Isobutane

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Isobutane
Skeletal formula of isobutane
Skeletal formula of isobutane with all implicit carbons shown, and all explicit hydrogens added
Ball and stick model of isobutaneSpacefill model of isobutane
Identifiers
CAS number75-28-5 YesY
PubChem6360
ChemSpider6120 YesY
UNIIBXR49TP611 YesY
EC number200-857-2
UN number1969
KEGGD04623 N
ChEBICHEBI:30363 YesY
RTECS numberTZ4300000
Beilstein Reference1730720
Gmelin Reference1301
Jmol-3D imagesImage 1
Properties
Molecular formulaC4H10
Molar mass58.12 g mol−1
AppearanceColorless gas
OdorOdorless
Density2.51 mg mL−1 (at 15 °C, 100 kPa)
Melting point−233.2 to −33.1 °C; −387.7 to −27.7 °F; 40.0 to 240.0 K
Boiling point−13 to −9 °C; 8 to 16 °F; 260 to 264 K
Vapor pressure204.8 kPa (at 21 °C)
kH8.6 nmol Pa−1 kg−1
Thermochemistry
Specific
heat capacity
C
96.65 J K−1 mol−1
Std enthalpy of
formation
ΔfHo298
−134.8–−133.6 kJ mol−1
Std enthalpy of
combustion
ΔcHo298
−2.86959–−2.86841 MJ mol−1
Hazards
MSDSExternal MSDS
GHS pictogramsThe flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal wordDANGER
GHS hazard statementsH220
GHS precautionary statementsP210
EU Index601-004-00-0
EU classificationExtremely Flammable F+
R-phrasesR12
S-phrases(S2), S16
NFPA 704
Flash point−83 °C (−117 °F; 190 K)
Explosive limits1.4–8.3%
Related compounds
Related alkaneIsopentane
Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral dataUV, IR, NMR, MS
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
 
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Isobutane
Skeletal formula of isobutane
Skeletal formula of isobutane with all implicit carbons shown, and all explicit hydrogens added
Ball and stick model of isobutaneSpacefill model of isobutane
Identifiers
CAS number75-28-5 YesY
PubChem6360
ChemSpider6120 YesY
UNIIBXR49TP611 YesY
EC number200-857-2
UN number1969
KEGGD04623 N
ChEBICHEBI:30363 YesY
RTECS numberTZ4300000
Beilstein Reference1730720
Gmelin Reference1301
Jmol-3D imagesImage 1
Properties
Molecular formulaC4H10
Molar mass58.12 g mol−1
AppearanceColorless gas
OdorOdorless
Density2.51 mg mL−1 (at 15 °C, 100 kPa)
Melting point−233.2 to −33.1 °C; −387.7 to −27.7 °F; 40.0 to 240.0 K
Boiling point−13 to −9 °C; 8 to 16 °F; 260 to 264 K
Vapor pressure204.8 kPa (at 21 °C)
kH8.6 nmol Pa−1 kg−1
Thermochemistry
Specific
heat capacity
C
96.65 J K−1 mol−1
Std enthalpy of
formation
ΔfHo298
−134.8–−133.6 kJ mol−1
Std enthalpy of
combustion
ΔcHo298
−2.86959–−2.86841 MJ mol−1
Hazards
MSDSExternal MSDS
GHS pictogramsThe flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal wordDANGER
GHS hazard statementsH220
GHS precautionary statementsP210
EU Index601-004-00-0
EU classificationExtremely Flammable F+
R-phrasesR12
S-phrases(S2), S16
NFPA 704
Flash point−83 °C (−117 °F; 190 K)
Explosive limits1.4–8.3%
Related compounds
Related alkaneIsopentane
Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral dataUV, IR, NMR, MS
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

Isobutane (i-butane), also known as methylpropane, is a chemical compound with molecular formula C
4
H
10
and is an isomer of butane. It is the simplest alkane with a tertiary carbon. Concerns with depletion of the ozone layer by freon gases have led to increased use of isobutane as a gas for refrigeration systems, especially in domestic refrigerators and freezers, and as a propellant in aerosol sprays. When used as a refrigerant or a propellant, isobutane is also known as R-600a. Some portable camp stoves use a mixture of isobutane with propane, usually 80:20.[2][spam link?] Isobutane is used as a feedstock in the petrochemical industry, for example in the synthesis of isooctane.[3]

Nomenclature[edit]

Isobutane is the trivial name retained by the International Union of Pure and Applied Chemistry (IUPAC) in its 1993 Recommendations for the Nomenclature of Organic Chemistry.[4] Since the longest continuous chain in isobutane contains only three carbon atoms, the full systematic name is 2-methylpropane but the locant (2-) is typically omitted as redundant; C2 is the only position on a propane chain where a methyl substituent can be located without altering the main chain.

