Synthesis of novel immobilized tridentate Schiff base dioxomolybdenum(VI) complexes as efficient and reusable catalysts for epoxidation of unfunctionalized olefins

A series of tridentate Schiff base dioxomolybdenum(VI) complexes have been immobilized onto modified synergistic organic–inorganic hybrid support chloromethyl-ZPS-PVPA [zirconium poly (styrene-phenylvinylphosphonate)-phosphate] to prepare a new type of heterogeneous catalyst. The as-synthesized catalysts exhibited good to excellent catalytic efficiency in epoxidation of unfunctionalized olefins, using tert-butyl hydroperoxide (TBHP) as oxidant. Surprisingly, up to 99% ee values were obtained when α-methylstyrene was chosen as substrate in this oxidant system with these heterogeneous catalysts. Furthermore, the immobilized catalyst showed a stable catalytic activity in manifold reuses.

Graphical abstractNew types of immobilized tridentate Schiff base dioxomolybdenum(VI) complexes onto organic–inorganic hybrid support were prepared and exhibited excellent activity for olefins epoxidation reaction. These promising heterogeneous catalysts are of higher stability and reusability, which can be reused ten times, retaining a large part of the activity of the fresh catalyst.Figure optionsDownload full-size imageDownload high-quality image (12 K)Download as PowerPoint slide