pentane

n-Pentane
IUPAC name	pentane
Other names	n-pentane amyl hydride Skellysolve A
Identifiers
CAS number	109-66-0 Y
PubChem	8003
RTECS number	RZ9450000
SMILES	CCCCC
InChI	1/C5H12/c1-3-5-4-2/h3-5H2,1-2H3
ChemSpider ID	7712
Properties
Molecular formula	C5H12
Molar mass	72.15 g/mol
Appearance	Colourless liquid
Density	0.626 g/cm³, liquid
Melting point	−129.8 °C (143 K)
Boiling point	36.1 °C (308 K)
Solubility in water	0.004 g/100 mL (20 °C)[1]
Acidity (pKa)	~45
Viscosity	0.240 cP at 20 °C
Hazards
MSDS	External MSDS
R/S statement	R: R12, R51/53, R65, R66, R67 S: (S2), S9, S16, S29, S33, S61, S62
NFPA 704	4 1 0
Flash point	−49 °C
Related compounds
Related alkanes	Butane, Isopentane, Neopentane, Hexane
Related compounds	Cyclopentane
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Pentane is an organic compounds with the formula C₅H₁₂ — that is, an alkane with five carbon atoms. The term may refer to any of three structural isomers, or to a mixture of them:

normal pentane unbranched pentane n-pentane	isopentane methylbutane	neopentane dimethylpropane

In the IUPAC nomenclature, however, "pentane" means exclusively n-pentane; the other two being called "methylbutane" and "dimethylpropane".

Pentanes are components of some fuels and are employed as a specialty solvents in the laboratory. Their properties are very similar to those of butane and of the hexanes.

The branched isomers are more stable (have lower heat of formation and heat of combustion) than normal pentane. The difference is 1.8 kcal/mol for isopentane, and 5 kcal/mol for neopentane.^[2]

Rotation about two central single C-C bonds of n-pentane produces four different conformations.^[3]

Laboratory use

As the most volatile hydrocarbon that is liquid at room temperature, pentane is often used in the laboratory as a solvent that can be conveniently evaporated. Also because of its nonpolarity and lack of functionality, its dissolving power is poor, thus only non-polar and alkyl-rich compounds are soluble in it. Pentane is miscible, however, with most common nonpolar solvents such as chlorocarbons, aromatics, and ethers.

One of its applications as a laboratory solvent is in liquid chromatography.

Reactions

All pentane isomers burn with oxygen to form carbon dioxide and water:

C₅H₁₂ + 8 O₂ → 5 CO₂ + 6 H₂O

As with other hydrocarbons, pentanes undergo free radical chlorination:

C₅H₁₂ + Cl₂ → C₅H₁₁Cl + HCl

Such reactions are unselective; with n-pentane, the result is a mixture of the 1-, 2-, and 3-chloropentanes, as well as more highly chlorinated derivatives. Other radical halogenations can also occur.

While n-butane is the conventional feedstock in the production of maleic anhydride, n-pentane is also a substrate:

CH₃CH₂CH₂CH₂CH₃ + 5 O₂ → C₂H₂(CO)₂O + 5 H₂O + CO₂

Industrial uses

Pentane is one of the primary blowing agents used in the production of polystyrene foam.

Pentane is used as a working medium in geothermal power stations.

References

External links

• International Chemical Safety Card 0534
• NIOSH Pocket Guide to Chemical Hazards
• Material Safety Data Sheet for Pentane
• Phytochemical database entry