Recoverable Catalyst Research Articles

Urea-dithiocarbamic acid functionalized magnetic nanoparticles modified with Ch-Cl: Catalytic application for the synthesis of novel hybrid pyridones via cooperative geminal-vinylogous anomeric-based oxidation

This investigation was focused on the novel magnetic nanoparticles anchored deep eutectic solvent namely Fe3O4@SiO2@(CH2)3-urea-dithiocarbamic acid/Ch-Cl as a heterogeneous catalyst. The formation of the catalyst was confirmed by several techniques including FT-IR spectroscopy, FE-SEM, TEM, EDX, elemental mapping, TGA/DTG and VSM analysis. Fe3O4@SiO2@(CH2)3-urea-dithiocarbamic acid/Ch-Cl was applied as environmentally sustainable and recoverable catalyst for the synthesis of novel hybrid pyridones containing triazole and sulfonamide moieties. X-ray crystallography was also used for the accurate determination of the structure of hybrid pyridones. In addition, based on revealed results, pyridone isomer was solely confirmed compared to its relevant tautomer (pyridine). In the current study, cooperative geminal-vinylogous anomeric-based oxidation concept has been used for suggesting a plausible mechanism for the synthesis of target molecules.

Fabrication and Characterization of a Novel and Efficient Zinc Nanomagnetic Catalyst for Multicomponent Synthesis of Heterocycles

The zinc (II) complex supported on magnetic nanoparticles Fe3O4 as a novel and efficient magnetically recoverable catalyst (Fe3O4-Phenanthroline-Zn) was designed and characterized using the most common spectroscopic techniques including FT-IR spectroscopy, SEM, TEM, EDX, XRD, VSM, and ICP-OES. The Fe3O4-Phenantroline-Zn catalyst is shown to be efficient for the multicomponent synthesis of heterocycles including highly substituted piperidines and pyrano[2,3-d]pyrimidines. This system has many advantages, such as excellent level of reusability of magnetic catalysts, high yields, simplicity of separation of catalysts using an external magnet, environmental benignity and ease of handling. To the best of our knowledge, it is the first report on the utilization of zinc nanomagnetic catalyst for the multicomponent synthesis of highly substituted piperidines.

Synthesis of novel pyrano[2,3-f]chromene-dione derivatives using phosphoric acid-functionalized silica-coated Fe3O4 nanoparticles as a new reusable solid acid nanocatalyst.

In this research, the synthesis of novel indeno[1,2-b]pyrano[2,3-f]chromene-2,12(13H)-dione derivatives in the presence of a newly introduced magnetically recoverable nanosolid acid catalyst is reported. At the first, phosphoric acid-functionalized silica-coated Fe3O4 nanoparticles (Fe3O4@SiO2-(CH2)3OPO3H2) were prepared and well characterized using infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and energy-dispersive X-ray spectroscopy (EDS) techniques. Then, the catalytic activity of the prepared Fe3O4@ SiO2-(CH2)3OPO3H2 nanocatalyst was investigated for the synthesis of novel indeno[1,2-b]pyrano[2,3-f]chromene-2,12(13H)-dione derivatives via a one-pot and three-component condensation between 5,7-dihydroxy-4-methylcoumarin, indane-1, 3-dione, and various aromatic aldehydes under solvent-free condition. All the products are unknown, and their characterization was performed with the spectral data information obtained from their FT-IR, 1H and 13CNMR, elemental analysis, and their melting points. The reusability study of the introduced nanosolid acid catalyst showed that the catalytic stability is almost completely remained up to five consecutive runs.

Palladium nanoparticles stabilized on the amino acids-functionalized Fe3O4 as the magnetically recoverable nanocatalysts for Heck and Suzuki reactions

Regarding the green chemistry goals, well-organized processes for catalyst separation and reuse have drawn much attention in the past few decades. The strategy of magnetic separation offers a convenient approach for recycling catalysts by applying an appropriate magnetic field. In this paper, a palladium nanoparticle-based catalyst that is stabilized on the glutathione and aspartic acid-functionalized superparamagnetic Fe3O4 nanoparticles has been prepared by an eco-friendly, economical and effective procedure. The catalytic performance of these novels, highly active and recoverable catalysts was investigated under low loading of the supported palladium nanoparticles for Heck and Suzuki reactions. Under optimal reaction conditions, the nanocomposites afford the corresponding products in excellent yield. The catalysts could be easily separated from the reaction system and efficiently recycled for four consecutive runs without a remarkable loss of their activity. The structural and magnetic properties of the catalysts were identified by Fourier transform infrared (FT-IR), Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), vibration sample magnetometer (VSM), inductively coupled plasma atomic emission analysis (ICP-AES) and thermogravimetric analysis (TGA).

