Editing Isobutane

{{Chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 443882541
| ImageFileR1 = Isobutane simple.svg
| ImageNameR1 = Skeletal formula of isobutane
| ImageClassR1 = skin-invert
| Name = 
| ImageFile = 
| ImageFileL1 = Isobutane 1.svg
| ImageNameL1 = Chemical structure of isobutane with all atoms explicitly shown
| ImageClassL1 = skin-invert
| ImageFileL2 = Isobutane-3D-balls.png
| ImageFileL2_Ref = {{chemboximage|correct|??}}
| ImageNameL2 = Ball and stick model of isobutane
| ImageClassL2 = bg-transparent
| ImageFileR2 = isobutane3.png
| ImageFileR2_Ref = {{chemboximage|correct|??}}
| ImageNameR2 = Spacefill model of isobutane
| ImageClassR2 = bg-transparent
| PIN = 2-Methylpropane<ref name=iupac2013_652>{{cite book |title= Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) |publisher= [[Royal Society of Chemistry|The Royal Society of Chemistry]] |date= 2014 |location= Cambridge |page= 652 |doi= 10.1039/9781849733069-FP001 |isbn= 978-0-85404-182-4 |quote= The names 'isobutane', 'isopentane', and 'neopentane' are no longer recommended.}}</ref>
| SystematicName = 
| OtherNames = {{Unbulleted list|Isobutane|R600a}}
| IUPACName = 
| Section1 = {{Chembox Identifiers
| CASNo = 75-28-5
| CASNo_Ref = {{cascite|correct|CAS}}
| PubChem = 6360
| ChemSpiderID = 6120
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| UNII = BXR49TP611
| UNII_Ref = {{fdacite|correct|FDA}}
| EINECS = 200-857-2
| UNNumber = 1969
| KEGG = D04623
| KEGG_Ref = {{keggcite|changed|kegg}}
| ChEBI = 30363
| ChEBI_Ref = {{ebicite|correct|EBI}}
| RTECS = TZ4300000
| Beilstein = 1730720
| Gmelin = 1301
| SMILES = CC(C)C
| StdInChI = 1S/C4H10/c1-4(2)3/h4H,1-3H3
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = NNPPMTNAJDCUHE-UHFFFAOYSA-N
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
}}
| Section2 = {{Chembox Properties
| C=4 | H=10
| Appearance = Colorless gas
| Odor = Odorless
| Density = {{ubl
 | 2.51{{nbsp}}kg/m<sup>3</sup> (at 15&nbsp;°C, 100{{nbsp}}kPa)
 | 563&nbsp;kg/m<sup>3</sup> (at 15&nbsp;°C, boiling liquid)
 }}
| MeltingPtC = −159.42
| MeltingPt_ref = <ref name=GESTIS>{{GESTIS|ZVG=25040}}</ref>
| BoilingPtC = −11.7
| MagSus = −51.7·10<sup>−6</sup> cm<sup>3</sup>/mol
| BoilingPt_ref = <ref name=GESTIS/>
| Solubility = 48.9{{nbsp}}mg⋅L<sup>−1</sup> (at {{convert|25|C}})<ref>{{cite web|title=Solubility in Water|url=https://pubchem.ncbi.nlm.nih.gov/compound/isobutane#section=Solubility|website=PubChem|publisher=National Center for Biotechnology Information|access-date=6 April 2017}}</ref>
| VaporPressure = {{convert|3.1|atm|abbr=on}} (at {{convert|21|C|K F}})<ref>{{cite web |title=CDC - NIOSH Pocket Guide to Chemical Hazards - Isobutane |url=https://www.cdc.gov/niosh/npg/npgd0350.html |website=CDC - NIOSH Pocket Guide to Chemical Hazards |publisher=CDC |access-date=28 December 2018}}</ref>
| HenryConstant = 8.6{{nbsp}}nmol⋅Pa<sup>−1</sup>⋅kg<sup>−1</sup>
| ConjugateAcid = [[Isobutanium]]
}}
| Section3 = {{Chembox Thermochemistry
| DeltaHf = −134.8{{nbsp}}–{{nbsp}}−133.6{{nbsp}}kJ⋅mol<sup>−1</sup>
| DeltaHc = −2.86959{{nbsp}}–{{nbsp}}−2.86841{{nbsp}}MJ⋅mol<sup>−1</sup>
| HeatCapacity = 96.65{{nbsp}}J⋅K<sup>−1</sup>⋅mol<sup>−1</sup>
}}
| Section4 = {{Chembox Hazards
| ExternalSDS = [https://www.lindeus.com/-/media/corporate/praxairus/documents/sds/isobutane-c4h10-safety-data-sheet-sds-p4613.pdf?la=en lindeus.com]
| GHSPictograms = {{GHS flame}}
| GHSSignalWord = '''DANGER'''
| HPhrases = {{H-phrases|220}}
| PPhrases = {{P-phrases|210}}
| NFPA-H = 1
| NFPA-F = 4
| NFPA-R = 0
| FlashPtC = −83
| AutoignitionPtC = 460
| ExploLimits = 1.4–8.3%
| IDLH = N.D.<ref name=PGCH>{{PGCH|0350}}</ref>
| PEL = None<ref name=PGCH/>
| REL = TWA 800{{nbsp}}ppm (1900 mg/m<sup>3</sup>)<ref name=PGCH/>
}}
| Section5 = {{Chembox Related
| OtherFunction_label = alkane
| OtherFunction = [[Isopentane]]
}}
| Section6 = 
}}
[[File:R600a product image.png|thumb|R600-Isobutane 13.6Kg Cylinder by Starke Hvac]]
'''Isobutane''', also known as '''''i''-butane''', '''2-methylpropane''' or '''methylpropane''', is a [[chemical compound]] with [[molecular formula]] HC(CH<sub>3</sub>)<sub>3</sub>. It is an [[isomer]] of [[butane]]. Isobutane is a colorless, odorless gas.
It is the simplest [[alkane]] with a [[tertiary carbon]] atom. Isobutane is used as a precursor molecule in the [[petrochemical industry]], for example in the synthesis of [[isooctane]].<ref>{{cite web |url=http://www.chemistry.org/portal/a/c/s/1/acsdisplay.html?DOC=patentwatch%5Carchive%5C073106_patentwatch.html |title=Patent Watch, July 31, 2006. |access-date=August 8, 2006 |url-status=dead |archive-url=https://web.archive.org/web/20070311154937/http://www.chemistry.org/portal/a/c/s/1/acsdisplay.html?DOC=patentwatch%5Carchive%5C073106_patentwatch.html |archive-date=March 11, 2007}}</ref> 
==Production==
Isobutane is obtained by [[isomerization]] of [[butane]].
[[File:ButaneIsomerization.svg|class=skin-invert-image|center|thumb|240px|Isomerization of butane]]

