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In this work, a Pd(II)-C,N-cyclometalated complex was grafted to polysiloxanes via azide–alkyne cycloaddition. The obtained polymer–metal complex (Pd-PDMS) acts as a catalyst in the Suzuki–Miyaura reaction. Pd-PDMS was drop-casted onto a carbon fiber support, and the resulting membrane demonstrated catalytic activity in the cross-coupling reaction without yield loss after several catalytic cycles. The catalytic membrane allows for easy catalyst recycling and provides ultra-low palladium levels in Suzuki–Miyaura reaction products. [ABSTRACT FROM AUTHOR]

The design and synthesis of polyhedra using coordination‐driven self‐assembly has been an intriguing research area for synthetic chemists. Metal‐organic polyhedra are a class of intricate molecular architectures that have garnered significant attention in the literature due to their diverse structures and potential applications. Hereby, we report Cu‐MOP, a bifunctional metal‐organic cuboctahedra built using 2,6‐dimethylpyridine‐3,5‐dicarboxylic acid and copper acetate at room temperature. The presence of both Lewis basic pyridine groups and Lewis acidic copper sites imparts catalytic activity to Cu‐MOP for the tandem one‐pot deacetalization‐Knoevenagel/Henry reactions. The effect of solvent system and time duration on the yields of the reactions was studied, and the results illustrate the promising potential of these metal‐organic cuboctahedra, also known as nanoballs for applications in catalysis. [ABSTRACT FROM AUTHOR]

The hydrocarboxylation of styrene in the presence of PdCl2(PPh3)2 was studied to investigate the influence of the nature of the solvent, promoters, and reaction conditions on the yield of the target 2-phenylpropionic acid. Cation exchange resins Amberlyst 15 and KU-2 were proposed as suitable alternatives to liquid acid promoters, making it possible to achieve a high catalytic activity with up to 99% regioselectivity. [ABSTRACT FROM AUTHOR]

Asparaginyl ligases have been extensively utilized as valuable tools for site-specific bioconjugation or surface-modification. However, the application is hindered by the laborious and poorly reproducible preparation processes, unstable activity and ambiguous substrate requirements. To address these limitations, this study employed a structure-based rational approach to obtain a high-yield and high-activity protein ligase called OaAEP1-C247A-aa55-351. It was observed that OaAEP1-C247A-aa55-351 exhibits appreciable catalytic activities across a wide pH range, and the addition of the Fe3+ metal ion effectively enhances the catalytic power. Importantly, this study provides insight into the recognition and nucleophile peptide profiles of OaAEP1-C247A-aa55-351. The ligase demonstrates a higher recognition ability for the "Asn-Ala-Leu" motif and an N-terminus "Arg-Leu" as nucleophiles, which significantly increases the reaction yield. Consequently, the catalytic activity of OaAEP1-C247A-aa55-351 with highly efficient recognition and nucleophile motif, "Asn-Ala-Leu" and "Arg-Leu" under the buffer containing Fe3+ is 70-fold and 2-fold higher than previously reported OaAEP1-C247A and the most efficient butelase-1, respectively. Thus, the designed OaAEP1-C247A-aa55-351, with its highly efficient recognition and alternative nucleophile options, holds promising potential for applications in protein engineering, chemo-enzymatic modification, and the development of drugs. Asparaginyl ligases have been utilized as valuable tools for protein engineering, such as through site-specific bioconjugation or surface modification, however, their application is limited due to time-consuming preparation processes and unstable activities. Here, the authors develop a truncated protein ligase OaAEP1-C247A-aa55-351 from an OaAEP1-C247A mutant, which simplifies the preparation steps, tolerates a wider pH range, and enhances the catalytic activities by using efficient recognition and nucleophile motifs. [ABSTRACT FROM AUTHOR]

Copper-containing Fe2O3 with g-C3N4 framework (Fe2O3-g-C3N4/Cu(II)) composite is fabricated and its characterization was followed by various analyses. Firstly, the compound MIL-53(Fe) was constructed and utilized as a precursor to generate Fe2O3. Fe2O3-g-C3N4 was prepared by pyrolysis of MIL-53(Fe) material in the presence of urea and KBr at 550 °C and then treated with Cu(NO3)2.3H2O to produce Fe2O3-g-C3N4/Cu(II) composite. The constructed hybrid nanomaterial was applied as a nanocatalyst in the formation of polyhydroquinoline derivatives via Hantzsch reaction with excellent yields between 91 and 97% in the absence of solvent at 75 °C (10 mg catalyst loading within 20–35 min). Owing to the synergistic effect of basic sites (C3N4) and acidic sites (Cu), Fe2O3-g-C3N4/Cu(II) displayed exceptional catalytic activity. Moreover, Fe2O3-g-C3N4/Cu(II) has exhibited recyclability for six runs. [ABSTRACT FROM AUTHOR]

The present work describes the synthesis of a material consisting of a bisimidazolium ionic liquid supported on graphene oxide. The prepared nanocomposite was characterized by different physicochemical techniques such as FT-IR, XRD, CHN, SEM, TEM and EDAX. The synthesized nanocomposite was further utilized as an effective heterogeneous catalyst for the synthesis of tetraketone derivatives, which are biologically significant, using dimedone and aryl aldehydes as the substrates at 50 °C and a green solvent. One of the tetraketone products has been confirmed by single crystal XRD. The catalyst displayed high reaction yields, facile separation, short reaction time, good stability and recoverability up to six consecutive reaction rounds with no discernible loss in its catalytic activity. [ABSTRACT FROM AUTHOR]

This work describes the development of DABCO-based di-cationic ionic liquid immobilized over graphene oxide as a heterogeneous nanocomposite. Different physico-chemical characterization techniques were utilized to characterize the synthesized nanocomposite, including FT-IR, XRD, NMR, TGA, SEM, TEM, elemental mapping and EDX analysis. Next, the successfully prepared nanocomposite was employed for the Knoevenagel and Hantzsch reactions. The main advantages of this nanocomposite include the excellent product yield in mild reaction conditions and the tolerance ability towards various substrates with different substituents. Moreover, the nanocomposite could be recycled multiple times without any noticeable loss in its catalytic activity and morphology. [ABSTRACT FROM AUTHOR]

