Heterogeneous Copper Catalyst Research Articles

A New Insight Into The Huisgen Reaction: Heterogeneous Copper Catalyzed Azide-Alkyne Cycloaddition for the Synthesis of 1,4-Disubstituted Triazole (From 2018-2023).

The Huisgen cycloaddition, often referred to as 1,3-Dipolar cycloaddition, is a well-established method for synthesizing 1,4-disubstituted triazoles. Originally conducted under thermal conditions [3+2] cycloaddition reactions were limited by temperature, prolonged reaction time, and regioselectivity. The introduction of copper catalyzed azide-alkyne cycloaddition (CuAAC) revitalized interest, giving rise to the concept of "click chemistry". The CuAAC has emerged as a prominent method for producing 1,2,3-triazole with excellent yields and exceptional regioselectivity even in unfavorable conditions. Copper catalysts conventionally facilitate azide-alkyne cycloadditions, but challenges include instability and recycling issues. In recent years, there has been a growing demand for heterogeneous and porous catalysts in various chemical reactions. Chemists have been more interested in heterogenous catalysts as a result of the difficulties in separating homogenous catalysts from reaction products. These catalysts are favored for their abundant active sites, extensive surface area, easy separation from reaction mixtures, and the ability to be reused. Heterogeneous catalysts have garnered significant attention due to their broad industrial utility, characterized by cost-effectiveness, stability, resistance to thermal degradation, and ease of removal compared to their homogeneous counterparts. The present review covers recent advancements from year 2018 to 2023 in the field of click reactions for obtaining 1,2,3-triazoles through Cu catalyzed 1,3-dipolar azide-alkyne cycloaddition and the properties of the catalyst, reaction conditions such as solvent, temperature, reaction time, and the impact of different heterogeneous copper catalysts on product yield.

A Novel Heterogeneous Copper Catalyst Immobilized on Polydopamine‐Coated Magnetite for Click Reaction

AbstractA novel catalyst has been afforded by immobilizing Cu(OAc)2 salt to polydopamine‐coated magnetite (Fe3O4). The catalytic platform (Fe3O4@PDA@Cu) was fully characterized by Fourier transform infrared, Energy‐dispersive X‐ray, Scanning Electron Microscopy, and Thermogravimetric Analysis. The catalytic activity of the Fe3O4@PDA@Cu nanocatalyst was investigated in a green and effective synthesis of click reaction by applying three‐component reactions of azide, alkyne, and benzyl surrogates in water, providing the corresponding 1,2,3‐triazoles in high yield. Furthermore, the present nanocatalyst could be easily separated by an external magnet and reused several times without considerable reduction of its catalytic efficiency. Operational simplicity, environmental friendliness, economical processing, and easy workup are the features of the present protocol.

A sustainable avenue for the synthesis of propargylamines and benzofurans using a Cu-functionalized MIL-101(Cr) as a reusable heterogeneous catalyst

A heterogeneous copper-catalyzed A3 coupling reaction of aldehydes, amines, and alkynes for the synthesis of propargylamines and benzofurans has been developed. Here, the modified metal–organic framework MIL-101(Cr)-SB-Cu complex was chosen as the heterogeneous copper catalyst and prepared via post-synthetic modification of amino-functionalized MIL-101(Cr). The structure, morphology, thermal stability, and copper content of the catalyst were determined by FT-IR, PXRD, SEM, TEM, EDX, TGA, XPS, and ICP-OES. The catalyst shows high catalytic activity for the aforementioned reactions under solvent-free reaction conditions. High yields, low catalyst loading, easy catalyst recovery and reusability with not much shrink in catalytic activity, and a good yield of 82% in gram-scale synthesis are some of the benefits of this protocol that drove it towards sustainability.

