Synthesis of mixed halogenated dibenzofurans (X = Cl, Br)

The reaction of dibenzofuran with CuCl2×2 H2O and CuBr2 gives rise to polyhalogenated dibenzofurans. Chlorination of mono- to tetrabromo-dibenzofurans produces a mixture of polychlorinated, polybrominated, and mixed halogenated dibenzofurans. This mixture can be used as a “windows defining mixture”.