Process for brominating unsaturated organic compounds with removal of quaternary ammonium or quaternary phosphonium monochlorides

A process comprising

• a) contacting an unsaturated compound containing aliphatic carbon-carbon double bonds with a quaternary ammonium tribromide or a quaternary phosphonium tribromide in the presence of at least one solvent for the unsaturated compound under conditions such that the unsaturated compound becomes brominated and, as a by-product, (1) a mixture of a quaternary ammonium monobromide salt and a quaternary ammonium monochloride salt or (2) a mixture of a quaternary phosphonium monobromide salt and a quaternary phosphonium monochloride salt is formed,
• b) separating the quaternary ammonium monochloride salt or quaternary phosphonium monochloride salt from the brominated unsaturated compound, then
• c) contacting a solution of said separated quaternary ammonium or quaternary phosphonium monochloride salt with a source of bromide ions under conditions that at least a portion of the quaternary ammonium or quaternary phosphonium monochloride salt reacts with said source of bromide ions to regenerate a quaternary ammonium monobromide salt or quaternary phosphonium monobromide salt and a chloride by-product;
• d) contacting the regenerated quaternary ammonium monobromide salt or regenerated quaternary phosphonium monobromide salt with bromine to form the corresponding quaternary ammonium tribromide or quaternary phosphonium tribromide;
• and then
• e) before, during or after step d), separating the chloride by-product from the regenerated quaternary ammonium or quaternary phosphonium monobromide salt or quaternary ammonium or quaternary phosphonium tribromide and then
• f) recycling quaternary ammonium tribromide or quaternary phosphonium tribromide obtained in step d) back into step a).