Efficient preparation of Zr(IV)-salen grafted mesoporous MCM-41 catalyst for chemoselective oxidation of sulfides to sulfoxides and Knoevenagel condensation reactions

Zr(IV)-salen-MCM-41 was prepared by reaction of NH2-MCM-41 with salicylaldehyde to afford Schiff base ligands. Thereafter, ZrOCl2·8H2O was reacted with the Schiff base ligands for complex formation. The structural properties of the synthesized materials were investigated by a number of analytical techniques including X-ray diffraction, N2 sorption-desorption, thermogravimetric analysis, Fourier transform infrared spectroscopy, inductively coupled plasma atomic emission spectroscpopy, and energy dispersive X-ray spectroscopy. Catalytic studies of the mesoporous materials functionalized with Zr(IV)-Schiff base complexes were investigated and extended to selective oxidation of sulfides to sulfoxides and the Knoevenagel condensation reactions of aldehydes with malononitriles and ethyl cyanoacetate. Additionally, catalyst recycling of the Zr-salen-MCM-41 materials was also studied.

Graphical AbstractZirconium-imine-MCM-41 catalyst was prepared by reaction of NH2-MCM-41 with salicylaldehyde to afford the Schiff base ligands. Then zirconyl chloride octahydate was added to Schiff base ligands for complex formation. This Zr(IV)-Schiff base mesoporous material can be used as a solid acid catalyst for the selective oxidation of sulfides to sulfoxides and Knoveonagel condensation reaction of aldehydes.Figure optionsDownload as PowerPoint slide