Some common halogen-based catalysts include: - Chlorinated Catalysts: Widely used in industrial processes, such as the production of vinyl chloride and ethyl chloride. - Fluorinated Catalysts: Often employed in the pharmaceutical industry for the synthesis of complex organic molecules. - Brominated Catalysts: Utilized in bromination reactions and in the preparation of flame retardants. - Iodine-based Catalysts: Known for their use in the hydroiodination of alkenes and alkynes.