefin", the class of hydrocarbons in which ethylene is the first member.{{Citation needed|date=January 2021}}

In the mid-19th century, the suffix ''-ene'' (an Ancient Greek root added to the end of female names meaning "daughter of") was widely used to refer to a molecule or part thereof that contained one fewer hydrogen atoms than the molecule being modified. Thus, ''ethylene'' ({{chem|C|2|H|4}}) was the "daughter of [[ethyl group|ethyl]]" ({{chem|C|2|H|5}}). The name ethylene was used in this sense as early as 1852.<ref>{{Cite web |title=ethylene {{!}} Etymology, origin and meaning of ethylene |url=https://www.etymonline.com/word/ethylene |access-date=2022-07-19 |website=etymonline |language=en |archive-date=2022-07-19 |archive-url=https://web.archive.org/web/20220719133429/https://www.etymonline.com/word/ethylene |url-status=live }}</ref>

In 1866, the [[Germany|German]] chemist [[August Wilhelm von Hofmann]] proposed a system of hydrocarbon nomenclature in which the suffixes -ane, -ene, -ine, -one, and -une were used to denote the hydrocarbons with 0, 2, 4, 6, and 8 fewer hydrogens than their parent [[alkane]].<ref>{{cite web|url=http://www.chem.yale.edu/~chem125/125/history99/5Valence/Nomenclature/Hofmannaeiou.html|title=Hofmann's Proposal for Systematic Nomenclature of the Hydrocarbons| vauthors = Hofmann AW |access-date=2007-01-06|publisher=www.chem.yale.edu|url-status=dead|archive-url=https://web.archive.org/web/20060903081507/http://www.chem.yale.edu/~chem125/125/history99/5Valence/Nomenclature/Hofmannaeiou.html|archive-date=2006-09-03}}</ref> In this system, ethylene became ''ethene''. Hofmann's system eventually became the basis for the Geneva nomenclature approved by the International Congress of Chemists in 1892, which remains at the core of the [[IUPAC]] nomenclature. However, by that time, the name ethylene was deeply entrenched, and it remains in wide use today, especially in the chemical industry.

Following experimentation by Luckhardt, Crocker, and Carter at the University of Chicago,<ref>{{cite journal | vauthors = Luckhardt A, Carter JB |date=1 December 1923 |title=Ethylene as a gas anesthetic |journal=Current Researches in Anesthesia & Analgesia |volume=2 |issue=6 |pages=221–229 |doi=10.1213/00000539-192312000-00004|s2cid=71058633 }}</ref> ethylene was used as an anesthetic.<ref>{{cite journal | vauthors = Johnstone GA | title = Advantages of Ethylene-Oxygen as a General Anesthetic | journal = California and Western Medicine | volume = 27 | issue = 2 | pages = 216–8 | date = August 1927 | pmid = 18740435 | pmc = 1655579 }}</ref><ref name=UllmannEthylene>{{cite book |first1=Heinz |last1=Zimmermann |first2=Roland |last2=Walz | name-list-style = vanc |chapter=Ethylene |title=Ullmann's Encyclopedia of Industrial Chemistry |publisher=Wiley-VCH |location=Weinheim |year=2008 |doi=10.1002/14356007.a10_045.pub3|isbn=978-3527306732}}</ref> It remained in use through the 1940s, even while chloroform was being phased out. Its pungent odor and its explosive nature limit its use today.<ref>{{cite journal | vauthors = Whalen FX, Bacon DR, Smith HM | title = Inhaled anesthetics: an historical overview | journal = Best Practice & Research. Clinical Anaesthesiology | volume = 19 | issue = 3 | pages = 323–30 | date = September 2005 | pmid = 16013684 | doi = 10.1016/j.bpa.2005.02.001}}</ref>

===Nomenclature===
The 1979 IUPAC nomenclature rules made an exception for retaining the non-systematic name ''ethylene'';<ref>[http://www.acdlabs.com/iupac/nomenclature/79/r79_53.htm#a_3__1 IUPAC nomenclature rule A-3.1 (1979)] {{Webarchive|url=https://web.archive.org/web/20001010202833/http://www.acdlabs.com/iupac/nomenclature/79/r79_53.htm#a_3__1 |date=2000-10-10 }}. Acdlabs.com. Retrieved on 2016-04-24.</ref> however, this decision was reversed in the 1993 rules,<ref>[http://www.acdlabs.com/iupac/nomenclature/93/r93_684.htm Footnote to IUPAC nomenclature rule R-9.1, table 19(b)] {{Webarchive|url=https://web.archive.org/web/20071219101601/http://www.acdlabs.com/iupac/nomenclature/93/r93_684.htm |date=2007-12-19 }}. Acdlabs.com. Retrieved on 2016-04-24.</ref> and it remains unchanged in the newest 2013 recommendations,<ref>{{cite book |title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 |date=2014 |publisher=[[Royal Society of Chemistry]] |editor1=Favre, Henri A. |editor2=Powell, Warren H. |isbn=9781849733069 |location=Cambridge |oclc=865143943}}</ref> so the IUPAC name is now ''ethene''. In the IUPAC system, the name ''ethylene'' is reserved for the [[divalent]] group -CH<sub>2</sub>CH<sub>2</sub>-. Hence, names like ''ethylene oxide'' and ''ethylene dibromide'' are permitted, but the use of the name ''ethylene'' for the two-carbon alkene is not. Nevertheless, use of the name ''ethylene'' for H<sub>2</sub>C=CH<sub>2</sub> (and propylene for H<sub>2</sub>C=CHCH<sub>3</sub>) is still prevalent among chemists in North America.<ref>{{Cite book |last1=Vollhardt |first1=K. Peter C. |last2=Schore |first2=Neil Eric |title=Organic chemistry : structure and function|date=2018 |isbn=978-1-319-07945-1 |edition=8 |location=New York |publisher=Macmillan Learning |pages=470 |oclc=1007924903}}</ref>

==Safety==
Like all hydrocarbons, ethylene is a combustible [[Asphyxiant gas|asphyxiant]]. It is listed as an [[International Agency for Research on Cancer|IARC]] [[IARC Group 3|group 3 agent]], since there is no current evidence that it causes cancer in humans.<ref>{{cite web |url=http://www.inchem.org/documents/iarc/vol60/m60-01.html |title=Ethylene (IARC Summary & Evaluation, Volume 60, 1994) |website=www.inchem.org |access-date=2019-01-13 |archive-date=2019-01-13 |archive-url=https://web.archive.org/web/20190113232534/http://www.inchem.org/documents/iarc/vol60/m60-01.html |url-status=live }}</ref>

==See also==
*[[RediRipe]], an ethylene detector for fruits.

== References ==
{{reflist|35em}}

== External links ==
{{Commons category|Ethylene}}
*[http://www.inchem.org/documents/icsc/icsc/eics0475.htm International Chemical Safety Card 0475]
*[https://web.archive.org/web/20061113092037/http://www.novachem.com/ProductServices/docs/Ethylene_MSDS_EN.pdf MSDS]

{{Alkenes}}
{{Functional Groups}}
{{Molecules detected in outer space}}
{{General anesthetics}}
{{Hydrides by group}}
{{Authority control}}

[[Category:Ethylene| ]]
[[Category:Alkenes]]
[[Category:General anesthetics]]
[[Category:Monomers]]
[[Category:Commodity chemicals]]
[[Category:Petrochemicals]]
[[Category:Industrial gases]]
[[Category:Greenhouse gases]]
[[Category:Organic compounds with 2 carbon atoms]]