Tetrahalophthalic anhydride process

摘要

This invention relates to an improvement in a process for preparing tetrabromophthalic anhydride whereby there is a substantial recovery of reactants such as halogen and SO3 from a vent stream exiting the reaction vessel. The improvement comprises contacting the vent stream with a fluid having a first oleum concentration and recovering a halogen stream and a second stream, having a second oleum concentration wherein the second oleum concentration is greater than the first oleum concentration.