Higher alkanes
Encyclopedia
Higher alkanes are often defined as alkane
s having nine or more carbon atoms. Nonane
is the lightest alkane to have a flash point
above 25 °C, and so not to be classified as dangerously flammable.
The scientific literature uses the term higher alkanes arbitrarily: sometimes literally as “alkanes with a higher number of carbon atoms”, sometimes according to a definition. For instance, other than based on nonane, one definition distinguishes the higher alkanes as the n-alkanes that are solid under natural conditions.
to, for instance, hexadecane
(an alkane with sixteen carbon atoms) are liquids of higher viscosity
, less and less suitable for use in gasoline. They form instead the major part of diesel and aviation fuel
. Diesel fuels are characterised by their cetane number
, cetane being an old 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.
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, for example in candle
s. This should not be confused however with true wax
, which consists primarily of ester
s.
Alkanes with a chain length of approximately 35 or more carbon atoms are found in bitumen, used for example in road surfacing. However, the higher alkanes have little value and are usually split into lower alkanes by cracking
.
Alkane
Alkanes are chemical compounds that consist only of hydrogen and carbon atoms and are bonded exclusively by single bonds without any cycles...
s having nine or more carbon atoms. Nonane
Nonane
Nonane is a linear alkane hydrocarbon with the chemical formula C9H20.Nonane has 35 structural isomers. Tripropylene is a mixture of three specific isomers of nonane.Its substituent form is nonyl. Its cycloalkane counterpart is cyclononane, ....
is the lightest alkane to have a flash point
Flash point
The flash point of a volatile material is the lowest temperature at which it can vaporize to form an ignitable mixture in air. Measuring a flash point requires an ignition source...
above 25 °C, and so not to be classified as dangerously flammable.
The scientific literature uses the term higher alkanes arbitrarily: sometimes literally as “alkanes with a higher number of carbon atoms”, sometimes according to a definition. For instance, other than based on nonane, one definition distinguishes the higher alkanes as the n-alkanes that are solid under natural conditions.
Uses
Alkanes from nonaneNonane
Nonane is a linear alkane hydrocarbon with the chemical formula C9H20.Nonane has 35 structural isomers. Tripropylene is a mixture of three specific isomers of nonane.Its substituent form is nonyl. Its cycloalkane counterpart is cyclononane, ....
to, for instance, hexadecane
Hexadecane
Hexadecane 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 14 other carbon atoms.Cetane is often used as a short-hand for cetane...
(an alkane with sixteen carbon atoms) are liquids of higher viscosity
Viscosity
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity...
, less and less suitable for use in gasoline. They form instead the major part of diesel and aviation fuel
Aviation fuel
Aviation fuel is a specialized type of petroleum-based fuel used to power aircraft. It is generally of a higher quality than fuels used in less critical applications, such as heating or road transport, and often contains additives to reduce the risk of icing or explosion due to high temperatures,...
. Diesel fuels are characterised by their cetane number
Cetane number
Cetane number or CN is a measurement of the combustion quality of diesel fuel during compression ignition. It is a significant expression of diesel fuel quality among a number of other measurements that determine overall diesel fuel quality.- Definition :...
, cetane being an old 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.
Alkanes from hexadecane upwards form the most important components of fuel oil
Fuel oil
Fuel oil is a fraction obtained from petroleum distillation, either as a distillate or a residue. Broadly speaking, fuel oil is any liquid petroleum product that is burned in a furnace or boiler for the generation of heat or used in an engine for the generation of power, except oils having a flash...
and lubricating oil
Lubricant
A lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles and of distributing heat...
. 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, for example in candle
Candle
A candle is a solid block or cylinder of wax with an embedded wick, which is lit to provide light, and sometimes heat.Today, most candles are made from paraffin. Candles can also be made from beeswax, soy, other plant waxes, and tallow...
s. This should not be confused however with true wax
Wax
thumb|right|[[Cetyl palmitate]], a typical wax ester.Wax refers to a class of chemical compounds that are plastic near ambient temperatures. Characteristically, they melt above 45 °C to give a low viscosity liquid. Waxes are insoluble in water but soluble in organic, nonpolar solvents...
, which consists primarily of ester
Ester
Esters are chemical compounds derived by reacting an oxoacid with a hydroxyl compound such as an alcohol or phenol. Esters are usually derived from an inorganic acid or organic acid in which at least one -OH group is replaced by an -O-alkyl group, and most commonly from carboxylic acids and...
s.
