View source for Ethane

{{Short description|Organic compound (H<sub>3</sub>C–CH<sub>3</sub>)}}
{{About|the chemical compound|the emergency service protocol|ETHANE}}
{{Distinguish|Ethene|Ethyne|Methane}}
{{Chembox
| Watchedfields  = changed
| verifiedrevid  = 477168309
| ImageFile1     = Ethane-staggered-CRC-MW-dimensions-2D.png
| ImageClass1 = skin-invert-image
| ImageFile1_Ref = {{chemboximage|correct|??}}
| ImageName1     = Skeletal formula of ethane with all hydrogens and carbons shown
| ImageCaption1  = [[Molecular geometry]] of ethane based on [[rotational spectroscopy]].
| ImageFile2     = Ethan Skelett.svg
| ImageClass2 = skin-invert-image
| ImageFile2_Ref = {{chemboximage|correct|??}}
| ImageName2     = Skeletal formula of ethane with all implicit carbons shown, and all explicit hydrogens added
| ImageFileL2    = Ethane-A-3D-balls.png
| ImageClassL2 = bg-transparent
| ImageFileL2_Ref = {{chemboximage|correct|??}}
| ImageNameL2    = Ball and stick model of ethane
| ImageFileR2    = Ethane-3D-vdW.png
| ImageClassR2 = bg-transparent
| ImageFileR2_Ref = {{chemboximage|correct|??}}
| ImageNameR2    = Spacefill model of ethane
| OtherNames     = {{Unbulleted list|Dimethyl ({{chem2|CH3CH3}}, {{chem2|Me2}} or {{chem2|(CH3)2}})|Ethyl hydride}}
| PIN            = Ethane<ref>{{Cite book|author=[[International Union of Pure and Applied Chemistry]]|date=2014|title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013|publisher=[[Royal Society of Chemistry|The Royal Society of Chemistry]]|page=133|doi=10.1039/9781849733069|isbn=978-0-85404-182-4|quote=The saturated unbranched acyclic hydrocarbons C<sub>2</sub>H<sub>6</sub>, C<sub>3</sub>H<sub>8</sub>, and C<sub>4</sub>H<sub>10</sub> have the retained names ethane, propane, and butane, respectively.|ref={{sfnref|IUPAC|2014}}}}</ref>
| SystematicName = Dicarbane (never recommended{{sfn|IUPAC|2014|p=4|ps=. "Similarly, the retained names 'ethane', 'propane', and 'butane' were never replaced by systematic names 'dicarbane', 'tricarbane', and 'tetracarbane' as recommended for analogues of silane, 'disilane'; phosphane, 'triphosphane'; and sulfane, 'tetrasulfane'."}})
| Section1       = {{Chembox Identifiers
| CASNo = 74-84-0
| CASNo_Ref = {{cascite|correct|CAS}}
| PubChem = 6324
| ChemSpiderID = 6084
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = L99N5N533T
| EINECS = 200-814-8
| UNNumber = 1035
| MeSHName = Ethane
| ChEBI = 42266
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 135626
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| RTECS = KH3800000
| Beilstein = 1730716
| Gmelin = 212
| SMILES = CC
| StdInChI = 1S/C2H6/c1-2/h1-2H3
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = OTMSDBZUPAUEDD-UHFFFAOYSA-N
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
}}
| Section2       = {{Chembox Properties
| C=2 | H=6
| Appearance = Colorless gas
| Odor = Odorless
| Density = {{Unbulleted list| 1.3562{{nbsp}}kg/m<sup>3</sup> (gas at 0&nbsp;°C)<ref name=pubchem>{{cite web|title=Ethane – Compound Summary|url=https://pubchem.ncbi.nlm.nih.gov/compound/6324|work=PubChem Compound|publisher=National Center for Biotechnology Information|access-date=7 December 2011|location=US|date=16 September 2004}}</ref>}}<br />
544.0&nbsp;kg/m<sup>3</sup> (liquid at -88,5&nbsp;°C)<br />
206&nbsp;kg/m<sup>3</sup> (at critical point 305.322&nbsp;K)
| MeltingPtK = 90.4
| BoilingPtK = 184.6
| CriticalTP = {{convert|305.32 |K}} {{convert|48.714|bar}}
| Solubility = 56.8 mg/L<ref>{{RubberBible86th|page=8.88}}</ref>
| VaporPressure = 3.8453 MPa (at 21.1&nbsp;°C)
| HenryConstant = 19 nmol Pa<sup>−1</sup> kg<sup>−1</sup>
| pKa = 50
| pKb = −36
| ConjugateAcid = [[Ethanium]]
| MagSus = −37.37·10<sup>−6</sup> cm<sup>3</sup>/mol
}}
| Section3       = {{Chembox Thermochemistry
| DeltaHf = −84 kJ mol<sup>−1</sup>
| DeltaHc = −1561.0–−1560.4 kJ mol<sup>−1</sup>
| HeatCapacity = 52.14{{Plusminus|0.39}} J K<sup>−1</sup> mol<sup>−1</sup> at 298 Kelvin<ref>{{Cite web |url=https://webbook.nist.gov/cgi/cbook.cgi?ID=C74840&Mask=1 |title=Ethane |access-date=2024-05-16 |website=webbook.nist.gov |agency=[[National Institute of Standards and Technology]]}}</ref>
}}
| Section4       = {{Chembox Hazards
| ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics0266.htm inchem.org]
| GHSPictograms = {{GHS flame}}
| GHSSignalWord = '''DANGER'''
| HPhrases = {{H-phrases|220|280}}
| PPhrases = {{P-phrases|210|410+403}}
| NFPA-H = 1
| NFPA-F = 4
| NFPA-R = 0
| NFPA-S = SA
| FlashPtC = −135
| AutoignitionPtC = 472
| ExploLimits = 2.9–13%
}}
| Section5       = {{Chembox Related
| OtherFunction_label = alkanes
| OtherFunction = {{Unbulleted list|[[Methane]]|[[Propane]]|[[Butane]]}}
| OtherCompounds = {{Unbulleted list|[[Disilane]]|[[Digermane]]}}
}}
}}

