Butane

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Butane
Butan Lewis.svg
Butane simple.svg
Butane-3D-balls.png
Butane-3D-space-filling.png
Names
Preferred IUPAC name
Butane [1]
Systematic IUPAC name
Tetracarbane (never recommended [1] )
Other names
  • Butyl hydride [2]
  • Quartane [3]
  • R600
Identifiers
3D model (JSmol)
969129
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.003.136 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 203-448-7
E number E943a (glazing agents, ...)
1148
KEGG
MeSH butane
PubChem CID
RTECS number
  • EJ4200000
UNII
UN number 1011
  • InChI=1S/C4H10/c1-3-4-2/h3-4H2,1-2H3 Yes check.svgY
    Key: IJDNQMDRQITEOD-UHFFFAOYSA-N Yes check.svgY
  • CCCC
Properties
C4H10
Molar mass 58.124 g·mol−1
AppearanceColorless gas
Odor Gasoline-like or natural gas-like [2]
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
61 mg/L (at 20 °C (68 °F))
log P 2.745
Vapor pressure ~170 kPa at 283 K [4]
11 nmol Pa−1 kg−1
−57.4·10−6 cm3/mol
Thermochemistry
98.49 J/(K·mol)
−126.3–−124.9 kJ/mol
−2.8781–−2.8769 MJ/mol
Hazards [5]
GHS labelling:
GHS-pictogram-flamme.svg
Danger
H220
P210
NFPA 704 (fire diamond)
NFPA 704.svgHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 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. propaneInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazard SA: Simple asphyxiant gas. E.g. nitrogen, helium
1
4
0
SA
Flash point −60 °C (−76 °F; 213 K)
405 °C (761 °F; 678 K)
Explosive limits 1.8–8.4%
NIOSH (US health exposure limits):
PEL (Permissible)
none [2]
REL (Recommended)
TWA 800 ppm (1900 mg/m3) [2]
IDLH (Immediate danger)
1600 ppm [2]
Related compounds
Related alkanes
Related compounds
Perfluorobutane
Supplementary data page
Butane (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

Butane ( /ˈbjuːtn/ ) is an alkane with the formula C4H10. Butane exists as two isomers, n-butane with connectivity CH3CH2CH2CH3 and iso-butane with the formula (CH3)3CH. Both isomers are highly flammable, colorless, easily liquefied gases that quickly vaporize at room temperature and pressure. Butanes are a trace components of natural gases (NG gases). The other hydrocarbons in NG include propane, ethane, and especially methane, which are more abundant. Liquified natural gas is a mixture of propane and some butanes. [6]

The name butane comes from the root but- (from butyric acid, named after the Greek word for butter) and the suffix -ane.

History

The first synthesis of butane was accidentally achieved by British chemist Edward Francland in 1849 from ethyl iodide and zinc, but he had not realized that the ethyl radical dimerized and misidentified the substance. [7]

It was discovered in crude petroleum in 1864 by Edmund Ronalds, who was the first to describe its properties, [8] [9] which he named "hydride of butyl", [10] based on the naming for the then-known butyric acid, which had been named and described by the French chemist Michel Eugène Chevreul [11] 40 years earlier. Other names arose in the 1860s: "butyl hydride", [12] "hydride of tetryl" [13] and "tetryl hydride", [14] "diethyl" or "ethyl ethylide" [15] and others. August Wilhelm von Hofmann, in his 1866 systemic nomenclature, proposed the name "quartane", [3] and the modern name was introduced to English from German around 1874. [16]

Butane did not have much practical use until the 1910s, when W. Snelling identified butane and propane as components in gasoline. He found that if they were cooled, they could be stored in a volume-reduced liquified state in pressurized containers. In 1911, Snelling's liquified petroleum gas was publicly available, and his process for producing the mixture was patented in 1913. [17] Butane is one of the most produced industrial chemicals in the 21st century, with around 80-90 billion lbs (40 million US tons, 36 million metric tons) produced by the United States every year. [18]

Density

The density of butane is highly dependent on temperature and pressure in the reservoir. [19] For example, the density of liquid butane is 571.8±1 kg/m3 (for pressures up to 2 MPa and temperature 27±0.2 °C), while the density of liquid butane is 625.5±0.7 kg/m3 (for pressures up to 2 MPa and temperature −13±0.2 °C).