Heterogeneous Copper Catalysts in the Aqueous Phase Hydrogenation of Maltose to Sorbitol

A one-pot hydrogenolysis/hydrogenation reaction of maltose to two moles of sorbitol has been carried out over different supported Cu catalysts in water at 180 °C and 40 bar of H2. Only the catalysts supported on silicas were found to be effective in this reaction, giving up to 86% yield in the desired product while the bare supports and the catalysts supported on alumina or silica alumina gave messy reactions. The peculiar activity of the two Cu/Silica systems tested was ascribed to high metal dispersion and suitable polarity of the catalyst surface. In exposing metallic Cu particles on the surface, the reduced catalyst showed unusual stability in the presence of water as a solvent and could be reused several times without any treatment.

Antibacterial effect of metal-enzyme hybrid nanomaterials

The heterogeneous copper and cobalt catalysts (CoNPs-hybrid and CuNPs-hybrid) were synthesized using a protein-directed method to obtain catalytically active nanoparticles for wastewater disinfection, and fully characterized by ICP-OES, XRD, XPS, TEM and SEM analysis. CuNPs-hybrid demonstrated antibacterial capabilities, total removal of Enterococcus sp. (≈ 5-log reduction (LR)) in 120 min, at a concentration of 0.1 g/L, and efficient recyclability, by retaining this removal efficiency in the third cycle. Therefore, its high recyclability, low use of additional reagents, the sustainable nature of its synthesis, and high catalytic efficiency make this material a potentially attractive disinfectant. However, the opposite behavior was observed for the CoNPs-hybrid case, without disinfectant capabilities by its own. While with a Turnover Frequency (TOF) of the CoNPs-hybrid, of 1.84 h−1, and 99.9 % degradation of pAP in 30 min, the analysis demonstrated the catalytic capacity of the CoNPs-hybrid. Therefore, the intensification of the process was performed adding peroxymonosulfate (PMS) and solar radiation. It was achieved a 2.5-LR disinfection rate in 120 min at a concentration of 0.05 g/L when activated by solar radiation, but it is still less than that obtained with external actors on an individual basis. X-ray diffraction showed that the catalyst composition is not stable throughout use, which is reflected in its low recyclability.

Some Insights into the Use of Heterogeneous Copper Catalysts in the Hydroprocessing of Levulinic Acid

Levulinic acid and its esters are close to being extensively produced through consolidated industrial processes, thus playing a central role in biobased industries producing commodities within the principles of the circular economy. One of the main pathways of levulinic acid and ester valorization is their transformation with hydrogen to obtain γ-valerolactone, valeric esters, 1,4-pentanediol and 2-methyl tetrahydrofuran. These reactions are catalyzed by noble and non-noble metal-based heterogeneous catalysts. The use of an abundant and non-toxic element, such as copper, is advantageous with respect to expensive or harmful metals, such as Rh, Ru, Pt or Ni. In this critical review, we wish to give a deeper insight into research advancements in the last ten years regarding the processing of levulinic acid and its esters with hydrogen using heterogeneous copper catalysts.

Synthesis of green solvents from bio-based lactones using heterogeneous copper catalysts

In this paper, the synthesis of green solvents N-alkyl-pyrrolidinones starting from γ-valerolactone using non-noble, supported copper catalysts is proposed. The reaction setup has been improved to limit both harsh conditions and auxiliaries and to avoid any catalyst pretreatment or a too high hydrogen pressure use. A CuO/Al2O3 catalyst with a high dispersion of the metal phase combined with a low Cu nanoparticle size proved to be the best for the process. The catalytic system has proven to be suitable for other lactones such as γ-butyrolactone, γ-caprolactone, ε-caprolactone and dihydrocoumarin.

Magnetically separable triazine-based Cu(ii)-vitamin B5 complex in nitromethane toward efficient heterogeneous cyanation reaction of aryl halides.

In the current study, a highly efficient heterogeneous copper catalyst has been developed by supporting copper acetate on a magnetically separable triazine-vitamin B5 system. After the successful characterization of the prepared nanoparticles by various techniques such as FT-IR, FE-SEM, EDX/MAP, XRD, TEM, TGA, VSM, and ICP-OES, the catalytic efficiency of them were evaluated in the cyanation reaction of aryl halides in the presence of nitromethane as a non-toxic and cost-effective cyanation source. The cyanation products were obtained in desirable yields. Notably, the magnetic nanocatalyst can be easily recovered and reused at least five times without a significant decrease in its performance.

