Ethylene: Difference between revisions

{{Chembox

| Watchedfields  = changed

| 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

| MeltingPtC = -169.2

| BoilingPtC = -103.7

| Solubility1 = 4.22&nbsp;mg/L<ref name="neilands" />

| Solvent1 = ethanol

'''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 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]].

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}}

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]]

{{clear|left}}

===Oxidation===

{{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}}

===Hydration===

:C₂H₄  +  H₂O  →    CH₃CH₂OH

===Fruit and flowering===

{{main|Ethylene (plant hormone)}}

===Niche uses===

==Ligand==

|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

==History==

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 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.

===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 -CH₂CH₂-. 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 H₂C=CH₂ (and propylene for H₂C=CHCH₃) 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==