Isopentane

Isopentane
IUPAC name

2-Methylbutane
Other names

Methylbutane
Identifiers
CAS number 78-78-4 Y
ChemSpider 6308 Y
UNII ZH67814I0O Y
ChEBI CHEBI:30362 Y
RTECS number EK4430000
Jmol-3D images Image 1
Properties
Molecular formula C5H12
Molar mass 72.15 g/mol
Appearance colorless liquid
Density 0.616 g/ml, liquid[1]
Melting point

−159.9 °C (113.3 K)[1]
Boiling point

27.7 °C (300.9 K)[1]
Solubility in water Immiscible
Thermochemistry
Std enthalpy of
formation ΔfHo298		 −179 kJ/mol
Std enthalpy of
combustion ΔcHo298		 −3504 kJ/mol
Standard molar
entropy So298		 260.7 J·K−1·mol−1
Hazards
EU classification Highly flammable (F+)
Harmful (Xn)
Dangerous for
the environment (N)
R-phrases R12, R51/53, R65,
R66, R67
S-phrases (S2), S9, S16, S29,
S33, S61, S62
NFPA 704
4
1
0
Flash point <−51 °C
Autoignition
temperature		 420 °C
Explosive limits 1.4–7.6%
Related compounds
Related alkane Isobutane
Neopentane
2-Methylpentane
Related compounds Pentane
Cyclopentane
 Y (verify) (what is: Y/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
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.

An isopentyl group is a subset of the generic pentyl group. It has the chemical structure -CH3CH2CH(CH3)2.

Contents

Nomenclature

Isopentane is the name recommended by the International Union of Pure and Applied Chemistry (IUPAC) in its 1993 Recommendations for the Nomenclature of Organic Chemistry.[2] It is one of only four acyclic hydrocarbons to retain its pre-IUPAC name. 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 dimethyl propane (neopentane).

Uses

Isopentane is one of the ingredients in both Aquafresh® and Sensodyne®.[3]

References

  1. ^ a b c James Wei (1999), Molecular Symmetry, Rotational Entropy, and Elevated Melting Points. Ind. Eng. Chem. Res., volume 38 issue 12, pp. 5019–5027
  2. ^ Panico, R.; & Powell, W. H. (Eds.) (1994). A Guide to IUPAC Nomenclature of Organic Compounds 1993. Oxford: Blackwell Science. ISBN 0-632-03488-2. http://www.acdlabs.com/iupac/nomenclature/93/r93_679.htm. 
  3. ^ Aquafresh Website

External links

Methane (CH4) · Ethane (C2H6) · Propane (C3H8) · Butane (C4H10) · Pentane (C5H12) · Hexane (C6H14) · Heptane (C7H16) · Octane (C8H18) · Nonane (C9H20) · Decane (C10H22) · Undecane (C11H24) · Dodecane (C12H26) · Hexadecane / Cetane (C16H34)