Catalysts For Organic Reactions Research Articles

Advancing Heterogeneous Organic Synthesis With Coordination Chemistry-Empowered Single-Atom Catalysts.

For traditional metal complexes, intricate chemistry is required to acquire appropriate ligands for controlling the electron and steric hindrance of metal active centers. Comparatively, the preparation of single-atom catalysts is much easier with more straightforward and effective accesses for the arrangement and control of metal active centers. The presence of coordination atoms or neighboring functional atoms on the supports' surface ensures the stability of metal single-atoms and their interactions with individual metal atoms substantially regulate the performance of metal active centers. Therefore, the collaborative interaction between metal and the surrounding coordination environment enhances the initiation of reaction substrates and the formation and transformation of crucial intermediate compounds, which imparts single-atom catalysts with significant catalytic efficacy, rendering them a valuable framework for investigating the correlation between structure and activity, as well as the reaction mechanism of catalysts in organic reactions. Herein, comprehensive overviews of the coordination interaction for both homogeneous metal complexes and single-atom catalysts in organic reactions are provided. Additionally, reflective conjectures about the advancement of single-atom catalysts in organic synthesis are also proposed to present as a reference for later development.

Exploring Sulphonated Calix[n]arenes as Catalysts in Organic Reactions

Catalysis plays a crucial role in modern chemistry, with macrocyclic compounds like calixarenes serving as key players in organic transformations through supramolecular chemistry. These macrocycles, synthesized from phenol and formaldehyde condensation, exhibit a variety of conformations, such as cone and partial‐cone, due to their flexible structures. Their effectiveness as catalysts arises from their lipophilic cavities and the ease of functionalization on both the upper and lower rims. Water‐soluble calixarenes, in particular, have gained attention for their ability to interact with hydrophobic cavities, facilitating molecular recognition in aqueous environments. A landmark achievement in this field was Shinkai's synthesis of water‐soluble calix[4]arene in 1984, which involved sulphonation using tert‐butyl groups, resulting in compounds known for their low toxicity and encapsulation capabilities. This review provides a comprehensive overview of the advancements in sulphonated calixarenes as catalysts, emphasizing their diverse applications and potential for future development. Key catalytic reactions and their substrate scopes are discussed, along with future perspectives on how these compounds can further revolutionize catalytic processes.

Thiamine (Vitamin B1) Promoted Organic Transformations: A Recent Updates.

Due to the growing significance of sustainable and environmentally friendly organic transformations, there has been increasing interest in utilizing vitamins as catalysts owing to their green nature, biocompatibility, and ease of preparation. Among these, Vitamin B1, also known as thiamine stands out for its nonflammable, water-soluble, inexpensive, and non-toxic characteristics. This review summarized recent developments on the catalytic application of Vitamin B1 in organic transformations, particularly in facilitating C-C and C-X (N, O, S) bond formations, thus demonstrating its efficacy in synthesizing complex molecules. Vitamin B1 exhibits versatility in these reactions, functioning as both an organocatalyst as well as a co-catalyst or ligand with other metal catalysts. The review also delves into the application of thiamine diphosphate-dependent enzymes as catalysts in organic reactions, drawing inspiration from natural enzymatic processes. Additionally, the mechanistic intricacies of thiamine-catalyzed reactions and the roles of co-catalysts or additives are thoroughly examined, providing insights into reaction pathways and facilitating informed catalyst design strategies.

Photoinduced Ordered Growth of Copper-Doped Polyaniline Nanotubes: A Method to Improve the Catalytic Activity for C-N Coupling Reactions.

Polyaniline-supported metal nanoparticles (M@PANIs) have been widely employed as catalysts for organic reactions. Traditionally, the catalytic activities of the materials can be improved by introducing functional groups onto the aniline monomers, but it may enhance the catalyst cost and reduce the production yield of the material. This work reports a new strategy for improving the catalytic activity of M@PANIs. It was found that induced by visible light in the presence of a polymeric carbon nitride catalyst and copper dopant, the oxidative polymerization of simple aniline occurred slowly and orderly to produce the copper-doped polyaniline nanotubes. The unique tubular structure protected the catalytically active Cu(I) inside and endowed even more sufficient contact of the catalytic sites with reactants so that the material exhibited excellent catalytic performances in C-N coupling reactions.

