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
Identifiers
CAS number 78-78-4 YesY
PubChem 6556
ChemSpider 6308 YesY
UNII ZH67814I0O YesY
EC number 201-142-8
UN number 1265
MeSH isopentane
ChEBI CHEBI:30362 YesY
RTECS number EK4430000
Beilstein Reference 1730723
Gmelin Reference 49318
Jmol-3D images Image 1
Properties
Molecular formula C5H12
Molar mass 72.15 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)
kH 7.2 nmol Pa−1 kg−1
λmax 192 nm
Refractive index (nD) 1.354
Thermochemistry
Specific
heat capacity
C
164.85 J K−1 mol−1
Std molar
entropy
So298
260.41 J K−1 mol−1
Std enthalpy of
formation
ΔfHo298
−179.1–−177.3 kJ mol−1
Std enthalpy of
combustion
ΔcHo298
−3.5052–−3.5036 MJ mol−1
Hazards
GHS pictograms The flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The health hazard pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The environment pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
GHS hazard statements H224, H304, H336, H411
GHS precautionary statements P210, P261, P273, P301+310, P331
EU Index 601-006-00-1
EU classification Extremely Flammable F+ Harmful Xn Dangerous for the Environment (Nature) N
R-phrases R12, R51/53, R65, R66, R67
S-phrases (S2), S16, S29, S33
NFPA 704
Flammability code 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., propane Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point −51 °C (−60 °F; 222 K)
Explosive limits 1.4–8.3%
Related compounds
Related alkanes
Related compounds 2-Ethyl-1-butanol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Isopentane, C5H12, also called methylbutane or 2-methylbutane, is a branched-chain alkane with five carbon atoms. Isopentane is an extremely volatile and extremely flammable liquid at room temperature and pressure. 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. It is 1% or less of natural gas.[3]

Nomenclature[edit]

Isopentane is the name recommended by the International Union of Pure and Applied Chemistry (IUPAC).[4] An isopentyl group is a subset of the generic pentyl group. It has the chemical structure -CH2CH2CH(CH3)2.

Isomers[edit]

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

Uses[edit]

Isopentane is one of the ingredients in both Aquafresh and Sensodyne.[5]

References[edit]

  1. ^ "isopentane - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records. Retrieved 5 March 2012. 
  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. ^ Panico, R.; & Powell, W. H. (Eds.) (1994). A Guide to IUPAC Nomenclature of Organic Compounds 1993. Oxford: Blackwell Science. ISBN 0-632-03488-2. 
  5. ^ Aquafresh Website

External links[edit]