Use of sodium bromate for aromatic bromination: Research and development

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