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Skeletal formula of tetramethylbutane
Spacefill model of tetramethylbutane
CAS number 594-82-1 YesY
PubChem 11675
ChemSpider 11185 N
EC number 209-855-6
UN number 1325
Jmol-3D images Image 1
Molecular formula C8H18
Molar mass 114.23 g mol−1
Appearance White, opaque, waxy crystals
Odor Odorless
Melting point 98 to 104 °C; 208 to 219 °F; 371 to 377 K
Boiling point 106.0 to 107.0 °C; 222.7 to 224.5 °F; 379.1 to 380.1 K
kH 2.9 nmol Pa−1 kg−1
heat capacity
232.2 J K−1 mol−1 (at 2.8 °C)
Std molar
273.76 J K−1 mol−1
Std enthalpy of
−270.3 – −267.9 kJ mol−1
Std enthalpy of
−5.4526 – −5.4504 MJ mol−1
EU Index 601-009-00-8
EU classification Highly Flammable F Harmful Xn Dangerous for the Environment (Nature) N
R-phrases R11, R38, R65, R67, R50/53
S-phrases (S2), S16, S29, S33
Flash point 4 °C (39 °F; 277 K)
Explosive limits 1–?%
Related compounds
Related alkanes
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Tetramethylbutane, sometimes called hexamethylethane, is a hydrocarbon with formula C8H18 or (H3C-)3C-C(-CH3)3. It is the most heavily branched and most compact of the many octane isomers, the only one with a butane (C4) backbone. Because of its highly symmetrical structure, it has a very high melting point and a short liquid range.

The compound can be obtained by reaction of Grignard reagent tert-butylmagnesium bromide with ethyl bromide, or of ethylmagnesium bromide with tert-butyl bromide in the presence of manganese(II) ions.[2] This transformation is believed to go through the dimerization of two tert-butyl radicals, which are generated by decomposition of the organomanganese compounds generated in situ.

The full IUPAC name of the compound is 2,2,3,3-tetramethylbutane, but the numbers are superfluous in this case because there is no other possible arrangement of "tetramethylbutane".


  1. ^ "Hexamethylethane - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification and Related Information. Retrieved 11 March 2012. 
  2. ^ M. S. KHARASCH, J. W. HANCOCK, W. NUDENBERG, P. O. TAWNEY (1956). "Factors Influencing the Course and Mechanism of Grignard Reactions. XXII. The Reaction of Grignard Reagents with Alkyl Halides and Ketones in the Presence of Manganous Salts". Journal of Organic Chemistry 21 (3): 322–327. doi:10.1021/jo01109a016.