Magnetic Nanocatalyst Research Articles

Infusion of Magnetic Nanocatalyst to Microwave Propped Synthesis of Bioactive Azaheterocycles

Abstract: Microwave-assisted synthesis is a powerful tool in organic chemistry, providing a rapid and efficient method for the synthesis of bioactive heterocycles. The application of micro-waves significantly reduces reaction times and increases percentage yields with high purity of the final product. To make the synthetic protocol greener, the application of the magnetic nanocata-lyst is a rapidly growing area of interest nowadays. Magnetic nanocatalyst, with its unique fea-tures like magnetic separable facile recovery from the reaction media heterogeneously, makes the overall synthetic strategy cleaner, faster, and cost-effective. Aiming this, in the present review, we will focus on the infusion of Magnetic nanocatalyst to microwave-assisted synthesis of vari-ous classes of azaheterocyclic compounds, including pyridines, pyrimidines, quinolines, and ben-zimidazoles. The synthetic methodologies involved in the preparation of these heterocycles are highlighted, along with their biological activities. Furthermore, in this review, the most recent and advanced strategies to incorporate nanocatalysts in the microwave-assisted synthesis of nat-ural products containing azaheterocyclic moieties in drug discovery programs are elucidated in detail, along with the incoming future scope and challenges.

Enhanced conversion of non-edible Jatropha oil to biodiesel utilizing highly reusable Mg decorated CoFe2O4 nanocatalyst: Optimization by RSM

This paper aims to develop a novel and efficient magnetic nanocatalyst for producing biodiesel from Jatropha oil. Therefore, Mg@CoFe2O4 nanocomposite as a retrievable, and strong catalyst was synthesized and employed for transesterification of Jatropha oil. After that, various analyzes were employed for characterizing Mg@CoFe2O4 nanocomposite, including XRD, Raman, FTIR, FESEM, EDX, CO2/TPD, BET, VSM, and TEM. These analyzes confirmed that Mg was successfully decorated on CoFe2O4. Response surface methodology (RSM) was employed to optimize efficient variables on biodiesel generation. The utmost biodiesel efficiency utilizing CoFe2O4 and Mg@CoFe2O4 nanocatalysts were 93.99 % and 95.49 %, respectively, which are obtained at ultrasonication time of 32.21 and 33.96 min, respectively. These biodiesel yields indicate the extraordinary efficiency of both nanocatalysts. Also, Mg@CoFe2O4 indicated a high biodiesel yield (i.e., 87.43 %) after seven reuse steps, indicating the remarkable reusability of this nanocatalyst. The thermodynamics and kinetics of transesterification showed that the biodiesel generation reaction is endothermic and the reaction speed enhanced with enhancing temperature. Moreover, decoration of CoFe2O4 with Mg led to improved catalytic performance and boosted biodiesel yield. Overall, the Mg@CoFe2O4 nanocatalyst is strongly recommended for future investigation owing to its excellent biodiesel performance, short reaction time, and extraordinary reusability of the catalyst.

CuCoFe2O4@AC magnetic nanocomposite as a novel heterogeneous Fenton-like nanocatalyst for Ciprofloxacin degradation from aqueous solutions

CuCoFe2O4@Activated Carbon (AC) was synthesized by a fast, simple, and green microwave-assisted coprecipitation method, and then used as a new heterogeneous magnetic nanocatalyst in Fenton-like reaction for ciprofloxacin (CIP) degradation from aqueous media. CuCoFe2O4@AC was characterized by Field emission scanning electron microscopy (FE-SEM), Energy-Dispersive Spectroscopy (EDS), Mapping, Line scan, Fourier-transform infrared spectroscopy (FT-IR), Thermal gravimetric analysis (TGA), X-Ray diffraction analysis (XRD), vibrating-sample magnetometer (VSM), and Brunauer–Emmett–Teller (BET) techniques. The characterization results showed that the CuCoFe2O4@AC nanocomposite was in the ferrite phase with a mesoporous, uniform, quasi-spherical surface and a particle size of about 25 nm. The total volume of single-point adsorption pores was equal to 0.22 cm3 g−1 and the specific surface area was determined to be 199.54 m2 g−1. This nanocomposite had good thermal stability with high magnetic strength. In the presence of H2O2, the synthesized nanocomposite provided a Fenton-like reaction for CIP removal from aqueous solutions. The investigation of this process showed that neutral pH, 1 g L−1 of the nanocomposite, and 73.5 mM of H2O2 were the optimal conditions for CIP removal with an initial CIP concentration of 20 mg L−1. The maximum removal efficiency of 95.77% was attained after 120 min of contact time under the optimum conditions. The CIP degradation during this Fenton-like process followed a pseudo-first-order kinetic model with rate constants (Kapp) of 0.01 min−1. Finally, the CIP removal efficiency after 5 cycles of recovery and regeneration of CuFe2O4@AC was 87.65%. The excellent performance and high catalytic activity of CuCoFe2O4@AC in Fenton-like reaction for CIP removal make it have potential application foreground in the treatment of pharmaceutical wastewater.

