Isobutane
IUPAC name	Methylpropane 2-Methylpropane
Other names	Isobutane
Identifiers
CAS number	75-28-5 Y
SMILES	CC(C)C
Properties
Molecular formula	C4H10
Molar mass	58.12 g mol−1
Appearance	colorless gas
Density	2.51 kg/m3, gas (15 °C, 1 atm) 593.4 kg/m3, liquid
Melting point	-159.6 °C, 114 K, -255 °F
Boiling point	-11.7 °C, 261 K, 11 °F
Solubility in water	Insoluble
Hazards
MSDS	External MSDS
EU classification	Highly flammable (F+)
R-phrases	R12
S-phrases	(S2), S9, S16
NFPA 704	4 1 0
Flash point	flammable gas
Autoignition temperature	460 °C
Explosive limits	1.8–8.4%
Related compounds
Related alkane	Butane
Related compounds	Isopentane Neopentane
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Isobutane, also known as methylpropane or 2-methylpropane, is an alkane, isomeric with butane. It is the simplest alkane with a tertiary carbon. Recent 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. Isobutane is used as a feedstock in the petrochemical industry, for example in the synthesis of isooctane.^[1]
Its UN number (for hazardous substances see shipping) is UN 1969. Isobutane is the R group for the amino acid leucine.

[edit] Nomenclature

Structures of the two isomers of butane

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.^[2]

Methylpropane is the systematic name. The substituent number (2-) is unnecessary because there is no isomer of this molecule with methylpropane as part of its name.

[edit] Uses

• As a refrigerant.
• As a propellant for aerosol cans and foam products, such as reddi wip.

[edit] Safety Concerns

Reports surfaced in late 2009 suggesting the use of isobutane as a refrigerant in domestic refrigerators was potentially dangerous. Several explosions resulting from the isobutane leaking into the refrigerator cabinet and a spark from the electrical system have been reported in the United Kingdom. ^[3] 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.

[edit] References

1. ^ Patent Watch, July 31, 2006.
2. ^ 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
3. ^ http://www.telegraph.co.uk/news/picturegalleries/howaboutthat/6120297/Exploding-fridges-ozone-friendly-gas-theory-for-mystery-blasts.html

[edit] External links

• International Chemical Safety Card 0901
• NIOSH Pocket Guide to Chemical Hazards
• IUPAC Nomenclature of Organic Chemistry (online version of the "Blue Book")
• Data from Air Liquide