Octane

Last updated
Octane
Octane-2D-Skeletal.svg
OctaneFull.png
Octane 3D ball.png
N-octane-spaceFilling.png
Names
Systematic IUPAC name
Octane [1]
Other names
n-Octane
Identifiers
3D model (JSmol)
3DMet
1696875
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.003.539 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 203-892-1
82412
KEGG
MeSH octane
PubChem CID
RTECS number
  • RG8400000
UNII
UN number 1262
  • InChI=1S/C8H18/c1-3-5-7-8-6-4-2/h3-8H2,1-2H3 Yes check.svgY
    Key: TVMXDCGIABBOFY-UHFFFAOYSA-N Yes check.svgY
  • CCCCCCCC
Properties
CH3(CH2)6CH3
Molar mass 114.232 g·mol−1
AppearanceColourless liquid
Odor Gasoline-like [2]
Density 0.703 g/cm3
Melting point −57.1 to −56.6 °C; −70.9 to −69.8 °F; 216.0 to 216.6 K
Boiling point 125.1 to 126.1 °C; 257.1 to 258.9 °F; 398.2 to 399.2 K
0.007 mg/dm3 (at 20 °C)
log P 4.783
Vapor pressure 1.47 kPa (at 20.0 °C)
29 nmol/(Pa·kg)
Conjugate acid Octonium
−96.63·10−6 cm3/mol
1.398
Viscosity
  • 0.509 mPa·s (25 °C) [3]
  • 0.542 mPa·s (20 °C)
Thermochemistry
255.68 J/(K·mol)
Std molar
entropy (S⦵298)
361.20 J/(K·mol)
−252.1 to −248.5 kJ/mol
−5.53 to −5.33 MJ/mol
Hazards
GHS labelling:
GHS-pictogram-flamme.svg GHS-pictogram-exclam.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
Danger
H225, H304, H315, H336, H410
P210, P261, P273, P301+P310, P331
NFPA 704 (fire diamond)
NFPA 704.svgHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
3
0
Flash point 13.0 °C (55.4 °F; 286.1 K)
220.0 °C (428.0 °F; 493.1 K)
Explosive limits 0.96 – 6.5%
Lethal dose or concentration (LD, LC):
428 mg/kg (mouse, intravenous) [4]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 500 ppm (2350 mg/m3) [2]
REL (Recommended)
TWA 75 ppm (350 mg/m3) C 385 ppm (1800 mg/m3) [15-minute] [2]
IDLH (Immediate danger)
1000 ppm [2]
Related compounds
Related alkanes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Octane is a hydrocarbon and an alkane with the chemical formula C8H18, and the condensed structural formula CH3(CH2)6CH3. Octane has many structural isomers that differ by the location of branching in the carbon chain. One of these isomers, 2,2,4-trimethylpentane (commonly called iso-octane), is used as one of the standard values in the octane rating scale.

Contents

Octane is a component of gasoline and petroleum. Under standard temperature and pressure, octane is an odorless, colorless liquid. Like other short-chained alkanes with a low molecular weight, it is volatile, flammable, and toxic. Octane is 1.2 to 2 times more toxic than Heptane. [5]

Isomers

N-octane has 23 constitutional isomers. 8 of these isomers have one stereocenter; 3 of them have two stereocenters.

(3S,4S)-3,4-Dimethylhexane (top left) and (3R,4R)-3,4-Dimethylhexane (top right) are non-superimposable mirror images, so they are chiral enantiomers. (meso)-3,4-Dimethylhexane (bottom) has a superimposable mirror image, so it is an achiral meso compound. Octane stereo isomers 10 3 4 dimethylhexane.svg
(3S,4S)-3,4-Dimethylhexane (top left) and (3R,4R)-3,4-Dimethylhexane (top right) are non-superimposable mirror images, so they are chiral enantiomers. (meso)-3,4-Dimethylhexane (bottom) has a superimposable mirror image, so it is an achiral meso compound.

Achiral Isomers:

Chiral Isomers:

Production and Use

In petrochemistry, octanes are not typically differentiated or purified as specific compounds. Octanes are components of particular boiling fractions. [6]

A common route to such fractions is the alkylation reaction between iso-butane and 1-butene, which forms iso-octane. [7]

Octane is commonly used as a solvent in paints and adhesives.

N-octane is the octane isomer that has the longest carbon skeleton. Unlike its constitutional isomers, it has a very low knock resistance. N-octane.jpg
N-octane is the octane isomer that has the longest carbon skeleton. Unlike its constitutional isomers, it has a very low knock resistance.
The octane isomer, iso-octane, is used as one of the standards for octane ratings. It has a rating of 100 by definition. Iso-octane.jpg
The octane isomer, iso-octane, is used as one of the standards for octane ratings. It has a rating of 100 by definition.
The octane isomer 2,3,3-Trimethylpentane has an octane rating exceeding 100. 2,3,3-Trimethylpentane (view 2).jpg
The octane isomer 2,3,3-Trimethylpentane has an octane rating exceeding 100.

Related Research Articles

<span class="mw-page-title-main">Alkane</span> Type of saturated hydrocarbon compound

In organic chemistry, an alkane, or paraffin, is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which all the carbon–carbon bonds are single. Alkanes have the general chemical formula CnH2n+2. The alkanes range in complexity from the simplest case of methane, where n = 1, to arbitrarily large and complex molecules, like pentacontane or 6-ethyl-2-methyl-5-(1-methylethyl) octane, an isomer of tetradecane.