Uses[edit]

Isobutane is used as a refrigerant.[5] The use in refrigerators started in 1993 when Greenpeace presented the Greenfreeze project with the German company Foron.[6] In this regard, blends of pure, dry "isobutane" (R-600a) (that is, isobutane mixtures) have negligible ozone depletion potential and very low Global Warming Potential (having a value of 3.3 times the GWP of carbon dioxide) and can serve as a functional replacement for R-12, R-22, R-134a, and other chlorofluorocarbon or hydrofluorocarbon refrigerants in conventional stationary refrigeration and air conditioning systems.

In the Chevron Phillips slurry process for making high-density polyethylene, isobutane is used as a diluent. As the slurried polyethylene is removed, isobutane is "flashed" off, and condensed, and recycled back into the loop reactor for this purpose.[7]

Isobutane is also used as a propellant for aerosol cans and foam products.

Isobutane is used as part of blended fuels, especially common in fuel canisters used for camping.[8]

Refrigerant use[edit]

As a refrigerant, isobutane has an explosion risk in addition to the hazards associated with non-flammable CFC refrigerants. Reports surfaced in late 2009 suggesting the use of isobutane as a refrigerant in domestic refrigerators was potentially dangerous. Several refrigerator explosions reported in the United Kingdom are suspected to have been caused as a result of isobutane leaking into the refrigerator cabinet and being ignited by sparks in the electrical system.[9] Although unclear how serious this could be, at the time this report came out it was estimated 300 million refrigerators worldwide use isobutane as a refrigerant.

Substitution of this refrigerant for motor vehicle air conditioning systems not originally designed for isobutane is widely prohibited or discouraged, on the grounds that using flammable hydrocarbons in systems originally designed to carry non-flammable refrigerant presents a significant risk of fire or explosion.[10][11][12][13][14][15][16]

Vendors and advocates of hydrocarbon refrigerants argue against such bans on the grounds that there have been very few such incidents relative to the number of vehicle air conditioning systems filled with hydrocarbons.[17][18]

References[edit]

  1. ^ "ISOBUTANE - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records. Retrieved 5 March 2012. 
  2. ^ MSR Isopro
  3. ^ Patent Watch, July 31, 2006.
  4. ^ Panico, R.; & Powell, W. H. (Eds.) (1994). A Guide to IUPAC Nomenclature of Organic Compounds 1993. Oxford: Blackwell Science. ISBN 0-632-03488-2.  http://www.acdlabs.com/iupac/nomenclature/93/r93_679.htm
  5. ^ "European Commission on retrofit refrigerants for stationary applications" (PDF). Retrieved 2010-10-29. 
  6. ^ Page - March 15, 2010 (2010-03-15). "GreenFreeze". Greenpeace. Retrieved 2013-01-02. 
  7. ^ Kenneth S. Whiteley (2005), "Polyethylene", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a21_487.pub2 
  8. ^ Rietveld, Will (2005-02-08). "Frequently Asked Questions About Lightweight Canister Stoves and Fuels". Backpacking Light. Retrieved 2014-07-26. 
  9. ^ Bingham, John (September 1, 2009). "Exploding fridges: ozone friendly gas theory for mystery blasts". The Daily Telegraph (London). Retrieved May 5, 2010. 
  10. ^ "U.S. EPA hydrocarbon-refrigerants FAQ". Epa.gov. Retrieved 2010-10-29. 
  11. ^ Compendium of hydrocarbon-refrigerant policy statements, October 2006
  12. ^ "MACS bulletin: hydrocarbon refrigerant usage in vehicles" (PDF). Retrieved 2010-10-29. 
  13. ^ "Society of Automotive Engineers hydrocarbon refrigerant bulletin". Sae.org. 2005-04-27. Retrieved 2010-10-29. 
  14. ^ "Saskatchewan Labour bulletin on hydrocarbon refrigerants in vehicles". Labour.gov.sk.ca. 2010-06-29. Retrieved 2010-10-29. 
  15. ^ VASA on refrigerant legality & advisability[dead link]
  16. ^ "Queensland (Australia) government warning on hydrocarbon refrigerants". Energy.qld.gov.au. Retrieved 2010-10-29. 
  17. ^ "New South Wales (Australia) Parliamentary record, 16 October 1997". Parliament.nsw.gov.au. 1997-10-16. Retrieved 2010-10-29. 
  18. ^ "New South Wales (Australia) Parliamentary record, 29 June 2000". Parliament.nsw.gov.au. Retrieved 2010-10-29. 

External links[edit]