Copper oxide (CuO) nanoparticles are prepared by the hydrothermal method which is used as a heterogeneous catalyst to synthesize 3-(2-chlorophenyl)-2,4-Pentadione. The energy band gap of HOMO-LUMO of CuO NPs is calculated using a UV-vis study which is found to be 1.96 eV. The crystalline development in the CuO NPs is investigated by X-ray peak broadening of the characteristic peak (111) of the XRD-diffractogram using Scherrer's formula, the average particle size (D), and d-spacing of the CuO NPs are evaluated 15.04 nm and 2.761 A°, respectively. The catalytic activity of CuO NPs is higher than the normal bulk form of CuO in the synthesis of3-(2-chlorophenyl)-2,4-Pentadione. The use of CuO NPs catalyst minimizes the reaction time. The percent yields of the product obtained by the same quantity and concentration of 5 mmol of CuO NPs and bulk CuO are 78 and 45, respectively. [ABSTRACT FROM AUTHOR]

The conversion of lignocellulosic biomass into platform chemicals and fuels by metal single atoms is a new domain in solid catalysis research. Unlike the conventional catalysis route, single‐atom catalysts (SACs) proliferate maximum utilization efficiency, high catalytic activity, and good selectivity to the desired product with an ultralow loading of the active sites. More strikingly, SACs show a unique cost‐effective pathway for the conversion of complex sugar molecules to value‐added chemicals in high yield and selectivity, which may be hindered by conventional metal nanoparticles. Primarily, SACs having adjustable active sites could be easily modified using sophisticated synthetic techniques based on their intended reactions. This review covers current research on the use of SACs with a strong emphasis on the fundamentals of catalyst design, and their distinctive activities in each type of reaction (hydrogenation, hydrogenolysis, hydrodeoxygenation, oxidation, and dehydrogenation). Furthermore, the fundamental insights into the superior actions of SACs within the opportunity and prospects for the industrial‐scale synthesis of value‐added products from the lignocelluloses are covered. [ABSTRACT FROM AUTHOR]

In this study, a mono-functional ZrO2 nanomaterial was treated with sulfur and loaded with two different percentages of platinum metals (i.e., 0.5 and 1 wt%) to generate an acidic bi-functional Pt/SZrO2 nanocatalyst for the purpose of increasing the catalytic activity and selectivity together. This work aims to determine the least amount of the costly platinum metal that can be added to the catalyst to achieve the appropriate balance between the acidic and metallic sites. Both rapid deactivation of the super-acid nanaocatalyst and fast cleavage of the zero-octane n-heptane chain can consequently be prevented throughout the reaction. This can be achieved by accelerating the hydroisomerization reactions at a pressure of 5 bar to reach the highest selectivity towards producing the desired multi-branched compound in fuel. Several characterization techniques, including XRD, SEM, EDX, BET, and FTIR, have been used to evaluate the physical properties of the catalysts. The best reaction product was obtained at 230 °C compared to the other tested temperatures. The conversion, selectivity, and yield of reaction products over the surfaces of the prepared catalysts followed this order: 0.5 wt% Pt/SZrO2 > 1 wt% Pt/SZrO2 > 0.5 wt% Pt/ZrO2 > 1 wt% Pt/ZrO2 > SZrO2 > ZrO2. The highest conversion, selectivity, and yield values were obtained on the surface of the 0.5 wt% Pt/SZrO2 catalyst, which are 69.64, 81.4 and 56.68 wt%, respectively, while the lowest values were obtained on the surface of the parent ZrO2 catalyst, which are 43.9, 61.1 and 26.82, respectively. The kinetic model and apparent activation energies were also implemented for each of the hydroisomerization, hydrogenation/dehydrogenation, and hydrocracking reactions, which track the following order: hydroisomerization < hydrogenation/dehydrogenation < hydrocracking. The lowest apparent activation energy value of 123.39 kJ/mol was found on the surface of the most active and selective 0.5% Pt/SZrO2 nanocatalyst. [ABSTRACT FROM AUTHOR]

A pioneering robust and green heterogeneous acidic catalyst (CSA@g-C3N4) was rationally designed via immobilization of camphorsulfonic acid (CSA) on the g-C3N4 surface under mild conditions. Grafting CSA in the g-C3N4 lattice is distinguished as the root cause of facilitating the structure change of g-C3N4, leading to a unique morphology, accordingly the remarkable catalytic efficiency of CSA@g-C3N4. The morphology of new as-prepared nano-catalyst was specified by means of FT-IR, XRD, SEM, EDS, TEM, TGA, and BET. For the first time, it is exhibited that the efficient catalyst CSA@g-C3N4 can productively accomplish the three-component reactions with high yields and also serve as an inspiration for easily performing various sorts of MCRs based on our finding. The recommended synthesis pathway of chromenes derivatives is facile and cost-effective which applies a condensation reaction of salicylaldehyde, thiophenol, and malononitrile followed by ready purification in a benign manner. Moreover, the CSA@g-C3N4 nanocomposite can be promptly reused, illustrating no sensational decrease in the catalytic activity after ten times. [ABSTRACT FROM AUTHOR]

An efficient, economical, and green, sustainable synthesis of fused azines using Mg-Al hydrotalcite under a high-pressure Q-Tube reactor has been developed. This reaction proceeds through the aza-Michael addition of α,β-unsaturated ketone with different aminoazoles. This method offered excellent yields in a short reaction time that economically saved energy in addition to the protocol showing the reuse of the catalyst seven times without losing its catalytic activity. [ABSTRACT FROM AUTHOR]

