Mimicking the vanadium bromoperoxidases reactions:Mild and selective bromination of arenes and alkenes in a two-phase system

Abstract

Vanadium bromoperoxidases catalyze the oxidation of bromide ion by hydrogen peroxide to a bromine-equivalent intermediate. This, in turn, brominates organic molecules. The hypothesis is made that the former reaction takes place in the hydrophilic portion of the enzyme whereas the latter proceeds in a hydrophobic one in which the brominating intermediate is rapidly transferred. We have reproduced such situation by employing a two-phase (H 2O/CHCl 3) system. In the aqueous acid phase H 2O 2 and catalytic amounts of NH 4VO 3 are present, together with KBr. The substrates, i.e. aromatic hydrocarbons and alkenes are dissolved in CHCl 3. The bromination proceeds smoothly with stirring, at 25°C, providing high yields of the corresponding brominated products.