Isobutane

Last updated
Isobutane
Chemical structure of isobutane with all atoms explicitly shown Isobutane 1.svg
Chemical structure of isobutane with all atoms explicitly shown
Skeletal formula of isobutane Isobutane simple.svg
Skeletal formula of isobutane
Ball and stick model of isobutane Isobutane-3D-balls.png
Ball and stick model of isobutane
Spacefill model of isobutane Isobutane3.png
Spacefill model of isobutane
Names
Preferred IUPAC name
2-Methylpropane [1]
Other names
  • Isobutane
  • R600a
Identifiers
3D model (JSmol)
1730720
ChEBI
ChemSpider
ECHA InfoCard 100.000.780 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 200-857-2
E number E943b (glazing agents, ...)
1301
KEGG
PubChem CID
RTECS number
  • TZ4300000
UNII
UN number 1969
  • InChI=1S/C4H10/c1-4(2)3/h4H,1-3H3 Yes check.svgY
    Key: NNPPMTNAJDCUHE-UHFFFAOYSA-N Yes check.svgY
  • CC(C)C
Properties
C4H10
Molar mass 58.124 g·mol−1
AppearanceColorless gas
Odor Odorless
Density
  • 2.51 kg/m3 (at 15 °C, 100 kPa)
  • 563 kg/m3 (at 15 °C, boiling liquid)
Melting point −159.42 °C (−254.96 °F; 113.73 K) [2]
Boiling point −11.7 °C (10.9 °F; 261.4 K) [2]
48.9 mg⋅L−1 (at 25 °C (77 °F)) [3]
Vapor pressure 3.1 atm (310 kPa) (at 21 °C (294 K; 70 °F)) [4]
8.6 nmol⋅Pa−1⋅kg−1
Conjugate acid Isobutanium
−51.7·10−6 cm3/mol
Thermochemistry
96.65 J⋅K−1⋅mol−1
−134.8  −133.6 kJ⋅mol−1
−2.86959  −2.86841 MJ⋅mol−1
Hazards
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 hazards (white): no code
1
4
0
Flash point −83 °C (−117 °F; 190 K)
460 °C (860 °F; 733 K)
Explosive limits 1.4–8.3%
NIOSH (US health exposure limits):
PEL (Permissible)
None [5]
REL (Recommended)
TWA 800 ppm (1900 mg/m3) [5]
IDLH (Immediate danger)
N.D. [5]
Safety data sheet (SDS) lindeus.com
Related compounds
Related alkane
Isopentane
Supplementary data page
Isobutane (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)
R600-Isobutane 13.6Kg Cylinder by Starke Hvac R600a product image.png
R600-Isobutane 13.6Kg Cylinder by Starke Hvac

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. [6]

Contents

Production

Isobutane is obtained by isomerization of butane.

Isomerization of butane ButaneIsomerization.svg
Isomerization of butane

Uses

Isobutane is the principal feedstock in alkylation units of refineries. Using isobutane, gasoline-grade "blendstocks" are generated with high branching for good combustion characteristics. Typical products created with isobutane are 2,4-dimethylpentane and especially 2,2,4-trimethylpentane. [7]

Typical acid-catalyzed route to 2,4-dimethylpentane. 2,4-Me2pentaneRoute.png
Typical acid-catalyzed route to 2,4-dimethylpentane.

Solvent

In the Chevron Phillips slurry process for making high-density polyethylene, isobutane is used as a diluent. As the slurried polyethylene is removed, isobutane is "flashed" off, and condensed, and recycled back into the loop reactor for this purpose. [8]

Precursor to tert-butyl hydroperoxide

Isobutane is oxidized to tert-butyl hydroperoxide, which is subsequently reacted with propylene to yield propylene oxide. The tert-butanol that results as a by-product is typically used to make gasoline additives such as methyl tert-butyl ether (MTBE).

Miscellaneous uses

Isobutane is also used as a propellant for aerosol spray cans.

Isobutane is used as part of blended fuels, especially common in fuel canisters used for camping. [9]

Refrigerant

Isobutane is used as a refrigerant. [10] Use in refrigerators started in 1993 when Greenpeace presented the Greenfreeze project with the former East German company Foron  [ de ]. [11] [12] In this regard, blends of pure, dry "isobutane" (R-600a) (that is, isobutane mixtures) have negligible ozone depletion potential and very low global warming potential (having a value of 3.3 times the GWP of carbon dioxide) and can serve as a functional replacement for R-12, R-22 (both of these being commonly known by the trademark Freon), R-134a, and other chlorofluorocarbon or hydrofluorocarbon refrigerants in conventional stationary refrigeration and air conditioning systems.