The direct CO2 hydrogenation to formic acid is appealing since it is a potential hydrogen storage material and can be a precursor of higher value-added products. Due to thermodynamic limitations, developing an efficient catalyst system for this process is quite a challenge. Herein, a Ni-based N-modified TiO2-supported catalyst that showed exemplary activity and selectivity toward formic acid synthesis (757 TON), which was reported to be the highest over noble metal-free catalyst system, is designed. The combined impact of Ni and N over TiO2 as a support was thoroughly investigated in this research for improved activity in the selective conversion of CO2 to formic acid. X-ray photoelectron spectroscopy and X-ray absorption spectroscopy investigations showed direct coordination between Ni and N, which emphasizes the metal support interaction for significantly higher catalytic activity. In-depth characterization of Ni/N-TiO2 reveals that CO2 undergoes insertion reaction with H2 to yield formic acid on Ni0 as an active surface via the formate intermediate. Complementary DFT studies elucidate the pivotal effect of nitrogen doping on the TiO2 surface, which provides a more feasible pathway than pure TiO2 by lowering the activation barriers. More significantly, the catalyst demonstrated a steady performance in experiments involving continuous recycling and long-term study. [ABSTRACT FROM AUTHOR]

Biomass is the only renewable organic material that has high energy content. Due to the significant amount of biomass resources, especially crop residues, the valorization of biomass to fuel or fuel additives have received more attention. In the present paper, biomass-derived butyl levulinate was prepared from starch in the presence of Al-modified mesoporous KIT-5 silica to improve its catalytic activity. Accordingly, the acidity character of KIT-5 was improved by two methods: wetness impregnation and in situ incorporation of aluminum. The essential properties of these catalysts were characterized by different techniques including N 2 adsorption-desorption analysis, ICP-OES, FT-IR, and Pyridine-FT-IR analyses, XRD, SEM, TEM. A series of important parameters influencing the reaction yield was thoroughly investigated. Under the optimized conditions (230 °C, 10 h, 30 mg catalyst, and 70 mg starch), 31% n-butyl levulinate yield and 74% starch conversion were obtained, respectively. Finally, the selected catalyst was regenerated and reused in starch valorization reaction for four successive runs. [ABSTRACT FROM AUTHOR]

It is shown that deposition of Rh-CD (CDs are carbon dots)onto SiO2, Al2O3, and ZrO2 oxide supports contributes to the appearance of the catalytic activity in the process of glycerol conversion. It is established that acrolein and acetaldehyde are oxygen-containing products in this reaction system. It is found that the yield of reaction products increases when using a support with a smaller specific surface area, which is caused by an increase in the surface concentration of acid sites. [ABSTRACT FROM AUTHOR]

The design and development of a low-cost and sustainable catalytic system to replace expensive Pd-catalysts for the Suzuki cross-coupling reaction is one of the major challenging areas of research in synthetic organic chemistry. Cross-coupling reactions with good yield in the presence of the Cu-based monometallic catalyst at room temperature have not been realized in previous works. We herein report the fabrication of a novel "single-atom" Cu catalyst (Cu-TAPB-BTDA-COF) for the Suzuki-coupling reaction at room temperature. The catalyst was obtained by post-synthetic metalation of the COF, synthesized by the combination of 4,4′-(benzothiadiazole-4,7-diyl)dibenzaldehyde (BTDA) and 1,3,5-tris-(4-aminophenyl)-benzene (TAPB). Cu-TAPB-BTDA-COF shows excellent catalytic activity for the Suzuki cross-coupling reaction, which is able to effectively promote the Suzuki cross-coupling reaction under mild reaction conditions (room temperature, a nontoxic solvent, and air atmosphere). In addition, the catalyst could be recycled and reused multiple times without the loss of catalytic activity. Compared with other Cu-based catalysts, our COF-based Cu catalyst simultaneously demonstrates excellent performance and recyclability. [ABSTRACT FROM AUTHOR]

A new family of Cu(II) and Ni(II) salen complexes was synthesized and fully characterized through various physicochemical methods. Their catalytic activity was evaluated in the phase transfer Cα-alkylation reaction of the Schiff bases of D,L-alanine ester and benzaldehyde derivatives. It was found that the introduction of a chlorine atom into the ortho- and para-positions of the phenyl ring of the substrate resulted in an increase in both the chemical yield and the asymmetric induction (ee 66–98%). The highest enantiomeric excess was achieved in the case of a Cu(II) salen complex based on (S,S)-cyclohexanediamine and salicylaldehyde at −20 °C. The occurrence of a bulky substituent in the ligand present in the complexes led to a drastic decrease in ee and chemical yield. For instance, the introduction of bulky substituents at positions 3 and 5 of the phenyl ring of the catalyst resulted in a complete loss of the stereoselectivity control in the alkylation reaction. [ABSTRACT FROM AUTHOR]

At first, synthesis and characterization of a new core–shell magnetic nanomaterial, namely 4,4′-bipyridin-1-ium hydrogen sulfate grafted on chloropropyl functionalized silica gel-nano-Fe3O4 (BPHCSF), have been reported; the characterization has been done using EDS, FE-SEM, TEM, FT-IR, XRD, TGA and VSM analyses. Afterward, examining catalytic performance of BPHCSF for the solvent-free preparation of 4,4′-(arylmethylene)-bis(3-methyl-1-phenyl-1H-pyrazol-5-ol) derivatives from 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (2 eq.) and arylaldehydes (1 eq.) has been described. The products have been obtained in high yields and short reaction times, and the catalyst was successfully reused for three times without significant decrement of its catalytic activity. [ABSTRACT FROM AUTHOR]

8-Aryl-7H-acenaphtho[1,2-d] imidazoles were produced by a catalytic process utilizing diethanolamine sulfate-functionalized graphene oxide. The process was implemented using acenaphthoquinone, ammonium acetate, and aromatic aldehydes via a one-pot reaction under solvent-free conditions. The applied catalyst smoothly catalyzed the reactions at high yields. The developed catalyst offered several advantages including carbon structure, eco-friendliness, cost-effectiveness, and ease of handling and storage. The applied procedure also exhibited several priorities over reported ones such as high yield, short reaction time, no-byproducts, environmental compatibility, and simple work-up. Durability and stability of catalyst were also examined in five cycles which showed no significant reduction in the catalytic activity. [ABSTRACT FROM AUTHOR]

