4,6-Dibromodibenzofuran can be prepared by reacting bromine with dibenzofuran.
A mixture of 128 g bromine and 100 ml dichloroethane was added dropwise to a mixture of 67.3 g (0.4 mol) dibenzofuran and 500 ml dichloroethane. The mixture was stirred at room temperature for 10 hours. The precipitated solid was filtered off, and the filtrate was washed with an aqueous sodium thiosulfate solution and then with water. Dichloroethane was distilled off from the dichloroethane layer. The filtered solid was precipitated in an aqueous sodium thiosulfate solution and washed with water. The filtrates were combined, and chloroform was distilled off, giving the residue and solid. The residue and solid were recrystallized from isopropanol/toluene to give 101.7 g of colorless needle-like crystals of 4,6-dibromodibenzofuran.