As a refrigerant, isobutane poses a fire and explosion risk in addition to the hazards associated with non-flammable CFC refrigerants. Substitution of this refrigerant for motor vehicle air conditioning systems not originally designed for isobutane is widely prohibited or discouraged. [13] [14] [15] [16] [17] [18] [19]

Vendors and advocates of hydrocarbon refrigerants argue against such bans on the grounds that there have been very few such incidents relative to the number of vehicle air conditioning systems filled with hydrocarbons. [20] [21]

A leak of isobutane in the refrigerant system of a fridge initiated the 2024 Valencia residential complex fire in Spain, that claimed 10 lives. [22]

Nomenclature

The traditional name isobutane was still retained in the 1993 IUPAC recommendations, [23] but is no longer recommended according to the 2013 recommendations. [1] Since the longest continuous chain in isobutane contains only three carbon atoms, the preferred IUPAC name is 2-methylpropane but the locant (2-) is typically omitted in general nomenclature as redundant; C2 is the only position on a propane chain where a methyl substituent can be located without altering the main chain and forming the constitutional isomer n-butane.

Related Research Articles

<span class="mw-page-title-main">Ethylene</span> Hydrocarbon compound (H₂C=CH₂)

Ethylene is a hydrocarbon which has the formula C2H4 or H2C=CH2. It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene.

<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">Octane</span> Hydrocarbon compound with the formula C8H18

Octane is a hydrocarbon and an alkane with the chemical formula C8H18, and the condensed structural formula CH3(CH2)6CH3. Octane has many structural isomers that differ by the location of branching in the carbon chain. One of these isomers, 2,2,4-trimethylpentane (commonly called iso-octane), is used as one of the standard values in the octane rating scale.

<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.

<span class="mw-page-title-main">Pentane</span> Alkane with 5 carbon atoms

Pentane is an organic compound with the formula C5H12—that is, an alkane with five carbon atoms. The term may refer to any of three structural isomers, or to a mixture of them: in the IUPAC nomenclature, however, pentane means exclusively the n-pentane isomer, in which case pentanes refers to a mixture of them; the other two are called isopentane (methylbutane) and neopentane (dimethylpropane). Cyclopentane is not an isomer of pentane because it has only 10 hydrogen atoms where pentane has 12.

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

Acrylic acid (IUPAC: prop-2-enoic acid) is an organic compound with the formula CH2=CHCOOH. It is the simplest unsaturated carboxylic acid, consisting of a vinyl group connected directly to a carboxylic acid terminus. This colorless liquid has a characteristic acrid or tart smell. It is miscible with water, alcohols, ethers, and chloroform. More than a million tons are produced annually.

In organic chemistry, butyl is a four-carbon alkyl radical or substituent group with general chemical formula −C4H9, derived from either of the two isomers (n-butane and isobutane) of butane.

<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">2-Butanol</span> Secondary alcohol

Butan-2-ol, or sec-butanol, is an organic compound with formula CH3CH(OH)CH2CH3. Its structural isomers are 1-butanol, isobutanol, and tert-butanol. 2-Butanol is chiral and thus can be obtained as either of two stereoisomers designated as (R)-(−)-butan-2-ol and (S)-(+)-butan-2-ol. It is normally encountered as a 1:1 mixture of the two stereoisomers — a racemic mixture.

<i>tert</i>-Butyl alcohol Chemical compound

tert-Butyl alcohol is the simplest tertiary alcohol, with a formula of (CH3)3COH (sometimes represented as t-BuOH). Its isomers are 1-butanol, isobutanol, and butan-2-ol. tert-Butyl alcohol is a colorless solid, which melts near room temperature and has a camphor-like odor. It is miscible with water, ethanol and diethyl ether.

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

Pentenes are alkenes with the chemical formula C
5
H
10
. Each molecule contains one double bond within its molecular structure. Six different compounds are in this class, differing from each other by whether the carbon atoms are attached linearly or in a branched structure and whether the double bond has a cis or trans form.

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

Isobutanol (IUPAC nomenclature: 2-methylpropan-1-ol) is an organic compound with the formula (CH3)2CHCH2OH (sometimes represented as i-BuOH). This colorless, flammable liquid with a characteristic smell is mainly used as a solvent either directly or as its esters. Its isomers are 1-butanol, 2-butanol, and tert-butanol, all of which are important industrially.

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

Cumene (isopropylbenzene) is an organic compound that contains a benzene ring with an isopropyl substituent. It is a constituent of crude oil and refined fuels. It is a flammable colorless liquid that has a boiling point of 152 °C. Nearly all the cumene that is produced as a pure compound on an industrial scale is converted to cumene hydroperoxide, which is an intermediate in the synthesis of other industrially important chemicals, primarily phenol and acetone.

<i>m</i>-Xylene Chemical compound

m-Xylene (meta-xylene) is an aromatic hydrocarbon. It is one of the three isomers of dimethylbenzene known collectively as xylenes. The m- stands for meta-, indicating that the two methyl groups in m-xylene occupy positions 1 and 3 on a benzene ring. It is in the positions of the two methyl groups, their arene substitution pattern, that it differs from the other isomers, o-xylene and p-xylene. All have the same chemical formula C6H4(CH3)2. All xylene isomers are colorless and highly flammable.

