Carbon tetraiodide
From Wikipedia, the free encyclopedia
| Carbon tetraiodide | |
|---|---|
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| General | |
| Systematic name | Carbon tetraiodide |
| Other names | Tetraiodomethane |
| Molecular formula | CI4 |
| SMILES | IC(I)(I)I |
| Molar mass | 519.63 g/mol |
| Appearance | red crystals |
| CAS number | [507-25-5] |
| Properties | |
| Density and phase | 4.32 g/cm3 solid |
| Solubility in water | insoluble |
| Other solvents | non-polar organic solvents |
| Melting point | 171 °C with decomposition |
| Structure | |
| Molecular shape | tetrahedral |
| Crystal structure | monoclinic |
| Dipole moment | 0 D |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | skin irritant |
| NFPA 704 | |
| R/S statement | R: 36/37/38 S: 26-36 |
| RTECS number | FG4960000 |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Related compounds | CCl4 CHI3 |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Carbon tetraiodide is CI4, a tetrahalomethane. Being bright red, it is a relatively rare example of a highly colored methane derivative. It is only 2% by weight carbon, although other methane derivatives are known with still less carbon. The tetrahedral molecule features C-I distances of 2.12 ± 0.02 Å. [1] The molecule is slightly crowded with short I---I contacts of 3.459 ± 0.03 Å, and possibly for this reason, it is thermally and photochemically unstable. Hexaiodoethane is unknown, probably for the same reason.
Contents |
[edit] Properties, synthesis, uses
CI4 is slightly reactive towards water, giving iodoform and I2. Otherwise it is soluble in nonpolar organic solvents. It decomposes thermally and photochemically to tetraiodoethylene, I2C=CI2. Its synthesis entails AlCl3-catalyzed halide exchange, which is conducted at room temperature:[2]
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- CCl4 + 4 EtI → CI4 + 4 EtCl
The product crystallizes from the reaction solution.
CI4 is used as an iodination reagent, often upon reaction with base. [3] Ketones are converted to 1,1-diiodoethenes upon treatment with PPh3 and CI4. Alcohols are converted in and to iodide, by a mechanism similar to the Appel reaction. In an Appel reaction carbon tetrachloride is used to generate the chloride from alcohols.
[edit] Safety considerations
Manufacturers recommend that CI4 be stored near 0 °C. As a ready source of iodine, it is an irritant. LD50: 178 mg kg–1. In general perhalogenated organic compounds should be considered toxic.
[edit] References
- ^ Finbak, Chr.; Hassel, O. Kristallstruktur und Molekülbau von CI4 und CBr4" Zeitschrifte für Physikalische Chemie (1937), volume B36, page 301-8
- ^ McArthur, R. E.; Simons, J. H., “Carbon Tetraiodide” Inorganic Syntheses 1950, volume III, 37–39
- ^ P. R. Schreiner, A. A. Fokin, “Carbon Tetraiodide” in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2005; John Wiley & Sons, Ltd
[edit] Further reading
Sorros, H., Hinkam J. B. , “The Redistribution Reaction. XI. Application to the Preparation of Carbon Tetraiodide and Related Halides” Journal of the American Chemical Society 1945, 67, 1643. DOI.
