Octane

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For the gasoline rating system, see octane rating. For other uses, see Octane (disambiguation).
Octane
Skeletal formula of octane
Skeletal formula of octane with all implicit carbons shown, and all explicit hydrogens added
Ball and stick model of octane
Spacefill model of octane
Identifiers
CAS number 111-65-9 YesY
PubChem 356
ChemSpider 349 YesY
EC number 203-892-1
UN number 1262
DrugBank DB02440
KEGG C01387 YesY
MeSH octane
ChEBI CHEBI:17590 N
ChEMBL CHEMBL134886 YesY
RTECS number RG8400000
Beilstein Reference 1696875
Gmelin Reference 82412
3DMet B00281
Jmol-3D images Image 1
Properties
Molecular formula C8H18
Molar mass 114.23 g mol−1
Appearance Colorless liquid
Odor Odorless
Density 0.703 g cm−3
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
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
Specific
heat capacity
C
255.68 J K−1 mol−1
Std molar
entropy
So298
361.20 J K−1 mol−1
Std enthalpy of
formation
ΔfHo298
−252.1–−248.5 kJ mol−1
Std enthalpy of
combustion
ΔcHo298
−5.53–−5.33 MJ mol−1
Hazards
GHS pictograms The flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The health hazard pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The environment pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
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 Highly Flammable F Harmful Xn Dangerous for the Environment (Nature) N
R-phrases R11, R38, R50/53, R65, R67
S-phrases (S2), S16, S29, S33
NFPA 704
Flammability code 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., gasoline) Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 13.0 °C (55.4 °F; 286.1 K)
Explosive limits 0.96–6.5%
Related compounds
Related alkanes
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
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.

Octane is a component of gasoline (petrol). As with all low molecular weight hydrocarbons, octane is volatile and very flammable.

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" is recorded in a figurative sense from 1944.[3] 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):

References[edit]

  1. ^ "octane - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records. Retrieved 6 January 2012. 
  2. ^ eejit's guides – Octane ratings explained
  3. ^ Oxford English Dictionary. 

External links[edit]