Synthesis and characterization of an acidic nanostructure based on magnetic polyvinyl alcohol as an efficient heterogeneous nanocatalyst for the synthesis of α-aminonitriles

Utilizing magnetic xanthan gum nanocatalyst for the synthesis of acridindion derivatives via functionalized macrocycle Thiacalix[4]arene

An effective method for synthesizing acridinedione derivatives using a xanthan gum (XG), Thiacalix[4]arene (TC4A), and iron oxide nanoparticles (IONP) have been employed to construct a stable composition, which is named Thiacalix[4]arene-Xanthan Gum@ Iron Oxide Nanoparticles (TC4A-XG@IONP). The process used to fabricate this nanocatalyst includes the in-situ magnetization of XG, its amine modification by APTES to get NH2-XG@IONP hydrogel, the synthesis of TC4A, its functionalization with epichlorohydrine, and eventually its covalent attachment onto the NH2-XG@IONP hydrogel. The structure of the TC4A-XG@IONP was characterized by different analytical methods including Fourier-transform infrared spectroscopy, X-Ray diffraction analysis (XRD), Energy Dispersive X-Ray, Thermal Gravimetry analysis, Brunauer-Emmett-Teller, Field Emission Scanning Electron Microscope and Vibration Sample Magnetomete. With magnetic saturation of 9.10 emu g-1 and ~ 73% char yields, the TC4As-XG@IONP catalytic system demonstrated superparamagnetic property and high thermal stability. The magnetic properties of the TC4A-XG@IONP nanocatalyst system imparted by IONP enable it to be conveniently isolated from the reaction mixture by using an external magnet. In the XRD pattern of the TC4As-XG@IONP nanocatalyst, characteristic peaks were observed. This nanocatalyst is used as an eco-friendly, heterogeneous, and green magnetic catalyst in the synthesis of acridinedione derivatives through the one-pot pseudo-four component reaction of dimedone, various aromatic aldehydes, and ammonium acetate or aniline/substituted aniline. A combination of 10 mg of catalyst (TC4A-XG@IONP), 2 mmol of dimedone, and 1 mmol of aldehyde at 80 °C in a ethanol at 25 mL round bottom flask, the greatest output of acridinedione was 92% in 20 min.This can be attributed to using TC4A-XG@IONP catalyst with several merits as follows: high porosity (pore volume 0.038 cm3 g-1 and Pore size 9.309 nm), large surface area (17.306 m2 g-1), three dimensional structures, and many catalytic sites to active the reactants. Additionally, the presented catalyst could be reused at least four times (92-71%) with little activity loss, suggesting its excellent stability in this multicomponent reaction. Nanocatalysts based on natural biopolymers in combination with magnetic nanoparticles and macrocycles may open up new horizons for researchers in the field.

Silver-assisted reduction of nitroarenes by an Ag-embedded curcumin/melamine-functionalized magnetic nanocatalyst

In the current study, we introduce a hybrid magnetic nanocomposite comprised of curcumin (Cur), iron oxide magnetic nanoparticles (Fe₃O₄ MNPs), melamine linker (Mel), and silver nanoparticles (Ag NPs). Initially, a facile in situ route is administrated for preparing the Fe₃O₄@Cur/Mel-Ag effectual magnetic catalytic system. In addition, the advanced catalytic performance of the nanocomposite to reduce the nitrobenzene (NB) derivatives as hazardous chemical substances were assessed. Nevertheless, a high reaction yield of 98% has been achieved in short reaction times 10 min. Moreover, the Fe₃O₄@Cur/Mel-Ag magnetic nanocomposite was conveniently collected by an external magnet and recycled 5 times without a noticeable diminish in catalytic performance. Therefore, the prepared magnetic nanocomposite is a privileged substance for NB derivatives reduction since it achieved notable catalytic activity.

Promotion effects of halloysite nanotubes on catalytic activity of Co3O4 nanoparticles toward reduction of 4-nitrophenol and organic dyes

Nanosized clay minerals have been widely used as efficient supports to immobilize catalyst nanoparticles. However, clay support-induced interactions and their influences on the catalyst structure and performance currently have not been fully understood. Here, Co₃O₄ nanoparticles supported on halloysite nanotubes (HNTs) were synthesized by a facile deposition-precipitation approach followed by thermal treatment. A series of characterization methods were employed for the Co₃O₄/HNTs hybrid nanostructure to identify its crystal phase, chemical composition, morphology, specific surface area, surface chemical states, and redox property. Characterization results showed that HNTs not only impacted the particle size of Co₃O₄ nanoparticles, but also modified surface chemical surface states of the later, which ultimately promoted the effective catalytic reduction of 4-nitrophenol (4-NP) and azo dyes with sodium borohydride. The interaction between HNTs and Co₃O₄ nanoparticles was found to shorten the induction period of the 4-NP reduction. Meanwhile, the Co₃O₄/HNTs catalyst for the 4-NP reduction achieved an apparent rate constant of 0.265 min^-1 and an activity parameter of 1.63 × 10⁴ min^-1 g^-1 as well as a turnover frequency of 4.37 min^-1. In addition, Co₃O₄/HNTs showed an improvement in reduction efficiency of the azo dyes when compared to bare Co₃O₄ nanoparticles.

