Recyclable Catalyst For Aerobic Oxidation Research Articles

Phenanthroline-functionalized MCM-41-immobilized copper(I) chloride complex: A highly active and recyclable catalyst for aerobic oxidation of alcohols

A new 1,10-phenanthroline-functionalized MCM-41-immobilized copper(I) complex [MCM-41-Phen-CuCl] was prepared from 1-(1,10-phenanthrolin-5-yl)-3-(3-(triethoxysilyl)propyl)urea via immobilization on MCM-41, followed by reacting with copper(I) chloride. It was found that this heterogenized copper(I) complex is a highly efficient catalyst for the oxidation of a wide variety of alcohols into aldehydes and ketones using molecular oxygen as the stoichiometric oxidant and 5 mol% of di-tert-butyl hydrazine-1,2-dicarboxylate (DBAD-H2) as additive, and can be recycled more than eight cycles with almost consistent activity.

Metal-functionalized carbon nanotubes for biomass conversion: base-free highly efficient and recyclable catalysts for aerobic oxidation of 5-hydroxymethylfurfural

A noble and non-noble metal-confined CNT-based catalytic system was developed for the base-free selective oxidation of 5-hydroxymethylfurfural to produce 2,5-furandicarboxylic acid and 2,5-diformylfurane.

Highly dispersed cobalt nanoparticles supported on a mesoporous Al2O3: An efficient and recyclable catalyst for aerobic oxidation of alcohols in aqueous media

In this paper the catalytic performance of a Co/Al2O3 nanocatalyst is investigated on aerobic oxidation of alcohols in a water media at reflux condition. The catalyst was synthesized via a co-precipitation method and characterized by XRD, BET surface area, atomic absorption spectroscopy, SEM, TEM and EDS analysis. The catalyst exhibited a high efficiency on the oxidation of various alcohols into their corresponding carbonyl compounds at relatively short reaction time. Also the results exhibit a consistant activity after several consecutive runs of reaction and regeneration that demonstrates the stability and recyclability of the Co/Al2O3 nanocatalyst.

Nitrite-containing resin as an efficient and recyclable catalyst for aerobic oxidation of oximes to carbonyl compounds

ABSTRACTUsing novel nitrite-containing resin as an NO source and Amberlyst-15 as cocatalyst, we developed aerobic oxidation of oximes to corresponding carbonyl compounds with molecular oxygen as a clean oxidant reagent. It was distinguished from the previous related reports, and the experimental results indicated that additional water obviously decreased the yield. This process provides a better choice for oxidative deoximation with many advantages, such as high yield, simple procedure, high catalytic performance, and recyclable catalyst.

Ultrafine MnO2 nanoparticles decorated on graphene oxide as a highly efficient and recyclable catalyst for aerobic oxidation of benzyl alcohol

The highly active and selective aerobic oxidation of aromatic alcohols over earth-abundant, inexpensive and recyclable catalysts is highly desirable. We fabricated herein MnO2/graphene oxide (GO) composites by a facile in-situ growth approach at room temperature and used them in selective aerobic oxidation of benzyl alcohol to benzaldehyde. TEM, XRD, FTIR, XPS and N2 adsorption/desorption analysis were employed to systematically investigate the morphology, particle size, structure and surface properties of the catalysts. The 96.8% benzyl alcohol conversion and 100% benzaldehyde selectivity over the MnO2/GO (10/100) catalyst with well dispersive ultrafine MnO2 nanoparticles (ca. 3nm) can be obtained within 3h under 383K. Simultaneously, no appreciable loss of activity and selectivity occurred after recycling use up to six times. Due to their significant low cost, excellent catalytic performance, the MnO2/GO composites have huge application prospect in organic synthesis.

Cobalt nanoparticles as recyclable catalyst for aerobic oxidation of alcohols in liquid phase

Cobalt nanoparticles prepared at room temperature from cobalt sulphate and tetrabutyl ammonium bromide as surfactant have been found to be effective oxidation catalysts. Palladium and platinum nanoparticles (average size 4–6 nm) can also be prepared from PdCl2 and K2PtCl4, respectively, using the same surfactant but require high temperature (~120 °C) and much longer preparation time. Agglomeration of nanoparticles prepared from metals like palladium and platinum in common solvents, however, restricts their use as catalysts. It is therefore our endeavour to find the right combination of catalyst and solvent that will be beneficial from industrial point of view. Magnetic property measurement of cobalt nanoclusters was made using SQUID to identify their reusability nature. Herein, we report the use of cobalt nanoparticles (average size 90–95 nm) in dichloromethane solvent as effective reusable catalysts for aerobic oxidation of a variety of alcohols.