'''Ethane''' ({{IPAc-en|US|ˈ|ɛ|θ|eɪ|n}} {{respell|ETH|ayn}}, {{IPAc-en|UK|ˈ|iː|θ|eɪ|n}} {{respell|EE|thayn}}) is a naturally occurring [[Organic compound|organic]] [[chemical compound]] with [[chemical formula]] {{chem|C|2|H|6}}. At [[standard temperature and pressure]], ethane is a colorless, odorless [[gas]]. Like many [[hydrocarbon]]s, ethane is [[List of purification methods in chemistry|isolated]] on an industrial scale from [[natural gas]] and as a [[petrochemical]] by-product of [[oil refinery|petroleum refining]]. Its chief use is as [[feedstock]] for [[ethylene]] production.  The [[ethyl group]] is formally, although rarely practically, derived from ethane.

== History ==
Ethane was first synthesised in 1834 by [[Michael Faraday]], applying [[electrolysis]] of a [[potassium acetate]] solution. He mistook the hydrocarbon product of this reaction for [[methane]] and did not investigate it further.<ref name=Faraday/> The process is now called [[Kolbe electrolysis]]:
: [[acetate|CH<sub>3</sub>COO<sup>−</sup>]] → CH<sub>3</sub>• + [[carbon dioxide|CO<sub>2</sub>]] + [[electron|e<sup>−</sup>]]
: CH<sub>3</sub>• + •CH<sub>3</sub> → C<sub>2</sub>H<sub>6</sub>

During the period 1847–1849, in an effort to vindicate the [[radical theory]] of [[organic chemistry]], [[Hermann Kolbe]] and [[Edward Frankland]] produced ethane by the reductions of [[propionitrile]] ([[ethyl cyanide]])<ref name=Kolbe/> and [[ethyl iodide]]<ref name=Frankland/> with [[potassium]] metal, and, as did Faraday, by the electrolysis of [[Aqueous solution|aqueous]] acetates. They mistook the product of these reactions for the [[methyl radical]] ({{Chem2|CH3}}), of which ethane ({{Chem2|C2H6}}) is a [[Dimer (chemistry)|dimer]].

