PURPOSE: The bromination of diphenyls is conducted by using bromine chloride as a brominating agent, and 2 kinds of catalysts in a halogen-containing saturated hydrocarbon solvent to produce polybrominated diphenyls with reduced by-products in a short time.
CONSTITUTION: In the bromination of diphenyls of formulaI(A is alkylene, halogenated alkylene, -0-, -SO2-, -S-, -CO-, -NH-, or direct bonding) in a solvent of halogen-containing saturated aliphatic hydrocarbon with 4 or less carbon atoms containing chlorine or bromine such as carbon tetrachloride, it is conducted by using bromine chloride in the presence of an iron catalyst such as ferric chloride until 2 or more bromine atoms are introduced into one mole of the diphenyl. Then a catalyst of aluminum such as aluminum trichloride is admixed and the bromination is continued in the presence of combined catalysts of iron and aluminum to produce the objective compound of formula II (n is 6W10) such as decabromodiphenyl ether.
USE: Flame retarders for synthetic resin and fibers.
GOTOU ISAO
IKEMURA MASAAKI
