Higher_alkanes

Higher alkane

Higher alkane

Alkanes having nine or more carbon atoms


Higher alkanes are alkanes having nine or more carbon atoms. Nonane is the lightest alkane to have a flash point above 25 °C, and is not classified as dangerously flammable.

The term higher alkanes is sometimes used literally as "alkanes with a higher number of carbon atoms". One definition distinguishes the higher alkanes as the n-alkanes that are solid under natural conditions.[which?]

Synthesis

Uses

Alkanes from nonane to hexadecane (those alkanes with nine to sixteen carbon atoms) are liquids of higher viscosity, which are less suitable for use in gasoline. They form instead the major part of diesel, kerosene, and aviation fuel. Diesel fuels are characterised by their cetane number, cetane being an older name for hexadecane. However the higher melting points of these alkanes can cause problems at low temperatures and in polar regions, where the fuel becomes too thick to flow correctly. Mixtures of the normal alkanes are used as boiling point standards for simulated distillation by gas chromatography.[1]

Alkanes from hexadecane upwards form the most important components of fuel oil and lubricating oil. In latter function they work at the same time as anti-corrosive agents, as their hydrophobic nature means that water cannot reach the metal surface. Many solid alkanes find use as paraffin wax, used for lubrication, electrical insulation, and candles. Paraffin wax should not be confused with beeswax, which consists primarily of esters.

Alkanes with a chain length of approximately 35 or more carbon atoms are found in bitumen (asphalt), used (for example) in road surfacing. However, the higher alkanes have little value and are usually split into lower alkanes by cracking.

Names

Some alkanes have non-IUPAC trivial names:

Properties

The properties listed here refer to the straight-chain alkanes (or: n-alkanes).

Nonane to hexadecane

This group of n-alkanes is generally liquid under standard conditions.[3]

More information Nonane, Decane ...

Heptadecane to tetracosane

From this group on, the n-alkanes are generally solid at standard conditions.

More information Heptadecane, Octadecane ...

Pentacosane to triacontane

More information Pentacosane, Hexacosane ...

Hentriacontane to hexatriacontane

More information Hentriacontane, Dotriacontane ...

Heptatriacontane to dotetracontane

More information Heptatriacontane, Octatriacontane ...

Tritetracontane to octatetracontane

More information Triatetracontane, Tetratetracontane ...

Nonatetracontane to tetrapentacontane

More information Nonatetracontane, Pentacontane ...

Pentapentacontane to hexacontane

More information Pentapentacontane, Hexapentacontane ...

See also


References

  1. ASTM D5399-09, Standard Test Method for Boiling Point Distribution of Hydrocarbon Solvents by Gas Chromatography
  2. Donald Mackay, Handbook of Physical-Chemical Properties and Environmental Fate for Organic Chemicals, ISBN 1420044397, p. 206
  3. Karl Griesbaum, Arno Behr, Dieter Biedenkapp, Heinz-Werner Voges, Dorothea Garbe, Christian Paetz, Gerd Collin, Dieter Mayer Hartmut Höke "Hydrocarbons" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a13_227
  4. Weast, Robert C., ed. (1982). CRC Handbook of Chemistry and Physics (63rd ed.). Boca Raton, Fl: CRC Press. p. C-561.

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