Starch-coated maghemite nanoparticles functionalized by a novel cobalt Schiff base complex catalyzes selective aerobic benzylic C–H oxidation

Abstract

The CoL2@SMNP nanocatalyst catalyzed heterogeneous aerobic oxidation of benzylic C–H bonds of saturated hydrocarbons and alcohols to the related carbonyl compounds.

Silica iminopyridine‐functionalized nanomaghemite enhances the oxygenation activity and durability of simple Co(II) salophen complex

“…The FT‐IR spectrum of the SIPy Schiff base ligand (Figure S1) and Co(II) salophen (Figure S2) are given in Supporting information. Peaks at 1027 and 1125 cm −1 are assigned to the stretching vibrations of the Si‐O bond at the SIPy structure . The band at 1660 cm −1 in Figure S2 is characteristic of the C=N bond of SIPy confirming formation of anchoring Schiff base ligand .…”

“…Peaks at 1027 and 1125 cm −1 are assigned to the stretching vibrations of the Si‐O bond at the SIPy structure . The band at 1660 cm −1 in Figure S2 is characteristic of the C=N bond of SIPy confirming formation of anchoring Schiff base ligand . The peak at the 2950 cm −1 is attributed to the stretching vibrations of the aliphatic C‐H of propyl group.…”

Magnetically separable chicken feathers: a biopolymer based heterogeneous catalyst for the oxidation of organic substrates

“…However, limited efficiency, requirement of basic additives, difficult separation of catalysts and poor product yields are certain drawbacks. 26 Thus, considering the economy and environmental friendliness, it is highly desirable to develop less expensive, easily separable, reusable non-noble heterogeneous catalysts, particularly, based on bio-derived materials under base-free conditions using green oxidants and green media (e.g., water) as the solvent. In this context, several biodegradable supports such as chitosan 27 , wool, 28 cellulose, 29 and starch 30 have been reported.…”

N-Hydroxyphthalimide Immobilized on Poly(HEA-co-DVB) as Catalyst for Aerobic Oxidation Processes

“…Examples of heterogeneous NHPI catalysts include NHPI immobilized on silica gel by physical interaction [19], NHPI immobilized by chemical bonds on silica gel [20,21], polystyrene [22], copolymer microspheres of glycidyl and methyl methacrylate (GMA/MMA) [23] or glycidoxypropyl-SBA-15 [24] and NHPI incorporated into metal organic framework [25][26][27][28][29]. On the other hand, silica supported cobalt(II) [30,31], cobalt and manganese supported hexagonal mesoporous silicas [32] or cobalt Shiff base complex anchored on starch-coated magnetic nanoparticles [33] were also examined in the presence of homogeneous NHPI. The activity of these catalytic systems was demonstrated in aerobic oxidations of cyclohexane and other cyclic hydrocarbons [19,25,[27][28][29]32], toluenes [20][21][22]24], ethylbenzenes [23,25,30,31,33], styrenes [26] as well as other alkyl aromatic compounds [29,31,33] and benzylic alcohols [33].…”

“…On the other hand, silica supported cobalt(II) [30,31], cobalt and manganese supported hexagonal mesoporous silicas [32] or cobalt Shiff base complex anchored on starch-coated magnetic nanoparticles [33] were also examined in the presence of homogeneous NHPI. The activity of these catalytic systems was demonstrated in aerobic oxidations of cyclohexane and other cyclic hydrocarbons [19,25,[27][28][29]32], toluenes [20][21][22]24], ethylbenzenes [23,25,30,31,33], styrenes [26] as well as other alkyl aromatic compounds [29,31,33] and benzylic alcohols [33]. For example, when toluene was oxidized with oxygen in the presence of both NHPI and Co(II) chemically bonded to silica gel in AcOH as solvent, conversion of 18 % was achieved (100 °C, 0.1 MPa, 20 h) [20].…”