|Molar mass||58.12 g·mol−1|
|Odor||Gasoline-like or natural gas-like|
|Density||2.48 kg/m3 (at 15 °C (59 °F))|
|Melting point||−140 °C; −220 °F; 133 K|
|Boiling point||−1 °C; 30 °F; 272 K|
|61 mg L−1 (at 20 °C (68 °F))|
|Vapor pressure||~25 PSI (at 50 °F (10 °C)) |
|11 nmol Pa−1 kg−1|
|98.49 J K−1 mol−1|
Std enthalpy of
|−126.3–−124.9 kJ mol−1|
Std enthalpy of
|−2.8781–−2.8769 MJ mol−1|
|GHS signal word||DANGER|
|Flash point||−60 °C (−76 °F; 213 K)|
|288 °C (550 °F; 561 K)|
|US health exposure limits (NIOSH):|
|TWA 800 ppm (1900 mg/m3)|
LDLH (Immediate danger)
|Supplementary data page|
|Refractive index (n),
Dielectric constant (εr), etc.
|UV, IR, NMR, MS|
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
Butane (//) is an organic compound with the formula C4H10 that is an alkane with four carbon atoms. Butane is a gas at room temperature and atmospheric pressure. 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.
|Common name||normal butane
When there is sufficient oxygen:
- 2 C4H10 + 13 O2 → 8 CO2 + 10 H2O
When oxygen is limited:
- 2 C4H10 + 9 O2 → 8 CO + 10 H2O
- 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.
Normal butane can be used for gasoline blending, as a fuel gas, either alone or in a mixture with propane, and as a feedstock for the manufacture of ethylene and butadiene, a key ingredient of synthetic rubber. Isobutane is primarily used by refineries to enhance (increase) the octane number of motor gasoline.
When blended with propane and other hydrocarbons, it may be referred to commercially as LPG, for liquified petroleum gas. It is 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.
Butane is also used as lighter fuel for a common lighter or butane torch and is sold bottled as a fuel for cooking and camping. In this form it is often mixed with small amounts of hydrogen sulfide and mercaptans which will give the unburned gas an offensive smell easily detected by the human nose. In this way, butane leaks can easily be identified. Both hydrogen sulfide and mercaptans, while considered poisons, have low boiling points and quickly vaporize when not under pressure. Most commercially available butane also contains a certain amount of contaminant oil which can be removed through filtration but which will otherwise leave a deposit at the point of ignition and may eventually block the uniform flow of gas.
Effects and health issues
Inhalation of butane can cause euphoria, drowsiness, narcosis, asphyxia, cardiac arrhythmia, fluctuations in blood pressure, temporary memory loss and frostbite, and 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 (−4 °F) 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.
A small amount of nitrogen dioxide, a toxic gas, results from burning butane gas, along with any combustion in the earth's atmosphere, and represents a human health hazard from home heaters and stoves.
- Dimethyl ether
- Volatile substance abuse
- Butane (data page)
- Liquefied petroleum gas
- Industrial gas
- Butane torch
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