Wikipedia

2,2-Dimethylbutane

2,2-Dimethylbutane, trivially known as neohexane, 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.

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[2]
Other names
Neohexane,[1] 22DMB
Identifiers
3D model (JSmol)
1730736
ChEMBL
ChemSpider
ECHA InfoCard 100.000.825 Edit this at Wikidata
EC Number
  • 200-906-8
RTECS number
  • EJ9300000
UNII
UN number 1208
  • InChI=1S/C6H14/c1-5-6(2,3)4/h5H2,1-4H3 checkY
    Key: HNRMPXKDFBEGFZ-UHFFFAOYSA-N checkY
  • CCC(C)(C)C
Properties
C6H14
Molar mass 86.178 g·mol−1
Appearance Colorless liquid
Odor Odorless
Density 649 mg mL−1
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)
6.5 nmol Pa−1 kg−1
-76.24·10−6 cm3/mol
1.369
Thermochemistry
189.67 J K−1 mol−1
272.00 J K−1 mol−1
−214.4–−212.4 kJ mol−1
−4.1494–−4.1476 MJ mol−1
Hazards
GHS labelling:
GHS02: Flammable GHS07: Exclamation mark GHS08: Health hazard GHS09: Environmental hazard
Danger
H225, H304, H315, H336, H411
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)
425 °C (797 °F; 698 K)
Explosive limits 1.2–7.7%
NIOSH (US health exposure limits):
PEL (Permissible)
 none[3]
Related compounds
Related alkanes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Synthesis edit

2,2-Dimethylbutane can be synthesised by the hydroisomerisation of 2,3-dimethylbutane using an acid catalyst.[4]

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.[5][6][7]

Uses edit

Neohexane is used as an additive in fuels and in the manufacture of agricultural chemicals.[8] It is also used in a number of commercial, automobile and home maintenance products, such as adhesives, electronic contact cleaners and upholstery polish sprays.[9]

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.[10]

See also edit

References edit

  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. ^ "2,2-dimethylbutane". National Center for Biotechnology Information. 18 July 2015. Retrieved 20 July 2015.
  5. ^ 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.
  6. ^ 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.
  7. ^ 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.
  8. ^ "Hazardous Substance Fact Sheet - 2,2-Dimethylbutane" (PDF). New Jersey Department of Health. June 2008. Retrieved 2 July 2021.
  9. ^ "2,2-Dimethylbutane". Consumer Products Information Database. 2021. Retrieved 2 July 2021.
  10. ^ 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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