Isomers

Common namenormal butane
unbranched butane
n-butane
isobutane
i-butane
IUPAC namebutanemethylpropane
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. [20]

Reactions

Spectrum of the blue flame from a butane torch showing CH molecular radical band emission and C2 Swan bands Spectrum of blue flame - intensity corrected.png
Spectrum of the blue flame from a butane torch showing CH molecular radical band emission and C2 Swan bands

When oxygen is plentiful, butane undergoes complete combustion to form carbon dioxide and water vapor; when oxygen is limited, due to incomplete combustion, carbon (soot) or carbon monoxide may be formed instead of carbon dioxide. Butane is denser than air.

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

By weight, butane contains about 49.5  MJ / kg (13.8  kWh /kg; 22.5 MJ/ lb ; 21,300  Btu /lb) or by liquid volume 29.7 megajoules per liter (8.3 kWh/L; 112 MJ/U.S. gal; 107,000 Btu/U.S. gal).

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 chlorinations are partially explained by the differing bond dissociation energies: 425 and 411 kJ/mol for the two types of C-H bonds.

Uses

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. [21] [22] [23] [24]

For gasoline blending, n-butane is the main component used to manipulate the Reid vapor pressure (RVP). Since winter fuels require much higher vapor pressure for engines to start, refineries raise the RVP by blending more butane into the fuel. [25] n-Butane has a relatively high research octane number (RON) and motor octane number (MON), which are 93 and 92 respectively. [26]

When blended with propane and other hydrocarbons, the mixture may be referred to commercially as liquefied petroleum gas (LPG). 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. [27]

Pure forms of butane, especially isobutane, are used as refrigerants and have largely replaced the ozone-layer-depleting halomethanes in refrigerators, freezers, and air conditioning systems. The operating pressure for butane is lower than operating pressures for halomethanes such as Freon-12 (R-12). Hence, R-12 systems, such as those in automotive air conditioning systems, when converted to pure butane, will function poorly. Instead, a mixture of isobutane and propane is used to give cooling system performance comparable to R-12. [28]

Butane is also used as lighter fuel for common lighters or butane torches, and is sold bottled as a fuel for cooking, barbecues and camping stoves. In the 20th century, the Braun company of Germany made a cordless hair styling device product that used butane as its heat source to produce steam. [29]

As fuel, butane is often mixed with small amounts of mercaptans to 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. [30] [31] Most commercially available butane also contains some contaminant oil, which can be removed by filtration. If not removed, it will otherwise leave a deposit at the point of ignition and may eventually block the uniform flow of gas. [32]

The butane used as a solvent for fragrance extraction does not contain these contaminants. [33] Butane gas can cause gas explosions in poorly ventilated areas if leaks go unnoticed and are ignited by spark or flame. [5] Purified butane is used as a solvent in the industrial extraction of cannabis oils.

Health effects

Table from the 2010 ISCD study ranking various drugs (legal and illegal) based on statements by drug-harm experts. Butane was found to be the 14th overall most dangerous drug. HarmCausedByDrugsTable.svg
Table from the 2010 ISCD study ranking various drugs (legal and illegal) based on statements by drug-harm experts. Butane was found to be the 14th overall most dangerous drug.

Inhalation of butane can cause euphoria, drowsiness, unconsciousness, 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. Butane enters the blood supply, and within seconds, leads to intoxication. [35] Butane is the most commonly abused volatile substance in the UK, and was the cause of 52% of solvent related deaths in 2000. [36] By spraying butane directly into the throat, the jet of fluid can cool rapidly to −20 °C (−4 °F) by expansion, causing prolonged laryngospasm. [37] "Sudden sniffer's death" syndrome, first described by Bass in 1970, [38] is the most common single cause of solvent related deaths, resulting in 55% of known fatal cases. [37]

See also

Related Research Articles

<span class="mw-page-title-main">Alkane</span> Type of saturated hydrocarbon compound

In organic chemistry, an alkane, or paraffin, is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which all the carbon–carbon bonds are single. Alkanes have the general chemical formula CnH2n+2. The alkanes range in complexity from the simplest case of methane, where n = 1, to arbitrarily large and complex molecules, like pentacontane or 6-ethyl-2-methyl-5-(1-methylethyl) octane, an isomer of tetradecane.