Copper adorned magnetic nanoparticles as a heterogeneous catalyst for Sonogashira coupling reaction in aqueous media

A nanomagnetic hydrophilic heterogeneous copper catalyst, termed γ-Fe2O3@PEG@PAMAM G0-Cu, has been successfully prepared and characterized using FT–IR, XRD, FE-SEM, TEM, EDX, mapping, TGA/DTG, VSM and ICP analyses. The catalyst displayed excellent activity for the palladium-free Sonogashira cross coupling reaction of various aryl iodides and bromides with phenylacetylene derivatives in pure water. The presence of polyethylene glycol coupled with hydrophilic character of the Cu-catalyst adorned on γ-Fe2O3 MNPs provides the ready dispersion of the catalyst particles in water, leading to higher catalytic performance as well as facile catalyst recovery via simple magnetic decantation. The recovered catalyst was reused for at least six successive runs with little reduction in its catalytic activity and any noticeable changes in its structure. The use of water as a green solvent, without requiring any additive or organic solvent, as well as the exploitation of abundant and low-cost copper catalyst instead of expensive Pd catalyst along with the catalyst recovery and scalability, make this method favorable from environmental and economic points of view for the Sonogashira coupling reaction.

A Motor-Based Carbonaceous Nanocalabash Catalyst for Deep-Layered Bioorthogonal Chemistry.

Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction has been widely regarded as a promising avenue in bioorthogonal chemistry. The emerging heterogeneous copper catalysts have been developed with a series of exciting applications such as in situ activation of prodrugs because of their excellent stability and biocompatibility. However, due largely to the complex biophysical barriers in living organisms, most synthetic bioorthogonal drugs cannot penetrate deep pathological tissues. Especially in biofilm-associated infections, the biofilms severely block the penetration of traditional antimicrobial agents and increase the antibiotic resistance, which makes it extremely difficult to eliminate the biofilms. Inspired by self-propelled biological motors, such as enzymes, herein, we develop a NIR light-controllable carbonaceous nanocalabash (CNC) motor catalyst with good biocompatibility for active targeted synthesis of drugs inside the biofilms as a robust general-purpose bioorthogonal platform. Under the NIR laser, the CNC motor catalysts display a rapid autonomous motion and generate active molecules in the deep biofilm layers, removing the biofilms and eradicating the shielded bacteria. Our work will shed light on developing a robust bioorthogonal platform for active targeted synthesis of drugs in deep-layered living systems.

Polymer-Supported Chiral Heterogeneous Copper Catalyst for Asymmetric Conjugate Addition of Ketones and Imines under Batch and Flow

Enantioselective conjugate addition reactions are powerful methods in synthesizing optically active molecules. Procedures that employ chiral homogeneous catalysts have been developed extensively, but ones that use chiral heterogeneous catalysts are less explored and remain a challenge. Here we report a polymer-supported chiral heterogeneous copper catalyst that demonstrated high reactivity and enantioselectivity in asymmetric conjugate addition reactions of both ketones and imines. It was found that reduced steric hindrance inside the micro catalytic environment and a 1:1 ligand to metal ratio was crucial for the high efficiency and reusability of the chiral heterogeneous catalyst. Various α,β-unsaturated carbonyl substrates, including pharmaceutical intermediates and natural products, could be transformed in high yields with high enantioselectivities. Successful application of this methodology in a continuous flow fashion further broadened its usage in dealing with sensitive organozinc reagents. In addition, production was successfully scaled up under the flow condition.