Immobilization of palladium (II) complexes on ethylenediamine functionalized core–shell magnetic nanoparticles: An efficient and recyclable catalyst for aerobic oxidation of alcohols and carbonylative Suzuki coupling reaction

A novel Pd(II) complex immobilized on ethylenediamine-functionalized core–shell magnetic nanoparticles [Fe3O4@SiO2–2N–Pd(II)] was successfully synthesized by a facile procedure, and various characterizations (TEM, XRD, FT-IR, TGA, XPS and VSM) were performed to identify its intrinsic features. The amino groups in two kinds from ethylenediamine-functionalized magnetic nanoparticles (Fe3O4@SiO2–2N) performed as robust anchors and efficient stabilizers during the fabrication of Fe3O4@SiO2–2N–Pd(II). As a heterogeneous phosphine-free Pd(II) complex catalyst, it showed excellent catalytic activity for aerobic oxidation of alcohols, and up to >99% yield of unsymmetrical biaryl ketone was obtained in the carbonylative Suzuki coupling reaction of carbon monoxide, 4-methylbenzeneboronic acid and the 4-iodonitrobenzene. Moreover, the catalyst could be completely recovered by magnetic separation from the reaction mixture and remained unaltered activity even after six repeated cycles.

ChemInform Abstract: SBA‐15‐Functionalized 3‐Oxo‐ABNO as Recyclable Catalyst for Aerobic Oxidation of Alcohols under Metal‐Free Conditions.

AbstractThe SBA‐15‐functionalized 3‐oxo‐9‐azabicyclo[3.3.1]nonane‐N‐oxyl in combination with tert‐butylnitrite and acetic acid is found to be an efficient heterogeneous catalyst for the aerobic oxidation of primary and secondary alcohols.

SBA-15-functionalized 3-oxo-ABNO as recyclable catalyst for aerobic oxidation of alcohols under metal-free conditions.

The nitroxyl radical 3-oxo-9-azabicyclo [3.3.1]nonane-N-oxyl (3-oxo-ABNO) has been prepared using a simple protocol. This organocatalyst is found to be an efficient catalyst for the aerobic oxidation of a wide variety of alcohols under metal-free conditions. In addition, the preparation and characterization of a supported version of 3-oxo-ABNO on ordered mesoporous silica SBA-15 (SABNO) is described for the first time. The catalyst has been characterized using several techniques including simultaneous thermal analysis (STA), transmission electron microscopy (TEM), and nitrogen sorption analysis. This catalyst exhibits catalytic performance comparable to its homogeneous analogue and much superior catalytic activity in comparison with (2,2,6,6-tetramethylpiperidin-1-yl)oxy (TEMPO) for the aerobic oxidation of almost the same range of alcohols under identical reaction conditions. It is also found that SABNO can be conveniently recovered and reused at least 12 times without significant effect on its catalytic efficiency.

Palladium nanoparticles in ionic liquids: reusable catalysts for aerobic oxidation of alcohols

The search for more efficient catalytic systems that might combine the advantages of both homogenous (catalyst modulation) and heterogenous catalysis (catalyst recycling) is still the challenge of modern chemistry. With the advent of nanochemistry, it has been possible to prepare soluble analogues of heterogenous catalysts. These nanoparticles are generally stabilized against aggregation into larger less active particles by electrostatic or steric protection. In the present case, we demonstrate the use of room temperature ionic liquids (ILs) as effective agents of dispersion of palladium nanoparticles (prepared from palladium chloride with 5 ± 0.5 nm size distribution) that are recyclable catalysts for aerobic oxidation of alcohols under mild conditions. The particles suspended in ILs show no metal agglomeration or loss of catalytic activity even on prolonged use. An attempt has been made to elucidate the reaction mechanism of aerobic alcohol oxidation using a soluble palladium catalyst.

Covalently immobilized Mn(III)deuteroporphyrin on chitosan: An efficient and recyclable catalyst for aerobic oxidation of cyclohexane

AbstractChitosan‐supported Mn(III)deuteroporphyrin chlorine [Mn(III)DPCl‐CTS] catalyst was prepared by convalent binding of Mn(III)deuteroporphyrin‐bearing carboxyl groups on the side chain of the macrocycle ring to chitosan. The supported catalyst was found to efficiently catalyze the hydroxylation of cyclohexane with air as oxygen source. The effect of various reaction parameters, such as reaction time, temperature, and pressure on the catalytic performances, was in detail investigated and the designed installed oxidation equipment was convenient for on‐line sampling during the reaction every time. Under an optimum temperature of 140°C and a pressure of 0.7 MPa, the obtained cyclohexane conversion (16.9%) and chemoselectivity (88.7%) for cyclohexanol and cyclohexanone were much better than those observed with unsupported Mn(III)deuteroporphyrin and synthetic Mn(III) tetraphenylporphyrin. An intermolecular interaction between amino moieties in chitosan and dipropionic groups in Mn(III)deuteroporphyrin was suggested to play a role in the high conversion of this system. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

New recyclable catalysts for aerobic alcohols oxidation: sol-gel ormosils doped with TPAP

Novel nanoporous materials have been prepared that are recyclable catalysts for the aerobic oxidation of activated and non-activated alcohols. The catalysts are organically modified silicas (ormosils) doped with tetra- n-propylammonium perruthenate (TPAP) via the sol-gel process. Hydrophobicity and flexibility of the sol-gel cages were crucial in promoting catalysis.