Microwave irradiation has been used to enhance the reaction yields and selectivities for organic transformation. In this paper, microwave irradiation (MW) was investigated for the environmentally benign synthesis of benzoxazoles through the cyclization of 2-aminophenols and benzaldehydes using deep eutectic solvent (DES) as a catalyst. The [CholineCl][oxalic acid] was easily synthesized from choline chloride with oxalic acid and used without further purification. [CholineCl][oxalic acid] catalyzed the synthesis of benzoxazoles to produce the desired product in a good to excellent conversion and selectivity under MW irradiation. The presence of [CholineCl][oxalic acid] helps to promote the rapid heating transfer from microwave irradiation into the reaction mixture. The [CholineCl][oxalic acid] can be recovered and reused several times without a considerable degradation in catalytic activity. [ABSTRACT FROM AUTHOR]

Unusual tridentate β-diketiminato rare-earth metal chlorides LRECl(μ-Cl)2Li(THF)2 (RE = Y (1a), Yb (1b), and Lu (1c); L = MeC(NDipp)CHC(Me)N(CH2)2NC4H8O; Dipp = 2,6-iPr2C6H3) and the corresponding dialkyl complexes LRE(CH2SiMe3)2 (RE = Y (2a), Yb (2b), and Lu (2c)) were prepared by reaction of a morpholine-functionalized β-diketiminato proligand HL with anhydrous RECl3 and rare-earth metal trialkyl complexes RE(CH2SiMe3)3(THF)2, respectively. In 1 and 2, the morpholine moiety displayed a stable chair conformation and the resulting ligand coordinated to the rare-earth metal ion in a [NNN]-tridentate chelating fashion. Further studies demonstrated that these dialkyl complexes showed high activity towards the catalytic formation of C–O and C–N bonds in the alcoholysis of isothiocyanates and aminolysis of epoxides. A series of O-thiocarbamate derivatives were achieved in good to excellent yields by reaction of various alcohols with aromatic and aliphatic-substituted isothiocyanates at room temperature. In addition, under solvent-free conditions, the ring-opening reaction of terminal and internal epoxides with arylamines yielded the corresponding β-amino alcohols with excellent regioselectivity. More importantly, a novel β-diketiminato/anilido yttrium alkyl complex LY(NHDipp)(CH2SiMe3) (5a) was isolated and characterized by the stoichiometric reaction of 2a with diisopropylaniline. [ABSTRACT FROM AUTHOR]

A new heterogeneous catalyst, nanodiatomite@melamine-SO3H, was introduced for synthesizing 1,8‐dioxo-octahydroxanthenes via multicomponent reactions of aldehydes and dimedone. The prepared catalyst was characterized by employing several techniques, including FT-IR, XRD, TGA, EDX, BET, SEM, and TEM. The products were obtained under solvent-free conditions, with high yields in short reaction times. The nanodiatomite@melamine-SO3H was reused five times without substantial activity loss. Nanodiatomite@melamine-SO3H as a novel heterogeneous catalyst was successfully developed and defined through several techniques. The catalyst showed excellent catalytic activity in the xanthene synthesis. The good points of this methodology are ease of product isolation, catalyst efficiency and recycling, cleaner reaction profile, and the procedure agreement with the green chemistry. [ABSTRACT FROM AUTHOR]

A novel thermosensitive bifunctional sulfonamide microgel catalyst was synthesized by immobilization on a highly cross-linked three-dimensional network structure through covalent interactions. The microgel-supported organocatalyst has been successfully applied to catalyze the asymmetric alcoholysis reaction in high yields and good stereoselectivity (up to 90% ee). Furthermore, the polymeric catalysts could be recovered easily and reused multiple times (5 runs) without apparent loss of catalytic activity and enantioselectivity. [ABSTRACT FROM AUTHOR]

It is of great significance to efficiently synthesize compounds with pharmacological activities through CO2 conversion. Herein, polyionic liquids (PILs) with adjustable structures and multiple active sites were synthesized. With epoxy nucleoside as a solid substrate, cycloaddition and carbonate hydrolysis were carried out under the catalysis of polyionic liquid and the participation of CO2 and water. The amphiphilicity of P1, the adjustability of alkalinity and the regulation of the phase state in the presence of water played an important role in the high selectivity and high yield of the reaction. More importantly, the catalyst can be recycled 6 times to maintain high catalytic activity and selectivity. This work successfully provides a solvent-free, metal-free and recyclable green synthetic path for chiral drugs, which will further promote the highly efficient conversion and utilization of CO2. [ABSTRACT FROM AUTHOR]

New nickel complexes with tridentate phenoxy–amidate–aNHC donor groups were synthesized from the reactions between nickel acetate and imidazolium ligand precursors in net pyridine. An unusual degradation pathway was observed, leading to imidazole derivatives occupying the fourth coordination sites in these square planar complexes. A new imidazole-coordinated nickel complex was found to be efficient in catalyzing Suzuki–Miyaura cross-coupling with aryl chlorides under 3 mol% of catalyst loading. The catalytic activities were superior to those of its reported normal NHC counterpart. Instead of the common procedure of using additional phosphine, the addition of IMes·HCl significantly enhances the product yields of the catalytic reaction. [ABSTRACT FROM AUTHOR]

An efficient heterogeneous catalytic system for the N‐formylation of amines using CO2 as a sustainable C1 source was developed using unsupported nanoporous palladium (PdNPore). The PdNPore‐catalyzed N‐formylation of amines and CO2 with hydrosilane proceeded smoothly under mild reaction conditions to yield formamides in satisfactory to excellent yields. Various synthetically useful functional groups, such as halogen, hydroxyl, allyl, and cyano groups, remained intact during the N‐formylation of amines. No palladium leached from PdNPore during the hydrogenation reaction. Moreover, the catalyst was easily recovered and reused without any loss of catalytic activity. This study is the first to demonstrate that PdNPore catalyzed CO2 conversion to form C−N bond, which enriches the reaction types of CO2 conversion catalyzed by PdNPore catalyst. [ABSTRACT FROM AUTHOR]