Nano-Fe3O4@rGO@ZnO-H3PW12O40 as a recoverable magnetic catalyst for one-pot synthesis of benzo[f]furo[2, 3-h]quinoxaline-5, 6-dicarbonitrile under solvent-free conditions

A magnetic core-shell nanoparticle catalyst (MCNPs) (Fe3O4@rGO@ZnO-HPA) (HPA = H3PW12O40) has been used as a reusable solid catalyst for the one-pot, four-component microwave-assisted under solvent-free conditions synthesis of benzo[f]furo[2,3-h] quinoxaline-5,6-dicarbonitrile derivatives by the reaction of 2-hydroxynaphthalene-1,4-dione, diaminomaleonitrile, and phenacyl bromides. Mild reaction conditions and excellent yields are the main advantages of this method. The structural, morphological, magnetically, optical and chemical bonding studies; X-ray diffraction, FESEM, TEM, VSM, UV-Vis, and FTIR measurements were carried out. the results of the above analyses demonstrated core-shell the structure is formed. As an application for the synthesized structure, the degradation of methylene blue as a heavy-mass organic pollutions were measured.

Pd Nanoparticles Decorated on Ionic Liquid Modified Magnetite Nanoparticles as a Recyclable and Active Nanocatalyst for Reduction of Nitro Compounds and Degradation of Organic Dyes

AbstractThe development of new technologies for the efficient degradation of toxic organic pollutants from water resources has received great attention. In this study, we described an effective method for the preparation of Pd nanoparticles (NPs) decorated on nitrogen rich ionic liquid (IL) modified magnetic nanoparticles and its application as the green and recoverable heterogeneous catalyst in the reductive degradation of organic dyes and reduction of nitro compounds. The Fe3O4/SiO2−IL−Pd nanocatalyst was characterized by several techniques namely, FT‐IR, FE‐SEM, EDX‐ elemental mapping, XRD, TEM, XPS, TGA and VSM. The Fe3O4/SiO2‐IL−Pd nanocatalyst was applied for the efficient reduction of structurally different nitroarenes, methyl orange (MO), methylene blue (MB) and methyl red (MR) in aqueous media using NaBH4 as reducing agent at room temperature. Using this catalyst nitroarenes were reduced to corresponding amines very efficiently and organic dyes reduced quantitatively under short reaction times. The catalyst can be recovered and recycled for at least ten runs without a notable decrease in the activity.

Basified Graphene Oxide and PPO Composite Aerogel with Basified Graphene Oxide for Henry Reaction in Solvent-Free Conditions: A Green Approach

Novel basified graphene oxide and high-porosity monolithic composite aerogels of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) containing basified graphene oxide (b-eGO) have been prepared as recoverable and reusable catalysts for the Henry reaction in solvent-free conditions at room temperature. The results showed that, although b-eGO was able to promote the reaction, it suffered from reduced stability. On the other hand, PPO/b-eGO aerogels were able to efficiently promote the Henry reaction in solvent-free conditions. The product could be obtained pure without a purification step, and the catalyst was stable for over 15 months and could be easily recycled without losing catalytic efficiency. The stereochemical outcome was further investigated in the presence of PPO/b-eGO. Despite its negligible influence on diastereoselectivity, better efficiency and a sensible reduction of reaction time were observed.

Encapsulated peroxophosphotungstates catalyst into magnetic MOF: Magnetically recoverable heterogeneous high efficiency desulfurization catalyst

High activity peroxophosphotungstates with different organic cations were encapsulated into the metal-organic framework modified by magnetic nanoparticle (Fe2O3/MIL-101) to prepare the magnetic supported catalysts, which were used to improve the diesel desulfurization efficiency. The desulfurization result shows that one selected catalyst, (BTA)3PW4 @Fe2O3/MIL-101, possesses high catalytic activity in the oxidation of various organic sulfides with H2O2 as green oxidant. The catalyst can be magnetically recycled and reused for ten consecutive cycles without significant decrease in activity. Based on the GC-MS and EPR results, it is confirmed that sulfides are oxidized to corresponding sulfones in the presence of •OH radical. In a word, the high activity, good stability and reusability of catalyst prepared in this work make it have a good prospect of industrial application.

Simple Halogen-Free, Biobased Organic Salts Convert Glycidol to Glycerol Carbonate under Atmospheric CO2 Pressure.