Recent Developments in the Use of Spinel Ferrite Nanoparticles as Catalysts in Organic Reactions

Recent Developments in the Use of Spinel Ferrite Nanoparticles as Catalysts in Organic Reactions

Magnetic Aerogels for Room-Temperature Catalytic Production of Bis(indolyl)methane Derivatives.

The potential of aerogels as catalysts for the synthesis of a relevant class of bis-heterocyclic compounds such as bis(indolyl)methanes was investigated. In particular, the studied catalyst was a nanocomposite aerogel based on nanocrystalline nickel ferrite (NiFe2O4) dispersed on amorphous porous silica aerogel obtained by two-step sol-gel synthesis followed by gel drying under supercritical conditions and calcination treatments. It was found that the NiFe2O4/SiO2 aerogel is an active catalyst for the selected reaction, enabling high conversions at room temperature, and it proved to be active for three repeated runs. The catalytic activity can be ascribed to both the textural and acidic features of the silica matrix and of the nanocrystalline ferrite. In addition, ferrite nanocrystals provide functionality for magnetic recovery of the catalyst from the crude mixture, enabling time-effective separation from the reaction environment. Evidence of the retention of species involved in the reaction into the catalyst is also pointed out, likely due to the porosity of the aerogel together with the affinity of some species towards the silica matrix. Our work contributes to the study of aerogels as catalysts for organic reactions by demonstrating their potential as well as limitations for the room-temperature synthesis of bis(indolyl)methanes.

The untold story of starch as a catalyst for organic reactions.

Starch is one of the members of the polysaccharide family. This biopolymer has shown many potential applications in different fields such as catalytic reactions, water treatment, packaging, and food industries. In recent years, using starch as a catalyst has attracted much attention. From a catalytic point of view, starch can be used in organic chemistry reactions as a catalyst or catalyst support. Reports show that as a catalyst, simple starch can promote many heterocyclic compound reactions. On the other hand, functionalized starch is not only capable of advancing the synthesis of heterocycles but also is a good candidate catalyst for other reactions including oxidation and coupling reactions. This review tries to provide a fair survey of published organic reactions which include using starch as a catalyst or a part of the main catalyst. Therefore, the other types of starch applications are not the subject of this review.

Carbon derived from orange peel waste for preparation of benign bimetallic catalyst in organic reactions

In this work, a convenient approach has been applied to discover the potential valorization of biomass waste such as orange peel in which PdCu-based nanostructured systems were synthesized via a one-step in-situ dry-milling approach to obtain the benign bimetallic catalysts with different palladium(Pd) and Copper(Cu) loadings on the orange peel support (Pd1%Cu1%, Pd0.3%Cu0.7%, Pd0.5%Cu0.5%, Pd0.5%Cu1%). Catalytic applications of these new composites were investigated in the Sonogashira-Hagihara coupling reaction as well as the Sonogashira–click reaction sequence to the preparation of substituted 4-aryl-1,2,3-triazoles and reduction of nitroaromatics under mild reaction conditions. Catalytic tests with the four activated carbons catalysts showed that the C@Pd1%Cu1% catalyst was the most active in the Sonogashira-Hagihara coupling reaction compared to the other catalysts. Also, the C@Pd0.5%Cu0.5% catalyst showed the highest catalytic activity in the reduction of 1-chloro-4-nitrobenzene and 4-nitrophenol in comparison with other prepared carbon catalysts.