An experimental and theoretical investigation of corrosion inhibitive behaviour of 4-amino antipyrine and its schiff’s base (BHAP) on mild steel in 1 M HCl solution

Corrosion inhibitive behaviour of 4–aminoantipyrine (AAP) and its Schiff base 4 – ((4–bromo-2–hydroxybenzylidene)amino)–1,5–dimethyl–2–phenyl–1H–pyrazole–3(2H)-one (BHAP) derived from 4–aminoantipyrine and 4-bromosalicylaldehyde has been investigated on mild steel specimen in 1 M HCl solution using potentiodynamic polarisation (PDP), EIS (electrochemical impedance spectroscopy). The AAP and BHAP compounds were synthesized by green, eco-friendly magnetic nanocatalyst, which can be further reused. Moreover, the previously reported catalysts are inorganic which are hardly degraded, while organic compound-based corrosion inhibitors are biocompatible. SEM (scanning electron microscopy) micrographs and Gravimetric measurement (weight loss) indicate that the rate of corrosion decreases with an increase in the concentration of inhibitor. The obtained result shows that 200 ppm BHAP has a maximum efficiency of 93.9%, while AAP has a slightly lower efficiency of 81%. The adsorption of BHAP on a mild steel surface followed the Langmuir adsorption isotherm and was found to involve chemisorption. Further insight into the mechanism of interaction of BHAP molecules with mild steel was obtained by Density Functional Theory (DFT).

Ultrasound assisted Sono-Fenton process including FeMnO3 nanocatalysts for degradation of phenazopyridine

This study describes the synthesis of FeMnO3 magnetic nanocatalysts using a hydrothermal method. The nanocatalysts were used to degrade phenazopyridine hydrochloride (PhP) through the Sono-Fenton method, an advanced oxidation technique. The fabricated FeMnO3 nanocatalysts underwent various characterization techniques, including field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometry (VSM), and Brunauer Emmett Teller (BET) analysis. Based on the XRD pattern and FE-SEM images, the cubic crystal structure and particle uniformity were confirmed. The catalytic performance of FeMnO3 nanocatalysts was examined in terms of their ability to remove PhP. Additionally, the impact of various parameters on the degradation rate of phenazopyridine was investigated. The optimal values for pH, nanocatalyst dosage, H2O2 concentration, and sonication time were found to be 10, 1 g/L, 1.2 mol/L, and 30 min, respectively. The degradation efficiency was eventually found to be 97 %. The most significant advantages of these nanocatalysts include their reusability without any significant decrease in reaction efficiency, rapid reaction time, ease of synthesis, and lack of requirement for complex systems.

Development of nanostructured catalysts for catalytic oxidative water purification from organic impurities, including phenolic compounds