The first system controlled anomeric isomerism of glucopyranoside-functionalized N-heterocyclic carbenes based pyridine enhanced precatalyst preparation, stabilization and initiation type palladium(II) complexes (Glu-NHCs-Pd(II)-PEPPSI, 2a–d) were prepared and fully characterized. It is interesting to note that pure β–anomer PEPPSI complex 2d was obtained, in which the Glu-substituent connects to the imidazole heterocycle ring N through ethoxy bridged anomeric carbon. In addition, the catalytic activities revealed that Glu-NHCs-Pd(II)-PEPPSI complexes 2a-d are efficient catalysts for the aqueous Suzuki reaction. Under optimized conditions, a series of fluorene-cored functional materials with different aryl-substituents were synthesized through the Suzuki reaction with excellent yields. The Glu-NHCs-Pd(II)-PEPPSI complex containing bulky and rigid 2,5-dimethylphenyl group played an important role in maintaining the β conformation and improving the catalytic activity significantly. [ABSTRACT FROM AUTHOR]

Metal-aluminophosphate solid acids (m-AlPO) were prepared and characterized by various techniques such as powder-XRD, FT-IR, BET surface area, SEM, TEM, EDAX, NH3-TPD/n-butylamine back titration and ICP-OES techniques. These materials were used as catalysts in liquid phase etherification reaction of glycerol with alcohol. In order to obtain good yield of the reaction product, optimization reaction was carried out by varying time, temperature, catalyst weight and molar ratio of reactants. CuAlPO solid acid showed superior performance in a short period of time with 95% glycerol conversion and 68% selectivity to higher ethers (di and tri). The catalytic activity was investigated by three heating techniques (microwave, ultrasonic and conventional). The pre-adsorption experiment obeys the Langmuir--Hinshelwood type mechanism. Kinetic studies were also carried out to determine the activation energy (Ea) and temperature coefficient (Tc) of the catalyst. The catalyst was reused for several reaction cycles without much loss of catalytic activity. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles have received much attention in synthesizing organic compounds due to their unique properties such as high contact surface, recyclability, and easy separation. In this study, Rice husk ash (RHA), an agriculture waste, was used as a silica source for MCM-41 synthesis. Ag2S/RHA-MCM-41 nanocomposite synthesized and characterized with FT-IR, SEM, and XRD. Prepared nanocomposite used for the synthesis of azo-linked 1, 2, 4-triazole-3-thione derivatives. Our study result showed that Ag2S/RHA-MCM-41 nanocomposite showed high activity in the synthesis of azo-linked 1, 2, 4-triazole-3-thione derivatives because of good yields and desirable reaction time. The structure of all compounds was determined by FTIR, ¹H-NMR and 13C-NMR spectroscopy. In all reactions, the catalyst is easily removable and reusable, and its catalytic activity is maintained after five runs. [ABSTRACT FROM AUTHOR]

Conversion of levulinic acid (LA) to γ-valerolactone (GVL) via catalytic transfer hydrogenation (CTH) using conventional heating (CH) involves long reaction times, and low yields. Microwave (MW) heating seems a solution to address these issues as MW accelerates reactions and enhances yields. In this study, three typical catalysts, Ru/C, Pt/C and Pd/C, are compared for LA conversion using MW heating. In comparison to CH processes, MW-assisted processes significantly enhance LA conversion to GVL with higher yields by Ru/C and Pt/C. While elevated temperatures and secondary alcohols are favorable for LA conversion by these catalysts, Ru/C appears as the most effective catalyst as it can reach LA conversion as 100%, selectivity of GVL as 99% and yield of GVL as 99% at 160 °C. The results of this study confirm that MW was a promising process for enhancing LA conversion and Ru/C shows the highest catalytic activity, followed by Pt/C and Pd/C. [ABSTRACT FROM AUTHOR]

In this article, Fe3O4 nanoparticles, 2D Fe3O4/Mg(OH)2, and 2D Fe3O4/MgO nanocomposites were synthesized using ionic liquid [OMIM]Br as green designer and stabilizer at ambient pressure. Here, we report a special method for a sandwich like magnetic nanocomposites synthesis. The characterization of these nanocomposites was performed by IR, XRD, SEM, TEM, BET, and VSM techniques. Synthesized nanostructures were employed in the synthesis of 4H-chromene, 4H-pyran, and oxepine derivatives in three-component tandem reactions. Although, Fe3O4/Mg(OH)2 nanocomposite, as magnetically separable heterogeneous catalyst, has showed lower surface area in comparison to Fe3O4/MgO, exhibited a significant enhancement in the yield of the desired products. The described protocol has various advantages including simple work-up, mild reaction condition, green solvent, and the high atomic economy that make attractive procedure. The nanocatalysts exhibited remarkable reusable activity. Also, investigation of green chemistry metrics approved that Fe3O4/Mg(OH)2 nanocomposites play an essential role in the improvement of the reaction yield of 4H-chromene, among other products. [ABSTRACT FROM AUTHOR]

An efficient and eco-friendly synthetic protocol via a one-pot three-component reaction to yield thiophene containing aminonaphthols (Betti bases) is reported. Kaolin was used as a heterogeneous catalyst and a series of Betti bases were synthesized under solvent-free condition. The synthesized derivatives were characterized by various techniques, viz. FTIR, 1H-NMR, 13C-NMR, mass spectrometry and elemental analysis. The synthesized compounds were screened for in vitro anticancer and antioxidant activities. Compounds 4d, 4i, 4j exhibited excellent anticancer activity (GI50 < 10 µg/ml) against all four cell lines which was comparable with the standard drug doxorubicin. Compound 4d was found to be the most potent antioxidant against DPPH radical and H2O2. The reusability studies demonstrated the retention in catalytic activity for up to six cycles. The current synthetic methodology offers several advantages such as excellent yields, mild reaction conditions, short reaction span, ease of work-up, broad substrate scope and reusability. [ABSTRACT FROM AUTHOR]