Glycerol carbonate (GC) has emerged as an attractive synthetic target due to various promising technological applications. Among several viable strategies to produce GC from CO2 and glycerol and its derivatives, the cycloaddition of CO2 to glycidol represents an atom-economic an efficient strategy that can proceed via a halide-free manifold through a proton-shuttling mechanism. Here, it was shown that the synthesis of GC can be promoted by bio-based and readily available organic salts leading to quantitative GC formation under atmospheric CO2 pressure and moderate temperatures. Comparative and mechanistic experiments using sodium citrate as the most efficient catalyst highlighted the role of both hydrogen bond donor and weakly basic sites in the organic salt towards GC formation. The citrate salt was also used as a catalyst for the conversion of other epoxy alcohols. Importantly, the discovery that homogeneous organic salts catalyze the target reaction inspired us to use metal alginates as heterogeneous and recoverable bio-based catalysts for the same process.

Synthesis of 9,9-dimethyl-12-(aryl)-8,9,10,12-tetrahydrobenzo[a]xanthene-11-ones by modified kaolinite nanoclay as an efficient and reusable heterogeneous catalyst via a green protocol

9,9-Dimethyl-12-(aryl)-8,9,10,12-tetrahydrobenzo[a]xanthene-11-one derivatives have been prepared via three component reaction of various aromatic aldehydes, dimedone and 2-naphthol. This green methodology has been effectively catalyzed by sulfonyl- functionalized kaolinite nanoclay (nano-kaolin-SO 3 H) as a recoverable solid catalyst. This type of solid acid which contains the properties of a Lewis acid (Al 3+ cation) and a Brønsted acid (SO 3 H group), has been characterized by ATR, TEM, FESEM, EDS, EDS mapping, XRD, TGA, BET and XRF techniques. Compared with conventional methods, this protocol has promising features for the reaction response such as simplicity in the experimental procedure, easier work-up, shorter reaction times and ease of separation of pure products with high yields.

Tribromide Immobilized on Amino-Functionalized Magnetic Nanoparticles: A Active Magnetically Recoverable Catalyst for the Synthesis of Heterocycles

A novel tribromide nanocatalyst was successfully fabricated via the heterogenization of tribromide ion on the surface of silica-coated magnetic nanoparticles modified with N2,N4,N6-tris(aminomethyl)-1,3,5-triazine-2,4,6-triamin [Fe3O4@SiO2-tris(triazine-triamine)-Br3] and was well characterized by Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-Ray Analysis (EDX), vibrating-sample magnetometer (VSM), X-ray diffraction analysis (XRD) and Thermogravimetric analysis (TGA) spectroscopic techniques. TEM and SEM analysis confirmed that the typical silica shell thickness was assessed to be around 20 nm. The as-fabricated Fe3O4@SiO2-tris(triazine-triamine)-Br3 nanomaterial was shown high catalytic activity in the multicomponent synthesis of highly substituted piperidines and polyhydroquinolines. Recycling experiments revealed that the Fe3O4@SiO2-tris(triazine-triamine)-Br3 could be easily recovered by a simple magnetic separation and recycled at least 7 times without deterioration in catalytic activity.

Efficient and Recoverable Bio-Organic Catalyst Cysteine for Synthesis, Docking Study, and Antifungal Activity of New Bio-Active 3,4-Dihydropyrimidin-2(1H)-ones/thiones Under Microwave Irradiation

An eco-friendly green bio-organic catalyst and low-cost 3,4-dihydropyrimidin-2(1H)-ones/thione derivatives 4–7 have been synthesized using a high-yield, synthetic method via a one-pot, three-component process between 4-formylphenyl-4-methylbenzenesulfonate (1), thiourea, or urea and ethyl acetoacetate or acetylacetone under microwave irradiation in aqueous media of water and ethanol (3:1 ratio) as a green solvent in the presence of cysteine as a new green bio-organic catalyst. The reaction between compound 1, 4-(carbamothioylhydrazono) methyl]phenyl 4-methyl benzenesulfonate (3c), and ethyl acetoacetate or acetylacetone under the same condition afforded novel pyrimidines. Similarly, compound 1 was allowed to react with a mixture of 4-(carbamothioylhydrazono)methyl]phenyl 4-methyl benzenesulfonate (3c) and ethyl acetoacetate or acetylacetone under the same condition to afford pyrimidine derivatives 8 and 9. Excellent yields (90–98%) were obtained within short reaction times, and problems associated with the toxic solvents used (cost, safety, and pollution) were avoided. The structures of the new compounds were elucidated by elemental and spectral analyses. All compounds were studied using molecular docking, and their antifungal activity was investigated.

