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 ?)

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]

Nomenclature

The traditional name isobutane was still retained in the 1993 IUPAC recommendations, [22] 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">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 commonly used as a fuel in domestic and industrial applications and in low-emissions public transportation. Discovered in 1857 by the French chemist Marcellin Berthelot, it became commercially available in the US by 1911. Propane is one of a group of liquefied petroleum gases. The others include propylene, butane, butylene, butadiene, isobutylene, and mixtures thereof. Propane has lower volumetric energy density, but higher gravimetric energy density and burns more cleanly than gasoline and coal.

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

Heptane or n-heptane is the straight-chain alkane with the chemical formula H3C(CH2)5CH3 or C7H16. When used as a test fuel component in anti-knock test engines, a 100% heptane fuel is the zero point of the octane rating scale (the 100 point is 100% iso-octane). Octane number equates to the anti-knock qualities of a comparison mixture of heptane and iso-octane which is expressed as the percentage of iso-octane in heptane, and is listed on pumps for gasoline (petrol) dispensed globally.

<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">Propylene oxide</span> Chemical compound

Propylene oxide is an acutely toxic and carcinogenic organic compound with the molecular formula CH3CHCH2O. This colourless volatile liquid with an odour similar to ether, is produced on a large scale industrially. Its major application is its use for the production of polyether polyols for use in making polyurethane plastics. It is a chiral epoxide, although it is commonly used as a racemic mixture.

<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.

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">Bromoform</span> Chemical compound

Bromoform is an organic compound with the chemical formula CHBr3. It is a colorless liquid at room temperature, with a high refractive index and a very high density. Its sweet odor is similar to that of chloroform. It is one of the four haloforms, the others being fluoroform, chloroform, and iodoform. It is a brominated organic solvent. Currently its main use is as a laboratory reagent. It is very slightly soluble in water and is miscible with alcohol, benzene, chloroform, ether, petroleum ether, acetone and oils.

<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">Maleic anhydride</span> Chemical compound

Maleic anhydride is an organic compound with the formula C2H2(CO)2O. It is the acid anhydride of maleic acid. It is a colorless or white solid with an acrid odor. It is produced industrially on a large scale for applications in coatings and polymers.

<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.

<i>sec</i>-Butyl acetate Chemical compound

sec-Butyl acetate, or s-butyl acetate, is an ester commonly used as a solvent in lacquers and enamels, where it is used in the production of acyclic polymers, vinyl resins, and nitrocellulose. It is a clear flammable liquid with a sweet smell.

<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 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).
  6. ↑ "Patent Watch, July 31, 2006". Archived from the original on March 11, 2007. Retrieved August 8, 2006.
  7. ↑ Bipin V. Vora; Joseph A. Kocal; Paul T. Barger; Robert J. Schmidt; James A. Johnson (2003). "Alkylation". Kirk-Othmer Encyclopedia of Chemical Technology. doi:10.1002/0471238961.0112112508011313.a01.pub2. ISBN   0471238961.
  8. ↑ Kenneth S. Whiteley. "Polyethylene". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a21_487.pub2. ISBN   978-3527306732.
  9. ↑ Rietveld, Will (2005-02-08). "Frequently Asked Questions About Lightweight Canister Stoves and Fuels" . Backpacking Light (subscription required). Retrieved 2022-06-03.
  10. ↑ "Technical Meeting on HCFC Phase-Out: Overview of Advantages and Disadvantages of Alternatives (Montreal, Canada; European Commission on retrofit refrigerants for stationary applications)" (PDF). April 2008. Archived (PDF) from the original on 2009-08-05. Retrieved 2021-05-21.
  11. ↑ "GreenFreeze". Greenpeace. 2010-03-15. Archived from the original on 2010-10-05. Retrieved 2013-01-02.
  12. ↑ Wolfgang Lohbeck (June 2004). "Greenfreeze: from a snowball to an industrial avalanche" (PDF). Retrieved 2021-05-21.
  13. ↑ "U.S. EPA hydrocarbon-refrigerants FAQ". Epa.gov. Retrieved 2010-10-29.
  14. ↑ "Compendium of hydrocarbon-refrigerant policy statements, October 2006" (PDF). Archived from the original (PDF) on 2014-08-08. Retrieved 2014-08-01.
  15. ↑ "MACS bulletin: hydrocarbon refrigerant usage in vehicles" (PDF). Archived from the original (PDF) on 2011-01-05. Retrieved 2010-10-29.
  16. ↑ "Society of Automotive Engineers hydrocarbon refrigerant bulletin". Sae.org. 2005-04-27. Archived from the original on 2005-05-05. Retrieved 2010-10-29.
  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.
  20. ↑ "New South Wales (Australia) Parliamentary record, 16 October 1997". Parliament.nsw.gov.au. 1997-10-16. Archived from the original on 1 July 2009. Retrieved 2010-10-29.
  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. ↑ 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
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