Hexamethylbenzene
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Preferred IUPAC name
Hexamethylbenzene
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| Other names
1,2,3,4,5,6-Hexamethylbenzene
Mellitene |
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3D model (JSmol)
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| ECHA InfoCard | 100.001.616 | ||
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PubChem CID
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| Properties | |||
| C12H18 | |||
| Molar mass | 162.28 g·mol−1 | ||
| Appearance | White crystalline powder | ||
| Density | 1.0630 g cm−3 | ||
| Melting point | 165.6 ± 0.7 °C | ||
| Boiling point | 265.2 °C (509.4 °F; 538.3 K) | ||
| insoluble | |||
| Solubility | acetic acid, acetone, benzene, chloroform, diethyl ether, ethanol | ||
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is   ?) |
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| Infobox references | |||
Hexamethylbenzene, also known as mellitene, is a hydrocarbon with the molecular formula C12H18 and the condensed structural formula C6(CH3)6. It is an aromatic compound and a derivative of benzene where its six hydrogen atoms have been replaced with six methyl groups. In 1929 Kathleen Lonsdale reported the crystal structure of hexamethylbenzene, demonstrating that the central ring is hexagonal and flat and thereby ending an ongoing debate about the physical parameters of the benzene system. This was a historically significant result, both for the field of X-ray crystallography and for understanding aromaticity.
The compound can be prepared by reacting phenol with methanol at elevated temperatures over a suitable solid catalyst such as alumina. The mechanism of the process has been studied extensively, with several intermediates having been identified.Alkyne trimerisation of dimethylacetylene also yields hexamethylbenzene in the presence of a suitable catalyst. Hexamethylbenzene can be oxidised to mellitic acid, which is found in nature as its aluminium salt in the rare mineral mellite. Hexamethylbenzene can be used as a ligand in organometallic compounds. An example from organoruthenium chemistry shows structural change in the ligand associated with changes in the oxidation state of the metal centre, though the same change is not observed in the analogous organoiron system.
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