Silver nanoparticles supported on ionic-tagged magnetic hydroxyapatite as a highly efficient and reusable nanocatalyst for hydrogenation of nitroarenes in water

A new strategy for immobilization of copper on the Fe3O4@EDTA nanocomposite and its efficient catalytic applications in reduction and one-pot reductive acetylation of nitroarenes and also N-acetylation of arylamines

A new and efficient Cu(II)-containing mesoporous nanocatalytic system was synthesized by direct immobilization of copper metal powder on the Fe3O4@EDTA nanocomposite. The as-prepared Fe3O4@EDTA@Cu(II) nanocomposite was then characterized by FT-IR, XRD, SEM, TEM, SEM-based EDX and elemental mapping, XPS, TGA, VSM, and also BET and BJH analyses. The resulting Fe3O4@EDTA@Cu(II) mesoporous nanocomposite exhibited satisfactory catalytic activity towards the reduction and one-pot reductive acetylation of nitroarenes and also N-acetylation of arylamines in water at 60 °C. Notably, the applied Cu(II)-containing nanocatalyst was efficiently recovered from the reaction mixture using an external magnetic field and could be reused successfully for five cycles. The protocol developed in this study offers several advantages in terms of mild reaction conditions, simple workflows, using water as a green solvent, and easy recovery and catalyst reuse, making it more ecologically and economically attractive.

NiII-containing l-glutamic acid cross-linked chitosan anchored on Fe3O4/f-MWCNT: a sustainable catalyst for the green reduction and one-pot two-step reductive Schotten-Baumann-type acetylation of nitroarenes

In this research, new and eye-catching catalytic applications of the nickelII (NiII) nanoparticles (NPs)-containing l-glutamic acid cross-linked chitosan anchored on magnetic carboxylic acid-functionalized multi-walled carbon nanotube (Fe3O4/f-MWCNT-CS-Glu/NiII) system, which was characterized by Fourier transform infrared (FT-IR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), SEM-based energy-dispersive X-ray (EDX) and elemental mapping, inductively coupled plasma-optical emission spectrometry (ICP-OES), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and vibrating sample magnetometry (VSM), have been introduced for the environmentally benign and efficient reduction and one-pot two-step reductive Schotten-Baumann-type acetylation of nitroarenes in water at 60 °C under an air atmosphere. It is worth noting that the NiII-containing hybrid nanocatalyst, in the mentioned organic reactions, showed short reaction times, high yields of the desired products, acceptable turnover numbers (TONs) and turnover frequencies (TOFs), and also satisfactory magnetic recycling and reusability performance even after ten times of reuse. As another significant point, all the titled organic transformations have been carried out in water as an entirely favorable and green solvent for chemical reactions.

Multicomponent synthesis via acceptorless alcohol dehydrogenation: an easy access to tri-substituted pyridines

Herein, we report palladium supported on a hydroxyapatite catalyst for synthesizing tri-substituted pyridines using ammonium acetate as the nitrogen source via acceptorless alcohol dehydrogenation strategy. The strategy offers a broad substrate scope using inexpensive and readily available alcohols as the starting material. The catalyst was prepared using a simple method and analyzed by several techniques, including FE-SEM, EDS, HR-TEM, BET, XRD, FT-IR, UV-visible spectroscopy, and XPS, demonstrating the anchoring of Pd nanoparticles on hydroxyapatite in the zero oxidation state. Moreover, several controlled experiments were carried out to understand the reaction pathway and a suitable mechanism has been proposed.

S-Alkylation of dithiocarbamates via a hydrogen borrowing reaction strategy using alcohols as alkylating agents

Herein, we report an operationally simple, environmentally benign and scalable approach towards the synthesis of S-benzyl/alkyl dithiocarbamates via a hydrogen borrowing reaction between alcohols and dithiocarbamate anions catalyzed using a hydroxyapatite-supported copper nano-catalyst. This strategy has a broad substrate scope and offers high yields of products using inexpensive and readily available alcohols as starting materials. The catalyst was prepared by easy and straightforward methods and analyzed by several analytical techniques, e.g., FESEM, HR-TEM, BET, XRD, EDS, and XPS, demonstrating the anchoring of Cu nanoparticles on hydroxyapatite in the zero oxidation state.