<span class="mw-page-title-main">Hexane</span> Chemical compound

Hexane or n-hexane is an organic compound, a straight-chain alkane with six carbon atoms and the molecular formula C6H14.

<span class="mw-page-title-main">Heptane</span> Chemical compound

Heptane or n-heptane is the straight-chain alkane with the chemical formula H3C(CH2)5CH3 or C7H16. When used as a test fuel component in anti-knock test engines, a 100% heptane fuel is the zero point of the octane rating scale (the 100 point is 100% iso-octane). Octane number equates to the anti-knock qualities of a comparison mixture of heptane and iso-octane which is expressed as the percentage of iso-octane in heptane, and is listed on pumps for gasoline (petrol) dispensed globally.

<span class="mw-page-title-main">Pentane</span> Alkane with 5 carbon atoms

Pentane is an organic compound with the formula C5H12—that is, an alkane with five carbon atoms. The term may refer to any of three structural isomers, or to a mixture of them: in the IUPAC nomenclature, however, pentane means exclusively the n-pentane isomer, in which case pentanes refers to a mixture of them; the other two are called isopentane (methylbutane) and neopentane (dimethylpropane). Cyclopentane is not an isomer of pentane because it has only 10 hydrogen atoms where pentane has 12.

<span class="mw-page-title-main">2,2,4-Trimethylpentane</span> Chemical compound

2,2,4-Trimethylpentane, also known as isooctane or iso-octane, is an organic compound with the formula (CH3)3CCH2CH(CH3)2. It is one of several isomers of octane (C8H18). This particular isomer is the standard 100 point on the octane rating scale (the zero point is n-heptane). It is an important component of gasoline, frequently used in relatively large proportions (around 10%) to increase the knock resistance of fuel.

<span class="mw-page-title-main">2-Methylheptane</span> Chemical compound

2-Methylheptane is a branched-chain alkane and an isomer of octane. It is an heptane molecule with a methyl group attached to its second atom. It is a flammable colorless liquid used as fuel.

<span class="mw-page-title-main">2,2-Dimethylbutane</span> Chemical compound

2,2-Dimethylbutane, trivially known as neohexane, is an organic compound with formula C6H14 or (H3C-)3-C-CH2-CH3. It is therefore an alkane, indeed the most compact and branched of the hexane isomers — the only one with a quaternary carbon and a butane (C4) backbone.

Xylidine can refer to any of the six isomers of xylene amine, or any mixture of them.

3-Methylpentane is a branched alkane with the molecular formula C6H14. It is a structural isomer of hexane composed of a methyl group bonded to the third carbon atom in a pentane chain. It is of similar structure to the isomeric 2-methylpentane, which has the methyl group located on the second carbon of the pentane chain.

<span class="mw-page-title-main">2-Methylpentane</span> Chemical compound

2-Methylpentane, trivially known as isohexane, is a branched-chain alkane with the molecular formula C6H14. It is a structural isomer of hexane composed of a methyl group bonded to the second carbon atom in a pentane chain. Using a quantitative structure-activity relationship (QSAR) prediction model, 2-Methylpentane has a research octane number (RON) of 75, motor octane number (MON) of 77, and cetane number (CN) of 29.

The molecular formula C8H18 (molar mass: 114.23 g/mol) may refer to:

<span class="mw-page-title-main">Cyclitol</span> Class of chemical compounds

In organic chemistry, a cyclitol is a cycloalkane containing at least three hydroxyl, each attached to a different ring carbon atom. The general formula for an unsubstituted cyclitol is C
nH
2n-x(OH)
x or C
nH
2nO
x where 3 ≤ x ≤ n.

<span class="mw-page-title-main">Dinitroaniline</span> Class of chemical compounds

Dinitroanilines are a class of chemical compounds with the chemical formula C6H5N3O4. They are derived from both aniline and dinitrobenzenes. There are six isomers: 2,3-dinitroaniline, 2,4-dinitroaniline, 2,5-dinitroaniline, 2,6-dinitroaniline, 3,4-dinitroaniline, and 3,5-dinitroaniline.

<span class="mw-page-title-main">2,3-Dimethylpentane</span> Chemical compound

2,3-Dimethylpentane is an organic compound of carbon and hydrogen with formula C
7H
16, more precisely CH
3–CH(CH
3)–CH(CH
3)–CH
2–CH
3: a molecule of pentane with methyl groups –CH
3 replacing hydrogen atoms on carbon atoms 2 and 3. It is an alkane, a fully saturated hydrocarbon; specifically, one of the isomers of heptane.

References

  1. ↑ "octane - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records. Retrieved 6 January 2012.
  2. 1 2 3 4 NIOSH Pocket Guide to Chemical Hazards. "#0470". National Institute for Occupational Safety and Health (NIOSH).
  3. ↑ Dymond, J. H.; Oye, H. A. (1994). "Viscosity of Selected Liquid n-Alkanes". Journal of Physical and Chemical Reference Data. 23 (1): 41–53. Bibcode:1994JPCRD..23...41D. doi:10.1063/1.555943. ISSN   0047-2689.
  4. ↑ "Octane". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  5. ↑ "1988 OSHA PEL Project - Octane | NIOSH | CDC". www.cdc.gov. 2020-02-27. Retrieved 2024-04-19.
  6. ↑ "Fractionation". www.appliedcontrol.com. Retrieved 2024-04-19.
  7. ↑ Ross, Julian (January 1986). "Ullmann's Encyclopedia of industrial chemistry". Applied Catalysis. 27 (2): 403–404. doi:10.1016/s0166-9834(00)82943-7. ISSN   0166-9834.
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