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Higher alkane#Heptatriacontane to dotetracontane

{{synthesis|date=May 2024}}

{{Short description|Alkanes having nine or more carbon atoms}}

Higher alkanes refer to alkanes with a high number of carbon atoms. There does not exist a formal definition for when an alkane is classified as a 'higher alkane', but one definition says higher alkanes are alkanes having nine or more carbon atoms. Thus, according to this definition, nonane is the lightest higher alkane.{{Cite web |title=Higher alkanes |url=https://www.wartsila.com/encyclopedia/term/higher-alkanes |access-date=2025-05-06 |website=Wartsila.com |language=en}}

Synthesis

{{Expand section|date=April 2023}}

Higher alkanes can be produced in several ways, they are naturally present in crude oil and can be obtained via fractional distillation. Similar to low molecular weight alkanes, there are several ways to synthesize higher alkanes:

=Decarboxylation of fatty acids=

Synthesis from saturated fatty acids decarboxylation leads to the formation of higher alkanes, as fatty acids chain length is usually between C10 and C22.{{Cite web |title= Fatty Acids - an overview |url=https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/fatty-acids |access-date=2025-05-06 |website=www.sciencedirect.com |language=en}}

=Fischer-Tropsch process=

Fischer-Tropsch process (or FT process) consist of the reaction of syngas: a mixture of hydrogen and carbon monoxide. The reaction is carried out at temperatures of 200°C-350°C at pressures of 20 Bar-50 Bar in the presence of a metal catalyst (iron or cobalt). The products obtained are liquid hydrocarbons and waxy solids, mostly n-paraffins. The liquid fraction ranges from C6 to C20, while the solid fraction consists of hydrocarbons above C21.{{Cite web |title= Fischer-Tropsch Process |url=https://www.sciencedirect.com/topics/earth-and-planetary-sciences/fischer-tropsch-process|access-date=2025-05-06 |website=www.sciencedirect.com |language=en}}{{Cite web |title= Fischer-Tropsch products from biomass-derived syngas and renewable hydrogen |url=https://link.springer.com/article/10.1007/s13399-019-00459-5|access-date=2025-05-06 |language=en}}

=Hydrogenation of long chain olefins=

Long alkenes (olefins) possess at least one double bond. Being quite reactive, it can easily break under the right conditions. Using hydrogen in the presence of a metal catalyst, such as platinum, palladium or nickel, the long alkene can undergo an addition reaction, forming long alkanes as products.{{Cite web |date=2013-10-02 |title=Catalytic Hydrogenation of Alkenes |url=https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Alkenes/Reactivity_of_Alkenes/Catalytic_Hydrogenation |access-date=2025-05-06 |website=Chemistry LibreTexts |language=en}}

=Urea extraction crystallization=

n-alkanes can be isolated via the formation of urea clathrates.

=Kolbe electrolysis=

They can also be synthesized through Kolbe electrolysis

=Wurtz reaction=

They can be synthesized via Wurtz reaction.

Reactions

Higher alkanes in general are relatively inert, just like low molecular weight alkanes they can react with oxygen and start a combustion reaction. They can undergo pyrolisis in the presence of alumina

or silica catalysts, forming lower alkanes and alkenes.{{Cite book|url=https://courseware.cutm.ac.in/wp-content/uploads/2020/05/preparationofalkanesclass11-151207081547-lva1-app6891.pdf|title="ALKANES AND THEIR PREPARATION"|language=en|access-date=2025-05-06}}

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.ASTM D5399-09, Standard Test Method for Boiling Point Distribution of Hydrocarbon Solvents 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 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:

  • cetane, for hexadecane
  • cerane, for hexacosaneDonald Mackay, Handbook of Physical-Chemical Properties and Environmental Fate for Organic Chemicals, {{isbn|1420044397}}, p. 206

Properties

{{also|List of straight-chain alkanes}}

Nonane is the lightest alkane to have a flash point above 25 °C, and is classified as flammable under the US National Library of Medicine. {{Cite web |date=26 October 2024 |title=Nonane |url=https://pubchem.ncbi.nlm.nih.gov/compound/nonane |website=PubChem}}

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. {{doi| 10.1002/14356007.a13_227}}

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! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Nonane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Decane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Undecane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Dodecane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Tridecane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Tetradecane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Pentadecane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Hexadecane

Formula

| 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 (g/mol)

| 128.26

| 142.29

| 156.31

| 170.34

| 184.37

| 198.39

| 212.42

| 226.45

Melting point (°C)

| −53.5

| −29.7

| −25.6

| −9.6

| −5.4

| 5.9

| 9.9

| 18.2

Boiling point (°C)

| 150.8

| 174.1

| 195.9

| 216.3

| 235.4

| 253.5

| 270.6

| 286.8

Density (g/ml at {{val|20|u=degC}})

| 0.71763

| 0.73005

| 0.74024

| 0.74869

| 0.75622

| 0.76275

| 0.76830

| 0.77344

Viscosity (cP at {{val|20|u=degC}})

| 0.7139

| 0.9256

| 1.185

| 1.503

| 1.880

| 2.335

| 2.863

| 3.474

Flash point (°C)

| 31

| 46

| 60

| 71

| 79

| 99

| 132

| 135

Autoignition
temperature (°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 at standard conditions.

