Hexaphenylbenzene

Hexaphenylbenzene is an aromatic compound composed of a benzene ring substituted with six phenyl rings. It is a colorless solid. The compound is the parent member of a wider class of hexaarylbenzenes, which are mainly of theoretical interest.[2]

Hexaphenylbenzene
Names
IUPAC name
1,2,3,4,5,6-hexa(phenyl)benzene
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.012.356
Properties
C42H30
Molar mass 534.702 g·mol−1
Appearance white solid
Melting point 454 to 456 °C (849 to 853 °F; 727 to 729 K)[1]
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

Preparation

It is prepared by heating tetraphenylcyclopentadienone and diphenylacetylene in benzophenone or other high-temperature solvent. The reaction proceeds via a Diels-Alder reaction to give the hexaphenyldienone, which then eliminates carbon monoxide.[1]

Together with 1,2,3,4-tetraphenylnaphthalene, hexaphenylbenzene forms by the chromium-catalyzed oligomerization of diphenylacetylene.[3]

Structure
Perspective view of the crystal structure of hexaphenylbenzene, showing the rotation of the phenyl rings. Hydrogen atoms have been omitted for clarity.[4]

The stable conformation of this molecule has the phenyl rings rotated out of the plane of the central benzene ring. The molecule adopts a propeller-like conformation in which the phenyl rings are rotated about 65°,[4] while in the gas phase, they are perpendicular with some slight oscillations.[5]

References
  1. Louis Fieser (1966). "Hexaphenylbenzene". Organic Syntheses. 46: 44. doi:10.15227/orgsyn.046.0044.
  2. Varun Vij, Vandana Bhalla, and Manoj Kumar (2016). "Hexaarylbenzene: Evolution of Properties and Applications of Multitalented Scaffold". Chemical Reviews. 116 (16): 9565–9627. doi:10.1021/acs.chemrev.6b00144. PMID 27498592.CS1 maint: multiple names: authors list (link)
  3. W. Herwig, W. Metlesics, H. Zeiss (1959). "π-Complexes of the Transition Metals. X. Acetylenic π-Complexes of Chromium in Organic Synthesis". J. Am. Chem. Soc. 81 (23): 6203–6207. doi:10.1021/ja01532a024.CS1 maint: multiple names: authors list (link)
  4. Bart, J. C. J. (1968). "The crystal structure of a modification of hexaphenylbenzene" (PDF). Acta Crystallographica Section B. 24 (10): 1277–1287. doi:10.1107/S0567740868004176.
  5. Gust, D. (1977). "Restricted Rotation in Hexaarylbenzenes". J. Am. Chem. Soc. 99 (21): 6980–6982. doi:10.1021/ja00463a034.
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