Unique properties of 1,2,3‐triazoles on the one hand and necessity of usage of an efficient catalyst with fidelity in principles of green chemistry on the other hand impelled us to design and synthesis of a novel heterogeneous nanocatalyst (Cu@Arg‐MWCNTs) with simple synthesis, immense power, high regioselectivity, and easy separation and recyclability. The Cu@Arg‐MWCNT structure is characterized by different analyses and used for the synthesis of various triazoles. Its high catalytic activity is confirmed by high yields and short reaction times under mild conditions in click reaction. [ABSTRACT FROM AUTHOR]

Construction of heterogeneous Pd/SiO2 catalyst via the pollution-free strategy marked strong electrostatic adsorption has been reported for the application to Suzuki–Miyaura cross-coupling reactions. The exposed negatively charged oxygen groups, which were converted from the hydroxyl groups on the surface of silica under the alkaline atmosphere, could effectively anchor palladium species to form ultrafine Pd nanoparticles (Pd NPs) with an average particle size of 1.3 nm and high dispersion (43%). Pd/SiO2 catalyst was endowed with the excellent catalytic performance which was that the yield of the Suzuki–Miyaura reaction between bromobenzene and phenylboronic acid at 40 °C was > 99% for 30 min and the TOF was ~ 80,000 h−1. The catalyst could be easily recovered and recycled by facile procedure without a significant decrease in catalytic activity, which was able to maintain the 90% yield after repeated for 8 times. In addition, a continuous flow reaction device was designed using the Pd/SiO2 catalyst to effectively improve the production efficiency of biphenyl. Pd/SiO2 catalyst constructed with the strategy of strong electrostatic adsorption (SEA) possesses uniformly dispersed and highly exposed Pd sites which can be easily transformed into electron-deficient Pdδ+ and strengthened stability for itself due to its strong interaction with the front surface of the carrier, and has been endowed the outstanding catalytic performance for Suzuki−Miyaura cross-coupling reaction. [ABSTRACT FROM AUTHOR]

A quantitative approach for the development of halogenbonding- driven anion-binding catalysts was studied using 4- substituted perfluorinated iodobenzene. 19F NMR titrations were used to determine the binding constants K for chloride, and their catalytic activities were evaluated in the allylation reaction of a N-activated pyridine. We discovered that the log K and product yields were linearly correlated, and that they were dependent on the Hammett substituent parameter, σmeta (r²= 0.99). This linear correlation provided a quantitative predictive model for both the binding constant and the reaction yield. Concomitantly, this efficiently permitted the development of a highly active anion-binding catalyst, namely 4-CNC6F4I (K= 489±5 M-1. Additionally, the catalytic activity of 4-CNC6F4I was established in the allylation and crotylation of N-activated isoquinolines (7 examples). Overall, this approach highlights the value of quantitative analysis by exploring experimentally informed correlations in the development of halogen bond donor catalysts. [ABSTRACT FROM AUTHOR]

Eggshell as a solid waste was loaded on a nano-Fe3O4 surface. Then, in one step, it (Fe3O4@eggshell) was converted to Fe3O4@Ca3(PO4)2 as a nano-magnetic, green, cheap, and environmentally friendly catalyst. Techniques such as FT-IR, VSM, FESEM, TEM, EDX, XRD, and TGA were used to characterize the as-synthesized catalyst. The catalytic activity of Fe3O4@Ca3(PO4)2 was evaluated in the synthesis of 1,2,4,5-tetra-substituted imidazole derivatives through a one-pot multicomponent reaction. The design of the experiment as a systematic statistical approach was used to obtain the optimum point of the reaction condition so that 0.05 g of the as-synthesized catalyst and 94.77 °C were the best condition (which provides 90% yield for the benchmark reaction). Then, 1,2,4,5-tetra-substituted imidazole derivatives in the optimum condition were synthesized with very low reaction times in good yields. The as-prepared catalyst was retrieved through a magnet and used several times without significant loss of catalytic activity. [ABSTRACT FROM AUTHOR]

An effective and efficient catalytic system has been reported for the synthesis of C5-arylated 2-isobutylthiazoles. Pd-N-heterocyclic carbene complexes like [Pd(μ-Cl)Cl(SIPr)]2 (2) and (LCl2Pd-SIPr) (3: L = PPh3, 4: L = Py; 5: L = 3-CHO-Py) were synthesized and characterized by 1H, 13C, 31P NMR, LC-MS/MS, elemental analysis, and FTIR spectroscopy. These Pd-N-heterocyclic carbene complexes were assessed for the first time as catalysts for the C–H arylation reaction of 2-isobutylthiazole at the C5 position with different (hetero)aryl bromides. The catalytic system showed a low catalyst loading (1 mol%) and did not require the use of additional additives such as pivalic acid. The catalytic system developed with these catalysts enables the synthesis of fine chemicals in high yields under aerobic or anaerobic conditions. All complexes showed moderate to good yields in the C5 direct arylation of 2-isobutylthiazole, while complex 2 exhibited higher catalytic activity than the other complexes. [ABSTRACT FROM AUTHOR]

Magnetic nano catalysts are widely used in various organic reactions due to their characteristics of magnetic separation and recycling. Magnetic Fe3O4@SiO2 nano catalyst modified by 1, 8-diazabicyclo [5.4.0]-7-undecene (DBU) was prepared and applied in the Knoevenagel reaction. The results showed that the catalyst has an excellent effect on the Knoevenagel reaction, which not only improves the reaction rate and yield, but also it can be easily separated from the reaction mixture driven by external magnetic force. Furthermore, the catalyst can be recycled 10 cycles with no loose of the catalytic activity. [ABSTRACT FROM AUTHOR]

