Process for separation of bromine from gaseous hydrogen bromide and use of such process in production of decabromodiphenylethane

A process of producing a decabromodiphenylethane product, which process comprises:

• 1) passing a feed of a gaseous mixture of hydrogen bromide and bromine into a mixture having a liquid phase, which mixture having a liquid phase is formed from components comprising (i) diphenylethane and/or partially brominated diphenylethane having an average bromine number less than about 2 and (ii) a catalytic quantity of iron and/or at least one iron halide in which the halogen atoms as initially charged are bromine atoms and/or chlorine atoms, wherein the mixture having a liquid phase is at one or more temperatures at which (i) is in the liquid state, whereby (i) is brominated so that the amount of bromine in said gaseous mixture is decreased, and a reaction mixture comprising partially brominated diphenylethane having an average bromine number less than about 4 and iron catalyst residues is formed;
• 2) feeding at least a portion of said reaction mixture formed in 1) and optionally diphenylethane to a mixture comprising excess liquid bromine, and a Lewis acid bromination catalyst composed of aluminum and/or aluminum halide in which the halogen atoms in the form initially charged are bromine atoms and/or chlorine atoms to produce a bromination reaction mixture comprising a decabromodiphenylethane product, molecular bromine, aluminum catalyst and aluminum catalyst residues, and iron catalyst residues, and to produce as a coproduct, a gaseous mixture of hydrogen bromide and molecular bromine;
• 3) deactivating said aluminum catalyst and removing aluminum catalyst residues and iron catalyst residues from said bromination reaction mixture formed in 2), and recovering decabromodiphenylethane product;
• and
• 4) utilizing coproduct gaseous mixture of hydrogen bromide containing molecular bromine as feed in 1).

A process of producing a decabromodiphenylethane product which process comprises:

• I) brominating a feed of (A) partially brominated diphenylethane having an average bromine number less than about 4, (B) a mixture of (A) and diphenylethane, or (C) diphenylethane, the bromination being effected with excess bromine in the presence of a Lewis acid bromination catalyst to produce a decabromodiphenylethane product and wherein a gaseous mixture of hydrogen bromide coproduct containing free molecular bromine is formed;
• II) passing at least a portion of said gaseous mixture into a liquid mixture formed from components comprising (i) diphenylethane and/or partially brominated diphenylethane having an average bromine number less than about 2 and (ii) a catalytic quantity of an iron-based catalyst which, as initially charged, is iron and/or at least one iron halide in which the halogen atoms are bromine atoms and/or chlorine atoms, the liquid mixture being at a temperature at which (i) is in the liquid state, whereby (i) is brominated to form a reaction mixture comprising partially brominated diphenylethane having an average bromine number of less than about 4 and iron catalyst residues, and the bromine content of said gaseous mixture is reduced or eliminated;
• III) removing iron catalyst residues from reaction mixture formed in II);
• and
• IV) utilizing as (A) in I), at least a portion of reaction mixture of III) from which iron catalyst residues have been removed in III).