Efficient heck and Suzuki-Miyaura cross-coupling reactions catalyzed by heterogeneous Pd NPs-decorated porous MOF catalysts under mild conditions

Carbon-carbon coupling reactions are extremely interesting for a variety of applications, including pharmaceuticals and biologically active compounds. In this study, we investigated the utilization of functionalized MIL-101 porous MOF for stabilizing palladium nanoparticles (NPs) and examined their catalytic performance in the cross-coupling reaction of aryl halides with phenylboronic acid and methyl acrylate under mild conditions. To achieve this, MIL-101(Al) was synthesized using a solvothermal method, followed by functionalization with environmentally friendly l-Cysteine (CYS). Subsequently, the MIL-101(Al)-CYS compound was immersed in an ethanolic solution of palladium and stirred overnight. The catalyst exhibited remarkable efficiency (over 90 %) in Suzuki and Heck cross-coupling reactions, demonstrating excellent activity and recyclability. The reactions were conducted in polyethylene glycol 200 (PEG 200), a green reaction medium, at temperatures of 70 °C and 60 °C, with Pd loadings of 0.22 and 0.08 mol%, respectively. MOF-based catalysts, owing to their highly tunable structures and porosity, hold great promise as heterogeneous catalysts in organic reactions.

Mechanochemistry-based liquid-assisted synthesis of hydrophobic Zr-Beta with high metal loading for Meerwein-Ponndorf-Verley reduction

Heteroatom-incorporated zeolite catalysts are critical for biomass utilization and feedstock valorization in green chemistry. Key features are adjustable acidity, high stability, and a tailored range of functionalities. However, an environmentally benign synthesis of zeolites with good crystallinity and especially with high levels of metal substitution into the lattice remains challenging. Here, we propose a mechanochemistry-based liquid-assisted method (MCLA) for Zr-incorporated Beta zeolites that is high yielding, facile and sustainable. Compared with the fluoride-mediated hydrothermal method, crystallization times were considerably shortened so that Si-Beta and Zr-Beta (Si/Zr 100) zeolites can be synthesized within 9 and 15 h, respectively. Using the MCLA route, Beta zeolites with Zr loading up to 10.4 wt% (Si/Zr 12.5) were obtained. The materials have excellent catalytic activity for Meerwein-Ponndorf-Verley reductions with much higher water tolerance compared to Zr-Beta prepared by the post-synthesis method. The hydrophobic nature of the MCLA-synthesized zeolites makes them particularly useful as catalysts for organic reactions.

Biosynthesis of zinc oxide nanoparticles mediated by Strobilanthes hamiltoniana: Characterizations, and its biological applications

Nanoparticles of Zinc oxide (ZnONPs), has a variety of applications such as antibacterial property, water treatment for pollutant removal, and as catalysts for organic reactions etc. and have been synthesized utilizing a variety of approaches, including green synthesis, chemical precipitation, sol–gel, hydrothermal synthesis, and microwave-assisted synthesis. In the present work, easy and economically viable ZnONPs were synthesized utilizing Strobilanthes hamiltoniana (SH) leaf extracts. Phytochemicals form S. hamiltoniana act as agents for reducing and capping the metal oxide ions. A range of analytical and microscopic techniques have been used to investigate the physical and chemical properties of ZnONPs. At 360 ​nm, green synthesized SH-ZnONPs showed robust UV–Vis absorption. The nanosize, shape, and crystalline structure of SH-ZnO NPs were characterized using XRD and electron microscopy techniques. Using SH-ZnO NPs, the photocatalytic activity of textile dyes such as Reactive blue 220 (RB-220), Reactive blue 222A (RB-222A), Reactive yellow 145 (RY-145) and Reactive yellow 86 (RY-86) dyes showed degradation efficiency of 97.3%, 78.57%, 88.88%, and 83.33% after 320 ​min. ZnONPs exhibited remarkable antibacterial effectiveness against bacterial and fungal pathogens using the Minimum inhibitory concentration approach. Their MIC values were calculated, and free radical scavenging experiments showed antioxidant activity. The SH-ZnONPs were validated using HepG2 (IC50) cancerous cells lines and showed promising anti-cancer activity. These results revealed that SH-ZnO NPs had promising benefits that could be utilized as a viable therapeutic candidate.

Synthesis of Azoxy Compounds: from Copper Compounds to Mesoporous Silica-Encaged Ultrasmall Copper Catalysts.

