Higher alkanes are alkanes having nine or more

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...

atoms.

Nonane Nonane is a linear alkane hydrocarbon with the chemical formula C9H20. It is a colorless, flammable liquid, occurring primarily in the component of the petroleum distillate fraction commonly called kerosene, which is used as a heating, tractor, ...

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.

Uses

Alkanes from

nonane Nonane is a linear alkane hydrocarbon with the chemical formula C9H20. It is a colorless, flammable liquid, occurring primarily in the component of the petroleum distillate fraction commonly called kerosene, which is used as a heating, tractor, ...

hexadecane Hexadecane (also called cetane) is an alkane hydrocarbon with the chemical formula C16H34. Hexadecane consists of a chain of 16 carbon atoms, with three hydrogen atoms bonded to the two end carbon atoms, and two hydrogens bonded to each of the ...

(those alkanes with nine to sixteen carbon atoms) are liquids of higher

viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the inte ...

, which are less suitable for use in

gasoline Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organi ...

. They form instead the major part of

diesel Diesel may refer to: * Diesel engine, an internal combustion engine where ignition is caused by compression * Diesel fuel, a liquid fuel used in diesel engines * Diesel locomotive, a railway locomotive in which the prime mover is a diesel engin ...

kerosene Kerosene, paraffin, or lamp oil is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from el, κηρός (''keros'') meaning "wax", and was regi ...

, and aviation fuel. Diesel fuels are characterised by their

cetane number Cetane number (cetane rating) is an indicator of the combustion speed of diesel fuel and compression needed for ignition. It plays a similar role for diesel as octane rating does for gasoline. The CN is an important factor in determining the quali ...

, 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 The polar regions, also called the frigid zones or polar zones, of Earth are the regions of the planet that surround its geographical poles (the North and South Poles), lying within the polar circles. These high latitudes are dominated by floa ...

, where the fuel becomes too thick to flow correctly. Mixtures of the normal alkanes are used as boiling point standards for simulated

distillation Distillation, or classical distillation, is the process of separating the components or substances from a liquid mixture by using selective boiling and condensation, usually inside an apparatus known as a still. Dry distillation is the heat ...

by gas chromatography. 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 In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, t ...

nature means that water cannot reach the metal surface. Many solid alkanes find use as

paraffin wax Paraffin wax (or petroleum wax) is a soft colorless solid derived from petroleum, coal, or oil shale that consists of a mixture of hydrocarbon molecules containing between 20 and 40 carbon atoms. It is solid at room temperature and begins to ...

, used for lubrication,

electrical insulation An electrical insulator is a material in which electric current does not flow freely. The atoms of the insulator have tightly bound electrons which cannot readily move. Other materials—semiconductors and conductors—conduct electric current ...

, and

candle A candle is an ignitable wick embedded in wax, or another flammable solid substance such as tallow, that provides light, and in some cases, a fragrance. A candle can also provide heat or a method of keeping time. A person who makes candle ...

s. Paraffin wax should not be confused with

beeswax Beeswax (''cera alba'') is a natural wax produced by honey bees of the genus ''Apis''. The wax is formed into scales by eight wax-producing glands in the abdominal segments of worker bees, which discard it in or at the hive. The hive work ...

, which consists primarily of

ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides a ...

s. 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: * cetane, for

* cerane, for hexacosane

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.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.

Heptadecane to tetracosane

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

Pentacosane to triacontane

Hentriacontane to hexatriacontane

Heptatriacontane to dotetracontane

Tritetracontane to octatetracontane

Nonatetracontane to tetrapentacontane

Pentapentacontane to hexacontane

References

External links

International Chemical Safety Card 1245
(nonane)

(nonane)

(decane) {{alkanes Alkanes