Flow Hydrogenation of 1,3,5-Trinitrobenzenes over Cu-Based Catalysts as an Efficient Approach for the Preparation of Phloroglucinol Derivatives

AbstractAn environmentally friendly and safe synthesis of phloroglucinol and its derivatives through the flow hydrogenation of 1,3,5-trinitrobenzenes on heterogeneous copper catalysts is reported. It was found that hydrogenation of 1,3,5-trinitrobenzene, 2,4,6-trinitrotoluene, 2,4,6-trinitroxylene, and 2,4,6-trinitromesitylene in methanol over Cu–Al mixed oxides derived from layered double hydroxides led to selective formation of the corresponding triaminobenzenes, which were isolated from the reaction mixture in the form of double salts with sulfuric acid and were stable in storage. Subsequent hydrolysis in aqueous solution gave the phloroglucinol derivatives in good yields (75–82%).

Copper-Containing Catalysts for Azide–Alkyne Cycloaddition in Supercritical CO2

Background: Chemical industry has increased the investment into and innovation capacity to supply chemicals from safe and sustainable sources, which will be essential to offering new solutions and supporting the green transition of the global economy and society. In this sense, the use of green solvents and reusable heterogeneous catalysts has emerged as a promising sustainable process strategy for engineering, chemistry and the environment. In this work, different homogeneous (copper bromide, CuBr and copper(II) acetate, Cu (CH3COO)2·H2O) and heterogeneous (Cu Wire, Cu Plate, Cu/β-SiC, pre-treated Cu Wire and pre-treated Cu Plate) copper catalysts were tested for the copper(I)-catalyzed alkyne–azide cycloaddition (CuAAC) reaction. In addition, the influence of different reaction media was analyzed, comparing the use of an organic solvent such as toluene and a green solvent such as supercritical CO2 (scCO2). Methods: Characterization of the catalysts includes by X-ray diffraction (XRD), Scan Electron Microscopy (SEM), Atomic absorption spectrophotometry (AA) and Temperature Programmed Reduction (TPR). Parameters such as catalyst loading, reaction time, reusability and leaching of the catalysts were studied to obtain more information on the CuAAC reaction in scCO2. Results: The pre-treated copper plate achieved a 57% increase in reaction yield compared to the non pre-treated copper plate. However, the recovery and reuse of the pre-treated copper plate showed a severe deterioration and a considerable change in its surface. Cu Wire (without pre-treatment) achieved yields of up to 94.2% after reusing it for five cycles. Conclusions: These results suggest the possibility to exploit the combination of heterogeneous catalysts and scCO2 and justify further research to highlight green solvents and simultaneously address the challenges of reaction, purification and recycling.

Efficient Heterogeneous Copper-Catalyzed Alder-Ene Reaction of Allenynamides to Pyrrolines.

Herein, we describe an efficient nanocopper-catalyzed Alder-ene reaction of allenynamides. The copper nanoparticles were immobilized on amino-functionalized microcrystalline cellulose. A solvent-controlled chemoselectivity of the reaction was observed, leading to the chemodivergent synthesis of pyrrolines (2,5-dihydropyrroles) and pyrroles. The heterogeneous copper catalyst exhibits high efficiency and good recyclability in the Alder-ene reaction, constituting a highly attractive catalytic system from an economical and environmental point of view.

Synthesis and characterization of nano-cellulose immobilized phenanthroline-copper (I) complex as a recyclable and efficient catalyst for preparation of diaryl ethers, N-aryl amides and N-aryl heterocycles

Functionalized nanocellulose was prepared and employed for immobilization of phenanthroline-copper(I) complex to afford cellulose nanofibril grafted heterogeneous copper catalyst [CNF-phen-Cu(I)]. This nanocatalyst was well characterized using FT-IR, NMR, XRD, CHNS, AAS, TGA, EDX and SEM. The activities of the synthesized catalyst were examined in the synthesis of diaryl ethers via C-O cross-coupling of phenols and aryl iodides, as well as, the preparation of N-aryl amides and N-aryl heterocycles through C-N cross-coupling of amides and N-H heterocycle compounds with aryl halides. In this trend, various substrates containing electron-donating and electron-withdrawing groups were exploited to evaluate the generality of this catalytic protocol. Accordingly, the catalyst demonstrated remarkable catalytic efficiency for both C-N and C-O cross-coupling reactions, thereby resulting in good to excellent yields of the desired products. Furthermore, the recoverability experiments of the catalyst showed that it can be readily retrieved by simple filtration and successfully reused several times with negligible loss of its catalytic activity.