Azoxy compounds have aroused extensive attention due to their unique biological activities, but the chemical synthesis of these compounds often suffers from limitations due to their requirement for stoichiometric oxidants, high costs, and restricted substrate range. Herein, a series of azoxy compounds were constructed via facile coupling reactions by using cost-effective N-methoxyformamide and nitroso compounds over Cu-based catalysts, affording high product yields with excellent tolerance of functional groups. Significantly, the mesoporous silica nanosphere-encapsulated ultrasmall Cu (Cu@MSN) catalyst was developed via a one-pot synthetic method and first used for the synthesis of azoxy compounds. As compared with copper salt catalysts, the Cu@MSN catalyst exhibited remarkably enhanced catalytic activity and superior recycling stability. Such a Cu@MSN catalyst overcame the inherent drawbacks of low activity, fast deactivation, and difficult recycling of traditional metal salt catalysts in organic reactions. This work provides a green and efficient method for the construction of azoxy compounds and also creates new prospects for the application of nanoporous materials confined metal catalysts in organic synthesis.

Ferrite Nanoparticles as Catalysts in Organic Reactions: A Mini Review

Ferrites have excellent magnetic, electric, and optical properties that make them an indispensable choice of material for a plethora of applications, such as in various biomedical fields, magneto–optical displays, rechargeable lithium batteries, microwave devices, internet technology, transformer cores, humidity sensors, high-frequency media, magnetic recordings, solar energy devices, and magnetic fluids. Recently, magnetically recoverable nanocatalysts are one of the most prominent fields of research as they can act both as homogeneous and heterogenous catalysts. Nano-ferrites provide a large surface area for organic groups to anchor, increase the product and decrease reaction time, providing a cost-effective method of transformation. Various organic reactions were reported, such as the photocatalytic decomposition of a different dye, alkylation, dehydrogenation, oxidation, C–C coupling, etc., with nano-ferrites as a catalyst. Metal-doped ferrites with Co, Ni, Mn, Cu, and Zn, along with the metal ferrites doped with Mn, Cr, Cd, Ag, Au, Pt, Pd, or lanthanides and surface modified with silica and titania, are used as catalysts in various organic reactions. Metal ferrites (MFe2O4) act as a Lewis acid and increase the electrophilicity of specific groups of the reactants by accepting electrons in order to form covalent bonds. Ferrite nanocatalysts are easily recoverable by applying an external magnetic field for their reuse without significantly losing their catalytic activities. The use of different metal ferrites in different organic transformations reduces the catalyst overloading and, at the same time, reduces the use of harmful solvents and the production of poisonous byproducts, hence, serving as a green method of chemical synthesis. This review provides insight into the application of different ferrites as magnetically recoverable nanocatalysts in different organic reactions and transformations.

Single Atom and Metal Cluster Catalysts in Organic Reactions: From the Solvent to the Solid

AbstractThe supporting of pre‐formed soluble metal catalysts on solids is a typical methodology to transform soluble but unrecoverable metal complexes into recoverable and reusable solid catalysts. However, this methodology has been barely implemented for ligand‐less, bare single metal atoms (SMAs) and nanoclusters (NCs) in organic synthesis, despite these ultrasmall species can be formed in‐situ during reaction and be the truly catalytic species. The aim of this review is to explore how to speciate active single metal atoms and clusters during homogeneous catalysis (in solution), without ligands, and to prepare them independently, to be transferred to solid supports and catalyze organic reactions. In many cases, the translation to solids gives single atom catalysts (SACs). Supporting of ultrasmall metal aggregates gives more stable, reusable and, sometimes, chemoselective catalysts for representative organic reactions.

Harnessing Protonated 2,2'-Bipyridinium Salts as Powerful Brønsted Acid Catalysts in Organic Reactions.

