Carbon tetraiodide is a tetrahalomethane with the molecular formula . Being bright red, it is a relatively rare example of a highly colored methane derivative. It is only 2.3% by weight carbon, although other methane derivatives are known with still less carbon.
Structure
The tetrahedral molecule features C–I distances of 2.12 ± 0.02 Å.
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)).
It has zero dipole moment due to its symmetrically substituted Tetrahedron geometry.
Properties, synthesis, and uses
Carbon tetraiodide is slightly reactive towards water, giving
iodoform and I
2. It is soluble in nonpolar organic solvents. It decomposes thermally and photochemically to , C
2I
4. Its synthesis entails AlCl
3-catalyzed halide exchange, which is conducted at room temperature:
The product crystallizes from the reaction solution.
Carbon tetraiodide is used as an iodination reagent, often upon reaction with bases.
Safety considerations
Manufacturers recommend that carbon tetraiodide be stored near . As a ready source of iodine, it is an irritant. Its LD
50 on
is 18 mg/kg. In general, organic compounds should be considered toxic, with the narrow exception of small perfluoroalkanes (essentially inert due to the strength of the C–F bond).
Further reading