The purpose of this work was to create magnetic nanocatalysts that could be used for the oxidation of organic water pollutants – phenol and its derivatives – and to determine the physicochemical characteristics of the catalysts. The development of such active nanocomposite catalysts would solve the environmental problem in the Republic of Kazakhstan in the field of wastewater treatment from organic impurities, including phenols, and would also contribute to the subsequent creation of domestic production of oxygen-containing compounds, since almost the entire spectrum of oxygen-containing compounds for various industries is imported into the Republic. Nanosized magnetic composites based on Fe and Co were obtained by chemical deposition, in some cases, using polyethyleneimine and polyvinylpyrrolidone. It was shown that the interaction between nanoparticles and the polymer takes place in the case of a CoFe2O4 catalyst stabilized with polyvinylpyrrolidone or polyethyleneimine, which may indicate the efficient formation of nanocomposites. According to the IR study, for the CoFe2O4 nanocomposite stabilized with polyvinylpyrrolidone, the absorption bands at 735, 663, 649, 626 cm–1 are natural vibrations for the composite nanoparticles embedded in a polyvinylpyrrolidone matrix. The synthesized nanocomposites were tested in the oxidation of phenol with oxygen. The results demonstrate that the catalysts are promising both for the purification of industrial wastewater from phenol and for the synthesis of oxygen-containing compounds in the liquid phase under mild conditions.

A magnetic catalytic substrate based on Fe/Pd nanoparticles and vanillin-functionalized κ-carrageenan for quick Suzuki–Miyaura coupling reactions

A novel magnetic nanocatalyst was prepared by functionalization of κ-carrageenan (Car) natural polymer with vanillin linker (Van) and then immobilization of palladium nanoparticles (Pd NPs) on it utilizing a facile approach. The analytical characterization of the prepared Fe3O4@Car/Van-Pd catalyst was carried out through appropriate analyses. Applying the prepared Pd-containing nanocomposites in Suzuki − Miyaura cross-coupling reactions exhibited privileges, such as enhanced thermal stability up to 450 °C, low toxicity, and insensitiveness to moisture and oxygen. However, this nanocatalyst presented many remarkable characteristics, such as excellent dispersion of spherical Pd NPs on the Fe3O4@Car/Van support and short-time catalysis of the biphenyl derivatives with exceptional yields. The prepared nanocatalyst exhibited 97.0 ± 0.32% Suzuki − Miyaura cross-coupling reaction yield after 12 min at ambient temperature and pH of 9.0 by applying only 0.01 g of the catalyst. The heterogeneous Fe3O4@Car/Van-Pd magnetic nanocomposite with superparamagnetic behavior (Ms = 30.9 emu g−1) was collected using an external magnet with convenience. Besides, the catalytic activity of this magnetic nanocatalyst was preserved even after ten reaction cycles without any considerable catalytic performance decrease. Moreover, applying a natural polymeric substrate, the cost-effectiveness, the raw materials availability, good thermal stability, convenient magnetic recovery, simplicity in operation, and high reaction yields are beneficial parameters that make the Fe3O4@Car/Van-Pd heterogeneous catalyst superior to other catalysts.

Immobilization of Ionic Liquid–Triethanolammonium Bicarbonate on Magnetic Nanoparticles as an Efficient Catalyst for Knovenegel Condensation

In this paper, a new nano-magnetic catalyst has been synthesized by immobilization of ionic liquid triethanolammonium bicarbonate with modified Fe3O4 NPs ([Fe3O4@Si-(CH2)3-TEA] [HCO3]). After, its characterization by different techniques such as FT-IR, XRD, FE-SEM, and EDX, it was used as an efficient catalyst for the knovenegel condensation. The protocol has a number of advantages which is including the ease of purification, recyclable by an external magnet, high yields (85-95% and time (15-50 min), the reusability of the catalyst (at least 5 times without reducing the catalytic activity), its high thermal and chemical stability, and its high selectivity and efficiency.

A new green system of biogenic Ni/DFNS@Pd nanoparticles for the production of 2-oxo-2-phenylethylbenzoate and cyclic carbonates by using the oxidative carboxylation of alkenes