It is the first time that the readily available protonated 2,2'-bipyridinium salts are used as Brønsted acid catalysts to accelerate a series of organic transformations that included the hydration of aromatic alkynes, etherification of alcohols, cyclotrimerization of aliphatic aldehydes, Ritter reaction, Mannich reaction, Biginelli reaction, preparation of substituted alkenes from alcohols, synthesis of spirooxindole, bisindolylmethane, and noncyclized tetraketone with good to excellent yields. These results strongly suggest that there exists enormous potentiality in the development of the protonated 2,2'-bipyridinium catalytic system.

USING THE METAL ORGANIC FRAMEWORKS (CUOBA) AS A CATALYST FOR REACTION OF 2-ACETYL-1-NAPTHOL AND BENZYL ETHER

This study aimed to synthesize the compound of copper and 4,4'-oxysbisbenzoic acid (CuOBA), analyze its physical and chemical properties and employ it as a heterogeneous catalyst for the C-O coupling reaction of 2-acetyl-1-napthol and benzyl ether. The metal-organic framework material CuOBA was synthesized using the solvothermal method. The physicochemical characteristics of CuOBA were determined by several different analytical techniques, including X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and Fourier transform infrared (FT-IR). CuOBA was used as a heterogeneous catalyst for the coupling reaction of the C-O connection between 2-acetyl-1-napthol and benzyl ether in good yield considering the factors of time, temperature, the concentration of reactants, solvents, and the mass of the catalyst. The results revealed that CuOBA, a catalyst for organic reactions, gave a conversion of 75.57%. The CuOBA catalyst was possible to reuse numerous times in the coupling reaction of 2-acetyl-1-napthol and benzyl ether without noticeable deterioration in catalytic efficiency. The direct esterification to produce 2-acetyl-1-naphthyl benzoate assisted by the CuOBA catalysts has not been reported in the literature before.

Zirconium-Based Catalysts in Organic Synthesis.

Zirconium is a silvery-white malleable and ductile metal at room temperature with a crustal abundance of 162ppm. Its compounds, showing Lewis acidic behavior and high catalytic performance, have been recognized as a relatively cheap, low-toxicity, stable, green, and efficient catalysts for various important organic transformations. Commercially available inorganic zirconium chloride was widely applied as a catalyst to accelerate amination, Michael addition, and oxidation reactions. Well-designed zirconocene perfluorosulfonates can be applied in allylation, acylation, esterification, etc. N-Chelating oganozirconium complexes accelerate polymerization, hydroaminoalkylation, and CO2 fixation efficiently. In this review, the applications of both commercially available and synthesized zirconium catalysts in organic reactions in the last 5years are highlighted. Firstly, the properties and application of zirconium and its compounds are simply introduced. After presenting the superiority of zirconium compounds, their applications as catalysts to accelerate organic transformations are classified and presented in detail. On the basis of different kinds of zirconium catalysts, organic reactions accelerated by inorganic zirconium catalysts, zirconium catalysts bearing Cp, and organozirconium catalysts without Cp are summarized, and the plausible reaction mechanisms are presented if available.

Metal Triflates as Catalysts in Organic Synthesis: Determination of Their Lewis Acidity by Mass Spectrometry.

Metal triflates have shown a large variety of possibilities as catalysts in organic reactions. Some selected examples of their catalytic activity, in particular in C-O and C-C bond formation are presented. A better understanding of the mode of interaction between these Lewis acids and organic functional groups as ligands should allow for an easier choice of a tailored metal cation for a given reaction. Electrospray ionization mass spectrometry enables the characterization and the quantification of the donor/acceptor interactions involved in the catalytic processes. Both gas-phase and solution-phase interactions between various metal triflates and organic functionalities were studied. Based on an original probabilistic model, ligand displacement experiments lead us to establish quantitative affinity scales of ligands toward the metal centers. The main structural effects governing the ranking are identified and discussed.

