Octane
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Octane[1] |
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| Identifiers | |
| CAS number | 111-65-9  |
| PubChem | 356 |
| ChemSpider | 349 |
| EC number | 203-892-1 |
| UN number | 1262 |
| DrugBank | DB02440 |
| KEGG | C01387 |
| MeSH | octane |
| ChEBI | CHEBI:17590  |
| ChEMBL | CHEMBL134886 |
| RTECS number | RG8400000 |
| Beilstein Reference | 1696875 |
| Gmelin Reference | 82412 |
| 3DMet | B00281 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C8H18 |
| Molar mass | 114.23 g mol−1 |
| Appearance | Colorless liquid |
| Odor | Gasoline-like |
| Density | 0.703 g cm−3 |
| Melting point |
-57--57 °C, 216.0-216.6 K, -71--70 °F |
| Boiling point |
125-126 °C, 398.2-399.2 K, 257-259 °F |
| Solubility in water | 0.007 mg dm−3 (at 20°C) |
| log P | 4.783 |
| Vapor pressure | 1.47 kPa (at 20.0 °C) |
| kH | 29 nmol Pa−1 kg−1 |
| Refractive index (nD) | 1.398 |
| Viscosity | 542 μPa s (at 20 °C) |
| Thermochemistry | |
| Std enthalpy of formation ΔfH |
−252.1–−248.5 kJ mol−1 |
| Std enthalpy of combustion ΔcH |
−5.53–−5.33 MJ mol−1 |
| Standard molar entropy S |
361.20 J K−1 mol−1 |
| Specific heat capacity, C | 255.68 J K−1 mol−1 |
| Hazards | |
| GHS pictograms |     |
| GHS signal word | DANGER |
| GHS hazard statements | H225, H304, H315, H336, H410 |
| GHS precautionary statements | P210, P261, P273, P301+310, P331 |
| EU Index | 601-009-00-8 |
| EU classification |  F  Xn  N |
| R-phrases | R11, R38, R50/53, R65, R67 |
| S-phrases | (S2), S16, S29, S33 |
| Flash point | 13.0 °C |
| Autoignition temperature |
220.0 °C |
| Explosive limits | 0.96–6.5% |
| Related compounds | |
| Related alkanes | |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
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 amount and location of branching in the carbon chain. One of these isomers, 2,2,4-trimethylpentane (isooctane) is used as one of the standard values in the octane rating scale.
As with all low-molecular weight hydrocarbons, octane and its isomers are very flammable. It and its isomers are components of gasoline (petrol).
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Use of the term in gasoline [edit]
"Octane" is colloquially used as a short form of "octane rating" (named for the ability of octane's branched-chain isomers, especially isooctane, to reduce engine knock), particularly in the expression "high octane." However, components of gasoline other than isomers of octane can also contribute to a high octane rating, while some isomers of octane can lower it, and n-octane itself has a negative octane rating.[2]
Metaphorical use [edit]
Octane became well known in American popular culture in the mid- and late 1960s, when gasoline companies boasted of "high octane" levels in their gasoline advertisements.
These commercials disappeared by the time of the 1973 Oil Crisis, which spared gasoline companies the need to compete in advertising. "Octane" was rarely cited in non-technical contexts over the next two decades.
The compound adjective "high-octane" was first used in its figurative sense (i.e., without reference to gasoline) in a book review of Michael Crichton's novel Jurassic Park (1990), which appeared in the newspaper New York Newsday.[citation needed] The review by Gregory Feeley called the novel "intellectually provocative, high-octane entertainment", and was quoted the following year in the front matter of the novel's paperback edition, which sold more than 15 million copies in the United States. By the mid-1990s, the phrase was commonly being used as an intensifier and has found a place in modern English vernacular.
Isomers [edit]
Octane has 18 structural isomers (24 including stereoisomers):
- Octane (n-octane)
- 2-Methylheptane
- 3-Methylheptane (2 enantiomers)
- 4-Methylheptane
- 3-Ethylhexane
- 2,2-Dimethylhexane
- 2,3-Dimethylhexane (2 enantiomers)
- 2,4-Dimethylhexane (2 enantiomers)
- 2,5-Dimethylhexane
- 3,3-Dimethylhexane
- 3,4-Dimethylhexane (2 enantiomers + 1 meso compound)
- 3-Ethyl-2-methylpentane
- 3-Ethyl-3-methylpentane
- 2,2,3-Trimethylpentane (2 enantiomers)
- 2,2,4-Trimethylpentane (isooctane)
- 2,3,3-Trimethylpentane
- 2,3,4-Trimethylpentane
- 2,2,3,3-Tetramethylbutane
References [edit]
- ^ "octane - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records. Retrieved 6 January 2012.
- ^ eejit's guides – Octane ratings explained
External links [edit]
- International Chemical Safety Card 0933
- NIOSH Pocket Guide to Chemical Hazards 0470
- Dr. Duke's Phytochemical and Ethnobotanical Databases, Octane, http://www.ars-grin.gov/cgi-bin/duke/chemical.pl?OCTANE
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