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2,2-Dimethylbutane

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2,2-Dimethylbutane
Stereo, skeletal formula of 2,2-dimethylbutane with some implicit hydrogens shown
Neohexane molecule
Ball stick model of 2,2-dimethylbutane
Neohexane molecule
Spacefill model of 2,2-dimethylbutane
Names
Preferred IUPAC name 2,2-Dimethylbutane
Other names Neohexane, 22DMB
Identifiers
CAS Number
3D model (JSmol)
Beilstein Reference 1730736
ChEMBL
ChemSpider
ECHA InfoCard 100.000.825 Edit this at Wikidata
EC Number
  • 200-906-8
PubChem CID
RTECS number
  • EJ9300000
UNII
UN number 1208
CompTox Dashboard (EPA)
InChI
  • InChI=1S/C6H14/c1-5-6(2,3)4/h5H2,1-4H3Key: HNRMPXKDFBEGFZ-UHFFFAOYSA-N
SMILES
  • CCC(C)(C)C
Properties
Chemical formula C6H14
Molar mass 86.178 g·mol
Appearance Colorless liquid
Odor Odorless
Density 649 mg mL
Melting point −102 to −98 °C; −152 to −145 °F; 171 to 175 K
Boiling point 49.7 to 49.9 °C; 121.4 to 121.7 °F; 322.8 to 323.0 K
log P 3.51
Vapor pressure 36.88 kPa (at 20 °C)
Henry's law
constant (kH) 		6.5 nmol Pa kg
Magnetic susceptibility (χ) -76.24·10 cm/mol
Refractive index (nD) 1.369
Thermochemistry
Heat capacity (C) 189.67 J K mol
Std molar
entropy (S298) 		272.00 J K mol
Std enthalpy of
formation (ΔfH298) 		−214.4–−212.4 kJ mol
Std enthalpy of
combustion (ΔcH298) 		−4.1494–−4.1476 MJ mol
Hazards
GHS labelling:
Pictograms GHS02: Flammable GHS07: Exclamation mark GHS08: Health hazard GHS09: Environmental hazard
Signal word Danger
Hazard statements H225, H304, H315, H336, H411
Precautionary statements P210, P261, P273, P301+P310, P331
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g. gasolineInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1 3 0
Flash point −29 °C (−20 °F; 244 K)
Autoignition
temperature 		425 °C (797 °F; 698 K)
Explosive limits 1.2–7.7%
NIOSH (US health exposure limits):
PEL (Permissible) none
Related compounds
Related alkanes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). ☒N verify (what is  ?) Infobox references
Chemical compound

2,2-Dimethylbutane, trivially known as neohexane at William Odling's 1876 suggestion, is an organic compound with formula C6H14 or (H3C-)3-C-CH2-CH3. It is therefore an alkane, indeed the most compact and branched of the hexane isomers — the only one with a quaternary carbon and a butane (C4) backbone.

Synthesis

Butlerov's student V. Goryainov originally discovered neohexane in 1872 by cross-coupling of zinc ethyl with tert-butyl iodide.

2,2-Dimethylbutane can be synthesised by the hydroisomerisation of 2,3-dimethylbutane using an acid catalyst.

It can also be synthesised by isomerization of n-pentane in the presence of a catalyst containing combinations of one or more of palladium, platinum, rhodium and rhenium on a matrix of zeolite, alumina, silicon dioxide or other materials. Such reactions create a mixture of final products including isopentane, n-hexane, 3-methylpentane, 2-methylpentane, 2,3-dimethylbutane and 2,2-dimethylbutane. Since the composition of the final mixture is temperature dependant the desired final component can be obtained choice of catalyst and by combinations of temperature control and distillations.

Uses

Neohexane is used as a high-octane anti-knock additive in gasoline and in the manufacture of agricultural chemicals. It is also used in a number of commercial, automobile and home maintenance products, such as adhesives, electronic contact cleaners and upholstery polish sprays.

In laboratory settings, it is commonly used as a probe molecule in techniques which study the active sites of metal catalysts. Such catalysts are used in hydrogen-deuterium exchange, hydrogenolysis, and isomerization reactions. It is well suited to this purpose as 2,2-dimethylbutane contains both an isobutyl and an ethyl group.

See also

References

  1. Haynes, William M. (2010). Handbook of Chemistry and Physics (91 ed.). Boca Raton, Florida, USA: CRC Press. p. 3-194. ISBN 978-1-43982077-3.
  2. "2,2-DIMETHYLBUTANE - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification and Related Records. Retrieved 9 March 2012.
  3. NIOSH Pocket Guide to Chemical Hazards. "#0323". National Institute for Occupational Safety and Health (NIOSH).
  4. Philosophical Magazine. Taylor & Francis. 1876.
  5. Журнал Русского физико-химического общества (in Russian). Тип-ія Б. Демакова. 1872.
  6. "2,2-dimethylbutane". National Center for Biotechnology Information. 18 July 2015. Retrieved 20 July 2015.
  7. Rabo, J. A.; Pickert, P. E.; Mays, R. L. (1961). "Pentane and Hexane Isomerization". Industrial & Engineering Chemistry. 53 (9). American Chemical Society (ACS): 733–736. doi:10.1021/ie50621a029. ISSN 0019-7866.
  8. Den Hartog, A. J.; Rek, P. J. M.; Botman, M. J. P.; De Vreugd, C.; Ponec, V. (1988). "Reactions of 2,2-dimethylbutane on platinum-rhenium/alumina catalysts. Effect of sulfur and chlorine on the selectivity". Langmuir. 4 (5). American Chemical Society (ACS): 1100–1103. doi:10.1021/la00083a006. ISSN 0743-7463.
  9. Brown, Ronald; Kemball, Charles; McDougall, Gordon S. (1995). "Exchange reactions of 2,2-dimethylpentane, 2,2-dimethylbutane and 2,2-dimethylpropane over Pt/SiO2 and Rh/SiO2". Journal of the Chemical Society, Faraday Transactions. 91 (7). Royal Society of Chemistry (RSC): 1131. doi:10.1039/ft9959101131. ISSN 0956-5000.
  10. "Hazardous Substance Fact Sheet - 2,2-Dimethylbutane" (PDF). New Jersey Department of Health. June 2008. Retrieved 2 July 2021.
  11. "2,2-Dimethylbutane". Consumer Products Information Database. 2021. Retrieved 2 July 2021.
  12. Burch, R.; Paál, Z. (1994). "The use of 2,2-dimethylbutane (neohexane) as a probe molecule of metal catalysts". Applied Catalysis A: General. 114 (1). Elsevier BV: 9–33. doi:10.1016/0926-860x(94)85106-9. ISSN 0926-860X.
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