==Uses==
Isobutane is the principal feedstock in [[alkylation unit]]s of refineries. Using isobutane, gasoline-grade "blendstocks" are generated with high branching for good combustion characteristics. Typical products created with isobutane are [[2,4-Dimethylpentane|2,4-dimethylpentane]] and especially [[2,2,4-Trimethylpentane|2,2,4-trimethylpentane]].<ref>{{cite encyclopedia |title=Alkylation |author=Bipin V. Vora |author2=Joseph A. Kocal |author3=Paul T. Barger |author4=Robert J. Schmidt |author5=James A. Johnson |year=2003 |encyclopedia=Kirk-Othmer Encyclopedia of Chemical Technology |doi=10.1002/0471238961.0112112508011313.a01.pub2 |isbn=0471238961}}</ref>
[[File:2,4-Me2pentaneRoute.png|class=skin-invert-image|center|thumb|288 px|Typical acid-catalyzed route to [[2,4-Dimethylpentane|2,4-dimethylpentane]].]]

===Solvent===
In the Chevron Phillips slurry process for making [[high-density polyethylene]], isobutane is used as a diluent. As the slurried polyethylene is removed, isobutane is "flashed" off, and condensed, and recycled back into the loop reactor for this purpose.<ref>{{Ullmann |title= Polyethylene |author= Kenneth S. Whiteley |doi= 10.1002/14356007.a21_487.pub2}}</ref>

===Precursor to ''tert''-butyl hydroperoxide===
Isobutane is oxidized to [[tert-Butyl hydroperoxide|''tert''-butyl hydroperoxide]], which is subsequently reacted with [[propylene]] to yield [[propylene oxide]]. The [[tert-butanol]] that results as a by-product is typically used to make gasoline additives such as [[methyl tert-butyl ether]] (MTBE).

===Miscellaneous uses===
Isobutane is also used as a propellant for [[aerosol spray#Aerosol propellants|aerosol spray cans]].