Direction of theoretical and experimental investigation into the mechanism of n-HA/Si-PA-SC@Ag as a bio-based heterogeneous catalyst in the reduction reactions

In the present study, a natural-based heterogeneous catalyst is synthesized. For this purpose, nano-hydroxyapatite (n-HA) is prepared, silica-modified and functionalized with phthalimide. Finally, Ag²⁺ was immobilized onto n-HA/Si-PA-SC and reduced to Ag nanoparticles by Bellis perennis flowers extract. n-HA/Si-PA-SC@Ag characterized by TGA, FTIR, SEM/EDX, XRD, TEM, BET and ICP-AES techniques. Moreover, metal-ligand interactions in n-HA/Si-PA-SC@Ag complex models were assessed to make a quantitative representation for the immobilization behavior of Ag NPs on the surface of n-HA/Si-PA-SC through quantum chemistry computations. Furthermore, the performance of n-HA/Si-PA-SC@Ag was studied in the nitroarene, methylene blue and congo red reductions. Finally, the recyclability study as well as Ag-leaching verified that, n-HA/Si-PA-SC@Ag was stable and reused-up to four times without losing its activity.

Diverse and efficient catalytic applications of new cockscomb flower-like Fe3O4@SiO2@KCC-1@MPTMS@CuII mesoporous nanocomposite in the environmentally benign reduction and reductive acetylation of nitroarenes and one-pot synthesis of some coumarin compounds

In this research, Fe3O4@SiO2@KCC-1@MPTMS@CuII as a new cockscomb flower-like mesoporous nanocomposite was prepared and characterized by various techniques including Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), SEM-based energy-dispersive X-ray (EDX) spectroscopy, inductively coupled plasma-optical emission spectrometry (ICP-OES), thermogravimetric analysis/differential thermal analysis (TGA/DTA), vibrating sample magnetometry (VSM), UV-Vis spectroscopy, and Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) analyses. The as-prepared Fe3O4@SiO2@KCC-1@MPTMS@CuII mesoporous nanocomposite exhibited satisfactory catalytic activity in the reduction and reductive acetylation of nitroarenes in a water medium and solvent-free one-pot synthesis of some coumarin compounds including 3,3'-(arylmethylene)bis(4-hydroxy-2H-chromen-2-ones) (namely, bis-coumarins) (3a-n) and 2-amino-4-aryl-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitriles (6a-n) along with acceptable turnover numbers (TONs) and turnover frequencies (TOFs). Furthermore, the mentioned CuII-containing mesoporous nanocatalyst was conveniently recovered by a magnet from reaction environments and reused for at least seven cycles without any significant loss in activity, which confirms its good stability.

Highly active heterogeneous hydrogenation catalysts prepared from cobalt complexes and rice husk waste

Highly active heterogeneous catalysts for the hydrogenation of nitro compounds were made by pyrolysis of rice husk waste impregnated with cobalt complexes followed by base-treatment. The catalysts show high selectivity and broad substrate scope.

Novel mesoporous Ag@SiO2 nanospheres as a heterogeneous catalyst with superior catalytic performance for hydrogenation of aromatic nitro compounds

Mesoporous core–shell structure Ag@SiO₂ nanospheres are constructed to prevent Ag nanoparticles from aggregation during the hydrogenation reaction. The prepared catalyst shows superior catalytic performance for hydrogenation of nitro compounds with 100% conversion and selectivity without any by-products, which also indicates good recycling performance for several times use.

Mesoporous core–shell structure Ag@SiO₂ nanospheres are constructed to prevent Ag nanoparticles from aggregation during the hydrogenation reaction.

Simple and Practical Synthesis of Various New Nickel Boride-Based Nanocomposites and their Applications for the Green and Expeditious Reduction of Nitroarenes to Arylamines under Wet-Solvent-Free Mechanochemical Grinding

In this paper, we report a simple synthesis of four new nickel boride-based nanocomposites, namely Ni2B@ZrCl4, Ni2B@Cu2O, Ni2B@CuCl2 and Ni2B@FeCl3, from commercially available and cheap starting materials. All of the new Ni2B-based nanocomposites were well characterized by Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Further, the catalytic applications of these new nanocomposites were successfully evaluated in the wet-solvent-free reduction of aromatic nitro compounds to arylamines with sodium borohydride (NaBH4) at room temperature by a mechanochemical grinding technique. All the introduced catalytic systems provide excellent yields of arylamines in very short reaction times for a wide range of substrates. Also, recoverability and reusability of the new nanocomposites were investigated.