In this paper, we report highly atom-selective and efficacious oxidation of styrenes with carbon dioxide to cyclic carbonates in the appearance of Ni/[email protected] as a magnetic nanocatalyst (MNPs). For convenient detachment of the catalyst by an exterior magnetic domain, the dendritic fibrous nanosilica (DFNS) outer layer was covered with nickel to magnetize the DFNS. Then, the palladium nanoparticles on the outer layer of Ni/DFNS were diminished. In spite of the possibility of using these biological processes in the sustainable recapturing of vital metals (e.g. Pd), the catalytic function of biosynthesised MNPs has not yet been scrutinized. Here, instead of a chemical approach, microorganisms were utilized as catalysts for the generation of Pd nanoparticles in a biological procedure. These biogenic magnetic nanoparticles have been utilized for the first time as a reusable catalyst with an exterior magnet. The catalyst’s attributes were distinguished by a variety of methods, including scanning electron microscopy (SEM), energy dispersive X-ray (EDX), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), and vibrating sample magnetometer (VSM) analyses. Biogenized Ni/[email protected] was generated as a heterogeneous catalyst to compete with a homogeneous structure. This robust metal catalyst with great accessibility level and reusability was generated by anaerobic bacteria. Examining different concentrations of the catalyst showed that the selectivity and efficiency of the reaction are significantly affected by the concentration of the catalyst. Heterogeneous reaction compounds did not cause any negative effects. The products were eliminated from the catalyst without any problems and the catalyst was employed many times without a conspicuous loss in selectivity and activity.

Highly active novel K2CO3 supported on MgFe2O4 magnetic nanocatalyst for low-temperature conversion of waste cooking oil to biodiesel: RSM optimization, kinetic, and thermodynamic studies

An innovative K2CO3/MgFe2O4 (KC/MGF) magnetic nanocatalyst for effective biodiesel generation from WCO is demonstrated here. To examine the physiochemical and morphological features of the catalyst, several characterization methods such as XRD, FT-IR, SEM-EDX, HR-TEM, AFM, XPS, BET, CO2-TPD, and VSM are used on the as-synthesized magnetic nanocatalyst. Optimization of K2CO3 loading on MgFe2O4 is achieved and 30KC/MGF was found as the optimum ratio. Response surface methodology (RSM) via central composite design (CCD) is constructed using optimization margins to clarify the optimal parametric conditions; catalyst loading (4–6 wt%), reaction time (90–120 min), and methanol to oil ratio (6:1–9:1) at a fixed low operating reaction temperature (50 ºC). The obtained optimum reaction conditions are 4.4 wt% catalyst loading, 108 min reaction time, 6.6:1 methanol to oil ratio, at 50 ºC achieving ca. 92.9% biodiesel conversion. 30KC/MGF is an energy-conserving magnetic nanocatalyst with excellent basicity that operates at low temperatures, for a markedly short period of time, and with a low methanol-to-oil molar ratio. Kinetics and thermodynamic parameters are estimated i.e., activation energy (Ea), change of enthalpy of activation (ΔH#), and change of entropy of activation (ΔS#) to be 31.5 kJ mol−1, 28.9 kJ mol −1, and −188.8 J mol−1 K−1, respectively. Gibbs free energy (ΔG#) is appraised at 308, 313, and 318 K to be 87.1, 88, and 88.9 kJ mol−1, respectively. Due to K+ leaching, utilizing 30KC/MGF in sequential runs results in a significant activity plummet. The catalyst activity is recovered by re-impregnation with K2CO3 precursor solution, resulting in the same high FAME conversion as fresh 30KC/MGF. Finally, the physicochemical properties of biodiesel are investigated and determined to be compliant with international American and European standards.

An efficient and sustainable Pd‐nanomagnetic heterogeneous catalyst for the reduction of nitroarene and environmental pollutant

This study reports the synthesis and characterization of an environmentally friendly, cost‐effective, and sustainable Pd‐heterogeneous catalyst anchored on superparamagnetic silica‐coated iron oxide. The synthesized Pd‐SB/MNP nanomagnetic catalyst was extensively characterized using Fourier transform infrared (FTIR), inductively coupled plasma optical emission spectroscopy (ICP‐OES), X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), energy‐dispersive spectrometry (EDS), vibrating sample magnetometry (VSM), field emission scanning electron microscopy (FE‐SEM), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET), and high‐resolution transmission electron microscopy (HR‐TEM). The Pd‐SB/MNP catalyst showed remarkable efficiency in catalyzing the reduction of nitroarene and Cr(VI) under mild reaction conditions using an eco‐friendly solvent. The catalyst exhibits facile recovery through external magnetization, enabling its efficient recycling and reutilization for at least 10 cycles while demonstrating minimal Pd loss, as confirmed by rigorous hot filtration testing and ICP‐OES analysis. These results comply with the industry's prescribed thresholds for permissible levels of residual metallic content. The results suggest that the synthesized Pd‐SB/MNP catalyst holds great potential for various industrial applications.

