Butane

n-Butane
Preferred IUPAC name butane
Identifiers
CAS number	106-97-8 Y
PubChem	7843
ChemSpider	7555 Y
UNII	6LV4FOR43R Y
UN number	1011 As Liquefied petroleum gas: 1075
KEGG	D03186 Y
ChEBI	CHEBI:37808 Y
ChEMBL	CHEMBL134702 Y
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 InChI=1/C4H10/c1-3-4-2/h3-4H2,1-2H3 Key: IJDNQMDRQITEOD-UHFFFAOYAE
Properties
Molecular formula	C4H10
Molar mass	58.12 g mol−1
Appearance	Colorless gas
Density	2.48 kg/m3, gas (15 °C, 1 atm) 600 kg/m3, liquid (0 °C, 1 atm)
Melting point	−138.4 °C (135.4 K)
Boiling point	−0.5 °C (272.6 K)
Solubility in water	6.1 mg/100 ml (20 °C)
Hazards
MSDS	External MSDS
EU classification	Highly flammable (F+)
NFPA 704	4 1 0
Flash point	−60 °C
Autoignition temperature	500 °C
Explosive limits	1.8 – 8.4% [1]
Related compounds
Related alkanes	Propane; Pentane
Related compounds	Isobutane; Cyclobutane
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 any of two structural isomers, or to a mixture of them: in the IUPAC nomenclature, however, butane refers only to the unbranched n-butane isomer; the other one being called "methylpropane" or isobutane.

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	methylpropane
Molecular diagram
Skeletal diagram

Rotation about the central C-C bond produces two different conformations (trans and gauche) for n-butane.^[2]

Reactions

Spectrum of the blue flame from a butane torch showing molecular radical band emission and 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. The two central carbon atoms have the slightly weaker C-H bonds.

Uses

Butane lighter in use

Butane lighter, showing liquid butane reservoir

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

Butane being sprayed from an aerosol spray can

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.^[3]

Effects and health issues

Butane gas cylinder used for cooking

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.^[4] By spraying butane directly into the throat, the jet of fluid can cool rapidly to −20 °C by expansion, causing prolonged laryngospasm.^[5] "Sudden sniffer's death" syndrome, first described by Bass in 1970,^[6] is the most common single cause of "solvent related" death, resulting in 55% of known fatal cases.^[5]

The paper "Emission of nitrogen dioxide from butane gas heaters and stoves indoors", from the American Journal of Applied Sciences, indicates that nitrogen dioxide, a toxic gas, results from burning butane gas, and represents a human health hazard from home heaters and stoves.

See also

• Calor
• Camping Gaz
• Volatile substance abuse

References

1. ^ MSDS Butane
2. ^ Roman M. Balabin (2009). "Enthalpy Difference between Conformations of Normal Alkanes: Raman Spectroscopy Study of n-Pentane and n-Butane". J. Phys. Chem. A 113 (6): 1012. doi:10.1021/jp809639s. PMID 19152252. 
3. ^ FAA: Hazardous Materials p. 4
4. ^ Trends in death Associated with Abuse of Volatile Substances 1971–2004 Field-Smith M, Bland JM, Taylor JC, et al., Department of Public Health Sciences. London: St George’s Medical School
5. ^ ^{a b} Ramsey J, Anderson HR, Bloor K, et al. An introduction to the practice, prevalence and chemical toxicology of volatile substance abuse. Hum Toxicol 1989;8:261–269
6. ^ Bass M. Sudden sniffing death. JAMA 1970;212:2075–2079

External links

• International Chemical Safety Card 0232
• NIOSH Pocket Guide to Chemical Hazards
• n-Butane Molecule of the Month
• World LP Gas Association (WLPGA)
• UKLPG Propane and Butane in the UK
• Global BioSciences In-Situ Bioremediation utilizing Butane