<span class="mw-page-title-main">Propane</span> Hydrocarbon compound

Propane is a three-carbon alkane with the molecular formula C3H8. It is a gas at standard temperature and pressure, but compressible to a transportable liquid. A by-product of natural gas processing and petroleum refining, it is often a constituent of liquefied petroleum gas (LPG), which is commonly used as a fuel in domestic and industrial applications and in low-emissions public transportation; other constituents of LPG may include propylene, butane, butylene, butadiene, and isobutylene. Discovered in 1857 by the French chemist Marcellin Berthelot, it became commercially available in the US by 1911. Propane has lower volumetric energy density than gasoline or coal, but has higher gravimetric energy density than them and burns more cleanly.

<span class="mw-page-title-main">Ethane</span> Organic compound (H3C–CH3)

Ethane is a naturally occurring organic chemical compound with chemical formula C
2
H
6
. At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petrochemical by-product of petroleum refining. Its chief use is as feedstock for ethylene production. The ethyl group is formally, although rarely practically, derived from ethane.

<span class="mw-page-title-main">Isobutane</span> Chemical compound

Isobutane, also known as i-butane, 2-methylpropane or methylpropane, is a chemical compound with molecular formula HC(CH3)3. It is an isomer of butane. Isobutane is a colorless, odorless gas. It is the simplest alkane with a tertiary carbon atom. Isobutane is used as a precursor molecule in the petrochemical industry, for example in the synthesis of isooctane.

<span class="mw-page-title-main">Oil refinery</span> Facility that processes crude oil

An oil refinery or petroleum refinery is an industrial process plant where petroleum is transformed and refined into products such as gasoline (petrol), diesel fuel, asphalt base, fuel oils, heating oil, kerosene, liquefied petroleum gas and petroleum naphtha. Petrochemical feedstock like ethylene and propylene can also be produced directly by cracking crude oil without the need of using refined products of crude oil such as naphtha. The crude oil feedstock has typically been processed by an oil production plant. There is usually an oil depot at or near an oil refinery for the storage of incoming crude oil feedstock as well as bulk liquid products. In 2020, the total capacity of global refineries for crude oil was about 101.2 million barrels per day.

<span class="mw-page-title-main">Liquefied petroleum gas</span> Fuel for heating, cooking and vehicles

Liquefied petroleum gas, also referred to as liquid petroleum gas, is a fuel gas which contains a flammable mixture of hydrocarbon gases, specifically propane, n-butane and isobutane. It can sometimes contain some propylene, butylene, and isobutene.

In petrochemistry, petroleum geology and organic chemistry, cracking is the process whereby complex organic molecules such as kerogens or long-chain hydrocarbons are broken down into simpler molecules such as light hydrocarbons, by the breaking of carbon–carbon bonds in the precursors. The rate of cracking and the end products are strongly dependent on the temperature and presence of catalysts. Cracking is the breakdown of large hydrocarbons into smaller, more useful alkanes and alkenes. Simply put, hydrocarbon cracking is the process of breaking long-chain hydrocarbons into short ones. This process requires high temperatures.

Natural-gas condensate, also called natural gas liquids, is a low-density mixture of hydrocarbon liquids that are present as gaseous components in the raw natural gas produced from many natural gas fields. Some gas species within the raw natural gas will condense to a liquid state if the temperature is reduced to below the hydrocarbon dew point temperature at a set pressure.

<span class="mw-page-title-main">Liquid fuel</span> Liquids that can be used to create energy

Liquid fuels are combustible or energy-generating molecules that can be harnessed to create mechanical energy, usually producing kinetic energy; they also must take the shape of their container. It is the fumes of liquid fuels that are flammable instead of the fluid. Most liquid fuels in widespread use are derived from fossil fuels; however, there are several types, such as hydrogen fuel, ethanol, and biodiesel, which are also categorized as a liquid fuel. Many liquid fuels play a primary role in transportation and the economy.

<span class="mw-page-title-main">MAPP gas</span> Fuel gas based on a stabilized mixture of methylacetylene and propadiene

MAPP gas was a trademarked name, belonging to The Linde Group, a division of the former global chemical giant Union Carbide, for a fuel gas based on a stabilized mixture of methylacetylene (propyne), propadiene and propane. The name comes from the original chemical composition, methylacetylene-propadiene propane. "MAPP gas" is also widely used as a generic name for UN 1060 stabilised methylacetylene-propadiene.

