Polymer-anchored peroxo compounds of molybdenum and tungsten as efficient and versatile catalysts for mild oxidative bromination

A polymer supported peroxomolybdate(VI) compound of the type [MoO2(O2)(CN)2]–PAN [PAN = poly(acrylonitrile)] (PANMo) was obtained by reacting H2MoO4 with 30% H2O2 and the macromolecular ligand, PAN at near neutral pH. The macrocomplex has been characterized by elemental analysis (CHN and EDX analysis), spectral (IR, UV–Vis and 13C NMR, 95Mo NMR), thermal (TGA-DTG) as well as SEM studies. The catalytic activity of PANMo and its previously reported tungsten containing analog PANW, in oxidative bromination of organic substrates has been explored. The supported complexes could serve as efficient heterogeneous catalysts for the oxidative bromination of a variety of structurally diverse aromatic compounds, with H2O2 as terminal oxidant, to afford bromo organics in impressive yields under environmentally clean conditions. The catalysts afforded regeneration and could be reused for a minimum of six reaction cycles.

Graphical abstractThe synthesis of a new polymer anchored Mo(VI) complex has been achieved by incorporating pMo species into poly(acrylonitrile) matrix. The immobilized pMo compound and its W(VI) containing analogue served as efficient heterogeneous catalyst in oxidative bromination of a variety of activated aromatics with H2O2 as terminal oxidant, under mild reaction conditions. The catalysts afforded regeneration and could be reused for at least six reaction cycles.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A new poly(acrylonitrile) (PAN) supported pMo(VI) complex has been synthesized. ► The PAN supported pMo and pW compounds efficiently catalyze oxidative bromination. ► Oxidative bromination of activated aromatics proceed under mild reaction conditions. ► The catalysts afforded regeneration.