Efficient Heterogeneous Catalyst For Oxidation Research Articles

A Stable Polyoxometalate-Based Metal-Organic Framework as Highly Efficient Heterogeneous Catalyst for Oxidation of Alcohols.

A novel copper-containing 3D polyoxometalate-based metal-organic framework (POMOF), H[Cu5ΙCuΙΙ(pzc)2(pz)4.5{P2W18O62}]·6H2O (HENU-1, HENU = Henan University; Hpzc = pyrazine-2-carboxylic acid, pz = pyrazine), was successfully isolated by a one-step hydrothermal method. In this compound, the {P2W18} polyanion acts as a seven-connected linker bridging adjacent 2D double-layer networks, as well as a template to induce the formation of the desired 3D framework. Particularly, the pz ligands are generated from pzc ligands in situ during the reaction process. HENU-1 exhibits not only good stability in air but also tolerance to acidic and basic media. It was first employed as a highly efficient heterogeneous catalyst for the oxidation of 1-phenylethanol into acetophenone, which shows 97% yield using tert-butyl hydroperoxide as oxidant with a turnover frequency of up to 9690·h-1, and was reused for at least five cycles without significant catalytic activity loss. No POM leaching or framework decomposition was observed in our study.

Cu(CH3CN)4PF6 immobilized on halloysite as efficient heterogeneous catalyst for oxidation of allylic C–H bonds in olefins under mild reaction condition

Considering the importance of oxidation of allylic C–H bonds in olefins and the unresolved challenging issues, such as long reaction time and the large quantity of catalyst required, and encouraged by the excellent performance of halloysite as a catalyst support, a novel catalytic system was developed to promote this reaction efficiently. To prepare the catalyst, halloysite was first functionalized with ionic liquid then reacted with 2-aminopyrimidine to afford a potential support, Hal-P. The latter was then used for in situ immobilization of Cu(CH3CN)4PF6 and applied to promote the reaction of cycloolefin and tert-butyl p-nitrobenzoperoxoate under mild reaction condition. The results showed that the nature of copper could play an important role in the catalytic activity. Moreover, the presence of ionic liquid and 2-aminopyrimidine in the structure could improve the activity of the final catalyst. Notably, low amounts of catalyst could catalyze the reaction to afford corresponding allylic esters in good yield. It was also found that the reaction was size selective and that cyclic olefins with lower strain could undergo this reaction more effectively. Study of the recyclability of the catalyst confirmed that it was recyclable and could be recovered and recycled for five consecutive reaction runs.

Ru (III) Schiff base Complex Anchored onto Rice Husk Derived Nanosilica Support: An Efficient Heterogeneous Catalyst for Oxidation of Alcohols

A Rice Husk based nanosilica anchored Ru(III) Schiff-base complex was found to be a very efficient and reusable heterogeneous catalyst for organic transformation of alcohol to carbonyl compounds. The catalyst was obtained by simple Schiff-base condensation between 3-aminopropyltriethoxysilane (APTES) functionalized nanosilica and acetamide. The characterization of the catalyst was carried out by various techniques such as FT-IR, XRD, ESR, BET surface area measurements, SEM-EDX mapping and ICP-AES. The alcohol oxidation reactions were performed at 50οC using acetonitrile and TBHP as solvent and oxidant, respectively. The catalyst was found to be very effective towards alcohol oxidation with excellent product yield and reusable upto minimum 5th reaction cycle. Keywords: Alcohol oxidation, heterogeneous catalyst, nanosilica, Ru (III) schiff base, organic, solvent.

ChemInform Abstract: Rice Husk Derived Nanosilica Supported Cu(II) Complex: An Efficient Heterogeneous Catalyst for Oxidation of Alcohols Using TBHP.

AbstractVarious primary and secondary alcohols are oxidized using a novel heterogenized catalyst of Cu(II) complex immobilized onto nanosilica obtained from rice husk.

Gold Nanoparticles Supported on Magnesium Oxide Nanorods for Oxidation of Alcohols.

Gold nanoparticles supported on magnesium oxide nanorods (Au-MgO) have been synthesised by a solution based chemical reduction method. Au-MgO nanorods were found to be an efficient heterogeneous catalyst for oxidation of alcohols with hydrogen peroxide in aqueous medium at room temperature. To find out the best reaction conditions for oxidation, optimization of catalyst quantity, solvent, mole equivalence of hydrogen peroxide were carried out. The scope of the reaction was extended to several aromatic and aliphatic alcohols, product yields were quantified by gas chromatography (GC) and GC/mass spectroscopy. Heterogeneity and reusability tests were performed. The use of water as a solvent and hydrogen peroxide as co-catalyst at room temperature makes the reaction interesting from sustainable development point of view.

Ultrasound promoted preparation of Mn(III)-porphyrin nanoparticles: An efficient heterogeneous catalyst for oxidation of alkenes, alkanes and sulfides

In the present research meso-tetrakis(4-carboxyphenyl)porphyrinatomanganese(III) acetate (Mn(TCPP)OAc) nanoparticles have been prepared for the first time without any stabilizing agent or supporting matrix under ultrasonic irradiation. Scanning electron microscopy (SEM) was used to characterize and investigate the nanocatalyst. Rapid, efficient, facile and highly selective oxidation of a wide range of olefins by tetra-[Formula: see text]-butylammonium hydrogen monopersulfate over the prepared manganese nanocatalyst was investigated. Also oxidation of sulfides and alkanes in the presence of the (Mn(TCPP)OAc) nanoparticles were studied. The catalyst is recovered by filtration and reused at least five times.