<span class="mw-page-title-main">Catalytic reforming</span> Chemical process used in oil refining

Catalytic reforming is a chemical process used to convert naphthas from crude oil into liquid products called reformates, which are premium "blending stocks" for high-octane gasoline. The process converts low-octane linear hydrocarbons (paraffins) into branched alkanes (isoparaffins) and cyclic naphthenes, which are then partially dehydrogenated to produce high-octane aromatic hydrocarbons. The dehydrogenation also produces significant amounts of byproduct hydrogen gas, which is fed into other refinery processes such as hydrocracking. A side reaction is hydrogenolysis, which produces light hydrocarbons of lower value, such as methane, ethane, propane and butanes.

<span class="mw-page-title-main">2,2,4-Trimethylpentane</span> Chemical compound

2,2,4-Trimethylpentane, also known as isooctane or iso-octane, is an organic compound with the formula (CH3)3CCH2CH(CH3)2. It is one of several isomers of octane (C8H18). This particular isomer is the standard 100 point on the octane rating scale (the zero point is n-heptane). It is an important component of gasoline, frequently used in relatively large proportions (around 10%) to increase the knock resistance of fuel.

<i>n</i>-Butyllithium Chemical compound

n-Butyllithium C4H9Li (abbreviated n-BuLi) is an organolithium reagent. It is widely used as a polymerization initiator in the production of elastomers such as polybutadiene or styrene-butadiene-styrene (SBS). Also, it is broadly employed as a strong base (superbase) in the synthesis of organic compounds as in the pharmaceutical industry.

Merox is an acronym for mercaptan oxidation. It is a proprietary catalytic chemical process developed by UOP used in oil refineries and natural gas processing plants to remove mercaptans from LPG, propane, butanes, light naphthas, kerosene, and jet fuel by converting them to liquid hydrocarbon disulfides.

<span class="mw-page-title-main">Natural-gas processing</span> Industrial processes designed to purify raw natural gas

Natural-gas processing is a range of industrial processes designed to purify raw natural gas by removing contaminants such as solids, water, carbon dioxide (CO2), hydrogen sulfide (H2S), mercury and higher molecular mass hydrocarbons (condensate) to produce pipeline quality dry natural gas for pipeline distribution and final use. Some of the substances which contaminate natural gas have economic value and are further processed or sold. Hydrocarbons that are liquid at ambient conditions: temperature and pressure (i.e., pentane and heavier) are called natural-gas condensate (sometimes also called natural gasoline or simply condensate).

Natural gasoline is a liquid hydrocarbon mixture condensed from natural gas, similar to common gasoline (petrol) derived from petroleum.

tert-Amyl methyl ether (TAME) is an ether used as a fuel oxygenate. TAME derives from C5 distillation fractions of naphtha. It has an ethereous odor. Unlike most ethers, it does not require a stabilizer as it does not form peroxides on storage.

<span class="mw-page-title-main">Petroleum refining processes</span> Methods of transforming crude oil

Petroleum refining processes are the chemical engineering processes and other facilities used in petroleum refineries to transform crude oil into useful products such as liquefied petroleum gas (LPG), gasoline or petrol, kerosene, jet fuel, diesel oil and fuel oils.

<span class="mw-page-title-main">Alkylation unit</span> Component of a petroleum refinery

An alkylation unit (alky) is one of the conversion processes used in petroleum refineries. It is used to convert isobutane and low-molecular-weight alkenes (primarily a mixture of propene and butene) into alkylate, a high octane gasoline component. The process occurs in the presence of an acid such as sulfuric acid (H2SO4) or hydrofluoric acid (HF) as catalyst. Depending on the acid used, the unit is called a sulfuric acid alkylation unit (SAAU) or hydrofluoric acid alkylation unit (HFAU). In short, the alky produces a high-quality gasoline blending stock by combining two shorter hydrocarbon molecules into one longer chain gasoline-range molecule by mixing isobutane with a light olefin such as propylene or butylene from the refinery's fluid catalytic cracking unit (FCCU) in the presence of an acid catalyst.

Herman Pines was a Russian Empire–born American chemist best known for his work with Vladimir Ipatieff on the catalytic conversion of high-octane aviation fuel. Because of his scientific contributions, new processes were developed for the isomerization of paraffins, the alkylation of aromatic compounds, and base-catalyzed organic reactions.

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