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Skeletal formula of tetramethylbutane
Spacefill model of tetramethylbutane
IUPAC name
3D model (Jmol)
ECHA InfoCard 100.008.961
EC Number 209-855-6
UN number 1325
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
2.9 nmol Pa−1 kg−1
232.2 J K−1 mol−1 (at 2.8 °C)
273.76 J K−1 mol−1
−270.3 – −267.9 kJ mol−1
−5.4526 – −5.4504 MJ mol−1
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 otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
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; in fact, it is the smallest saturated acyclic hydrocarbon that appears as a solid at a room temperature of 25 °C. (Among cyclic hydrocarbons, cubane, C8H8 is even smaller and is also solid at room temperature.)

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.