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! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Heptadecane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Octadecane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Nonadecane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Icosane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Heneicosane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Docosane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Tricosane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Tetracosane

Formula

| 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 (g/mol)

| 240.47

| 254.50

| 268.53

| 282.55

| 296.58

| 310.61

| 324.63

| 338.66

Melting point (°C)

| 21

| 28–30

| 32–34

| 36.7

| 40.5

| 42

| 48–50

| 52

Boiling point (°C)

| 302

| 317

| 330

| 342.7

| 356.5

| 224 at 2 kPa

| 380

| 391.3

Density (g/ml)

| 0.777

| 0.777

| 0.786

| 0.7886

| 0.792

| 0.778

| 0.797

| 0.797

Flash point (°C)

| 148

| 166

| 168

| 176

|

|

|

|

= Pentacosane to triacontane =

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! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Pentacosane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Hexacosane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Heptacosane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Octacosane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Nonacosane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Triacontane

Formula

| 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 (g/mol)

| 352.69

| 366.71

| 380.74

| 394.77

| 408.80

| 422.82

Melting point (°C)

| 54

| 56.4

| 59.5

| 64.5

| 63.7

| 65.8

Boiling point (°C)

| 401

| 412.2

| 422

| 431.6

| 440.8

| 449.7

Density (g/ml)

| 0.801

| 0.778

| 0.780

| 0.807

| 0.808

| 0.810

= Hentriacontane to hexatriacontane =

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! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Hentriacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Dotriacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Tritriacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Tetratriacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Pentatriacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Hexatriacontane

Formula

| 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 (g/mol)

| 436.85

| 450.88

| 464.90

| 478.93

| 492.96

| 506.98

Melting point (°C)

| 67.9

| 69

| 70–72

| 72.6

| 75

| 74–76

Boiling point (°C)

| 458

| 467

| 474

| 285.4 at 0.4 kPa

| 490

| 265 at 130 Pa

Density (g/ml)

| 0.781 at 68 °C{{cite book |editor1-first = Robert C. |editor1-last= Weast |title=CRC Handbook of Chemistry and Physics |edition=63rd |year=1982 |publisher=CRC Press |location=Boca Raton, Fl |page=C-561}}

| 0.812

| 0.811

| 0.812

| 0.813

| 0.814

= Heptatriacontane to dotetracontane =

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! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Heptatriacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Octatriacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Nonatriacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Tetracontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Hentetracontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Dotetracontane

Formula

| C37H76

| C38H78

| C39H80

| C40H82

| C41H84

| C42H86

CAS number

| [7194-84-5]

| [7194-85-6]

| [7194-86-7]

| [4181-95-7]

| [7194-87-8]

| [7098-20-6]

Molar mass (g/mol)

| 520.99

| 535.03

| 549.05

| 563.08

| 577.11

| 591.13

Melting point (°C)

| 77

| 79

| 78

| 84

| 83

| 86

Boiling point (°C)

| 504.14

| 510.93

| 517.51

| 523.88

| 530.75

| 536.07

Density (g/ml)

| 0.815

| 0.816

| 0.817

| 0.817

| 0.818

| 0.819

= Tritetracontane to octatetracontane =

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! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Triatetracontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Tetratetracontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Pentatetracontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Hexatetracontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Heptatetracontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Octatetracontane

Formula

| C43H88

| C44H90

| C45H92

| C46H94

| C47H96

| C48H98

CAS Number

| [7098-21-7]

| [7098-22-8]

| [7098-23-9]

| [7098-24-0]

| [7098-25-1]

| [7098-26-2]

Molar mass (g/mol)

| 605.15

| 619.18

| 633.21

| 647.23

| 661.26

| 675.29

Boiling point (°C)

| 541.91

| 547.57

| 553.1

| 558.42

| 563.6

| 568.68

Density (g/ml)

| 0.82

| 0.82

| 0.821

| 0.822

| 0.822

| 0.823

= Nonatetracontane to tetrapentacontane =

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! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Nonatetracontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Pentacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Henpentacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Dopentacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Tripentacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Tetrapentacontane

Formula

| C49H100

| C50H102

| C51H104

| C52H106

| C53H108

| C54H110

CAS number

| [7098-27-3]

| [6596-40-3]

| [7667-76-7]

| [7719-79-1]

| [7719-80-4]

| [5856-66-6]

Molar mass (g/mol)

| 689.32

| 703.34

| 717.37

| 731.39

| 745.42

| 759.45

Boiling point (°C)

| 573.6

| 578.4

| 583

| 587.6

| 592

| 596.38

Density (g/ml)

| 0.823

| 0.824

| 0.824

| 0.825

| 0.825

| 0.826

= Pentapentacontane to hexacontane =

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! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Pentapentacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Hexapentacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Heptapentacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Octapentacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Nonapentacontane

! cellspacing="3" style="border: 1px solid #C0C090; background-color: #F8EABA; margin-bottom: 3px;" | Hexacontane

Formula

| C55H112

| C56H114

| C57H116

| C58H118

| C59H120

| C60H122

CAS number

| [5846-40-2]

| [7719-82-6]

| [5856-67-7]

| [7667-78-9]

| [7667-79-0]

| [7667-80-3]

Molar mass (g/mol)

| 773.48

| 787.50

| 801.53

| 815.58

| 829.59

| 843.6

Boiling point (°C)

| 600.6

| 604.7

| ?

| 612.6

| ?

| 620.2

Density (g/ml)

| 0.826

| 0.826

| ?

| 0.827

| ?

| 0.827

See also

References

{{Reflist}}

External links

{{Wiktionary}}

{{Commons|Homologous series of alkanes|Higher alkanes}}

  • [http://www.inchem.org/documents/icsc/icsc/eics1245.htm International Chemical Safety Card 1245] (nonane)
  • [https://www.cdc.gov/niosh/npg/npgd0466.html NIOSH Pocket Guide to Chemical Hazards] (nonane)
  • [http://www.inchem.org/documents/icsc/icsc/eics0428.htm International Chemical Safety Card 0428] (decane)

{{alkanes}}

Category:Alkanes