Diazotization-bromination of aromatic amines using polymer-supported bromide via Sandmeyer-type reaction

A simple, efficient, and mild method for diazotization-bromination of arylamines using poly(4-vinylpyridine)-supported ethyl bromide is reported. Various aromatic amines, with electron-withdrawing groups as well as electron-donating groups, were transformed into aryl diazonium salts in good yields. On the other hand cross-linked poly (4-vinylpyridine) supported ethyl bromide, [P₄-VP]Et-Br, was easily prepared and then was applied for synthesis of arylbromide. When [P₄-VP]Et-Br in the presence of copper bromide treated with arenediazonium tetrafluoroborate by nucleophilic displacement of Br- by N₂ and the nitrogen gas (N₂) was evolved. The arylbromide products were characterized by Fourier transform infrared (FT-IR), and some of them were also characterized by proton nuclear magnetic resonance (¹H NMR) spectroscopy, and the physical properties were compared to the literature values of known compounds. The advantages of the present method over conventional classical methods are rapid and very simple work-up. The spent polymeric reagents can also be regenerated for several cycles with a little loss of its activity.