Fabrication of Copper(II)-Coated Magnetic Core-Shell Nanoparticles Fe3O4@SiO2: An Effective and Recoverable Catalyst for Reduction/Degradation of Environmental Pollutants

In this work, we report the synthesis of a magnetically recoverable catalyst through immobilizing copper (II) over the Fe3O4@SiO2 nanoparticles (NPs) surface [Fe3O4@SiO2-L–Cu(II)] (L = pyridine-4-carbaldehyde thiosemicarbazide). Accordingly, synthesized catalysts were determined and characterized by energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), field emission scanning electron microscopy (FESEM), and thermogravimetric-differential thermal analysis (TG-DTA) procedures. The [Fe3O4@SiO2-L–Cu(II)] was used for the reduction of Cr(VI), 4-nitrophenol (4-NP) and organic dyes such as Congo Red (CR) and methylene blue (MB) in aqueous media. Catalytic performance studies showed that the [Fe3O4@SiO2–L–Cu(II)] has excellent activity toward reduction reactions under mild conditions. Remarkable attributes of this method are high efficiency, removal of a homogeneous catalyst, easy recovery from the reaction mixture, and uncomplicated route. The amount of activity in this catalytic system was almost constant after several stages of recovery and reuse. The results show that the catalyst was easily separated and retained 83% of its efficiency after five cycles without considerable loss of activity and stability.

Chemoselective tetrahydropyranylation of alcohols and phenols using nanoencapsulated FeCl3 in linear polystyrene as a recoverable and reusable polymer-supported catalyst

A new, mild and efficient protocol for chemoselective protection of alcohols and phenols as tetrahydropyranyl ethers using linear polystyrene-encapsulated FeCl3 nanoparticles as a recyclable macromolecular Lewis acid catalyst at room temperature is described. This catalytic system allowed for the facile conversion of primary, secondary, and tertiary alcohols, as well as phenols to the corresponding tetrahydropyranyl ethers with short reaction times and high yields. The nanoencapsulated ferric chloride catalyst was found to be recoverable even after the sixth catalytic cycle without much depreciation in its activity.

Wang resin catalyzed sonochemical synthesis of dihydropyrano[2,3-c]pyrazole derivatives and their interactions with SIRT1

The pyrano[2,3-c]pyrazole framework was explored for the design and synthesis of compounds as potential inhibitors of SIRT1. The feasibility of this strategy was reasoned by the unique structural features of this scaffold and the reported cytotoxicity of compounds containing this framework. The sonochemical synthesis of target compounds was accomplished by using the Wang resin (Wang-OSO3H) as a recoverable catalyst under eco-friendly conditions. Thus, the desired 4-substituted 6-amino-3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile derivatives were prepared via a 4-component reaction of β-ketoester, hydrazine, aldehyde and malononitrile in pure water in good yields. The recyclability of the catalyst was demonstrated successfully. All the synthesized compounds were initially assessed in silico against the targeted protein i.e. hSIRT1 that indicated compound 5i and 5l along with several other compounds as possible inhibitors. Both of these compounds participated in two vital H-bond interactions with the residue GLN345 and ASN346 in silico that was reflected in their estimated total energy. In vitro assessment of these pyrano[2,3-c]pyrazoles against SIRT1 revealed encouraging inhibitory activities (> 50% inhibition) that was in agreement with the results of docking studies. Indeed, 5i and 5l were identified as the most active compounds in this series. The Structure-Activity-Relationship (SAR) study suggested important role of the C-4 aryl substituent along with the N-1 phenyl ring of the pyrano[2,3-c]pyrazole moiety in the SIRT1 inhibitory activities of this class of compounds. Thus, a OH or Cl group at the p-position of the C-4 benzene ring together with the N-1 phenyl moiety appeared to be beneficial for activity. Overall, the initial design and then sonochemical synthesis followed by in silico as well as in vitro studies allowed identification of pyrano[2,3-c]pyrazole based small molecules as potential inhibitors of SIRT1.

