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Isopentane
Names
	Preferred IUPAC name 2-Methylbutane
	Other names Isopentane
Identifiers
CAS Number	78-78-4 ;
3D model (JSmol)	Interactive image;
Beilstein Reference	1730723
ChEBI	CHEBI:30362 ;
ChemSpider	6308 ;
ECHA InfoCard	100.001.039
EC Number	201-142-8;
Gmelin Reference	49318
MeSH	isopentane
PubChem CID	6556;
RTECS number	EK4430000;
UNII	ZH67814I0O ;
UN number	1265
CompTox Dashboard (EPA)	DTXSID901335409, DTXSID201032357 DTXSID8025468, DTXSID901335409, DTXSID201032357 ;
	InChI InChI=1S/C5H12/c1-4-5(2)3/h5H,4H2,1-3H3 Key: QWTDNUCVQCZILF-UHFFFAOYSA-N ;
	SMILES CCC(C)C;
Properties
Chemical formula	C5H12
Molar mass	72.151 g·mol−1
Appearance	Colorless liquid
Odor	Gasoline-like
Density	616 mg mL−1
Melting point	−161 to −159 °C; −258 to −254 °F; 112 to 114 K
Boiling point	27.8 to 28.2 °C; 81.9 to 82.7 °F; 300.9 to 301.3 K
Vapor pressure	76.992 kPa (at 20 °C)
Henry's law; constant (kH)	7.2 nmol Pa−1 kg−1
UV-vis (λmax)	192 nm
Refractive index (nD)	1.354
Viscosity	0.214 cP (at 20 °C)
Thermochemistry
Heat capacity (C)	164.85 J K−1 mol−1
Std molar; entropy (S⦵298)	260.41 J K−1 mol−1
Std enthalpy of; formation (ΔfH⦵298)	−179.1–−177.3 kJ mol−1
Std enthalpy of; combustion (ΔcH⦵298)	~ 3.3 MJ mol−1, 19,664 Btu/lb
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H224, H301, H302, H305, H336, H411
Precautionary statements	P210, P261, P273, P301+P310, P331
NFPA 704 (fire diamond)	1 4 0
Flash point	−51 °C (−60 °F; 222 K)
Autoignition; temperature	420 °C (788 °F; 693 K)
Explosive limits	1.4–8.3%
Related compounds
Related alkanes	Isobutane; 2-Methylpentane; 3-Methylpentane; 3-Ethylpentane;
Related compounds	2-Ethyl-1-butanol
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Isopentane, also called methylbutane or 2-methylbutane, is a branched-chain saturated hydrocarbon (an alkane) with five carbon atoms, with formula C
₅H
₁₂ or CH(CH
₃)
₂(C
₂H
₅).

Isopentane is a volatile and flammable liquid. It is one of three structural isomers with the molecular formula C₅H₁₂, the others being pentane (n-pentane) and neopentane (2,2-dimethylpropane).

Isopentane is commonly used in conjunction with liquid nitrogen to achieve a liquid bath temperature of −160 °C. Natural gas typically contains 1% or less isopentane,^[3] but it is a significant component of natural gasoline.^[4]

Nomenclature

The traditional name isopentane was still retained in the 1993 IUPAC recommendations,^[5]^[6] but is no longer recommended according to the 2013 recommendations.^[1] The preferred IUPAC name is the systematic name 2-methylbutane. An isopentyl group is a subset of the generic pentyl group. It has the chemical structure -CH₃CH₂CH(CH₃)₂.

Uses

Isopentane is used in a closed loop in geothermal power production to drive turbines.^[7]

Isopentane is used, in conjunction with dry ice or liquid nitrogen, to freeze tissues for cryosectioning in histology. ^[8]

Isopentane is a major component (sometimes 30% or more) of natural gasoline, an analog of common petroleum-derived gasoline that is condensed from natural gas.^[4] It has a substantially higher octane rating (RON 93.7) than n-pentane (61.7), and therefore there is interest in conversion from the latter.^[9]

References

^ ^a ^b Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 652. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4. The names 'isobutane', 'isopentane' and 'neopentane' are no longer recommended.
^ James Wei (1999), Molecular Symmetry, Rotational Entropy, and Elevated Melting Points. Ind. Eng. Chem. Res., volume 38 issue 12, pp. 5019–5027 doi:10.1021/ie990588m
^ Georg Hammer, Torsten Lübcke, Roland Kettner, Mark R. Pillarella, Herta Recknagel, Axel Commichau, Hans-Joachim Neumann and Barbara Paczynska-Lahme "Natural Gas" in Ullmann's Encyclopedia of Industrial Chemistry 2006, Wiley-VCH, Weinheim. doi:10.1002/14356007.a17_073.pub2
^ ^a ^b Ivan F. Avery, L. V. Harvey (1958): Natural-gasoline and Cycling Plants in the United States, Information circular, U.S. Department of the Interior, Bureau of Mines. 12 pages.
^ Table 19(a) Acyclic and monocyclic hydrocarbons. Parent hydrocarbons
^ Panico, R. & Powell, W. H., eds. (1994). A Guide to IUPAC Nomenclature of Organic Compounds 1993. Oxford: Blackwell Science. ISBN 0-632-03488-2.
^ Byproduct Isopentane also used in some of the LPG plant to run the boiler and generate the power. HS Orka HF Energy Plant IV Archived 2014-10-18 at the Wayback Machine
^ "Animal Resources Program - the Office of the Vice President for Research | UAB".
^ Sheng Wang, Ying Zhang, Mao-Gang He, Xiong Zheng, and Li-Bin Chen (2014): "Thermal Diffusivity and Speed of Sound of Saturated Pentane from Light Scattering". International Journal of Thermophysics, volume 35, pages 1450–1464. doi:10.1007/s10765-014-1718-x