FeBr3

Iron tribromide, FeBr3, is an inorganic compound known as iron(III) bromide. It is a moisture-sensitive, reddish-brown crystalline solid that is typically prepared by direct combination of iron and bromine at elevated temperature: 2 Fe + 3 Br2 → 2 FeBr3.

FeBr3 is highly reactive with water and air moisture. In the presence of water, it rapidly hydrolyzes to form iron(III) hydroxide and hydrobromic acid: FeBr3 + 3 H2O → Fe(OH)3 + 3 HBr. Because of this reactivity, it is usually handled under strictly anhydrous conditions and stored in a desiccator or inert atmosphere. In nonaqueous media, it can act as a Lewis acid, forming adducts with bases and coordinating solvents such as THF or acetonitrile.

In organic chemistry, FeBr3 is valued as a Lewis acid catalyst for electrophilic bromination and related transformations. It can activate bromine toward arenes and other substrates, enabling selective bromination under suitable conditions. The compound is often used when catalytic amounts of FeBr3 are sufficient to promote a reaction, though its strong moisture sensitivity limits some practical applications.

Safety and handling considerations include its corrosivity and irritant nature. FeBr3 should be stored away from moisture, incompatible materials, and strong reducing agents. Appropriate personal protective equipment and ventilation are required when handling this compound. It is not typically encountered as a naturally occurring material and is prepared specifically for laboratory use.