This error was corrected in 1864 by [[Carl Schorlemmer]], who showed that the product of all these reactions was in fact ethane.<ref>{{cite journal|doi=10.1002/jlac.18641320217|title=Ueber die Identität des Aethylwasserstoffs und des Methyls|journal=Annalen der Chemie und Pharmacie|volume=132|issue=2|pages=234–238|year=1864|last1=Schorlemmer|first1=Carl|url=https://zenodo.org/record/1427237}}</ref> Ethane was discovered dissolved in [[Pennsylvania]]n light [[crude oil]] by [[Edmund Ronalds]] in 1864.<ref>{{Cite book|title=Treatise on Chemistry|last1=Roscoe|first1=H.E.|last2=Schorlemmer|first2=C.|publisher=Macmillan|year=1881|volume=3|pages=144–145}}</ref><ref>{{Cite book|title=Dictionary of Chemistry|last=Watts|first=H.|year=1868|volume=4|pages=385}}</ref>

==Properties==
At standard temperature and pressure, ethane is a colorless, odorless gas. It has a boiling point of {{cvt|-88.5|°C|F}} and melting point of {{cvt|-182.8|°C|F}}. Solid ethane exists in several modifications.<ref name="Nes">{{cite journal |doi= 10.1107/S0567740878007037 |title= Single-crystal structures and electron density distributions of ethane, ethylene and acetylene. I. Single-crystal X-ray structure determinations of two modifications of ethane |journal= Acta Crystallographica Section B |volume=34 |issue=6 |page= 1947 |year= 1978 |last1= Van Nes |first1= G.J.H. |last2= Vos |first2= A. |bibcode= 1978AcCrB..34.1947V |s2cid= 55183235 |url= http://www.rug.nl/research/portal/files/3440910/c3.pdf}}</ref> On cooling under normal pressure, the first modification to appear is a [[plastic crystal]], crystallizing in the cubic system. In this form, the positions of the hydrogen atoms are not fixed; the molecules may rotate freely around the long axis. Cooling this ethane below ca. {{convert|89.9|K|C F}} changes it to monoclinic metastable ethane II ([[space group]] P 21/n).<ref>{{cite web |url= https://log-web.de/chemie/Start.htm?name=ethaneCryst&lang=en |title= Ethane as a solid |access-date= 2019-12-10}}</ref> Ethane is only very sparingly soluble in water.

The bond parameters of ethane have been measured to high precision by microwave spectroscopy and electron diffraction: ''r''<sub>C−C</sub> = 1.528(3) Å, ''r''<sub>C−H</sub> = 1.088(5) Å, and ∠CCH = 111.6(5)°  by microwave and ''r''<sub>C−C</sub> = 1.524(3) Å, ''r''<sub>C−H</sub> = 1.089(5) Å, and ∠CCH = 111.9(5)° by electron diffraction (the numbers in parentheses represents the uncertainties in the final digits).<ref>{{Cite journal|last=Harmony|first=Marlin D.|date=1990-11-15|title=The equilibrium carbon–carbon single-bond length in ethane|journal=The Journal of Chemical Physics|language=en|volume=93|issue=10|pages=7522–7523|doi=10.1063/1.459380|issn=0021-9606|bibcode=1990JChPh..93.7522H}}</ref>

[[File:Ethane conformations and relative energies.svg|left|thumb|300px|Ethane (shown in [[Newman projection]]) barrier to rotation about the carbon-carbon bond. The curve is potential energy as a function of rotational angle. [[Activation energy|Energy barrier]] is 12 [[kJ/mol]] or about 2.9 [[kcal/mol]].<ref>{{Cite book|title=Organic chemistry|last=J|first=McMurry|date=2012|publisher=Brooks|isbn=9780840054449|edition=8|location=Belmont, CA|pages=95}}</ref>]]
Rotating a molecular substructure about a twistable bond usually requires energy. The minimum energy to produce a 360° bond rotation is called the [[rotational barrier]].

Ethane gives a classic, simple example of such a rotational barrier, sometimes called the "ethane barrier". Among the earliest experimental evidence of this barrier (see diagram at left) was obtained by modelling the entropy of ethane.<ref>{{cite journal |doi= 10.1021/ja01281a014 |title= The Entropy of Ethane and the Third Law of Thermodynamics. Hindered Rotation of Methyl Groups |journal= Journal of the American Chemical Society |volume=59 |issue=2 |pages=276 |year=1937 |last1=Kemp |first1=J. D. |last2=Pitzer |first2= Kenneth S.|bibcode= 1937JAChS..59..276K }}
</ref> The three hydrogens at each end are free to pinwheel about the central carbon–carbon bond when provided with sufficient energy to overcome the barrier. The physical origin of the barrier is still not completely settled,<ref>{{cite journal |doi= 10.1021/ed082p1703 |title= Determination of the Rotational Barrier in Ethane by Vibrational Spectroscopy and Statistical Thermodynamics |year=2005 |last1= Ercolani |first1=G. |journal= J. Chem. Educ. |volume=82 |issue=11 |pages= 1703–1708 |bibcode = 2005JChEd..82.1703E }}</ref> although the overlap (exchange) repulsion<ref>{{cite journal |doi= 10.1021/ar00090a004 |title= The Barrier to Internal Rotation in Ethane |year=1983 |last1= Pitzer |first1= R.M. |journal= Acc. Chem. Res. |volume=16 |issue=6 |pages= 207–210}}</ref> between the hydrogen atoms on opposing ends of the molecule is perhaps the strongest candidate, with the stabilizing effect of [[hyperconjugation]] on the staggered conformation contributing to the phenomenon.<ref>{{cite journal|doi=10.1002/anie.200352931|title=The Magnitude of Hyperconjugation in Ethane: A Perspective from Ab Initio Valence Bond Theory|year=2004|last1=Mo|first1=Y.|last2=Wu|first2=W.|last3=Song|first3=L.|last4=Lin|first4=M.|last5=Zhang|first5=Q.|last6=Gao|first6=J.|journal=Angew. Chem. Int. Ed.|volume=43|issue=15|pages=1986–1990|pmid=15065281 |bibcode=2004ACIE...43.1986M }}</ref> Theoretical methods that use an appropriate starting point (orthogonal orbitals) find that hyperconjugation is the most important factor in the origin of the ethane rotation barrier.<ref>{{cite journal |author1= Pophristic, V. |author2=Goodman, L.  |title= Hyperconjugation not steric repulsion leads to the staggered structure of ethane |journal= Nature |volume= 411 |issue= 6837 |pages= 565–8 |doi= 10.1038/35079036 |pmid= 11385566 |year=2001|bibcode=2001Natur.411..565P |s2cid=205017635 }}</ref><ref>{{cite journal |author= Schreiner, P. R. |title= Teaching the right reasons: Lessons from the mistaken origin of the rotational barrier in ethane |journal= Angewandte Chemie International Edition |volume=41 |issue=19 |pages=3579–81, 3513 |pmid= 12370897 |year= 2002 |doi= 10.1002/1521-3773(20021004)41:19<3579::AID-ANIE3579>3.0.CO;2-S}}
</ref>

As far back as 1890–1891, chemists suggested that ethane molecules preferred the staggered conformation with the two ends of the molecule askew from each other.<ref>{{cite journal |author= Bischoff, CA |title= Ueber die Aufhebung der freien Drehbarkeit von einfach verbundenen Kohlenstoffatomen |year=1890 |journal= Chem. Ber. |volume=23 |page= 623 |doi= 10.1002/cber.18900230197|url= https://zenodo.org/record/1425584 }}</ref><ref>{{cite journal |author= Bischoff, CA |title= Theoretische Ergebnisse der Studien in der Bernsteinsäuregruppe |year= 1891 |journal= Chem. Ber. |volume=24 |pages= 1074–1085 |doi= 10.1002/cber.189102401195|url= https://zenodo.org/record/1425620 }}</ref><ref>{{cite journal |author= Bischoff, CA |title= Die dynamische Hypothese in ihrer Anwendung auf die Bernsteinsäuregruppe |year= 1891 |journal= Chem. Ber. |volume=24 |pages=1085–1095 |doi= 10.1002/cber.189102401196 |url= https://zenodo.org/record/1425622 }}</ref><ref>{{cite journal |year=1893 |volume=26 |issue=2 |page= 1452 |doi= 10.1002/cber.18930260254 |title= Die Anwendung der dynamischen Hypothese auf Ketonsäurederivate |journal= Berichte der Deutschen Chemischen Gesellschaft |last1= Bischoff |first1=C.A. |last2= Walden |first2= P.|url=https://zenodo.org/record/1425708 }}</ref>

===Atmospheric and extraterrestrial===
[[File:Titan North Pole Lakes PIA08630.jpg|right|thumb|250px|A photograph of [[Titan (moon)|Titan]]'s northern latitudes. The dark features are hydrocarbon lakes containing ethane]]

