Chemistry:2,2-Dimethylbutane

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2,2-Dimethylbutane
Stereo, skeletal formula of 2,2-dimethylbutane with some implicit hydrogens shown
Neohexane molecule
Neohexane molecule
Names
Preferred IUPAC name
2,2-Dimethylbutane[2]
Other names
Neohexane,[1] 22DMB
Identifiers
3D model (JSmol)
1730736
ChEMBL
ChemSpider
EC Number
  • 200-906-8
RTECS number
  • EJ9300000
UNII
UN number 1208
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 pictograms GHS02: Flammable GHS07: Harmful GHS08: Health hazard GHS09: Environmental hazard
GHS Signal word DANGER
H225, H304, H315, H336, H411
P210, P261, P273, P301+310, P331
NFPA 704 (fire diamond)
Flammability code 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. gasolineHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
3
1
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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Infobox references
Tracking categories (test):

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.

Synthesis

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

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

References

  1. Haynes, William M. (2010). Handbook of Chemistry and Physics (91 ed.). Boca Raton, Florida: CRC Press. p. 3-194. ISBN 978-1439820773. 
  2. "2,2-DIMETHYLBUTANE - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification and Related Records. https://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=6403&loc=ec_rcs. Retrieved 9 March 2012. 
  3. NIOSH Pocket Guide to Chemical Hazards. "#0323". National Institute for Occupational Safety and Health (NIOSH). https://www.cdc.gov/niosh/npg/npgd0323.html. 
  4. "2,2-dimethylbutane". 18 July 2015. https://pubchem.ncbi.nlm.nih.gov/compound/6403. Retrieved 20 July 2015. 
  5. Rabo, J. A.; Pickert, P. E.; Mays, R. L. (1961). "Pentane and Hexane Isomerization". Industrial & Engineering Chemistry (American Chemical Society (ACS)) 53 (9): 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 (American Chemical Society (ACS)) 4 (5): 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 (Royal Society of Chemistry (RSC)) 91 (7): 1131. doi:10.1039/ft9959101131. ISSN 0956-5000. 
  8. "Hazardous Substance Fact Sheet - 2,2-Dimethylbutane". June 2008. https://nj.gov/health/eoh/rtkweb/documents/fs/1335.pdf. 
  9. "2,2-Dimethylbutane" (in en). 2021. https://www.whatsinproducts.com/chemicals/view/1/548/000075-83-2. 
  10. Burch, R.; Paál, Z. (1994). "The use of 2,2-dimethylbutane (neohexane) as a probe molecule of metal catalysts". Applied Catalysis A: General (Elsevier BV) 114 (1): 9–33. doi:10.1016/0926-860x(94)85106-9. ISSN 0926-860X.