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[1]
Other names
Isopentane
Identifiers
  • 78-78-4 checkY
3D model (JSmol)
1730723
ChEBI
ChemSpider
ECHA InfoCard 100.001.039 Edit this at Wikidata
EC Number
  • 201-142-8
49318
MeSH isopentane
RTECS number
  • EK4430000
UNII
UN number 1265
Properties
C5H12
Molar mass 72.151 g·mol−1
Appearance Colorless liquid
Odor Odorless
Density 616 mg mL−1[2]
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)
7.2 nmol Pa−1 kg−1
UV-vis (λmax) 192 nm
1.354
Viscosity 0.214 cP (at 20 °C)
Thermochemistry
164.85 J K−1 mol−1
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 pictograms GHS02: Flammable GHS07: Harmful GHS08: Health hazard GHS09: Environmental hazard
GHS Signal word Danger
GHS hazard statements
 H224, H301, H302, H305, H336, H411
P210, P261, P273, P301+310, P331
NFPA 704 (fire diamond)
1
4
0
Flash point −51 °C (−60 °F; 222 K)
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 [77 °F], 100 kPa).
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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 an extremely volatile and extremely flammable liquid at room temperature and pressure. It is also the least dense liquid at standard conditions.[citation needed] The normal boiling point is just a few degrees above room temperature and isopentane will readily boil and evaporate away on a warm day.

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.

Isomers[]

Isopentane is one of three structural isomers with the molecular formula C5H12, the others being pentane (n-pentane) and neopentane (dimethyl propane).

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[]

  1. ^ Jump up to: 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.
  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. ^ Jump up to: 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.
  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. ^ http://www.uab.edu/research/administration/offices/ARP/ComparativePathology/Pathology/Histopathology/TissueSubmission/Pages/Freezing-Tissues-for-Cryosectioning.aspx
  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[]

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