Ethane occurs as a trace gas in the [[Earth's atmosphere]], currently having a concentration at [[sea level]] of 0.5 [[parts per billion|ppb]].<ref>{{cite web|url=http://www.atmosphere.mpg.de/enid/3tg.html|title=Trace gases (archived)|website=Atmosphere.mpg.de|archive-url=https://web.archive.org/web/20081222061502/http://www.atmosphere.mpg.de/enid/3tg.html |access-date=2011-12-08|archive-date=2008-12-22 }}</ref> Global ethane quantities have varied over time, likely due to [[Gas flare|flaring]] at [[natural gas field]]s.<ref name="SimpsonSulbaek Andersen2012">{{cite journal|last1=Simpson|first1=Isobel J.|last2=Sulbaek Andersen|first2=Mads P.|last3=Meinardi|first3=Simone|last4=Bruhwiler|first4=Lori|last5=Blake|first5=Nicola J.|last6=Helmig|first6=Detlev|last7=Rowland|first7=F. Sherwood|last8=Blake|first8=Donald R.|title=Long-term decline of global atmospheric ethane concentrations and implications for methane|journal=Nature|volume=488|issue=7412|year=2012|pages=490–494|doi=10.1038/nature11342|pmid=22914166|url=https://zenodo.org/record/898122|bibcode=2012Natur.488..490S|s2cid=4373714}}</ref> Global ethane emission rates declined from 1984 to 2010,<ref name="SimpsonSulbaek Andersen2012"/> though increased [[shale gas]] production at the [[Bakken Formation]] in the U.S. has arrested the decline by half.<ref name="KortSmith2016">{{cite journal|last1=Kort|first1=E. A.|last2=Smith|first2=M. L.|last3=Murray|first3=L. T.|last4=Gvakharia|first4=A.|last5=Brandt|first5=A. R.|last6=Peischl|first6=J.|last7=Ryerson|first7=T. B.|last8=Sweeney|first8=C.|last9=Travis|first9=K.|title=Fugitive emissions from the Bakken shale illustrate role of shale production in global ethane shift|journal=Geophysical Research Letters|year=2016|doi=10.1002/2016GL068703|volume=43|issue=9|pages=4617–4623|bibcode=2016GeoRL..43.4617K|doi-access=free|hdl=2027.42/142509|hdl-access=free}}</ref><ref>{{cite web|url=http://ns.umich.edu/new/multimedia/videos/23735-one-oil-field-a-key-culprit-in-global-ethane-gas-increase|title=One oil field a key culprit in global ethane gas increase|date=April 26, 2016|publisher=University of Michigan}}</ref>

Although ethane is a [[greenhouse gas]], it is much less abundant than methane, has a lifetime of only a few months compared to over a decade,<ref name="Feasibility">{{cite journal|last1=Aydin|first1=Kamil Murat|last2=Williams|first2=M.B.|last3=Saltzman|first3=E.S.|title=Feasibility of reconstructing paleoatmospheric records of selected alkanes, methyl halides, and sulfur gases from Greenland ice cores|journal=Journal of Geophysical Research|volume=112|date=April 2007|issue=D7 |article-number=2006JD008027 |doi=10.1029/2006JD008027 |bibcode=2007JGRD..112.7312A }}</ref> and is also less efficient at absorbing radiation relative to mass. In fact, ethane's [[global warming potential]] largely results from its conversion in the atmosphere to methane.<ref>{{cite journal|last1=Hodnebrog|first1=Øivind|last2=Dalsøren|first2=Stig B.|last3=Myrhe|first3=Gunnar|title=Lifetimes, direct and indirect radiative forcing, and global warming potentials of ethane (C<sub>2</sub>H<sub>6</sub>), propane (C<sub>3</sub>H<sub>8</sub>), and butane (C<sub>4</sub>H<sub>10</sub>)|journal=Atmospheric Science Letters|year=2018|volume=19 |issue=2 |article-number=e804 |doi=10.1002/asl.804|doi-access=free|bibcode=2018AtScL..19E.804H }}</ref> It has been detected as a trace component in the atmospheres of all four [[giant planet]]s, and in the atmosphere of [[Saturn]]'s moon [[Titan (moon)|Titan]].<ref>{{cite web|first = Bob|last = Brown|year = 2008|url = http://www.jpl.nasa.gov/news/news.cfm?release=2008-152|title = NASA Confirms Liquid Lake on Saturn Moon|display-authors = et al|publisher = NASA Jet Propulsion Laboratory|access-date = 2008-07-30|archive-date = 2011-06-05|archive-url = https://web.archive.org/web/20110605031218/http://www.jpl.nasa.gov/news/news.cfm?release=2008-152|url-status = dead}}</ref>

