Carbon tetraiodide

Summary

Carbon tetraiodide
Stereo, skeletal formula of carbon tetraiodide
Carbon tetraiodide crystals and solution.jpg
Ball and stick model of carbon tetraiodide
Spacefill model of carbon tetraiodide
Names
Preferred IUPAC name
Tetraiodomethane[1]
Identifiers
  • 507-25-5 checkY
3D model (JSmol)
  • Interactive image
1733108
ChemSpider
  • 10055 checkY
ECHA InfoCard 100.007.335 Edit this at Wikidata
EC Number
  • 208-068-5
  • 10487
RTECS number
  • FG4960000
UNII
  • E22GNX36ZQ checkY
  • DTXSID0060145 Edit this at Wikidata
  • InChI=1S/CI4/c2-1(3,4)5 checkY
    Key: JOHCVVJGGSABQY-UHFFFAOYSA-N checkY
  • IC(I)(I)I
Properties
CI4
Molar mass 519.629 g·mol−1
Appearance Dark violet crystals
Density 4.32 g mL−1
-136·10−6 cm3/mol
Structure
Tetragonal
Tetrahedral
0 D
Thermochemistry
0.500 J K−1 g−1
384.0–400.4 kJ mol−1
−794.4–−778.4 kJ mol−1
Hazards
GHS pictograms GHS07: Exclamation mark
GHS Signal word Warning
H315, H319, H335
P261, P305+P351+P338
Related compounds
Other anions
Carbon tetrafluoride
Carbon tetrachloride
Carbon tetrabromide
Other cations
Silicon tetraiodide
Germanium tetraiodide
Tin(IV) iodide
Related alkanes
Related compounds
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

Carbon tetraiodide is a tetrahalomethane with the molecular formula CI4. 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.[citation needed]

Structure

The tetrahedral molecule features C-I distances of 2.12 ± 0.02 Å.[2] The molecule is slightly crowded with short contacts between iodine atoms of 3.459 ± 0.03 Å, and possibly for this reason, it is thermally and photochemically unstable.

Carbon tetraiodide crystallizes in tetragonal crystal structure (a 6.409, c 9.558 (.10−1 nm)).[3]

It has zero dipole moment due to its symmetrically substituted tetrahedral molecule.

Properties, synthesis, uses

Carbon tetraiodide is slightly reactive towards water, giving iodoform and I2. It is soluble in nonpolar organic solvents. It decomposes thermally and photochemically to tetraiodoethylene, C2I4. Its synthesis entails AlCl3-catalyzed halide exchange, which is conducted at room temperature:[4]

The product crystallizes from the reaction solution.

Carbon tetraiodide is used as an iodination reagent, often upon reaction with bases.[5] Ketones are converted to 1,1-diiodoalkenes upon treatment with triphenylphosphine (PPh3) and carbon tetraiodide. 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 alkyl chlorides from alcohols.

Safety considerations

Manufacturers recommend that carbon tetraiodide be stored near 0 °C (32 °F). As a ready source of iodine, it is an irritant. Its LD50 is 178 mg.kg−1. In general, perhalogenated organic compounds should be considered toxic, with the narrow exception of small perfluoroalkanes (essentially inert due to the strength of the C-F bond).

References

  1. ^ "Tetraiodomethane - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 27 March 2005. Identification and Related Records. Retrieved 29 February 2012.
  2. ^ Finbak, Chr.; Hassel, O. (1937). "Kristallstruktur und Molekülbau von CI4 und CBr4". Zeitschrift für Physikalische Chemie. B36: 301–308. doi:10.1515/zpch-1937-3621.
  3. ^ Pohl, S. (1982). "Die Kristallstruktur von CI4". Zeitschrift für Kristallographie. 159: 211–216. doi:10.1524/zkri.1982.159.14.211.
  4. ^ McArthur, R. E.; Simons, J. H. (1950). "Carbon Tetraiodide". Inorganic Syntheses. III: 37–39. doi:10.1002/9780470132340.ch8.
  5. ^ P. R. Schreiner, A. A. Fokin (2005). "Carbon Tetraiodide". In L. Paquette (ed.). Encyclopedia of Reagents for Organic Synthesis. John Wiley & Sons, Ltd.

Further reading

  • Sorros H., Hinkam J. B. (1945). "The Redistribution Reaction. XI. Application to the Preparation of Carbon Tetraiodide and Related Halides". Journal of the American Chemical Society. 67: 1643. doi:10.1021/ja01226a004.