2,2,4-Trimethylpentane

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{{#if:OdorlessOdorlessColorless liquid692 mg mL−1210 nm4.3735.5 kPa (at 21 °C)3.0 nmol Pa−1 kg−11.391165.71165.83188|! style="background: #F8EABA; text-align: center;" colspan="2" | Properties
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
IUPAC name

2,2,4-Trimethylpentane[1]

Identifiers
CAS number 540-84-1 7pxY
PubChem 10907
ChemSpider 10445 7pxY
EC number 208-759-1
UN number 1262
MeSH 2,2,4-trimethylpentane
ChEBI CHEBI:62805 7pxY
ChEMBL CHEMBL1797261 7pxY
RTECS number SA3320000
Beilstein Reference 1696876
Jmol-3D images Image 1
Molecular formula C8H18
Molar mass 114.23 g mol−1
Thermochemistry
Std enthalpy of
formation ΔfHo298 		−260.6–−258.0 kJ mol−1
Std enthalpy of
combustion ΔcHo298 		−5462.6–−5460.0 kJ mol−1
Standard molar
entropy So298 		328.03 J K−1 mol−1
Specific heat capacity, C 242.49 J K−1 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 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
4
1
0
Flash point −12 °C
Autoignition
temperature 		396 °C
Explosive limits 1.1–6.0%
Related compounds
Related alkanes
 14pxY (verify) (what is: 10pxY/10pxN?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

2,2,4-Trimethylpentane, also known as isooctane, 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 for 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]

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 using an Amberlyst catalyst to produce a mixture of iso-octenes. Hydrogenation of this mixture produces 2,2,4-trimethylpentane.[3]

File:Iso-octane synthesis.svg
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.[4] 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 with 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, inhalation or ingestion of large quantities of iso-octane is harmful. In rare cases a stronger reaction can occur.[5] It is also flammable (as one would expect for a fuel).

See also

References

  1. ↑ "2,2,4-trimethylpentane - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification and Related Records. http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=10907&loc=ec_rcs#x291. Retrieved 11 March 2012.
  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. ↑ Dimerization of isobutylene, Amberlyst.com
  4. ↑ Fuels and lubricants handbook, Volume 1, George E. Totten, Steven R. Westbrook, Rajesh J. Shah, page 62
  5. ↑ 2,2,4-Trimethylpentane, Integrated Risk Information System, United States Environmental Protection Agency

External links

cs:Isooktan

da:Isooktan de:2,2,4-Trimethylpentan es:2,2,4-trimetilpentano fr:Isooctane it:Isoottano id:2,2,4-Trimetilpentana ms:Iso-oktana nl:2,2,4-trimethylpentaan ja:イソオクタン pl:2,2,4-Trimetylopentan pt:2,2,4-Trimetilpentano ru:Изооктан fi:2,2,4-trimetyylipentaani sv:Isooktan vi:2,2,4-Trimêtylpentan zh:2,2,4-三甲基戊烷


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