2,2,4-Trimethylpentane

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2,2,4-Trimethylpentane
Skeletal formula of 2,2,4-trimethylpentane
Ball and stick model of 2,2,4-trimethylpentane
Spacefill model of 2,2,4-trimethylpentane
Names
IUPAC name
2,2,4-Trimethylpentane[1]
Identifiers
540-84-1 YesY
1696876
ChEBI CHEBI:62805 N
ChEMBL ChEMBL1797261 N
ChemSpider 10445 YesY
EC Number 208-759-1
Jmol 3D model Interactive image
MeSH 2,2,4-trimethylpentane
PubChem 10907
RTECS number SA3320000
UN number 1262
  • InChI=1S/C8H18/c1-7(2)6-8(3,4)5/h7H,6H2,1-5H3 YesY
    Key: NHTMVDHEPJAVLT-UHFFFAOYSA-N YesY
  • CC(C)CC(C)(C)C
Properties
C8H18
Molar mass 114.23 g·mol−1
Appearance Colorless liquid
Odor Odorless
Density 0.692 g cm−3
Melting point −107.38 °C; −161.28 °F; 165.77 K
Boiling point 99.30 °C; 210.74 °F; 372.45 K
log P 4.373
Vapor pressure 5.5 kPa (at 21 °C)
3.0 nmol Pa−1 kg−1
UV-vismax) 210 nm
1.391
Thermochemistry
242.49 J K−1 mol−1
328.03 J K−1 mol−1
−260.6 to −258.0 kJ mol−1
−5462.6 to −5460.0 kJ mol−1
Vapor pressure {{{value}}}
Related compounds
Related alkanes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

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 to increase the knock resistance of the fuel.[2]

Strictly speaking, if the standard meaning of ‘iso’ is followed, the name isooctane should be reserved for the isomer 2-methylheptane. However, 2,2,4-trimethylpentane is by far the most important isomer of octane and so, historically, it has ended up with this name.[3]

Production

Isooctane is produced on a massive scale in the petroleum industry by distillation of petroleum. It can also be produced from isobutylene by dimerization (a variant of alkylation) using an Amberlyst catalyst to produce a mixture of iso-octenes. Hydrogenation of this mixture produces 2,2,4-trimethylpentane.[4]

Dimerization of isobutylene followed by hydrogenation produces 2,2,4-trimethylpentane

History

Engine knocking is an unwanted process that can occur during combustion in internal combustion engines. Graham Edgar in 1926 added different amounts of n-heptane and 2,2,4-trimethylpentane to gasoline, and discovered that the knocking stopped when 2,2,4-trimethylpentane was added. This was the origin of the octane rating scale.[5] Test motors using 2,2,4-trimethylpentane gave a certain performance which was standardized as 100 octane. The same test motors, run in the same fashion, using heptane, gave a performance which was standardized as 0 octane. All other compounds and blends of compounds then were graded against these two standards and assigned octane numbers.

Safety

In common with all hydrocarbons, 2,2,4-trimethylpentane is exceedingly flammable in the presence of oxygen, and its vapours readily form explosive mixtures with air.

Also in common with all hydrocarbons, inhalation or ingestion of large quantities of 2,2,4-trimethylpentane is harmful. In rare cases a stronger reaction can occur.[6]

See also

References

  1. Lua error in package.lua at line 80: module 'strict' not found.
  2. Werner Dabelstein, Arno Reglitzky, Andrea Schütze and Klaus Reders "Automotive Fuels" in Ullmann's Encyclopedia of Industrial Chemistry 2007, Wiley-VCH, Weinheim.doi:10.1002/14356007.a16_719.pub2
  3. Lua error in package.lua at line 80: module 'strict' not found.
  4. Dimerization of isobutylene, Amberlyst.com
  5. Fuels and lubricants handbook, Volume 1, George E. Totten, Steven R. Westbrook, Rajesh J. Shah, page 62
  6. 2,2,4-Trimethylpentane, Integrated Risk Information System, United States Environmental Protection Agency

External links