Iron(III) bromide is the

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

with the formula FeBr₃. Also known as ferric bromide, this red-brown odorless compound is used as a

Lewis acid A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...

catalyst Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

in the halogenation of

aromatic compounds Aromatic compounds, also known as "mono- and polycyclic aromatic hydrocarbons", are organic compounds containing one or more aromatic rings. The parent member of aromatic compounds is benzene. The word "aromatic" originates from the past groupin ...

. It dissolves in water to give acidic solutions.

Structure, synthesis and basic properties

FeBr₃ forms a polymeric structure featuring six-coordinate,

octahedral In geometry, an octahedron (plural: octahedra, octahedrons) is a polyhedron with eight faces. The term is most commonly used to refer to the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet a ...

Fe centers.Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. . Although inexpensively available commercially, FeBr₃ can be prepared by treatment of iron metal with

bromine Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table (halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simila ...

: :2 Fe + 3 Br₂ → 2 FeBr₃ Above 200 °C, FeBr₃ decomposes to

ferrous bromide Iron(II) bromide is an inorganic compound with the chemical formula FeBr2. The anhydrous compound is a yellow or brownish-colored paramagnetic solid. Several hydrates of FeBr2 are also known, all being pale colored solids. It is a common precur ...

: :2FeBr₃ → 2FeBr₂ + Br₂ Iron(III) chloride is considerably more stable, reflecting the greater oxidizing power of

chlorine Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate betwee ...

. FeI₃ is not stable, as iron(III) will oxidize iodide ions.

Uses

Ferric bromide is occasionally used as an oxidant in

organic chemistry Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; ...

, e.g. for the conversion of

alcohols In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl () functional group bound to a saturated carbon atom. The term ''alcohol'' originally referred to the primary alcohol ethanol (ethyl alcohol), which is ...

to ketones. It is used as a

ic catalyst for bromination of aromatic compounds. For the latter applications, it is often generated in situ.

References

{{bromine compounds Iron(III) compounds Bromides Metal halides

Structure, synthesis and basic properties

Uses

See also

References