Strecker-Derived Methodology for Library Synthesis of N-Acylated α-Aminonitriles

The Strecker reaction is a three-component condensation of an aldehyde, an amine, and hydrogen cyanide, delivering an α-amino carbonitrile. Despite extensive investigations, the possibility to use amides instead of amines as one of the three condensation partners has been largely neglected. Nonetheless, the N-acylated α-aminocarbonitriles that are obtained in this way are of direct interest for drug discovery, because they make up a well-known class of mechanism-based inhibitors of serine- and cysteine-type hydrolases. In response, we have thoroughly explored the corresponding variant of the Strecker reaction, focusing on catalyst use, solvent, reaction time, and cyanide source. Optimized parameters were combined in a sequential one-pot protocol for which the scope was found to be compatible with library synthesis applications. Product yields ranged from 7 to 90%, and conditions were found to be mild and tolerant to a wide range of functional groups, including moieties that are typically present in druglike molecules.

Convenient conversion of hazardous nitrobenzene derivatives to aniline analogues by Ag nanoparticles, stabilized on a naturally magnetic pumice/chitosan substrate

Herein, silver nanoparticles (Ag NPs), as an effective catalyst for the reduction process of nitrobenzene derivatives to non-hazardous and useful aniline derivatives, are conveniently synthesized on an inherently magnetic substrate. For this purpose, an efficient combination of volcanic pumice (VP), which is an extremely porous igneous rock, and a chitosan (CTS) polymeric network is prepared and suitably used for the stabilization of the Ag NPs. High magnetic properties of the fabricated Ag@VP/CTS composite, which have been confirmed via vibrating-sample magnetometer (VSM) analysis, are the first and foremost advantage of the introduced catalytic system since it gives us the opportunity to easily separate the particles and perform purification processes. Briefly, higher yields were obtained in the reduction reactions of nitrobenzenes (NBs) under very mild conditions in a short reaction time. Also, along with the natural biocompatible ingredients (VP and CTS) in the structure, excellent recyclability has been observed for the fabricated Ag@VP/CTS catalytic system, which convinces us to do scaling-up and suggests the presented system can be used for industrial applications.

Fabrication of Fe3O4@PVA-Cu Nanocomposite and Its Application for Facile and Selective Oxidation of Alcohols

Fe₃O₄@PVA-Cu nanocomposite was introduced as an affordable catalyst for selective oxidation of alcohols into various aldehydes and ketones. The synthesized nanocomposite was characterized by applying essential analyses. The peaks that are appeared in FT-IR spectroscopy confirmed the production of the Fe₃O₄@PVA-Cu nanocomposite. In addition, EDX analysis proved the presence of oxygen, carbon, iron, and copper elements in the catalyst. Further, TGA analysis showed high thermal stability of the nanocomposite. VSM technique was applied to examine the magnetic property of the nanocomposite. The results demonstrated a high magnetic property in the catalyst, which enables easy separation of it from the reaction solution. TEM and SEM imaging showed the nanoscale size of the particles (~20 nm) in the catalyst. Additionally, XRD data was compatible with that of Fe₃O₄ nanoparticles. The application of the nanocomposite has been studied in the selective oxidation of alcohols in the presence of acetonitrile as solvent, and hydrogen peroxide as a supplementary oxidizing agent. This technique is remarkably facile and inexpensive. Further, the products showed high yields. In addition, the calculated TON and TOF values indicated the phenomenal efficiency of the nanocomposite in preparation of targeted products.

Cellulose-Supported Sulfonated Magnetic Nanoparticles: Utilized for One-pot Synthesis of α-Iminonitrile Derivatives

ntroduction: An instrumental strategy for α-iminonitrile derivatives preparation by Fe3O4@cellulose-OSO3H (MCSA) as an eco-friendly nanocatalyst and oxidative agent in aerobic condition, is presented.

MATERIALS AND METHODS

Through this method, a one-pot three-component condensation reaction of various aldehydes, primary amines and trimethylsilylcyanide (TMSCN) were applied to synthesize the desired products. It was performed in absolute ethanol and under a mild condition by using the presented nanocatalyst. High reaction yields were obtained through using the presented magnetic agent, as well. Moreover, the threecomponent reactions were executed using accessible and economical precursors. The convenient separation and recyclability of the used nanocatalyst were also precisely investigated.

RESULTS AND DISCUSSION

In this research, we identified novel α-iminonitrile derivatives using 1H NMR, 13C NMR, CHN, and FT-IR analyses, as well. In order to determine the well-known derivatives, we used FT-IR method as well as comparing their melting points with those of reported.

CONCLUSION

In summary, an extremely efficient method was used for the environmentally-friendly synthesis of α-iminonitrile derivatives that are important bioactive substances. The catalytic oxidative coupling reaction afforded the products via a one-pot three-component condensation reaction of various aldehydes, primary amines and TMSCN with great reaction yields, in ethanol under mild conditions.

Cellulose matrix embedded copper decorated magnetic bionanocomposite as a green catalyst in the synthesis of dihydropyridines and polyhydroquinolines

A new biopolymer-based magnetic nanocomposite was prepared and characterized by Fourier transform infrared (FT-IR) spectroscopy, energy-dispersive X-ray (EDX) analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images, inductively-coupled plasma atomic emission spectroscopy (ICP-AES) analysis, thermogravimetric/differential thermal (TG/DT) analysis and atomic force microscopy (AFM) image analysis. Then, it was applied as an efficient heterogeneous catalyst in two important three- and four-component one-pot organic condensation reactions for the synthesis of Hantzsch 1,4-dihydropyridine and polyhydroquinoline derivatives in high yields under solvent-free condition at room temperature. The first design and development of a low-leaching bionanostructure, easy separation and reusability of the nanocatalyst, simple work-up procedure, mild, green and environmentally friendly conditions are some important features and advantages of the present work.