Cobalt-based sandwich-type polyoxometalate supported on amino-silane decorated magnetic graphene oxide: A recoverable catalyst for extractive-catalytic oxidative desulfurization of model oil

In order to produce ultra-low sulfur fuel, a sandwich-type polyoxometalate (K10[Co4(H2O)2(PW9O34)2]10- (Co4-POM) was covalently immobilized on amino-modified magnetic graphene oxide, and employed as a novel heterogeneous catalyst in an extractive- catalytic oxidative desulfurization system (ECODS). The (Co4-POM@APTES-(Fe3O4/GO)) nanocomposites with various Co4-POM content were prepared. The obtained samples were characterized by XRD, FT-IR, SEM, EDX, N2 adsorption, and VSM techniques. Meanwhile, the effects of Co4-POM load percentage, reaction temperature, catalyst dosage, and H2O2/DBT molar ratio on desulfurization efficiency of the prepared catalyst were investigated. The highest catalytic activity was observed for the sample with 30 wt% Co4-POM content. Dibenzothiophene (DBT) could be completely removed within at 50 ℃ using 4 g catalyst L−1 fuel, and H2O2/DBT molar ratio of 4. In addition, BT and 4,6-DMDBT could be completely removed under the optimized conditions, which suggested a promising prospect of the catalyst for industrial applications. The nanocomposite could be easily separated and reused by utilizing an external magnetic field without any substantial decline in its catalytic activity even after five runs. The kinetic data were fitted to a pseudo-first-order model. Finally, a reaction mechanism for the catalytic oxidation of DBT in the presence of Co4-POM@APTES-(Fe3O4/GO) was proposed.

Fabrication and Characterization of Copper (II) Complex Supported on Magnetic Nanoparticles as a Green and Efficient Nanomagnetic Catalyst for Synthesis of Diaryl Sulfones

A novel magnetically recoverable copper catalyst was successfully fabricated through the immobilization of Cu(OAc)2 on the surface of silica-coated magnetic Fe3O4 nanoparticles (Fe3O4@SiO2) functionalized with amine and thiol groups as ligand. The as-fabricated Fe3O4@SiO2-Imine/Thio-Cu(II) nanocomposite was fully characterized by FT-IR spectroscopy, SEM, EDX, TEM, XRD, VSM, ASS and ICP-OES techniques. The Fe3O4@SiO2-Imine/Thio-Cu(II) nanocomposite exhibited high catalytic activity in the synthesis of biologically active diaryl sulfones. According to our research on the literature, this is the first report in the use of magnetic copper nanocatalyst for the synthesis of diaryl sulfones via sulfonylative Suzuki–Miyaura cross-coupling reactions. This method gives notable advantages such as easy separation of the catalyst by external magnetic field; excellent yields, short reaction times, nontoxic metal catalyst, and simplicity of operation make this method a facile tool for the synthesis of diaryl sulfones.

Application of Fe3O4@SiO2-Propyl@dapsone-copper Complex Nanoparticles as a Magnetically Recoverable Catalyst for the Synthesis of Azo-linked and bis- Benzo[d]imidazoles

Application of Fe3O4@SiO2-Propyl@dapsone-copper Complex Nanoparticles as a Magnetically Recoverable Catalyst for the Synthesis of Azo-linked and bis- Benzo[d]imidazoles

Pd-containing magnetic periodic mesoporous organosilica nanocomposite as an efficient and highly recoverable catalyst

A novel magnetic ionic liquid based periodic mesoporous organosilica supported palladium (Fe3O4@SiO2@IL-PMO/Pd) nanocomposite is synthesized, characterized and its catalytic performance is investigated in the Heck reaction. The Fe3O4@SiO2@IL-PMO/Pd nanocatalyst was characterized using FT-IR, PXRD, SEM, TEM, VSM, TG, nitrogen-sorption and EDX analyses. This nanocomposite was effectively employed as catalyst in the Heck reaction to give corresponding arylalkenes in high yield. The recovery test was performed to study the catalyst stability and durability under applied conditions.

One-pot synthesis of chromenes in the presence of magnetic nanocomposite based on NH2-UiO-66(Zr), graphene oxide and Fe3O4

In this research, GO/Fe3O4/UiO‑66-NH2, a new magnetically recoverable heterogeneous catalyst, was prepared and characterized using various spectroscopic techniques and elemental analysis methods. The promoting ability of GO/Fe3O4/UiO‑66-NH2 was studied in the synthesis of chromenes via one-pot three-component condensation of 4‐hydroxycoumarin, 2‐hydroxynaphthalene‐1,4‐dione and aromatic aldehydes at 110 °C under solvent-free conditions. This new protocol is included some important features such as lower loading of the catalyst, excellent yields (88%–98%), short reaction times (5–10 min), easy work-up procedure, and easy recovery using a simple magnet. The catalyst was characterized by SEM, XRD, EDX, BET, TGA and FT-IR analysis.