The hydrothermal synthesis of ZnO–NiO–NiFe2O4 nano-composite is reported. The sample was utilized to characterize via XRD, FE-SEM, EDS, FT-IR, UV–Vis, and BET techniques. The sample consisted of three different phases as ZnO (hexagonal), NiO (cubic), and NiFe2O4 (cubic) with the average particle size as 34 nm and specific surface area, average pore diameter, and pore volume as 64.35 m2 g−1, 13.02 nm, and 0.201 cm3 g−1, respectively. Catalytic behavior of the nano-composite was investigated on the synthesis of thiazolidin-4-one derivatives under thermal and ultrasonic irradiation condition. Our results show that the catalytic activity of ZnO–NiO–NiFe2O4 nano-composite is much higher than ZnO, NiO, and NiFe2O4 metal oxides. All products were prepared in high yields with short reaction times. In addition, the catalyst was recovered for at least five times. [ABSTRACT FROM AUTHOR]

In the present study, CuII immobilized on functionalized magnetic mesoporous MCM‐41 (Fe3O4@MCM‐41‐GPTMS‐Gu‐CuII) was prepared as a new, versatile, and magnetically nanocatalyst and characterized by FT‐IR, XRD, small‐angle XRD, BET, TEM, SEM, EDX, EDX‐mapping, TGA, VSM, XPS, and ICP techniques. The characterizations show the presence of MCM‐41 with a hexagonal structure, superparamagnetic behavior, and an average particle size of 8–25 nm. The catalytic activity of the nanocatalyst was evaluated towards the synthesis of structurally different 5‐phenyl‐5,10‐dihydropyrido[2,3‐d : 6,5‐d′]dipyrimidine‐2,4,6,8(1H,3H,7H,9H) tetraone derivatives through one‐pot multicomponent condensation under green conditions. Fe3O4@MCM‐41‐GPTMS‐Gu‐CuII catalyzed many consecutive trials at least five runs. High to excellent yields in short reaction times, simple procedure, environmental friendliness, less toxic solvents, high stability, and reusability of the catalyst are considerable advantages of the prepared catalytic system. [ABSTRACT FROM AUTHOR]

In the present study, CuII immobilized on functionalized magnetic mesoporous MCM‐41 (Fe3O4@MCM‐41‐GPTMS‐Gu‐CuII) was prepared as a new, versatile, and magnetically nanocatalyst and characterized by FT‐IR, XRD, small‐angle XRD, BET, TEM, SEM, EDX, EDX‐mapping, TGA, VSM, XPS, and ICP techniques. The characterizations show the presence of MCM‐41 with a hexagonal structure, superparamagnetic behavior, and an average particle size of 8–25 nm. The catalytic activity of the nanocatalyst was evaluated towards the synthesis of structurally different 5‐phenyl‐5,10‐dihydropyrido[2,3‐d : 6,5‐d′]dipyrimidine‐2,4,6,8(1H,3H,7H,9H) tetraone derivatives through one‐pot multicomponent condensation under green conditions. Fe3O4@MCM‐41‐GPTMS‐Gu‐CuII catalyzed many consecutive trials at least five runs. High to excellent yields in short reaction times, simple procedure, environmental friendliness, less toxic solvents, high stability, and reusability of the catalyst are considerable advantages of the prepared catalytic system. [ABSTRACT FROM AUTHOR]

A facile route towards new chitin derivatives with both catalytical and biological activities is proposed in the course of methodology development aimed at the design of polyfunctional materials on the basis of renewable and accessible natural polysaccharides. Ultrasound-promoted and Cu(I)-catalyzed azido-alkyne click cycloaddition of the propargylic ester of nicotinic acid and its N- methylated analogue to the azido chitin derivative allowed us to obtain previously unknown non-toxic water-soluble derivatives of chitin. The obtained polymers and their based nanoparticles demonstrated a high antibacterial activity in vitro , which is comparable or even superior to that of commercial antibiotics ampicillin and gentamicin. New derivatives of chitin were also shown to be highly efficient and reusable (at least for 10 times) green catalysts for the aldol reaction in water. The catalysts can be easily separated from the reaction mixture by their precipitation with ethanol. The results obtained highlight prospects of further studies on chitin's application in the rational design of novel functional materials with valuable properties. • A straightforward one-stage procedure for pre-click modification of chitin is described. • Ultrasound-promoted CuAAC reaction yields water-soluble, non-toxic chitin derivatives. • The newly synthesized derivatives demonstrated promising antibacterial activity and catalytic effect in the aldol reaction. [ABSTRACT FROM AUTHOR]

The catalytic activity of C,N-chelate diaminocarbene palladium(II) complexes containing a 3,4-diaryl-1H-pyrrol-2,5-diimine fragment in a copper-free Sonogashira reaction was studied. Reactions catalyzed by C,N-chelate diaminocarbene palladium(II) complexes do not require preliminary degassing, since such catalysts are air- and moisture-stable. In this work, comparative analysis of the catalytic activity of two types of C,N-chelate diaminocarbene complexes containing, along with the diaminocarbene ligand, isonitrile and chloride or two chloride ligands in the inner coordination sphere has been carried out. The steric and electronic effects of the substituents in the catalyst on the reaction yield has been studied. [ABSTRACT FROM AUTHOR]

In this work, a new core–shell magnetic silica nanocatalyst functionalized with 3,4-diaminobenzoic acid (Fe3O4@SiO2@PTS-DABA) was successfully prepared and characterized using different spectroscopic methods or techniques including FT-IR, FE-SEM, VSM, XRD, EDS and TGA. The Fe3O4@SiO2@PTS-DABA catalyst was applied, as a magnetically recoverable catalyst, for the synthesis of biologically active dihydropyranopyrazole and benzylpyrazolyl coumarin derivatives. These derivatives were prepared in the presence of Fe3O4@SiO2@PTS-DABA via a four-component reaction with yields of more than 90% under mild conditions. The Fe3O4@SiO2@PTS-DABA nanocatalyst is easily prepared from commercially available, lower toxicity and thermally stable precursors through a cost-effective, highly efficient and environmentally friendly procedure. It has a long life and can be reused for several catalytic cycles without significant loss of the catalytic activity. Finally, a possible mechanism is proposed for the preparation of dihydropyranopyrazole and benzylpyrazolyl coumarin derivatives in the presence of the Fe3O4@SiO2@PTS-DABA multifunctional magnetic catalyst. The structure of the products was identified by melting point measurement as well as FT-IR and 1H NMR spectroscopic methods. [ABSTRACT FROM AUTHOR]

