Synthesis and characterization of Ni and Zn Schiff base complexes supported on modified MCM-41 as reusable catalysts for various oxidation reactions

Abstract

Using post grafting method, two hybrids composite materials were prepared by anchoring Nickel and Zinc Schiff base complexes onto amino-modified MCM-41(Ni-MCM-41 and Zn-MCM-41). The prepared catalysts have been characterized by FT-IR spectroscopy, thermogravimetric analysis, and transmission electron microscopy, powder X-ray diffraction and N 2 adsorptiondesorption isotherms. The catalysts showed excellent catalytic efficiency in oxidation reaction of sulfides to sulfoxides and oxidative coupling of thiols to their corresponding disulfides using urea hydrogen peroxide as oxidant under mild reaction conditions. The supported Schiff base complexes can be recovered easily and reused many times without significant loss in catalytic activity and selectivity.

Investigation of a Ni-Modified MCM-41 Catalyst for the Reduction of Oxygenates and Carbon Deposits during the Co-Pyrolysis of Cellulose and Polypropylene

“…These are features of a highly ordered mesoporous zeolite structure with a hexagonal array of pores. 20 , 34 − 36 Figure 1 a shows the small-angle X-ray powder diffraction data for the five catalysts. It can be seen that no shifts in the SAXRD peaks were observed, but with the introduction of Ni, the intensity decreased slightly, indicating that the addition of Ni did not affect the ordered structure of the MCM-41 support; however, the crystallinity of MCM-41 was slightly reduced.…”

Functionalized MCM‐41: Versatile Catalysts for Organic Transformations

“…Similarly, Nikoorazm et al used a variety of metal-Schiff base complexes like Cu(II), [103] Ni or Cd(II) [104] or V(IV)O [105] or Co(II) or Fe(II) [106] or Ni(II)/Zn(II) [107] complexes anchored on MCM-41, for the same reaction (Figures 41b & c), by employing urea hydrogen peroxide as the oxidizing agent. In another report, Nikoorazm et al [108] used VO anchored on the Schiff base complex of vanillin-MCM-41[VO-vanillin-MCM-41], as a hybrid catalyst and hydrogen peroxide as an oxidant for the same transformation (Figure 41d).…”

“…[119] Functionalized MCM-41 may be useful in overcoming these shortcomings. Several research groups have reported the controlled oxidation of sulfides to sulfoxides, by employing functionalized MCM-41 [103][104][105][106][107][108][119][120][121][122][123] catalysts. The advantages of catalytic systems include easy operation, higher stability, chemoselective oxidation (100 %) and no overoxidation.…”

Functionalized Ordered Mesoporous Silicas (MCM-41): Synthesis and Applications in Catalysis

“…These catalysts exhibited good selectivity and catalytic activity in the oxidation of sulfides to sulfoxides and oxidative coupling of thiols to their corresponding disulfides using urea hydrogen peroxide (UHP) as oxidant at room temperature. The authors highlighted the absence of over-oxidation of sulfides and thiols to sulfoxides and sulfones, respectively [50] (Figure 36). A similar system was prepared by Rangappan et al [51] by condensation of 3-aminopropyltrimethoxysilane with o-hydroxyacetophenone and exposure to Cu(CH 3 COO) 2 •H 2 O to form a complex, which mimics the "CuN 2 O 2 " coordination site that resembles the galactose oxidase enzyme.…”