Magnetite dopamine‐decorated copper (Fe3O4@PDA/CuCl2): A robust and reusable catalyst for promoting green synthesis of benzimidazoles and benzothiazoles

A one‐pot and efficient catalytic protocol has been developed to synthesize pharmaceutically critical 2‐substituted benzimidazoles and benzothiazoles using magnetite dopamine‐supported copper nanoparticles (Fe3O4@PDA/CuCl2) as a heterogeneous catalyst. This selective transformation proceeds via oxidative cross‐coupling of readily available benzylic amines witho‐phenylenediamine/2‐aminothiophenol. This one‐pot green method proceeds smoothly, under mild conditions, avoids the usage of toxic metals, tolerates a variety of functionalities, and is amenable to gram scale. Furthermore, this easy‐to‐prepare magnetic nanocatalyst can be separated by magnetic decantation after the reaction, thereby making it more sustainable.

CoFe2O4@SiO2–NH2@MOF-5 magnetic nanocatalyst for the synthesis of biologically active quinazoline derivatives

Metal-organic frameworks (MOFs) offered excellent catalytic activity due to their superior porosity, and high densities of catalytic sites in remarkable specific surfaces. In this research, we prepared a magnetic nanocomposite based on MOF-5 which is one of the prominent and practical structures that have been reported in many applications, and investigated the advantages of it as a catalyst. The multi-functional catalyst was prepared in five steps including (1) preparation of cobalt ferrite nanoparticles (CoFe2O4), (2) surface modification of cobalt ferrite using tetraethyl orthosilicate, (3) surface functionalization using 3-aminopropyl triethoxysilane, (4) preparation of MOF-5, (5) preparation of CoFe2O4@SiO2–NH2@MOF-5 nanocomposite. The resulting catalyst was evaluated by FTIR, FESEM, EDX, XRD, and VSM analyses. The CoFe2O4@SiO2–NH2@MOF-5 nanocomposite was applied as a catalyst for the quinazoline derivatives' synthesis. Various products were prepared with significant yields (90–98%) in short reaction times (20–60 min) without difficult work-up. In addition, the magnetic behavior of the catalyst allows it to be collected and recycled by a magnet and applied for six consecutive cycles without significantly reducing its efficiency. Quinazoline derivatives showed significant biological activities so their antioxidant activity was between 23.7% and 88.9% and their antimicrobial activity was in contradiction of E. coli, S. enterica, L. monocytogenes, S. aureus, and E. faecalis.

Ni3Fe@N-doped carbon nanotubes 3D network induced by nanoconfined symmetry breaking for high-performance microwave absorption, corrosion protection, and pollutant purification

It remains challenging to develop multifunctional electromagnetic wave (EMW) absorbers with anti-corrosion and pollutant purification capabilities suitable for extremely harsh ocean environments. This study exploits symmetry breaking to construct a three-dimensional (3D) network of bamboo-like N-doped carbon nanotubes (NCNT) encapsulated with magnetic Ni3Fe nanocatalysts via facile coordination and catalytic chemical vapor deposition process. The resulting Ni3Fe@NCNT composite demonstrates outstanding EMW absorption performance, anti-corrosion behavior, and adsorption purification function. Its excellent EMW absorption performance, including a minimum reflection loss of −57.3 dB and a maximum effective absorption bandwidth of 6.0 GHz, is achieved by magnetic-dielectric match, inert space platform, and porosity architecture. The Ni3Fe@NCNT composite also shows corrosion resistance and self-cleaning function simultaneously because of the physical shield provided by the intrinsically impermeable, inert NCNT shells and their considerable chemically active site and high porosity. For the first time, the EMW absorber is endowed with cooperative multi-functionalities. Our findings may pave the way to manufacture versatile EMW materials for applications in complicated environments.