This work aims the synthesis of substituted alkenes via Knoevenagel condensation using the clay collected from the Agadir region and modified by KF as a heterogeneous catalyst (KF-modified clay). In this context, the influence of various parameters on the reaction yield was studied, and the reuse of catalyst was carried out. The results obtained show that KF-modified clay is very effective for the preparation of substituted alkenes giving excellent yields (87–99%) and in very short times (between 2–4 s and 8 min) under mild and heterogeneous conditions. In addition, the recycling of our catalyst indicates that our material can be reused several times without losing its catalytic activity. [ABSTRACT FROM AUTHOR]

Superparamagnetic copper ferrite (CuFe2O4) nanoparticles were utilized as a heterogenous catalyst for the cross-coupling reaction of indole to form 3,3'-diindolylmethane (DIM) as the desirable product. High reaction yield, at around 82%, was achieved under optimal conditions. The CuFe2O4 material could be easily separated from the reaction mixture by an external magnetic field and could be reutilized several times without a significant decrease in catalytic activity. We also showed that no sites of catalyst material leached into reaction solution was detected. To our best knowledge, the above cross-coupling reaction was not previously conducted under catalysis of superparamagnetic nanoparticles. [ABSTRACT FROM AUTHOR]

A novel, heterogeneous, and bifunctional metal organic framework containing palladium and manganese, Pd/APN-Mn(BTC), has been prepared and completely characterized using FTIR, XRD, SEM-EDS, N2 adsorption–desorption, TG-DTG, NH3-TPD, and ICP analytical techniques. The APN-Mn(BTC) framework has been shown to be a useful platform for the stabilization and support of palladium nanoparticles (Pd NPs). Very effective catalytic activity has been exhibited by the highly dispersed Pd particles, Pd-NPs/APN-Mn(BTC), in the Suzuki–Miyaura cross-coupling reaction with reasonable to excellent reaction yields under mild conditions in H2O–ethanol solvent. [ABSTRACT FROM AUTHOR]

Substituted imidazoles have wild applications in different area of sciences and industries. In this research, the catalytic activity of PPh3 as a cheap and efficient organocatalyst is reported for synthesis of 2,4,5‐trisubstituted imidazoles. In this method, ultrasonic assisted one‐pot, three‐component reaction of benzil, aldehydes, urea and PPh3 in ethylene glycol as a green solvent at room temperature has been achieved to afford the structurally diverse 2,4,5‐trisubstituted imidazoles in 80–95 %. The effect of different parameters on the reaction progress was also discussed. Utilizing ultrasonic irradiation dramatically improved the reaction in terms of yields and reaction times compared to conventional heating technique. The current protocol offers many advantages such as mild reaction conditions, short reaction time, the use of non‐metallic, harmless, and cheap catalyst, ease of separation and purification, simple work‐up procedure, and the reactivity to all types of aldehydes particularly the aliphatic aldehydes. [ABSTRACT FROM AUTHOR]

Waste Sesamum indicum plant derived heterogeneous catalyst was utilized for the first time for biodiesel synthesis from sunflower oil. The derived catalyst was characterized by using Powder XRD, FT-IR, BET, TGA, XRF, AAS, XPS, SEM-EDX and TEM, and the characterization revealed the presence of Na, K, Ca, Mg, Fe, Mn, Zn, Si, Sr and Cl with high percentage of K (29.64 wt %) and Ca (33.80 wt %) as oxides and carbonates. The catalyst with a moderate surface area of 3.66 m2 g−1 exhibited excellent catalytic activity producing a yield of 98.9% biodiesel under the optimized conditions of 12:1 methanol to oil molar ratio and catalyst loading of 7 wt % at the reaction temperature of 65 °C in a short reaction time of only 40 min. The catalyst could be reused up to the 3rd cycle of reaction with the yield of 94.2% biodiesel. The characterization of biodiesel was done by using FT-IR, NMR, and GC-MS techniques. The fuel property of produced biodiesel meets the prescribed limits of international standard. The prepared catalyst is easy to handle, reusable, and found to be highly efficient green catalyst that could help in reduction of biodiesel cost. Thus, the catalyst can be recommended as a potential candidate for cost-effective biodiesel production at a large scale. Image 1058 • Renewable heterogeneous catalyst derived from waste Sesamum indicum plant was employed in biodiesel synthesis. • High amounts of K and Ca in the catalyst were confirmed by AAS, EDX and XPS techniques. • Yield of 98.9% biodiesel was achieved at optimum conditions in a short reaction time of 40 min. • The catalyst showed promising catalytic activity up to 3rd cycle of reaction without any significant loss of activity. • Properties of produced biodiesel are compatible with international standard. [ABSTRACT FROM AUTHOR]

In this article, we have developed a straightforward, easy and exceedingly competent approach for the synthesis of 5‐phenyl‐5,6‐dihydropyrido[2,3‐d]pyrimidine‐2,4,7(1H,3H,8H)‐triones obtain in superior yields in a sole reaction pace with an air and humidity steady catalyst in water as a green solvent at 100°C. The present procedure paves the approach for the synthesis of biologically fascinating molecular frameworks and has reward in conditions of little catalyst loading with palpable ambiguous and straightforward‐to‐do reaction circumstances with easy purification process. The used β‐cyclodextrin catalyst was recuperated and repeated several times devoid of noteworthy loss of catalytic activity, which is a crucial parameter of green synthesis. [ABSTRACT FROM AUTHOR]