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Isopentane

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Isopentane
Skeletal formula of isopentane
Skeletal formula of isopentane with all implicit carbons shown, and all explicit hydrogens added
Ball and stick model of isopentane
Names
Preferred IUPAC name 2-Methylbutane
Other names Isopentane
Identifiers
CAS Number
3D model (JSmol)
Beilstein Reference 1730723
ChEBI
ChemSpider
ECHA InfoCard 100.001.039 Edit this at Wikidata
EC Number
  • 201-142-8
Gmelin Reference 49318
MeSH isopentane
PubChem CID
RTECS number
  • EK4430000
UNII
UN number 1265
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C5H12/c1-4-5(2)3/h5H,4H2,1-3H3Key: QWTDNUCVQCZILF-UHFFFAOYSA-N
SMILES
  • CCC(C)C
Properties
Chemical formula C5H12
Molar mass 72.151 g·mol
Appearance Colorless liquid
Odor Gasoline-like
Density 616 mg mL
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 kg
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 mol
Std molar
entropy (S298) 		260.41 J K mol
Std enthalpy of
formation (ΔfH298) 		−179.1–−177.3 kJ mol
Std enthalpy of
combustion (ΔcH298) 		~ 3.3 MJ mol, 19,664 Btu/lb
Hazards
GHS labelling:
Pictograms GHS02: Flammable GHS07: Exclamation mark GHS08: Health hazard GHS09: Environmental hazard
Signal word Danger
Hazard statements H224, H301, H302, H305, H336, H411
Precautionary statements P210, P261, P273, P301+P310, P331
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propaneInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
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
Related compounds 2-Ethyl-1-butanol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). ☒N verify (what is  ?) Infobox references
Chemical compound

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, but it is a significant component of natural gasoline.

Nomenclature

The traditional name isopentane was still retained in the 1993 IUPAC recommendations, but is no longer recommended according to the 2013 recommendations. 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.

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

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. 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.

References

  1. ^ 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.
  2. 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
  3. 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
  4. ^ 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.
  5. Table 19(a) Acyclic and monocyclic hydrocarbons. Parent hydrocarbons
  6. Panico, R. & Powell, W. H., eds. (1994). A Guide to IUPAC Nomenclature of Organic Compounds 1993. Oxford: Blackwell Science. ISBN 0-632-03488-2.
  7. 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
  8. "Animal Resources Program - the Office of the Vice President for Research | UAB".
  9. 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

External links

Alkanes
Category: