Butane

Butane
IUPAC name Butane
Identifiers
CAS number	106-97-8 Y
PubChem	7843
ChemSpider	7555 Y
UNII	6LV4FOR43R Y
EC number	203-448-7
UN number	1011
KEGG	D03186 Y
MeSH	butane
ChEBI	CHEBI:37808 Y
ChEMBL	CHEMBL134702 Y
RTECS number	EJ4200000
Beilstein Reference	969129
Gmelin Reference	1148
Jmol-3D images	Image 1
SMILES CCCC
InChI InChI=1S/C4H10/c1-3-4-2/h3-4H2,1-2H3 Y Key: IJDNQMDRQITEOD-UHFFFAOYSA-N Y
Properties
Molecular formula	C4H10
Molar mass	58.12 g mol−1
Appearance	Colorless gas
Odor	Odorless
Density	2.48 mg mL−1 (at 15 °C)
Melting point	-140--134 °C, 133-139 K, -220--209 °F
Boiling point	-1-1 °C, 272-274 K, 30-34 °F
Solubility in water	61 mg L−1 (at 20 °C)
log P	2.745
kH	11 nmol Pa−1 kg−1
Thermochemistry
Std enthalpy of formation ΔfHo298	−126.3–−124.9 kJ mol−1
Std enthalpy of combustion ΔcHo298	−2.8781–−2.8769 MJ mol−1
Specific heat capacity, C	98.49 J K−1 mol−1
Hazards
MSDS	External MSDS
GHS pictograms
GHS signal word	DANGER
GHS hazard statements	H220
GHS precautionary statements	P210
EU Index	601-004-00-0
EU classification	F+
R-phrases	R12
S-phrases	(S2) S16
NFPA 704	4 1 0
Flash point	−60 °C (−76 °F)
Autoignition temperature	288 °C (550 °F)
Explosive limits	1.8–8.4%
Related compounds
Related alkanes	Propane Isobutane Pentane
Related compounds	Perfluorobutane
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Butane is a gas with the formula C₄H₁₀ that is an alkane with four carbon atoms. The term may refer to either of two structural isomers, n-butane or isobutane (or "methylpropane"), or to a mixture of these isomers. In the IUPAC nomenclature, however, "butane" refers only to the n-butane isomer (which is the isomer with the unbranched structure). Butanes are highly flammable, colorless, easily liquefied gases. The name butane comes from the roots but- (from butyric acid) and -ane.

Isomers

Common name	normal butane unbranched butane n-butane	isobutane i-butane
IUPAC name	butane	2-methylpropane
Molecular diagram
Skeletal diagram

Rotation about the central C-C bond produces two different conformations (trans and gauche) for n-butane.

Reactions

Spectrum of the blue flame from a butane torch showing CH molecular radical band emission and C2 Swan bands

When oxygen is plentiful, butane burns to form carbon dioxide and water vapor; when oxygen is limited, carbon (soot) or carbon monoxide may also be formed.

2 C₄H₁₀ + 13 O₂ → 8 CO₂ + 10 H₂O

The maximum adiabatic flame temperature of butane with air is 2,243 K (1,970 °C; 3,578 °F).

n-Butane is the feedstock for DuPont's catalytic process for the preparation of maleic anhydride:

2 CH₃CH₂CH₂CH₃ + 7 O₂ → 2 C₂H₂(CO)₂O + 8 H₂O

n-Butane, like all hydrocarbons, undergoes free radical chlorination providing both 1-chloro- and 2-chlorobutanes, as well as more highly chlorinated derivatives. The relative rates of the chlorination is partially explained by the differing bond dissociation energies, 425 and 411 kJ/mol for the two types of C-H bonds.

Uses

The most common use of butane is as lighter fuel for a common lighter or butane torch.

Butane gas is sold bottled as a fuel for cooking and camping. When blended with propane and other hydrocarbons, it is referred to commercially as LPG, for liquified petroleum gas. It is also used as a petrol component, as a feedstock for the production of base petrochemicals in steam cracking, as fuel for cigarette lighters and as a propellant in aerosol sprays such as deodorants.

Very pure forms of butane, especially isobutane, can be used as refrigerants and have largely replaced the ozone layer-depleting halomethanes, for instance in household refrigerators and freezers. The system operating pressure for butane is lower than for the halomethanes, such as R-12, so R-12 systems such as in automotive air conditioning systems, when converted to butane will not function optimally.

Cordless hair irons are usually powered by butane cartridges.

Effects and health issues

Inhalation of butane can cause euphoria, drowsiness, narcosis, asphyxia, cardiac arrhythmia, temporary memory loss and frostbite, which can result in death from asphyxiation and ventricular fibrillation. Butane is the most commonly misused volatile substance in the UK, and was the cause of 52% of "solvent related" deaths in 2000. By spraying butane directly into the throat, the jet of fluid can cool rapidly to −20 °C by expansion, causing prolonged laryngospasm. "Sudden sniffer's death" syndrome, first described by Bass in 1970, is the most common single cause of "solvent related" death, resulting in 55% of known fatal cases.

Nitrogen dioxide, a toxic gas, results from burning butane gas and represents a human health hazard from home heaters and stoves.

See also

• Campingaz
• Dimethyl ether
• Volatile substance abuse

External links

• International Chemical Safety Card 0232
• NIOSH Pocket Guide to Chemical Hazards
• n-Butane Molecule of the Month

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  Butane lighter in use

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  Butane lighter, showing liquid butane reservoir

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  Butane being sprayed from an aerosol spray can

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  Butane gas cylinder used for cooking