Silver supported on hierarchically porous SiO2 and Co3O4 monoliths: Efficient heterogeneous catalyst for oxidation of cyclohexene

This study describes silver (Ag) nanoparticles supported on hierarchically porous SiO2 and Co3O4 monoliths and the use of these materials as heterogeneous catalysts for the oxidation of cyclohexene. Structural characterization of these materials was carried out by various techniques including scanning electron microscopy (SEM), N2 adsorption, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Characterization results revealed that Ag nanoparticles were incorporated into hierarchically porous SiO2 and Co3O4 without significantly affecting the structures of the supports. The oxidation of cyclohexene was investigated for hierarchically porous Ag/SiO2 and Ag/Co3O4 monoliths and powdered forms of the catalysts using H2O2 as oxidant. Detailed parameters including the effect of temperature, oxidant, catalyst loading, and substrate to oxidant ratio were thoroughly studied. The catalyst was found to be stable and could be reused several times without affecting its catalytic activity under the optimized reaction conditions.

Carbon nanofibers decorated with oxo–rhenium complexes: Highly efficient heterogeneous catalyst for oxidation of amines with hydrogen peroxide

Pyridine functionalized carbon nanofibers (Py-CNFs) were synthesized, characterized and used for the grafting of oxo–rhenium complex i.e., methyltrioxorhenium (MTO) via acid-base ionic interaction. The grafting of MTO to Py-CNFs was confirmed by FTIR, UV–vis, SEM, TEM and TGA analyses. The determination of rhenium content by ICP-AES further suggested the successful immobilization of MTO to the support. The developed heterogeneous material i.e., MTO@Py-CNFs was found to be an efficient catalyst for the oxidation of various secondary as well as tertiary amines to corresponding nitrones or N-oxides, respectively by using hydrogen peroxide. The developed catalyst was readily recovered by centrifugation and reused for subsequent ten runs without any significant loss in catalytic activity.

Rice husk derived nanosilica supported Cu(ii) complex: an efficient heterogeneous catalyst for oxidation of alcohols using TBHP

We have developed a heterogenized catalyst of Cu(ii) complex immobilized onto nanosilica obtained from rice husk (RH), through Schiff-base condensation between 3-aminopropyltriethoxysilane (APTES) functionalized nanosilica and acetamide.

Graphene oxide supported MnO2 nanorods: an efficient heterogeneous catalyst for oxidation of aromatic amines to azo-compounds

Graphene oxide supported MnO2 nanorods (GOnc), a composite material, has been synthesized and characterized by XRD, FE-SEM, EDX, BET surface area measurement, FTIR and Raman Spectroscopy.

A recyclable polymer anchored copper(II) catalyst for oxidation reaction of olefins and alcohols with tert-butylhydroperoxide in aqueous medium

Abstract A new reusable polymer anchored Cu(II) complex was synthesized which can acts as an efficient heterogeneous catalyst for oxidation of olefins and alcohols with tert -butylhydroperoxide (TBHP) in aqueous medium. The present catalyst well oxidized styrene and other olefins to their allylic products and alcohols were converted to their corresponding aldehydes in good-to-moderate yields. This catalyst can be easily recovered by filtration and recycled without significant loss of its catalytic performances.

Novel heterogeneous catalyst, supported undecamolybdophosphate: synthesis, physico-chemical characterization and solvent-free oxidation of styrene

A novel heterogeneous catalyst comprising undecamolybdophosphate and hydrous zirconia was synthesized, characterized by various physicochemical techniques and used as an efficient heterogeneous catalyst for oxidation of styrene using H(2)O(2) as an oxidant. The novelty of the present work lies in obtaining >99% conversion of styrene with >99% selectivity for benzaldehyde under solvent free mild reaction conditions.

Metalloporphyrins encapsulated mesoporous molecular sieves as efficient heterogeneous catalysts for oxidation of cyclohexene with iodosylbenzene

The cationic Fe, Mn or VO porphyrins were encapsulated in Si, Al, Ti and V-MCM-41. The catalytic activity was investigated for the oxidation of cyclohexene with iodosylbenzene (PhIO) as oxidant. Manganese porphyrin supported catalysts produces epoxide as major products whereas iron and vanadyl porphyrins gave allylic oxidation products as major constituents. The results obtained clearly shows that the selectivity of various products depends not only on the nature of the support materials but also on the combined effects of metalloporphyrins and the supports. The recyclability of the heterogeneous catalysts was also investigated. The decrease in catalytic activity and leaching of active centers were observed when porphyrins were supported on Si-MCM-41.

Sodium tungstate immobilized on plasma-treated PVDF membranes: New efficient heterogeneous catalyst for oxidation of secondary amines to nitrones

New heterogeneous oxidation catalysts have been obtained by immobilizing sodium tungstate (Na 2WO 4) on plasma-treated poly(vinyldene difluoride) (PVDF) membranes. This new generation of catalytically active membranes has been developed by coupling the advantages of low temperature plasma modification processes with surface chemical immobilization reactions of catalysts. Polymeric membranes with different thicknesses, morphologies and pore dimensions were prepared by a non-solvent induced phase inversion technique. Then the surface of the membranes have been surface modified with NH 3 radiofrequency glow discharges in order to graft active amino groups for immobilizing sodium tungstate in a stable way. The new catalytic membranes were successfully used for the oxidation of secondary amines to nitrones in a flat membrane reactor. A conversion to nitrone of 100% in less than 3 h (comparable to the homogeneous system) was achieved with the membrane having smallest pore diameter and finger like morphology.