Alkanes with a chain length of approximately 35 or more carbon atoms are found in bitumen, used for example in road surfacing. However, the higher alkanes have little value and are usually split into lower alkanes by cracking
Fluid catalytic cracking
Fluid catalytic cracking is the most important conversion process used in petroleum refineries. It is widely used to convert the high-boiling, high-molecular weight hydrocarbon fractions of petroleum crude oils to more valuable gasoline, olefinic gases, and other products...
.
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 natural conditions.| Nonane Nonane Nonane is a linear alkane hydrocarbon with the chemical formula C9H20.Nonane has 35 structural isomers. Tripropylene is a mixture of three specific isomers of nonane.Its substituent form is nonyl. Its cycloalkane counterpart is cyclononane, .... |
Decane Decane Decane is an alkane hydrocarbon with the chemical formula CH38CH3.75 structural isomers of decane exist, all of which are flammable liquids. Decane is one of the components of gasoline . Like other alkanes, it is nonpolar and therefore will not dissolve in polar liquids such as water... |
Undecane Undecane Undecane is a liquid alkane hydrocarbon with the chemical formula CH39CH3. It is used as a mild sex attractant for various types of moths and cockroaches, and an alert signal for a variety of ants. It has 159 isomers.... |
Dodecane Dodecane Dodecane is a liquid alkane hydrocarbon with the chemical formula CH310CH3 , an oily liquid of the paraffin series. It has 355 isomers.... |
Tridecane Tridecane Tridecane may refer to any alkane hydrocarbon with the chemical formula , or to a mixture of them. There are 802 constitutional isomers with that formula... |
Tetradecane | Pentadecane | Hexadecane Hexadecane Hexadecane 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 14 other carbon atoms.Cetane is often used as a short-hand for cetane... |
|
|---|---|---|---|---|---|---|---|---|
| Formula Chemical formula A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound.... |
C9H20 | C10H22 | C11H24 | C12H26 | C13H28 | C14H30 | C15H32 | C16H34 |
| CAS number | [111-84-2] | [124-18-5] | [1120-21-4] | [112-40-3] | [629-50-5] | [629-59-4] | [629-62-9] | [544-76-3] |
| Molar mass Molar mass Molar mass, symbol M, is a physical property of a given substance , namely its mass per amount of substance. The base SI unit for mass is the kilogram and that for amount of substance is the mole. Thus, the derived unit for molar mass is kg/mol... (g/mol) |
128.26 | 142.29 | 156.31 | 170.34 | 184.37 | 198.39 | 212.42 | 226.45 |
| Melting point Melting point The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure... (°C) |
−53 | −30 | −26 | −9.6 | −5 | 5.5 | 9.9 | 18 |
| Boiling point Boiling point The boiling point of an element or a substance is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid.... (°C) |
151 | 174 | 196 | 216.2 | 234 | 253 | 268–270 | 287 |
| Density Density The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight... (g/ml) |
0.718 | 0.73 | 0.74 | 0.75 | 0.763 | 0.769 | 0.773 | |
| Viscosity Viscosity Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity... (cP Poise The poise is the unit of dynamic viscosity in the centimetre gram second system of units. It is named after Jean Louis Marie Poiseuille .... at 20 °C) |
0.711 | 0.92 | 1.35 | 2.18 | 3.34 | |||
| Flash point Flash point The flash point of a volatile material is the lowest temperature at which it can vaporize to form an ignitable mixture in air. Measuring a flash point requires an ignition source... (°C) |
31 | 46 | 60 | 71 | 102 | 99 | 132 | 135 |
| Autoignition temperature Autoignition temperature The autoignition temperature or kindling point of a substance is the lowest temperature at which it will spontaneously ignite in a normal atmosphere without an external source of ignition, such as a flame or spark. This temperature is required to supply the activation energy needed for combustion... (°C) |
205 | 210 | 205 | 235 | 201 | |||
| Explosive limits | 0.9–2.9% | 0.8–2.6% | 0.45–6.5% | |||||
Heptadecane to Tetracosane
From this group on, the n-alkanes are generally solid under natural conditions.| Heptadecane | Octadecane | Nonadecane | Icosane | Henicosane | Docosane | Tricosane | Tetracosane Tetracosane Tetracosane, also called tetrakosane, is an alkane hydrocarbon with the structural formula H24H. As with other alkanes, its name is derived from Greek for the number of carbon atoms, 24, in the molecule... |