The Application of Modified SBA-15 as a Chemosensor

: The Santa Barbara Amorphous (SBA-15), with a large surface area covered with abundant Si-OH active groups on the walls of its pores, can be modified with various organic compounds to build organic-inorganic hybrid materials, which can be used as a catalyst in organic reactions, drug delivery systems, nano sorbent due to its high capacity for removing heavy metals in waste water and as chemosensors for ions. Tunable and straight channels of SBA-15 facilitate the entrance and diffusion of ions through the channels. This paper presents a review of the past five years of literature covering the application of SBA-15 as an ions chemosensor in the liquid and gaseous media.

Superparamagnetic Poly(aniline-co-m-phenylenediamine)@Fe3O4 Nanocomposite as an Efficient Heterogeneous Catalyst for the Synthesis of 1H-pyrazolo[1,2-a]pyridazine-5,8-diones & 1H-pyrazolo[1,2-b]phthalazine-5, 10-diones Derivatives.

The use of polymer-based catalysts has increased because of their high potential application as an effective catalyst in organic reactions. They have benefits such as high efficiency and reactivity, simple separation, and safety compared to other heterogeneous catalysts. The objective of the current research is to prepare solid polymer-based catalysts, poly(aniline-co-m-phenylenediamine) (PAmPDA), and its superparamagnetic nanocomposite. Then, the catalytic activity of the resulting superparamagnetic nanocomposite was investigated in the synthesis of 1H-pyrazolo[1,2-b]phetalazine-5,10-diones and 1H-pyrazolo[1,2-a]pyridazine-5,8-dione derivatives. A series of some 1H-pyrazolo[1,2-b]phetalazine-5,10-diones and 1H-pyrazolo[1,2-a]pyridazine-5,8-dione derivatives was tested for its antibacterial properties against the Staphylococcus aureus and E. coli bacteria. PAmPDA copolymer was synthesized in a 1:2 molar ratio of Ani to mPDA via radical oxidative polymerization at room temperature. Superparamagnetic PAmPDA@Fe3O4nanocompo-site was synthesized from a mixture of Fe(II), Fe(III) solution, and PAmPDA copolymer via the in-situ co-precipitation technique. 1H-pyrazolo[1,2-b]phetalazine-5,10-diones were synthesized via one-pot three-component condensation reaction of Phthalhydrazide, aromatic aldehyde derivatives, and malono-nitrile in the presence of PAmPDA under solvent-free conditions at 80 °C. The synthesis of 1H-pyrazolo[1,2-a]pyridazine-5,8-dione derivatives was carried out via a one-pot three-component condensa-tion reaction of maleic hydrazide, aromatic aldehyde derivatives, and malononitrile in the presence of PAmPDA under reflux conditions at EtOH/H2O 1:1. The antibacterial activity of some derivatives was tested against Gram-positive and Gram-negative bacteria. First, superparamagnetic PAmPDA@Fe3O4 nanocomposite was synthesized and characterized successfully, and then the resulting nanocatalyst was used for the synthesis of pyrazolo[1,2-b]phthalazine and pyrazolo[1,2-a]pyridazine. We obtained the maximum yield of the desired 1H-pyrazolo[1,2-b]phthalazine-5,10 dione derivatives with 0.05 g of catalyst at 80°C, under solvent free conditions, whereby the reaction was complete within 30 min. A wide range of 1H-pyrazolo[1,2-b]phthalazine-5,10 dione derivatives were synthesized in good to excellent yield. On the other hand, pyrazolo[1,2-a]pyridazine derivative was synthesized successfully in high yield using PAmPDA as a nanocatalyst. The antibacterial activity of some derivatives, according to the data (inhibition zone%), showed good ac-tivity against Staphylococcus aureus and E. coli. In this research, PAmPDA was used for mild preparation of 1H-pyrazolo [1,2-a]pyridazine-5,8-diones & 1H-pyrazolo[1,2-b]phetalazine-5,10-diones derivatives with excellent yields and short reac-tion times. The attractive features of this protocol are simple procedure, cleaner reaction, and the use of recyclable nanocatalyst. Satisfactory yields of products and easy workup make this a useful protocol for the green synthesis of this class of compounds. The antibacterial activity of some derivatives, according to the data (inhibition zone%), showed good activity against Staphylococcus aureus and E. coli.