Preparation
Iron(III) bromide is prepared by the action of bromine with iron filings:
2Fe + 3Br2 → 2FeBr3
The compound should be stored in dark bottles protected from air or light. It also may be obtained by double decompostion reactions between a ferric salt and a bromide (alkali metal bromide) in aqueous solution followed by evaporation and crystallization:
Fe2(SO4)3 + LiBr → 2FeBr3 + 3Li2SO4
It also may be prepared in high yield by photochemical reaction of dibromoirontetracarbonyl with bromine in hexane (Yoon, K.B. and J.K. Kochi.
1990. Inorg. Chem. 29, pp. 869):
(CO)4FeBr2 + ½ Br2 → FeBr3 + 4CO
Chemical Properties
Brown-red crystalline powder
Physical properties
Dark red hexagonal crystal; hygroscopic; partially decomposes to FeBr
2,losing some bromine on exposure to air or light; density 4.50 g/cm3; decomposes on heating; soluble in water, ethanol, and ether.
Uses
Iron(III) bromide is used as a Lewis acid catalyst in the halogenation of aromatic compounds. It is also used in the preparation of 2,5-dibromo-4-aryl-1,3-pentadiene by reacting with homoallenic bromohydrin.
Uses
Catalyst for organic reactions, particularly in bromination of aromatic Compounds.
General Description
This product has been enhanced for catalytic efficiency.
Purification Methods
Sublime it in a sealed tube with Br2 at 120o-200o. [Lux in Handbook of Preparative Inorganic Chemistry (Ed.Brauer) Academic Press Vol II p 1494 1965.]