Isobutane is used as part of blended fuels, especially common in fuel canisters used for [[camping]].<ref name="camp fuel">{{cite web |url=https://backpackinglight.com/canister_stove_faq/ |title=Frequently Asked Questions About Lightweight Canister Stoves and Fuels |first=Will |last=Rietveld |publisher=Backpacking Light (subscription required)|date=2005-02-08 |access-date=2022-06-03 |url-access=subscription}}</ref>

==Refrigerant==
Isobutane is used as a [[refrigerant]].<ref>{{cite web |url=https://ec.europa.eu/clima/sites/default/files/docs/0007/hcfc_technical_meeting_summary_en.pdf |title=Technical Meeting on HCFC Phase-Out: Overview of Advantages and Disadvantages of Alternatives (Montreal, Canada; European Commission on retrofit refrigerants for stationary applications) |date=April 2008 |access-date=2021-05-21 |url-status=live |archive-url=https://web.archive.org/web/20090805150605/http://ec.europa.eu/environment/ozone/pdf/hcfc_technical_meeting_summary.pdf |archive-date=2009-08-05}}</ref> Use in refrigerators started in 1993 when [[Greenpeace]] presented the Greenfreeze project with the former East German company {{Interlanguage link|Foron (company)|lt=Foron|de|Foron}}.<ref>{{cite web |url=http://www.greenpeace.org/usa/en/campaigns/global-warming-and-energy/green-solutions/greenfreeze/ |title=GreenFreeze |publisher=Greenpeace |date=2010-03-15 |access-date=2013-01-02 |url-status=dead |archive-url=https://web.archive.org/web/20101005093019/http://www.greenpeace.org/usa/en/campaigns/global-warming-and-energy/green-solutions/greenfreeze/ |archive-date=2010-10-05}}</ref><ref>{{cite web |title=Greenfreeze: from a snowball to an industrial avalanche |author=Wolfgang Lohbeck |date=June 2004 |url=https://www.greenpeace.org/usa/wp-content/uploads/legacy/Global/usa/report/2007/7/greenfreeze-from-snowball-to.pdf |access-date=2021-05-21}}</ref> In this regard, blends of pure, dry "isobutane" (R-600a) (that is, isobutane mixtures) have negligible [[ozone depletion potential]] and very low [[global warming potential]] (having a value of 3.3 times the GWP of carbon dioxide) and can serve as a functional replacement for [[dichlorodifluoromethane|R-12]], [[chlorodifluoromethane|R-22]] (both of these being commonly known by the trademark [[Freon]]), [[1,1,1,2-Tetrafluoroethane|R-134a]], and other [[chlorofluorocarbon]] or [[hydrofluorocarbon]] [[refrigerant]]s in conventional stationary refrigeration and air conditioning systems.

As a refrigerant, isobutane poses a fire and explosion risk in addition to the hazards associated with non-flammable CFC refrigerants. Substitution of this refrigerant for motor vehicle air conditioning systems not originally designed for isobutane is widely prohibited or discouraged.<ref>{{cite web |url=http://www.epa.gov/ozone/snap/refrigerants/hc12alng.html |title=U.S. EPA hydrocarbon-refrigerants FAQ |publisher=Epa.gov |access-date=2010-10-29}}</ref><ref>{{cite web |url=http://www.astreappliancerepair.com/wp-content/uploads/2014/07/hc_white_paper.pdf |title=Compendium of hydrocarbon-refrigerant policy statements, October 2006 |access-date=2014-08-01 |url-status=dead |archive-url=https://web.archive.org/web/20140808045013/http://www.astreappliancerepair.com/wp-content/uploads/2014/07/hc_white_paper.pdf |archive-date=2014-08-08}}</ref><ref>{{cite web |url=http://www.autoacforum.com/MACS/HCwarning.pdf |title=MACS bulletin: hydrocarbon refrigerant usage in vehicles |access-date=2010-10-29 |url-status=dead |archive-url=https://web.archive.org/web/20110105174944/http://www.autoacforum.com/MACS/HCwarning.pdf |archive-date=2011-01-05}}</ref><ref>{{cite web |url=http://www.sae.org/news/releases/05hydrocarbon_warning.htm |title=Society of Automotive Engineers hydrocarbon refrigerant bulletin |publisher=Sae.org |date=2005-04-27 |access-date=2010-10-29 |url-status=dead |archive-url=https://web.archive.org/web/20050505030057/http://www.sae.org/news/releases/05hydrocarbon_warning.htm |archive-date=2005-05-05}}</ref><ref>{{cite web |url=http://www.labour.gov.sk.ca/Default.aspx?DN=2fb5ac24-d90e-4408-bf40-559793bd8e96 |title=Saskatchewan Labour bulletin on hydrocarbon refrigerants in vehicles |publisher=Labour.gov.sk.ca |date=2010-06-29 |access-date=2010-10-29 |url-status=dead |archive-url=https://web.archive.org/web/20090701025850/http://www.labour.gov.sk.ca/Default.aspx?DN=2fb5ac24-d90e-4408-bf40-559793bd8e96 |archive-date=2009-07-01}}</ref><ref>[http://www.vasa.org.au/content/refriggas/index.php#Bookmark%202 VASA on refrigerant legality & advisability] {{webarchive |url=https://web.archive.org/web/20090113163519/http://www.vasa.org.au/content/refriggas/index.php#Bookmark |date=January 13, 2009}}</ref><ref>{{cite web |url=http://www.energy.qld.gov.au/zone_files/petroleum_pdf/safety_alert025.pdf |title=Queensland (Australia) government warning on hydrocarbon refrigerants |publisher=Energy.qld.gov.au |access-date=2010-10-29 |url-status=dead |archive-url=https://web.archive.org/web/20081217150006/http://www.energy.qld.gov.au/zone_files/petroleum_pdf/safety_alert025.pdf |archive-date=2008-12-17}}</ref>