<span class="mw-page-title-main">Butane-1-thiol</span> Chemical compound

Butane-1-thiol, also known as butyl mercaptan, is a volatile, clear to yellowish liquid with a fetid odor, commonly described as "skunk" odor. In fact, 1-butanethiol is structurally similar to several major constituents of a skunk's defensive spray but is not actually present in the spray. The scent of 1-butanethiol is so strong that the human nose can easily detect it in the air at concentrations as low as 10 parts per billion. The threshold level for 1-butanethiol is reported as 1.4 ppb

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

n-Butylamine is an organic compound (specifically, an amine) with the formula CH3(CH2)3NH2. This colourless liquid is one of the four isomeric amines of butane, the others being sec-butylamine, tert-butylamine, and isobutylamine. It is a liquid having the fishy, ammonia-like odor common to amines. The liquid acquires a yellow color upon storage in air. It is soluble in all organic solvents. Its vapours are heavier than air and it produces toxic oxides of nitrogen during combustion.

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

Hexachlorobutadiene, (often abbreviated as "HCBD") Cl2C=C(Cl)C(Cl)=CCl2, is a colorless liquid at room temperature that has an odor similar to that of turpentine. It is a chlorinated aliphatic diene with niche applications but is most commonly used as a solvent for other chlorine-containing compounds. Structurally, it has a 1,3-butadiene core, but fully substituted with chlorine atoms.

<i>tert</i>-Butyl hydroperoxide Chemical compound

tert-Butyl hydroperoxide (tBuOOH) is the organic compound with the formula (CH3)3COOH. It is one of the most widely used hydroperoxides in a variety of oxidation processes, like the Halcon process. It is normally supplied as a 69–70% aqueous solution. Compared to hydrogen peroxide and organic peracids, tert-butyl hydroperoxide is less reactive and more soluble in organic solvents. Overall, it is renowned for the convenient handling properties of its solutions. Its solutions in organic solvents are highly stable.

Isopropyl alcohol is a colorless, flammable organic compound with a pungent alcoholic odor.

<span class="mw-page-title-main">Butane</span> Organic compound

Butane or n-butane is an alkane with the formula C4H10. Butane is a highly flammable, colorless, easily liquefied gas that quickly vaporizes at room temperature and pressure. The name butane comes from the root but- (from butyric acid, named after the Greek word for butter) and the suffix -ane. It was discovered in crude petroleum in 1864 by Edmund Ronalds, who was the first to describe its properties, and commercialized by Walter O. Snelling in the early 1910s.

References

  1. 1 2 Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 652. doi:10.1039/9781849733069-FP001. ISBN   978-0-85404-182-4. The names 'isobutane', 'isopentane', and 'neopentane' are no longer recommended.
  2. 1 2 Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  3. "Solubility in Water". PubChem. National Center for Biotechnology Information. Retrieved 6 April 2017.
  4. "CDC - NIOSH Pocket Guide to Chemical Hazards - Isobutane". CDC - NIOSH Pocket Guide to Chemical Hazards. CDC. Retrieved 28 December 2018.
  5. 1 2 3 NIOSH Pocket Guide to Chemical Hazards. "#0350". National Institute for Occupational Safety and Health (NIOSH).
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  9. Rietveld, Will (2005-02-08). "Frequently Asked Questions About Lightweight Canister Stoves and Fuels" . Backpacking Light (subscription required). Retrieved 2022-06-03.
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  11. "GreenFreeze". Greenpeace. 2010-03-15. Archived from the original on 2010-10-05. Retrieved 2013-01-02.
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  13. "U.S. EPA hydrocarbon-refrigerants FAQ". Epa.gov. Retrieved 2010-10-29.
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  15. "MACS bulletin: hydrocarbon refrigerant usage in vehicles" (PDF). Archived from the original (PDF) on 2011-01-05. Retrieved 2010-10-29.
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  17. "Saskatchewan Labour bulletin on hydrocarbon refrigerants in vehicles". Labour.gov.sk.ca. 2010-06-29. Archived from the original on 2009-07-01. Retrieved 2010-10-29.
  18. VASA on refrigerant legality & advisability Archived January 13, 2009, at the Wayback Machine
  19. "Queensland (Australia) government warning on hydrocarbon refrigerants" (PDF). Energy.qld.gov.au. Archived from the original (PDF) on 2008-12-17. Retrieved 2010-10-29.
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  21. "New South Wales (Australia) Parliamentary record, 29 June 2000". Parliament.nsw.gov.au. Archived from the original on 22 May 2005. Retrieved 2010-10-29.
  22. Domínguez, Teresa (3 May 2024). "Una fuga del gas refrigerante de la nevera del piso 86 propició el inicio del incendio de Campanar". Levante-EMV (in European Spanish). Retrieved 15 October 2024.
  23. Panico, R. & Powell, W. H., eds. (1994). A Guide to IUPAC Nomenclature of Organic Compounds 1993. Oxford: Blackwell Science. ISBN   0-632-03488-2. https://www.acdlabs.com/iupac/nomenclature/93/r93_679.htm