Aluminium iodide

Chembox new
Name = Aluminum iodide
ImageFile = Aluminium-iodide-3D-balls.png ImageName = Aluminium iodide
OtherNames = Aluminium(III) iodide
Aluminum triiodide
Section1 = Chembox Identifiers
CASNo = 7784-23-8
Section2 = Chembox Properties
Formula = AlI₃
MolarMass = 407.695
Appearance = colorless powder
but impure samples
are often brown
Density = 3.98 g/cm³, solid
MeltingPt = 191 °C
BoilingPt = 360 °C

Aluminium iodide is any chemical compound containing only aluminium and iodine. Invariably, the name refers to a compound of the composition AlI₃, formed by the reaction of aluminium and iodine [G. W. Watt, J. L. Hall "Aluminum Iodide" Inorganic Syntheses, 1953, Volume IV, pages 117-119] or the action of HI on Al metal. As for the related chloride and bromide, AlI₃ is a strong Lewis acid and should be protected from the atmosphere.

Applications in organic synthesis

Aluminium iodide is employed to break certain kinds of C-O and N-O bonds. It cleaves aryl ethers and deoxygenates epoxides. [M. Gugelchuk "Aluminum Iodide" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI: 10.1002/047084289.]

Aluminium(I) iodide

The name "aluminium iodide" is widely assumed to describe the triiodide or its dimer. In fact, a monoiodide also enjoys a role in the Al-I system, although composition AlI is unstable at room temperature with respect to the triiodide [“Aluminum(I) and Gallium(I) Compounds: Syntheses, Structures, and Reactions” Dohmeier, C.; Loos, D.; Schnöckel, H. Angewandte Chemie International Edition in English (1996) Volume 35, Pages 129 - 149.] :6 AlI → Al₂I₆ + 4 AlAn illustrative derivative of aluminium monoiodide is the cyclic adduct formed with triethylamine, AI₄I₄(NEt₃)₄.

afety

Hydrolysis of aluminium triiodide will release some HI, which is corrosive. Lewis acids are skin irritants.

References