2,2-Dimethylbutane

Chemical compound From Wikipedia, the free encyclopedia

2,2-Dimethylbutane, trivially known as neohexane at William Odling's 1876 suggestion,[4] 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.

Quick facts Names, Identifiers ...
2,2-Dimethylbutane
Stereo, skeletal formula of 2,2-dimethylbutane with some implicit hydrogens shown
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[1]
Other names
Neohexane,[2] 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

Butlerov's student V. Goryainov originally discovered neohexane in 1872 by cross-coupling of zinc ethyl with tert-butyl iodide.[5]

2,2-Dimethylbutane can be synthesised by the hydroisomerisation of 2,3-dimethylbutane using an acid catalyst.[6]

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.[7][8][9]

Uses

Neohexane is used as a high-octane anti-knock additive in gasoline and in the manufacture of agricultural chemicals.[10] It is also used in a number of commercial, automobile and home maintenance products, such as adhesives, electronic contact cleaners and upholstery polish sprays.[11]

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.[12]

See also

References

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