In this work, copper(II) Schiff base complex immobilized on functionalized mesoporous silica MCM-41 as a heterogeneous catalyst, MCM-41-pr-NH2-CuL, was successfully used to oxidize a range of sulfides with 30% hydrogen peroxide under ultrasonic irradiation. The influence of different parameters namely solvent, catalyst amount, and kind of oxidant was investigated in order to find suitable reaction conditions. The obtained results demonstrated that this catalytic system was capable of catalyzing the selective oxidation of different sulfides to sulfones with 30% H2O2 under ultrasonic irradiation. The related sulfones were acquired in good to excellent yields (67–98%) in this system. Furthermore, the results indicated that this work could be appropriate for chemo-selective oxidation of sulfides to sulfones in the presence of other functional groups. Simple filtration recovered this catalyst, and no significant loss in its catalytic activity and selectivity was observed after using for five times. Also, no critical alteration was recognized in the FT-IR spectrum of the recovered catalyst after using five times.
Financial support for this work by the Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran is acknowledged. The corresponding author also thanks Prof. Majid Moghadam from University of Isfahan, and Prof. Reza Ranjbar-Karimi and Dr. Masoud Karimipour from Vali-e-Asr University of Rafsanjan for their helping hand.
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