- Carbon tetraiodide
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ImageFile1 = Carbon-tetraiodide-2D.png
ImageFileL1 = Carbon-tetraiodide-3D-balls.png
ImageFileR1 = Carbon-tetraiodide-3D-vdW.png
IUPACName = Tetraiodomethane Carbon tetraiodide
OtherNames = Carbon iodide
Section1 = Chembox Identifiers
CASNo = 507-25-5
EINECS = 208-068-5
PubChem = 10487
SMILES = C(I)(I)(I)I
InChI = 1/CI4/c2-1(3,4)5
RTECS = FG4960000
Section2 = Chembox Properties
Formula = CI4
MolarMass = 519.63 g/mol
Appearance = Red crystals
Density = 4.32 g/cm3
MeltingPt = 171 °C (444 K) decomp.
BoilingPt =
Solubility = Insoluble
Section3 = Chembox Structure
CrystalStruct = Monoclinic
Coordination =
MolShape = Tetrahedral
Section4 = Chembox Hazards
EUClass = Irritant (Xi)
RPhrases = R36/37/38
SPhrases = S26, S36
MainHazards =
FlashPt =
Autoignition =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 othermethane derivatives are known with still less carbon.The tetrahedral molecule features C-I distances of 2.12 ± 0.02 Å. [Finbak, Chr.; Hassel, O. "Kristallstruktur und Molekülbau von CI4 und CBr4" Zeitschrift für Physikalische Chemie (1937), volume B36, page 301-8] 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.
Carbon tetraiodide crystallizes in
monoclinic crystal structure ("a" 22.39, "b" 12.93, "c" 25.85 (.10-1 nm), "β" 125.26°).It has dipole moment of 0
Debye s due to its symmetrically substituted tetrahedral molecule.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: [McArthur, R. E.; Simons, J. H., “Carbon Tetraiodide” Inorganic Syntheses 1950, volume III, 37–39]::CCl4 + 4 EtI → CI4 + 4 EtClThe product crystallizes from the reaction solution.
CI4 is used as an iodination reagent, often upon reaction with base. [P. R. Schreiner, A. A. Fokin, “Carbon Tetraiodide” in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2005; John Wiley & Sons, Ltd] 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 reactioncarbon tetrachloride is used to generate the chloride from alcohols.afety 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.
References
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. [http://dx.doi.org/10.1021/ja01226a004 DOI] .See also
*
Haloalkane
*Halomethane
*Iodomethane
*Diiodomethane
*Iodoform (Triiodomethane)
*Tetrafluoromethane
*Carbon tetrachloride (Tetrachloromethane)
*Tetrabromomethane
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