Butane

Butane

Names
Preferred IUPAC name Butane[3]
Systematic IUPAC name Tetracarbane (never recommended[3])
Other names Butyl hydride[1] Quartane[2]
Identifiers
CAS Number	106-97-8 Y
3D model (JSmol)	Interactive image
Beilstein Reference	969129
ChEBI	CHEBI:37808 Y
ChEMBL	ChEMBL134702 Y
ChemSpider	7555 Y
ECHA InfoCard	100.003.136
EC Number	203-448-7
E number	E943a (glazing agents, ...)
Gmelin Reference	1148
KEGG	D03186 Y
MeSH	butane
PubChem CID	7843
RTECS number	EJ4200000
UNII	6LV4FOR43R Y
UN number	1011
InChI InChI=1S/C4H10/c1-3-4-2/h3-4H2,1-2H3 Y Key: IJDNQMDRQITEOD-UHFFFAOYSA-N Y
SMILES CCCC
Properties
Chemical formula	C4H10
Molar mass	58.12 g·mol−1
Appearance	Colorless gas
Odor	Gasoline-like or natural gas-like[1]
Density	2.48 kg/m3 (at 15 °C (59 °F))
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 (68 °F))
log P	2.745
Vapor pressure	~170 kPa at 283 K [4]
Henry's law constant (kH)	11 nmol Pa−1 kg−1
Magnetic susceptibility (χ)	-57.4·10−6 cm3/mol
Thermochemistry
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[5]
Safety data sheet	See: data page
GHS pictograms
GHS signal word	DANGER
GHS hazard statements	H220
GHS precautionary statements	P210
NFPA 704	4 1 0 SA
Flash point	−60 °C (−76 °F; 213 K)
Autoignition temperature	405 °C (761 °F; 678 K)
Explosive limits	1.8–8.4%
US health exposure limits (NIOSH):
PEL (Permissible)	none[1]
REL (Recommended)	TWA 800 ppm (1900 mg/m3)[1]
IDLH (Immediate danger)	N.D.[1]
Related compounds
Related alkanes	Propane Isobutane Pentane
Related compounds	Perfluorobutane
Supplementary data page
Structure and properties	Refractive index (n), Dielectric constant (εr), etc.
Thermodynamic data	Phase behaviour solid–liquid–gas
Spectral data	UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
Infobox references

Butane (/ˈbjuːteɪn/) 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 (also called "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 that quickly vaporize at room temperature. The name butane comes from the roots but- (from butyric acid, named after the Greek word for butter) and -ane. It was discovered by the chemist Edward Frankland in 1849.^[6]

Isomers[edit]

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.^[7]

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 can be used for gasoline blending, as a fuel gas, fragrance extraction solvent, 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.^{[8][9][10][11]}

When blended with propane and other hydrocarbons, it may be referred to commercially as LPG, for liquefied 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.^[12]

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 pure butane will not function optimally and therefore a mix of isobutane and propane is used to give cooling system performance comparable to R-12.

Butane is also used as lighter fuel for a common lighter or butane torch and is sold bottled as a fuel for cooking, barbecues and camping stoves. Butane canisters are almost exclusively manufactured in South Korea with the only exception being one manufacturer in Houston, Texas.^[13] Butane canisters manufactured in South Korea contain butane from Saudi Arabia, while the American manufacturer fills canisters with domestic butane.^[14]

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. While hydrogen sulfide and mercaptans are toxic, they are present in levels so low that suffocation and fire hazard by the butane becomes a concern far before toxicity. 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. Contaminants are not used in fragrance extraction and butane gasses can cause gas explosions in poorly ventilated areas if leaks go unnoticed and are ignited by spark or flame.

Butane fuel canisters for use in camping stoves.	Butane lighter, showing liquid butane reservoir	Butane being sprayed from an aerosol spray can	Butane gas cylinder used for cooking

Effects and health issues[edit]

Inhalation of butane can cause euphoria, drowsiness, narcosis, asphyxia, cardiac arrhythmia, fluctuations in blood pressure and temporary memory loss, when abused directly from a highly pressurized container, and can result in death from asphyxiation and ventricular fibrillation. It enters the blood supply and within seconds produces intoxication.^[15] Butane is the most commonly misused volatile substance in the UK, and was the cause of 52% of solvent related deaths in 2000.^[16] By spraying butane directly into the throat, the jet of fluid can cool rapidly to −20 °C (−4 °F) by expansion, causing prolonged laryngospasm.^[17] "Sudden sniffer's death" syndrome, first described by Bass in 1970,^[18] is the most common single cause of solvent related death, resulting in 55% of known fatal cases.^[17]

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.^[19]

See also[edit]

• Isobutane
• Cyclobutane
• Dimethyl ether
• Volatile substance abuse
• Butane (data page)
• Butanone
• n-Butanol
• Liquefied petroleum gas
• Industrial gas
• Butane torch
• Gas explosions

References[edit]

External links[edit]

Wikimedia Commons has media related to Butane.

• International Chemical Safety Card 0232
• NIOSH Pocket Guide to Chemical Hazards