Hexaiodobenzene is an aryl iodide and a six-substituted iodobenzene with the formula C6I6. Structurally, it is a derivative of benzene, in which all hydrogen atoms are replaced by iodine atoms. It forms orange crystals[1] that are poorly soluble in all solvents. It adopts the expected structure with a central C6 ring.[3]
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| Names | |
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| Preferred IUPAC name
Hexaiodobenzene | |
| Other names
Periodobenzene
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.009.246 |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| C6I6 | |
| Molar mass | 833.493 g·mol−1 |
| Appearance | orange crystals[1] |
| Density | 4.60 g/cm3 |
| Melting point | 430 °C (806 °F; 703 K)[1] |
| insoluble | |
| Structure[2] | |
| monoclinic | |
| P21/c, No. 14 | |
a = 8.87 Å, b = 4.29 Å, c = 16.28 Å α = 90°, β = 93°, γ = 90°
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| Related compounds | |
Related compounds
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Hexafluorobenzene Hexachlorobenzene Hexabromobenzene |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Preparation
editThe compound was first prepared by iodination of benzoic acid in the presence of hot fuming sulfuric acid.[4] Another method of synthesis is the reaction between benzene with periodic acid and potassium iodide in sulfuric acid at 100 °C. This method instead produces 1,2,4,5-tetraiodobenzene if done at room temperature.[5]
Properties
editPhysical properties
editHexaiodobenzene forms orange needles that are practically insoluble in water, but sparingly soluble in N-methyl-2-pyrrolidone and dimethyl sulfoxide. It melts at 430 °C, but also already begins to show some decomposition at 370 °C, forming I2.[1]
Crystallographic properties
editThe crystals are monoclinic and pseudohexagonal, with centrosymmetric C6I6 units. The carbon atoms lie in a plane with C–C distances about 141 pm, while the nearby iodine atoms show very small displacements (about 4 pm) above and below the ring. The shortest intermolecular distance, 376 pm, is notably short compared to twice the Van der Waals radius, which is 430 pm.[2] The structure is retained at high pressures up to 9.7 GPa.[6]
References
edit- ^ a b c d Mattern, Daniell Lewis (1983). "Periodination of benzene with periodate/Iodide". The Journal of Organic Chemistry. 48 (24): 4772–4773. doi:10.1021/jo00172a063.
- ^ a b Steer, Rosemary J.; Watkins, S. F.; Woodward, P. (1970). "Crystal and molecular structure of hexaiodobenzene". Journal of the Chemical Society C: Organic (2): 403. doi:10.1039/j39700000403. ISSN 0022-4952.
- ^ Ghosh, Sandip; Reddy, C. Malla; Desiraju, Gautam R. "Hexaiodobenzene: a redetermination at 100 K", Acta Crystallographica, Section E: Structure Reports Online, 2007, 63(2), o910–o911 (doi:10.1107/S1600536807002279).
- ^ Erwin Rupp "Ueber die perhalogenirten Phtalsäuren und das Hexajodbenzol", Chem. Ber., 1896, Volume 29, pp. 1625–1634 (doi:10.1002/cber.18960290293).
- ^ Mattern, Daniell Lewis (1983). "Periodination of benzene with periodate/iodide". The Journal of Organic Chemistry. 48 (24): 4772–4773. doi:10.1021/jo00172a063. ISSN 0022-3263.
- ^ Nakayama, Atsuko; Fujihisa, Hiroshi; Aoki, Katsutoshi; Carlón, Raquel Pérez (2000-10-01). "Structural study of hexaiodobenzene up to 9.7 GPa". Physical Review B. 62 (13): 8759–8765. doi:10.1103/PhysRevB.62.8759. ISSN 0163-1829.