From Mobile Phones to Catalysts: E-Waste-Derived Heterogeneous Copper Catalysts for Hydrogenation Reactions

Electronic waste or E-waste, produced from end-of-life electronic equipment, is the fastest growing solid waste stream, and its rapid generation creates significant environmental problems on a glob...

Copper‐Functionalized Silica‐Coated Magnetic Nanoparticles for an Efficient Suzuki Cross‐Coupling Reaction

AbstractIn this study, a new, efficient and inexpensive strategy has been developed based on the heterogeneous copper catalyst for the synthesis of different biaryl compoundsviathe Suzuki–Miyaura cross‐coupling reaction. In this respect, the core@shell modified Fe3O4@SiO2magnetic nanoparticles (MNPs) has been prepared by immobilization of aminoguanidine and then the copper (II) ion into the surface of magnetic nanoparticles. After full characterization of the prepared catalyst by various technique such as TEM, SEM, EDX, TGA, XRD, VSM, ICP and FT‐IR, its catalytic activity has been investigated in the synthesis of different biarly compounds through the Suzuki‐Miyaura cross‐coupling reaction. Interestingly, similar to Pd‐based catalysts, this new heterogeneous Cu‐based catalyst can catalyze the Suzuki–Miyaura reaction in solvent free condition with good to excellent yields. Besides, this heterogeneous nano copper catalyst was able to separate from the reaction mixture by easy separation procedures and can reuse more than six runs.

Copper-catalysed low-temperature water-gas shift reaction for selective deuteration of aryl halides.

The introduction of deuterium atoms into organic compounds is of importance for basic chemistry, material sciences, and the development of drugs in the pharmaceutical industry, specifically for identification and quantification of metabolites. Hence, methodologies for the synthesis of selectively labelled compounds continue to be a major area of interest for many scientists. Herein, we present a practical and stable heterogeneous copper catalyst, which permits for dehalogenative deuteration via water–gas shift reaction at comparably low temperature. This novel approach allows deuteration of diverse (hetero)aryl halides with good functional group tolerance, and no reduction of the aromatic rings or other easily reducible formyl and cyano groups. Multi-gram experiments show the potential of this method in organic synthesis and medicinal chemistry.

Activated charcoal supported copper nanoparticles: A readily available and inexpensive heterogeneous catalyst for the N-arylation of primary amides and lactams with aryl iodides

Abstract A novel heterogeneous copper catalyst has been developed by supporting copper nanoparticles on activated charcoal via in situ reducing copper(II) with aqueous hydrazine as reductant. The characterization of Cu/C catalyst showed that the Cu0 nano-particles were formed on the surface of charcoal. This catalyst displayed good catalytic activities toward the N-arylation of primary amides and lactams with aryl iodides.

Recent Advancement of Ullmann Condensation Coupling Reaction in the Formation of Aryl-Oxygen (C-O) Bonding by Copper-Mediated Catalyst

Transition metal-catalyzed chemical transformation of organic electrophiles and organometallic reagents belong to the most important cross coupling reaction in organic synthesis. The biaryl ether division is not only popular in natural products and synthetic pharmaceuticals but also widely found in many pesticides, polymers, and ligands. Copper catalyst has received great attention owing to the low toxicity and low cost. However, traditional Ullmann-type couplings suffer from limited substrate scopes and harsh reaction conditions. The introduction of homogeneous copper catalyst with presence of bidentate ligands over the past two decades has totally changed this situation as these ligands enable the reaction promoted in mild condition. The reaction scope has also been greatly expanded, rendering this copper-based cross-coupling attractive for both academia and industry. In this review, we will highlight the latest progress in the development of useful homogeneous copper catalyst with presence of ligand and heterogeneous copper catalyst in Ullmann type C-O cross-coupling reaction. Additionally, the application of Ullmann type C-O cross coupling reaction will be discussed.