Synthesis, Structures, Application And Mimicking Catalytic Oxidative Bromination Of Oxiovanadium-N-heterocyclic Complexes

Nowadays, aromatic compounds containing bromine are of great importance in all kindsof fields, such as Pesticide, Pharmacy, Dye and so on. In the areas of industry produce,electrophilic substitution has always been used as bromine oxidation method of aromaticcompounds, but the method has a lot of deficiencies, for one thing, a mass of bromine hasbeen turned into the by-product HBr which is severely corrosive in the reaction, it makes alower utilization rate of the bromine and a serious waste of the raw material; for another,some metal particles or metal bromine like belong to Lewis acid are absolutely necessary ascatalysts in the reaction. However, the method will produce large amounts of industrial waste,result in post-processing difficult issues and pollution of the environment. After then,researchers have developed a method called in situ bromated oxidation, namely, using theoxidant to oxidate HBr in the process, thus, the oxidation production Br2can go onparticipating the reaction as the material. The method referred above can only be achievedwhen both the oxidant and the catalyzers exist, H2O2is added into the reaction systembecause it has an advantage over the other oxidants, for its free of contamination, no residueof substances left and environmentally friendly condition. The vanadium complexes arechoosen as the catalysts of the reaction, because the vanadium is the essential element for thecenter of the haloperoxidases. As we all know, the natural enzymes get denaturalized andinactivated easily, so it’s important that vanadium complexes mimicking the natural enzymecatalyze brominated oxidation reaction. Searching for model vanadium complexes structuraland functional is still a hot point at present.Spatial configuration of the active center of the vanadium haloperoxidases (V-HPOs)guides the direction for our work of synthesizing model complexes. In the synthesis of themodel vanadium complexes, we mainly mimic the coordination environment of the activecenter of vanadium(V) haloperoxidases with N,O of the ligands, and the hydrogen bondinteraction with solvent molecules and active center.In this paper, some N-heterocycle ligands are choosen, we synthesized9modelcomplexes in total(their molecular formulas are listed below), which are determined by theX-ray single crystal diffraction, characterized by elemental analysis, IR spectra, UV-Visspectroscopy, thermal analysis and powder XRD diffraction. In addition, these complexes were studied their bromination catalytic activity, and the influence factors of brominationcatalytic activity were further investigated.