Aluminium iodide, with the chemical formula AlI3, is a chemical compound composed of aluminium (Al) and iodine (I). It is an ionic compound and belongs to the group of metal halides.

Aluminium iodide is a solid compound that is typically encountered as a white or off-white powder. It is highly reactive and hygroscopic, meaning it readily absorbs moisture from the air.

Some key properties and uses of aluminium iodide include:

1. Lewis Acid: Aluminium iodide is a Lewis acid, which means it can accept electron pairs during chemical reactions. It is used as a catalyst in various organic transformations, including Friedel-Crafts reactions and other chemical processes.
2. Chemical Synthesis: Aluminium iodide is employed in the preparation of certain organic compounds in chemical synthesis.
3. Research and Laboratory Applications: Aluminium iodide finds applications in research and laboratory settings, particularly in organic chemistry and as a catalyst for specific reactions.

As with other metal halides, aluminium iodide requires proper handling and storage to avoid exposure to moisture, as it can readily react with water or water-containing substances. It is essential to take appropriate safety precautions when working with aluminium iodide due to its reactivity and potential hazards.

Aluminium iodide’s significance lies mainly in its role as a Lewis acid catalyst and its use in certain chemical reactions. It is not a commonly encountered compound outside of specialized research or industrial applications in the field of organic chemistry.