Use of Sodium Bromate for Aromatic Bromination:  Research and Development

Abstract

Sodium bromate is a powerful brominating agent for aromatic compounds that contain deactivating substituents. A bromination process, in which sodium bromate was utilized, was optimized on laboratory scale. Addition of a strong acid into a stirred aqueous solution, or slurry, of the substrate and bromate salt at 40-100°C, leads to the decomposition of the bromate ions and production of the active brominating species. Substrates such as nitrobenzene, benzoic acid, and benzaldehyde were brominated in high yields (85-98%) and specificity. The reaction is especially useful for the bromination of disubstituted benzenes, such as 4-nitrofluorobenzene or 4-fluorobenzoic acid. Several substrates, such as dinitrobenzenes or nitrobenzoic acids, did not undergo bromination at all. The main parameters of the reaction and some of its synthetic potential are discussed.

Vanadium-Catalysed Oxidative Bromination Using Dilute Mineral Acids and Hydrogen Peroxide: An Option for Recycling Waste Acid Streams

“…22 As a result of the low cost and high productivity of molecular bromine, the MBr/acid/H 2 O 2 option will be economically viable only if bromine transportation costs become prohibitive, or if in-plant bromide and acid waste can be utilised. The latter option is increasingly relevant, as the chemical industry moves towards waste minimisation and zero-emission plants.…”

On oxyhalogenation, acids, and non-mimics of bromoperoxidase enzymes

“…Examples of such processes include: (i) oxidative bromination using alkali metal bromates, which facilitate the reaction of deactivated aromatics (e.g. PhNO 2 or PhCHO which react only sluggishly with molecular bromine); 15 (ii) in situ recycling of HBr waste from Br 2 brominations; (iii) oxybromination using alkali metal bromide salts with concurrent recycling of other acid waste; and (iv) possibly certain enzymatic reactions. Note that current ex situ HBr recycling technology cannot compete with bromine on a simple cost basis.…”

Sono-bromination of aromatic compounds based on the ultrasonic advanced oxidation processes

“…The most conventional brominating agent remains topically Br 2 , although it is hazardous and difficult in handling together with poor atom efficiency. A large panel of brominating reagents have been thus developed, including molecular bromine with or without catalysts [6][7][8][9], N-bromosuccinimide (NBS) [10-13], 1,3-dibromodimethylhydantoin (DBDMH) [13,14], N,N-dibromo-p-toluenesulfonamide (TsNBr 2 ) [15], KBrO 3 [16], or quaternary ammonium tribromide [17][18][19], etc. All of the aforementioned reagents are used in stoichiometry amount, more or less efficient, expensive, toxic, not commercially available and lead to large amounts of wastes at the end of the reaction.…”