Sustainable vanadium(V)-catalyzed oxybromination of styrene: Two-phase system versus ionic liquids*
Valeria Conte, Barbara Floris, Pierluca Galloni, and Adriano Silvagni
Dipartimento di Scienze e Tecnologie Chimiche, Università di Roma "Tor Vergata", via della Ricerca Scientifica, 00133 Roma, Italy
Abstract: Oxybromination reaction of styrene was performed in a two-phase system of water/ionic liquids (ILs). The aim of the work was to make the mild and efficient two-phase system previously developed for the vanadium(V)-catalyzed oxybromination of alkenes, inspired by the activity of haloperoxidase enzymes, even more interesting from a sustainable point of view. As in that case, a brominating intermediate was formed from the metal catalyst, H2O2, and bromide ion in the acid aqueous phase, but chlorinated solvents were replaced with ILs.
[bmim+][PF6-], [bm2im+][PF6-], [bmim+][BF4-], [bmim+][CF3SO3-], and [bmim+][(CF3SO2)2N-] were tested. We report on interesting results in terms of reaction rates and selectivities.
Keywords: Vanadium; hydrogen peroxide; oxidation; ionic liquids; styrene; oxybromination.
*Paper based on a presentation at the 4th International Symposium on Chemistry and Biological Chemistry of Vanadium, 3-5 September 2004, Szeged, Hungary. Other presentations are published in this issue, pp. 1497-1640.