Robust, magnetic, and effective Pd-based nanocatalyst for reduction of toxic hexavalent chromium and nitrophenols

A serial of magnetic and robust nanocatalysts of Pd nanoparticles with a mean size of 4 nm evenly supported on N-doped porous carbon with Co wrapped (Co-NC) were fabricated by a facile route at room temperature. Among these, 18 %Pd/Co-NC has regular morphology and exhibits the highest activity towards reduction of Cr (VI) with HCOOH and nitrophenols with NaBH4 in aqueous solution. What is more, 18 %Pd/Co-NC has a higher catalytic activity than that of 20 % commercial Pd/C towards the reduction of Cr(VI). The excellent performance may be due to the Pd nanoparticles of small size, uniform dispersion on Co-NC, large BET surface area, abundant active sites, nitrogen doping, and synergetic effect between Pd and the support of Co-NC. The introduction of Co nanoparticles to the support not only provides magnetism but also may prevent the oxidation of Pd, thus facilitating the separation of the catalyst from the solution and providing more active Pd species to catalyze the reduction reaction. The catalyst can be separated easily by an external magnet and remain the activity without obvious decline after the recycling experiment, indicating the catalyst has a good stability in acidic or basic solution. What is more, K2Cr2O7 can be catalytically reduced by Pd/Co-NC in an industrial environment, confirming the catalyst has a potential application in the remediation of industrial wastewater.

Immobilization of Ag nanoparticles on NiFe2O4@TiO2@PDA: Multifunctional catalytic action toward the reduction of 4-Nitrophenol and photodegradation of methylene blue and ciprofloxacin

Freshwater, an essential commodity of life, is under threat by the presence of pernicious chemicals, such as 4-nitrophenol (4-NP), organic azo dyes, and colorless antibiotic pollutants, leading to water pollution. It is an absolute necessity to transform these pernicious chemicals into benign compounds to mitigate water pollution and safeguard life on Earth. One such effort in the current work is the development of a recyclable, multifunctional, and heterogeneous NiFe2O4@TiO2@PDA-Ag magnetic nanocatalyst for the reduction of 4-NP to 4-aminophenol (4-AP) and the photocatalytic degradation of methylene blue (MB) (an organic azo dye) and ciprofloxacin (CIP) (a colorless antibiotic pollutant) under irradiation with direct sunlight. Characterization of the developed catalyst was achieved using various spectroscopic and analytical methods (XRD, FTIR & UV–Vis spectroscopy, SEM, TEM, and XPS). The visible light active nature of the catalyst was confirmed by our UV–Vis spectroscopic data. The reduction of 4-NP to 4-AP with 97% conversion was achieved using the catalyst at room temperature in an aqueous medium in the presence of sodium borohydride (NaBH4) at a rate constant of 0.462 min−1. The photocatalytic degradation of MB and CIP was achieved using the catalyst under irradiation with direct sunlight, in which 96.5 and 68% degradation was observed with a degradation rate constant of 0.0483 and 0.0750 min−1 respectively. The presence of a magnetic NiFe2O4 core in the catalyst enables its recovery with the aid of the external magnet, its reusability was assessed and exhibited good efficacy up to five cycles. The magnetic nature of the catalyst was confirmed using vibrating sample magnetometry (VSM). The synthesis of a sole reusable magnetic catalyst suitable for the removal of three toxic pollutants under normal conditions adopting a facile methodology with excellent activity up to five cycles is rare and thus, the findings from the present work provide helpful information in wastewater treatment.

Optimization of microreactor-assisted transesterification for biodiesel production using bimetal zirconium-titanium oxide doped magnetic graphene oxide heterogeneous nanocatalyst

The application of novel heterogeneous catalyst materials with unique physicochemical properties for the production of biodiesel can increase the sustainability of the process. In this study, a novel heterogeneous nanocatalyst (NCT) was developed and improved using a microreactor for biodiesel production from used cooking oil (UCO). The NCT was developed based on double-layered bimetal titanium-zirconium oxide nanoparticles (NPs) incorporated over magnetic graphene oxide (ZrO2-TiO2@MGO) using a simple hydrothermal method. The physiochemical morphology of newly developed NCT materials of ZrO2-TiO2 NPs and ZrO2-TiO2@MGO was investigated using FESEM, FTIR, VSM, XRD, and EDX. The effects of several independent variables, including residence duration (60–180 s), oil/methanol molar ratio (1–3), and catalyst concentration (1–5 wt.%) on biodiesel production yield were optimized. The optimum reaction conditions in the microreactor-intensified transesterification process were the ZrO2-TiO2@MGO concentration of 4.75 wt.% (oil-based), reaction duration of 180 s, and oil/ methanol ratio of 2.33. The designed microreactor-assisted ZrO2-TiO2@MGO provided a conversion rate of 99.32%. Consequently, the results revealed that the microreactor effectively shortens the transesterification time while producing a high rate of biodiesel.