Vendors and advocates of hydrocarbon refrigerants argue against such bans on the grounds that there have been very few such incidents relative to the number of vehicle air conditioning systems filled with hydrocarbons.<ref>{{cite web |url=http://www.parliament.nsw.gov.au/prod/parlment/HansArt.nsf/V3Key/LA19971016015 |title=New South Wales (Australia) Parliamentary record, 16 October 1997 |publisher=Parliament.nsw.gov.au |date=1997-10-16 |access-date=2010-10-29 |url-status=dead |archive-url=https://web.archive.org/web/20090701025536/http://www.parliament.nsw.gov.au/prod/parlment/HansArt.nsf/V3Key/LA19971016015 |archive-date=1 July 2009}}</ref><ref>{{cite web |url=http://www.parliament.nsw.gov.au/prod/parlment/hansart.nsf/V3Key/LC20000629051 |title=New South Wales (Australia) Parliamentary record, 29 June 2000 |publisher=Parliament.nsw.gov.au |access-date=2010-10-29 |url-status=dead |archive-url=https://web.archive.org/web/20050522080708/http://www.parliament.nsw.gov.au/prod/parlment/hansart.nsf/V3Key/LC20000629051 |archive-date=22 May 2005}}</ref>

A leak of isobutane in the refrigerant system of a fridge initiated the [[2024 Valencia residential complex fire]] in [[Spain]], that claimed 10 lives.<ref name="valencia_fridge">{{cite news |url=https://www.levante-emv.com/comunitat-valenciana/2024/05/03/incendio-valencia-fuga-gas-refrigerante-nevera-propicio-incendio-campanar-101873351.html |title=Una fuga del gas refrigerante de la nevera del piso 86 propició el inicio del incendio de Campanar |first=Teresa |last=Domínguez |work=[[Levante-EMV]] |date=3 May 2024 |access-date=15 October 2024 |language=es-ES}}</ref>

==Nomenclature==
The traditional name isobutane was still retained in the 1993 [[International Union of Pure and Applied Chemistry |IUPAC]] recommendations,<ref>{{cite book |editor=Panico, R. |editor2= Powell, W. H. |name-list-style= amp |title=A Guide to IUPAC Nomenclature of Organic Compounds 1993 |location=Oxford |publisher=Blackwell Science |year=1994 |isbn=0-632-03488-2}} https://www.acdlabs.com/iupac/nomenclature/93/r93_679.htm</ref> but is no longer recommended according to the 2013 recommendations.<ref name=iupac2013_652/> Since the longest continuous chain in isobutane contains only three carbon atoms, the [[preferred IUPAC name]] is 2-methylpropane but the [[locant]] (2-) is typically omitted in general nomenclature as redundant; C2 is the only position on a propane chain where a methyl substituent can be located without altering the main chain and forming the constitutional isomer ''n''-butane.

==References==
{{Reflist}}

==External links==
*[http://www.inchem.org/documents/icsc/icsc/eics0901.htm International Chemical Safety Card 0901]
*[https://www.cdc.gov/niosh/npg/npgd0350.html NIOSH Pocket Guide to Chemical Hazards]

{{E number infobox 930-949}}
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[[Category:Alkanes]]
[[Category:Butane]]
[[Category:E-number additives]]
[[Category:Propellants]]
[[Category:Refrigerants]]