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Names | |
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Systematic IUPAC name Octane [1] | |
Other names n-Octane | |
Identifiers | |
3D model (JSmol) | |
3DMet | |
1696875 | |
ChEBI | |
ChEMBL | |
ChemSpider | |
DrugBank | |
ECHA InfoCard | 100.003.539 |
EC Number |
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82412 | |
KEGG | |
MeSH | octane |
PubChem CID | |
RTECS number |
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UNII | |
UN number | 1262 |
CompTox Dashboard (EPA) | |
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Properties | |
CH3(CH2)6CH3 | |
Molar mass | 114.232 g·mol−1 |
Appearance | Colourless 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) |
Henry's law constant (kH) | 29 nmol/(Pa·kg) |
Conjugate acid | Octonium |
−96.63·10−6 cm3/mol | |
Refractive index (nD) | 1.398 |
Viscosity |
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Thermochemistry | |
Heat capacity (C) | 255.68 J/(K·mol) |
Std molar entropy (S⦵298) | 361.20 J/(K·mol) |
Std enthalpy of formation (ΔfH⦵298) | −252.1 to −248.5 kJ/mol |
Std enthalpy of combustion (ΔcH⦵298) | −5.53 to −5.33 MJ/mol |
Hazards | |
GHS labelling: | |
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Danger | |
H225, H304, H315, H336, H410 | |
P210, P261, P273, P301+P310, P331 | |
NFPA 704 (fire diamond) | |
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): | |
LDLo (lowest published) | 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). |
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.
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]
N-octane has 23 constitutional isomers. 8 of these isomers have one stereocenter; 3 of them have two stereocenters.
Achiral Isomers:
Chiral Isomers:
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.
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.
Hexane or n-hexane is an organic compound, a straight-chain alkane with six carbon atoms and the molecular formula C6H14.
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.
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.
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.
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.
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.
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:
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.
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.
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.