Fabrication of Fe3O4-Bis(Py-Imine)-PdCl2 Nanocomposite as a Highly Active Nanomagnetic Catalyst for Carbonylative Suzuki Reactions of Phenylboronic Acid with Aryl Iodides and Mo(CO)6

In the research work, a novel and recoverable nanomagnetic pallidum catalyst [Fe3O4-Bis(Py-Imine)-PdCl2 ] based on the immobilization of Pd on the surface of magnetic Fe3O4 nanoparticles modified with picolylamine as ligand was designed and fabricated. The structure of the as-fabricated Fe3O4-Bis(Py-Imine)-PdCl2 nanocatalyst was characterized by FT-IR spectroscopy, SEM, TEM, EDX, ICP-OES, TGA, VSM, XRD and EDX mapping techniques. The Fe3O4-Bis(Py-Imine)-PdCl2 nanocomposite demonstrated the high activity in the preparation of diaryl ketones through one-pot three-component Suzuki reactions of phenylboronic acids with aryl iodides and Mo(CO)6. The recycling of the Fe3O4-Bis(Py-Imine)-PdCl2 catalyst was examined in the coupling of phenylboronic acid with 4-methyl iodobenzene and Mo(CO)6; the results revealed that this catalyst could be reused for more than 6 consecutive runs without a loss of activity. This method offers several remarkable features, such as high yield of products, simplicity of separation of products from catalysts, performing reactions in green solvent and mild conditions, ability to recycle and reusing the catalyst without significant reduction in its catalytic activity.

Preparation of Fe3O4@Carrageenan-Metformin nanoparticles as a new bio-inspired magnetic nanocatalyst for the synthesis of dihydropyrano[2,3-c]pyrazoles

k-Carrageenan (Carr) is a significant constituent of red seaweeds with benign nature and easy modification due to available sulfate and hydroxyl functionalities. The current work illustrates the preparation and catalytic application of a magnetic nanocatalyst based on k-carrageenan. The Fe3O4@Carr-Met was prepared by coating magnetic Fe3O4 nanoparticles with Carr and metformin (Met). The successful synthesis of the catalyst was verified by different techniques. These nanoparticles showed excellent activity for the synthesis of dihydropyrano[2, 3-c] pyrazoles. The synergistic effect of sulfonic acid and amino groups may account for the catalytic activity of these nanoparticles. Moreover, Fe3O4 core provides effective magnetic separation. The ease of catalyst preparation, use of a benign solvent system, enhanced activity, and reusability are some of the prominent advantages of the present catalyst. The heterogeneity of Fe3O4@Carr-Met nanoparticles was also supported by a hot filtration test under optimal reaction conditions that confirmed the integrity of these nanoparticles.

Copper triazole complex supported on Fe3O4@SiO2 nanoparticles as eco‐friendly nanocatalysts in solvent‐free Biginelli reaction

In this work, a new heterogeneous catalyst based on 1,2,3‐triazole complex of copper supported on core–shell Fe3O4@SiO2 nanoparticles was designed and characterized by using several methods such as infrared spectroscopy (FTIR), X‐ray diffraction (XRD), thermogravimetry analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy‐dispersive X‐ray spectroscopy (EDX). The magnetic nanocatalyst was successfully employed for the synthesis of different functionalized 3,4‐dihydropyrimidin‐2(1H)‐ones/thiones by a one‐pot multicomponent condensation reaction under solvent‐free conditions. Among the advantages of the developed catalytic protocol are the high yields, short reaction times, ecofriendly, easy workup and purification conditions.