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Pentane is any or one of the organic compounds with the formula C5H12. This alkane is a component of some fuels and is employed as a specialty solvent in the laboratory. Its properties are very similar to those of butane and hexane. It exists in three structural isomers, the branched isomers are called isopentane and neopentane.
| pentane
| isopentane
| neopentane |
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The branched isomers are more stable. That is, they have lower heat of formation and heat of combustion. Isopentane is more stable than pentane by 1.8 kcal/mol, and neopentane by 5 kcal/mol.
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
Pentane burns to form carbon dioxide and water:
- C5H12 + 8 O2 → 5 CO2 + 6 H2O
As with other hydrocarbons, pentane undergoes free radical chlorination:
- C5H12 + Cl2 → C5H11Cl + HCl
Such reactions are unselective, yielding 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, 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.
References
External links