Octane

For the gasoline rating system, see octane rating. For other uses, see Octane (disambiguation).

{{#if:Gasoline-likeGasoline-likeColorless liquid703 mg mL⁻¹7 mg L⁻¹ (at 20 C°)4.7831.47 kPa (at 20.0 °C)29 nmol Pa⁻¹ kg⁻¹1.398542 μPa s (at 20 °C)216.0216.6188|! style="background: #F8EABA; text-align: center;" colspan="2" | Properties

Octane
IUPAC name Octane
Identifiers
CAS number	111-65-9 Y
PubChem	356
ChemSpider	349 Y
EC number	203-892-1
UN number	1262
DrugBank	DB02440
KEGG	C01387 Y
MeSH	octane
ChEBI	CHEBI:17590 N
ChEMBL	CHEMBL134886 Y
RTECS number	RG8400000
Beilstein Reference	1696875
Gmelin Reference	82412
3DMet	B00281
Jmol-3D images	Image 1
SMILES CCCCCCCC <p><p style="word-wrap: break-word;">
InChI InChI=1S/C8H18/c1-3-5-7-8-6-4-2/h3-8H2,1-2H3 Y Key: TVMXDCGIABBOFY-UHFFFAOYSA-N Y
Molecular formula	C8H18
Molar mass	114.23 g mol−1
Thermochemistry
Std enthalpy of formation ΔfHo298	−252.1–−248.5 kJ mol−1
Std enthalpy of combustion ΔcHo298	−5.53–−5.33 MJ mol−1
Standard molar entropy So298	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	Heptane Nonane
N (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
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).

Use of the term in gasoline

"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.

Metaphorical use

Octane became well known in American popular culture in the mid- and late-sixties, when gasoline companies boasted of "high octane" levels in their gasoline in advertisements.

These commercials disappeared by the time of the 1973 Oil Crisis, which spared gasoline companies the need to compete via advertising. "Octane" was rarely cited in non-technical contexts over the next two decades.

The compound adjective "high-octane" was apparently 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-nineties, the phrase was commonly being used as an intensifier and has apparently found a place in modern English vernacular.

Isomers

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

External links

• International Chemical Safety Card 0933
• NIOSH Pocket Guide to Chemical Hazards 0470
• Phytochemical database entry

ar:أوكتان