Atmospheric ethane results from the Sun's [[photochemistry|photochemical]] action on methane gas, also present in these atmospheres: [[ultraviolet]] photons of shorter [[wavelength]]s than 160 [[nanometer|nm]] can photo-dissociate the methane molecule into a [[methyl]] radical and a [[hydrogen]] atom. When two methyl radicals recombine, the result is ethane:

: CH<sub>4</sub> &nbsp;→&nbsp; CH<sub>3</sub>• + •H
: CH<sub>3</sub>• + •CH<sub>3</sub> &nbsp;→&nbsp; C<sub>2</sub>H<sub>6</sub>

In Earth's atmosphere, [[hydroxyl radical]]s convert ethane to [[methanol]] vapor with a half-life of around three months.<ref name="Feasibility"/>

It is suspected that ethane produced in this fashion on Titan rains back onto the moon's surface, and over time has accumulated into [[Lakes of Titan|hydrocarbon seas]] covering much of the moon's polar regions. In mid-2005, the ''[[Cassini-Huygens|Cassini]]'' orbiter discovered [[Ontario Lacus]] in Titan's south polar regions. Further analysis of infrared spectroscopic data presented in July 2008<ref>{{cite journal|doi=10.1038/nature07100|title=The identification of liquid ethane in Titan's Ontario Lacus|year=2008|last1=Brown|first1=R. H.|last2=Soderblom|first2=L. A.|last3=Soderblom|first3=J. M.|last4=Clark|first4=R. N.|last5=Jaumann|first5=R.|last6=Barnes|first6=J. W.|last7=Sotin|first7=C.|last8=Buratti|first8=B.|last9=Baines|first9=K. H.|last10=Nicholson|first10=P. D.|journal=Nature|volume=454|issue=7204|pages=607–10|pmid=18668101|bibcode = 2008Natur.454..607B |s2cid=4398324|display-authors=8}}</ref> provided additional evidence for the presence of liquid ethane in Ontario Lacus. Several significantly larger hydrocarbon lakes, [[Ligeia Mare]] and [[Kraken Mare]] being the two largest, were discovered near Titan's north pole using radar data gathered by Cassini. These lakes are believed to be filled primarily by a mixture of liquid ethane and methane.

In 1996, ethane was detected in [[Comet Hyakutake]],<ref name= Mumma/> and it has since been detected in some other [[comets]]. The existence of ethane in these distant solar system bodies may implicate ethane as a primordial component of the [[solar nebula]] from which the sun and planets are believed to have formed.

In 2006, Dale Cruikshank of NASA/Ames Research Center (a ''[[New Horizons]]'' co-investigator) and his colleagues announced the spectroscopic discovery of ethane on [[Pluto]]'s surface.<ref>{{Cite web |last=Stern |first= A. |author-link=Alan Stern |date=November 1, 2006 |title=Making Old Horizons New |url=http://pluto.jhuapl.edu/overview/piPerspectives/piPerspective_11_1_2006.php |url-status=dead |archive-url=https://web.archive.org/web/20080828012339/http://pluto.jhuapl.edu/overview/piPerspectives/piPerspective_11_1_2006.php |archive-date=August 28, 2008 |access-date=2007-02-12 |website=The PI's Perspective |publisher=Johns Hopkins University Applied Physics Laboratory}}</ref>

==Chemistry==
The reactions of ethane involve chiefly [[free radical reaction]]s. Ethane can react with the [[halogen]]s, especially [[chlorine]] and [[bromine]], by [[free-radical halogenation]]. This reaction proceeds through the propagation of the [[ethyl group|ethyl]] radical:<ref>{{cite book |doi=10.1002/14356007.o06_o01 |chapter=Chlorethanes and Chloroethylenes |title=Ullmann's Encyclopedia of Industrial Chemistry |date=2011 |last1=Dreher |first1=Eberhard-Ludwig |last2=Torkelson |first2=Theodore R. |last3=Beutel |first3=Klaus K. |isbn=978-3-527-30385-4 }}</ref>
: Cl<sub>2</sub> &nbsp;→&nbsp;  2 Cl•
: C<sub>2</sub>H<sub>6</sub>• + Cl• &nbsp;→&nbsp; C<sub>2</sub>H<sub>5</sub>• + HCl
: C<sub>2</sub>H<sub>5</sub>• + Cl<sub>2</sub> &nbsp;→&nbsp; C<sub>2</sub>H<sub>5</sub>Cl + Cl•
: Cl• + C<sub>2</sub>H<sub>6</sub> &nbsp;→&nbsp; C<sub>2</sub>H<sub>5</sub>• + HCl