|
|---|---|---|---|---|---|---|---|---|
| Formula Chemical formula A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound.... |
C17H36 | C18H38 | C19H40 | C20H42 | C21H44 | C22H46 | C23H48 | C24H50 |
| CAS number | [629-78-7] | [593-45-3] | [629-92-5] | [112-95-8] | [629-94-7] | [629-97-0] | [638-67-5] | [646-31-1] |
| Molar mass Molar mass Molar mass, symbol M, is a physical property of a given substance , namely its mass per amount of substance. The base SI unit for mass is the kilogram and that for amount of substance is the mole. Thus, the derived unit for molar mass is kg/mol... (g/mol) |
240.47 | 254.50 | 268.53 | 282.55 | 296.58 | 310.61 | 324.63 | 338.66 |
| Melting point Melting point The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure... (°C) |
21 | 28–30 | 32–34 | 36.7 | 40.5 | 42 | 48–50 | 52 |
| Boiling point Boiling point The boiling point of an element or a substance is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid.... (°C) |
302 | 317 | 330 | 342.7 | 356.5 | 224 at 2 kPa | 380 | 391.3 |
| Density Density The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight... (g/ml) |
0.777 | 0.777 | 0.792 | 0.797 | ||||
| Flash point Flash point The flash point of a volatile material is the lowest temperature at which it can vaporize to form an ignitable mixture in air. Measuring a flash point requires an ignition source... (°C) |
148 | 165 | 168 | |||||
Pentacosane to Triacontane
| Pentacosane | Hexacosane | Heptacosane | Octacosane | Nonacosane Nonacosane Nonacosane is a straight-chain hydrocarbon with a molecular formula of C29H60, and the structural formula CH327CH3. It has 1,590,507,121 constitutional isomers.... |
Triacontane | |
|---|---|---|---|---|---|---|
| Formula Chemical formula A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound.... |
C25H52 | C26H54 | C27H56 | C28H58 | C29H60 | C30H62 |
| CAS number | [629-99-2] | [630-01-3] | [593-49-7] | [630-02-4] | [630-03-5] | [638-68-6] |
| Molar mass Molar mass Molar mass, symbol M, is a physical property of a given substance , namely its mass per amount of substance. The base SI unit for mass is the kilogram and that for amount of substance is the mole. Thus, the derived unit for molar mass is kg/mol... (g/mol) |
352.69 | 366.71 | 380.74 | 394.77 | 408.80 | 422.82 |
| Melting point Melting point The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure... (°C) |
54 | 56.4 | 59.5 | 64.5 | 63.7 | 65.8 |
| Boiling point Boiling point The boiling point of an element or a substance is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid.... (°C) |
401.9 | 412.2 | 422 | 431.6 | 440.8 | 449.7 |
| Density Density The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight... (g/ml) |
0.801 | 0.778 | 0.780 | 0.807 | 0.808 | 0.810 |
Hentriacontane to hexatriacontane
| Hentriacontane Hentriacontane Hentriacontane, also called untriacontane, is a solid, long-chain alkane hydrocarbon with the structural formula CH329CH3. It is found in a variety of plants, including peas , gum arabic and others, and also comprises about 8-9% of beeswax. It has 10,660,307,791 constitutional isomers.- External... |
Dotriacontane | Tritriacontane | Tetratriacontane | Pentatriacontane | Hexatriacontane | |
|---|---|---|---|---|---|---|
| Formula Chemical formula A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound.... |
C31H64 | C32H66 | C33H68 | C34H70 | C35H72 | C36H74 |
| CAS number | [630-04-6] | [544-85-4] | [630-05-7] | [14167-59-0] | [630-07-9] | [630-06-8] |
| Molar mass Molar mass Molar mass, symbol M, is a physical property of a given substance , namely its mass per amount of substance. The base SI unit for mass is the kilogram and that for amount of substance is the mole. Thus, the derived unit for molar mass is kg/mol... (g/mol) |
436.85 | 450.88 | 464.90 | 478.93 | 492.96 | 506.98 |
| Melting point Melting point The melting point of a solid is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at standard atmospheric pressure... (°C) |
67.9 | 69 | 70–72 | 72.6 | 75 | 74–76 |
| Boiling point Boiling point The boiling point of an element or a substance is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid.... (°C) |
458 | 467 | 285.4 at 0.4 kPa | 490 | 265 at 130 Pa | |
External links
- International Chemical Safety Card 1245 (nonane)
- NIOSH Pocket Guide to Chemical Hazards (nonane)
- International Chemical Safety Card 0428 (decane)