Butane

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Butane
Skeletal formula of butane Skeletal formula of butane with all carbon and hydrogen atoms shown
Ball and stick model of butane Spacefill model of butane
Identifiers
CAS number 106-97-8 YesY
PubChem 7843
ChemSpider 7555 YesY
UNII 6LV4FOR43R YesY
EC number 203-448-7
UN number 1011
KEGG D03186 YesY
MeSH butane
ChEBI CHEBI:37808 YesY
ChEMBL CHEMBL134702 YesY
RTECS number EJ4200000
Beilstein Reference 969129
Gmelin Reference 1148
Jmol-3D images Image 1
Properties
Molecular formula C4H10
Molar mass 58.12 g mol−1
Appearance Colorless gas
Odor Odorless
Density 2.48 kg/m3 (at 15 °C)
Melting point −140 to −134 °C; −220 to −209 °F; 133 to 139 K
Boiling point −1 to 1 °C; 30 to 34 °F; 272 to 274 K
Solubility in water 61 mg L−1 (at 20 °C)
log P 2.745
Vapor pressure ~25 PSI (at 50 °F) [2]
kH 11 nmol Pa−1 kg−1
Thermochemistry
Specific
heat capacity
C
98.49 J K−1 mol−1
Std enthalpy of
formation
ΔfHo298
−126.3–−124.9 kJ mol−1
Std enthalpy of
combustion
ΔcHo298
−2.8781–−2.8769 MJ mol−1
Hazards[3]
MSDS External MSDS
GHS pictograms The flame pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
GHS hazard statements H220
GHS precautionary statements P210
EU Index 601-004-00-0
EU classification Extremely Flammable F+
R-phrases R12
S-phrases (S2) S16
NFPA 704
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g., propane Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point −60 °C (−76 °F; 213 K)
Explosive limits 1.8–8.4%
Related compounds
Related alkanes
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
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Butane (/ˈbjuːtn/) 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.

Isomers[edit]

Common name normal butane
unbranched butane
n-butane
isobutane
i-butane
IUPAC name butane 2-methylpropane
Molecular
diagram
Butan Lewis.svg Isobutane 1.svg
Skeletal
diagram
Butane simple.svg I-Butane-2D-Skeletal.svg

Rotation about the central C-C bond produces two different conformations (trans and gauche) for n-butane.[4]

Reactions[edit]

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.

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

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[edit]

Normal butane is mainly 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.[5][6][7][8]

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.[9]

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. Note that both hydrogen sulfide and mercaptans, while both 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.

Cordless hair irons are usually powered by butane cartridges.[10]

Effects and health issues[edit]

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.[11] By spraying butane directly into the throat, the jet of fluid can cool rapidly to −20 °C by expansion, causing prolonged laryngospasm.[12] "Sudden sniffer's death" syndrome, first described by Bass in 1970,[13] is the most common single cause of "solvent related" death, resulting in 55% of known fatal cases.[12]

A small amount of nitrogen dioxide, a toxic gas, results from burning butane gas, along with any combustion in the earths atmosphere, and represents a human health hazard from home heaters and stoves.[14]

See also[edit]

References[edit]

  1. ^ PubChem 7843
  2. ^ W. B. Kay. "Pressure-Volume-Temperature Relations for n-Butane". Standard Oil Company. 
  3. ^ "Safety Data Sheet, Material Name: N-Butane" (PDF). USA: Matheson Tri-Gas Incorporated. 5 February 2011. Retrieved 11 December 2011. 
  4. ^ 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): 1012–9. doi:10.1021/jp809639s. PMID 19152252. 
  5. ^ FORM 10-K. UNITED STATES SECURITIES AND EXCHANGE COMMISSION
  6. ^ Form 10-K. Sec.gov. Retrieved on 2012-12-03.
  7. ^ form10-k.htm. Sec.gov. Retrieved on 2012-12-03.
  8. ^ FORM 10-K. UNITED STATES SECURITIES AND EXCHANGE COMMISSION
  9. ^ A Primer on Gasoline Blending. An EPRINC Briefing Memorandum
  10. ^ FAA: Hazardous Materials p. 4
  11. ^ Field-Smith M, Bland JM, Taylor JC, et al. "Trends in death Associated with Abuse of Volatile Substances 1971–2004". Department of Public Health Sciences. London: St George’s Medical School. 
  12. ^ a b Ramsey J, Anderson HR, Bloor K, et al. (1989). "An introduction to the practice, prevalence and chemical toxicology of volatile substance abuse". Hum Toxicol 8 (4): 261–269. doi:10.1177/096032718900800403. PMID 2777265. 
  13. ^ Bass M. (1970). "Sudden sniffing death". JAMA 212 (12): 2075–2079. doi:10.1001/jama.1970.03170250031004. PMID 5467774. 
  14. ^ Ghosn, Marwan; Flouty, Roula; Saliba, Najat A. (2005). "Emission of Nitrogen Dioxide from Butane Gas Heaters and Stoves Indoors". American Journal of Applied Sciences 2 (3): 707. doi:10.3844/ajassp.2005.707.710. 

External links[edit]