The [[combustion]] of ethane releases 1559.7 kJ/mol, or 51.9 kJ/g, of heat, and produces [[carbon dioxide]] and [[water]] according to the [[chemical equation]]:
: 2 C<sub>2</sub>H<sub>6</sub> + 7 [[oxygen|O<sub>2</sub>]] &nbsp;→&nbsp; 4 [[carbon dioxide|CO<sub>2</sub>]] + 6 [[water|H<sub>2</sub>O]] + 3120 kJ

Combustion may also occur without an excess of oxygen, yielding [[carbon monoxide]], [[acetaldehyde]], [[methane]], [[methanol]], and [[ethanol]]. At higher temperatures, especially in the range {{cvt|600|-|900|°C|F}}, [[ethylene]] is a significant product:
: {{chem2|2 C2H6 + O2 → 2 C2H4  +  2 H2O}}
Such oxidative dehydrogenation reactions are relevant to the production of [[ethylene]].<ref>{{cite journal |doi=10.1039/D0CS01518K |title=Oxidative dehydrogenation of ethane: Catalytic and mechanistic aspects and future trends |date=2021 |last1=Najari |first1=Sara |last2=Saeidi |first2=Samrand |last3=Concepcion |first3=Patricia |last4=Dionysiou |first4=Dionysios D. |last5=Bhargava |first5=Suresh K. |last6=Lee |first6=Adam F. |last7=Wilson |first7=Karen |journal=Chemical Society Reviews |volume=50 |issue=7 |pages=4564–4605 |pmid=33595011 |s2cid=231946397 |hdl=10072/432915 |hdl-access=free }}</ref>

==Production==
After [[methane]], ethane is the second-largest component of [[natural gas]]. Natural gas from different gas fields varies in ethane content from less than 1% to more than 6% by volume. Prior to the 1960s, ethane and larger molecules were typically not separated from the methane component of natural gas, but simply burnt along with the methane as a fuel. Today, ethane is an important [[petrochemical]] [[feedstock]] and is separated from the other components of natural gas in most well-developed gas fields. Ethane can also be separated from [[petroleum gas]], a mixture of gaseous hydrocarbons produced as a byproduct of [[petroleum refining]].

Ethane is most efficiently separated from methane by liquefying it at cryogenic temperatures. Various refrigeration strategies exist: the most economical process presently in wide use employs a [[turboexpander]], and can recover more than 90% of the ethane in natural gas. In this process, chilled gas is expanded through a [[turbine]], reducing the temperature to approximately {{cvt|−100|°C|F}}. At this low temperature, gaseous methane can be separated from the liquefied ethane and heavier hydrocarbons by [[distillation]]. Further distillation then separates ethane from the [[propane]] and heavier hydrocarbons.

==Usage==
The chief use of ethane is the production of [[ethylene]] (ethene) by [[steam cracking]]. Steam cracking of ethane is fairly selective for ethylene, while the steam cracking of heavier hydrocarbons yields a product mixture poorer in ethylene and richer in heavier [[alkene|alkenes (olefins)]], such as [[propene|propene (propylene)]] and [[butadiene]], and in [[aromatic hydrocarbon]]s.

Ethane has been investigated as a feedstock for other commodity chemicals. [[Oxidative]] chlorination of ethane has long appeared to be a potentially more economical route to [[vinyl chloride]] than ethylene chlorination. Many patent exist on this theme, but poor selectivity for [[vinyl chloride]] and [[Corrosion|corrosive]] reaction conditions have discouraged the commercialization of most of them. Presently, [[Ineos]] operates a 1000 t/a ([[tonnes]] per [[annum]]) ethane-to-vinyl chloride pilot plant at [[Wilhelmshaven]] in [[Germany]].

[[SABIC]] operates a 34,000 t/a plant at [[Yanbu]] to produce [[acetic acid]] by ethane oxidation.<ref name="SABIC-plant-launch">{{Cite web |title = SABIC's Acetic Acid Plant Comes on Stream |last = Ramkumar |first=K.S. |work = Arab News |date = 26 May 2005 |access-date = 4 July 2024 |url = https://www.arabnews.com/node/267532 |archive-url=http://web.archive.org/web/20130609063705/http://arabnews.com/node/267532 |archive-date=9 June 2013}}</ref> The economic viability of this process may rely on the low cost of ethane near Saudi oil fields, and it may not be competitive with [[methanol carbonylation]] elsewhere in the world.<ref name="Mizuno2009">{{cite book |editor-last=Mizuno |editor-first=Noritaka |last1=Cavani |first1=Fabrizio |last2=Ballarini |first2=Nicola |title=Modern Heterogeneous Oxidation Catalysis |publisher=Wiley |year=2009 |isbn=978-3-527-62755-4 |url=https://books.google.com/books?id=66k5iyn9xmIC |access-date=4 July 2024 |page=291}}</ref>

Ethane can be used as a refrigerant in cryogenic refrigeration systems. 

===In the laboratory===
On a much smaller scale, in scientific research, liquid ethane is used to [[Cryopreservation#Vitrification|vitrify]] water-rich samples for [[cryo-electron microscopy]]. A thin film of water quickly immersed in liquid ethane at −150&nbsp;°C or colder freezes too quickly for water to crystallize. Slower freezing methods can generate cubic ice crystals, which can disrupt [[soft materials|soft structures]] by damaging the samples and reduce image quality by scattering the electron beam before it can reach the detector.

==Health and safety==
At room temperature, ethane is an extremely flammable gas. When mixed with air at 3.0%–12.5% by volume, it forms an [[explosion|explosive]] mixture.

Ethane is not a [[carcinogen]].<ref>{{Cite book | title = Environmental Biotechnology: A Biosystems Approach | author = Vallero, Daniel |doi=10.1016/B978-0-12-375089-1.10014-5|chapter=Cancer Slope Factors| publisher = Academic Press | date = June 7, 2010 | page = 641| isbn = 9780123750891 }}</ref>

==See also==
* [[Biogas]]: carbon-neutral alternative to natural gas
* [[Biorefining]]
* [[Biodegradable plastic]]
* [[Drop-in bioplastic]]

==References==
{{Reflist|35em|refs=

<ref name=Faraday>{{cite journal|first = Michael|last =Faraday|year = 1834|title = Experimental researches in electricity: Seventh series|journal = Philosophical Transactions|volume = 124|pages = 77–122|doi = 10.1098/rstl.1834.0008|bibcode =1834RSPT..124...77F|s2cid =116224057}}</ref>

<ref name=Mumma>{{cite journal|first1 =Michael J.|last1 = Mumma | year =1996|title = Detection of Abundant Ethane and Methane, Along with Carbon Monoxide and Water, in Comet C/1996 B2 Hyakutake: Evidence for Interstellar Origin|journal = Science|volume = 272| pages = 1310–1314|doi =10.1126/science.272.5266.1310|pmid=8650540|bibcode=1996Sci...272.1310M|issue=5266|display-authors =1|last2 =Disanti|first2 =M. A.|last3 =Russo|first3 =N. D.|last4 =Fomenkova|first4 =M.|last5 =Magee-Sauer|first5 =K.|last6 =Kaminski|first6 =C. D.|last7 =Xie|first7 =D. X.|s2cid = 27362518 }}</ref>

<ref name=Kolbe>{{cite journal|first1 = Hermann|last1 = Kolbe|first2= Edward|last2= Frankland|year = 1849|title = On the products of the action of potassium on cyanide of ethyl|journal = Journal of the Chemical Society|volume = 1 |pages = 60–74|doi=10.1039/QJ8490100060 |url = https://zenodo.org/record/2006217}}</ref>

<ref name=Frankland>{{cite journal|first= Edward|last = Frankland |year = 1850|title = On the isolation of the organic radicals|journal = Journal of the Chemical Society|volume = 2|issue = 3 |pages =263–296|doi=10.1039/QJ8500200263 |url = https://zenodo.org/record/1861200 }}</ref>
}}

==External links==
{{commons}}
*[http://www.inchem.org/documents/icsc/icsc/eics0266.htm International Chemical Safety Card 0266]
*[http://www.aet.com/gtip1.htm Market-Driven Evolution of Gas Processing Technologies for NGLs]
*[https://web.archive.org/web/20090204201325/http://wiki.jmol.org:81/index.php/User:Bduke Staggered and eclipsed ethane]

{{Alkanes}}
{{Hydrides by group}}
{{Authority control}}

[[Category:Ethane| ]]
[[Category:Alkanes]]
[[Category:Industrial gases]]
[[Category:Greenhouse gases]]