Recent Advances on Heteroatom-Doped Porous Carbon/Metal Materials: Fascinating Heterogeneous Catalysts for Organic Transformations.

Design and preparation of low-cost, effective, and novel catalysts are important topics in the field of heterogeneous catalysis from academic and industrial perspectives. Recently, heteroatom-doped porous carbon/metal materials have received significant attention as promising catalysts in divergent organic reactions. Incorporation of heteroatom into the carbon framework can tailor the properties of carbon, providing suitable interaction between support and metal, resulting in superior catalytic performance compared with those of traditional pure carbon/metal catalytic systems. In this review, we try to underscore the recent advances in the design, preparation, and application of heteroatom-doped porous carbon/metal catalysts towards various organic transformations.

One-pot synthesis of propargylamines using magnetic mesoporous polymelamine formaldehyde/zinc oxide nanocomposite as highly efficient, eco-friendly and durable nanocatalyst: optimization by DOE approach.

Magnetic mesoporous polymelamine formaldehyde nanocomposite-incorporating ZnO nanoparticles were successfully synthesized using solvothermal and sol-gel methods. Fourier-transform infrared spectrometry (FT-IR), X-ray diffraction, Brunauer-Emmett-Teller, vibrating sample magnetometer, thermogravimetric analysis, elemental analysis, transmission electron microscopy and field emission scanning electron microscopy techniques were then utilized for evaluation of nanocomposites. The as-prepared nanocomposite can be used as heterogeneous nanocatalyst with remarkable performance for A3 coupling reaction toward one-pot synthesis of propargylamine and its derivatives under solvent-less condition. In order to maximize the product yield, the variables, i.e., reaction time, temperature and catalyst amount, were optimized by using a statistical approach. The synthesized nanocomposite can be easily separated from the reaction medium and reused over and over, without significant changes in its catalytic activity.

Pyrolysis of functional cellulose by ionothermal method to synthesis of mesoporous triazine carbon for supporting of Pd and its application.

A mesoporous triazine-based carbon (MTC) supported Pd nanoparticles was synthesized and found to be a retrievable and efficient heterogeneous catalyst for Heck cross-coupling reaction between various aryl halides and alkenes. The MTC-supported Pd catalyst is synthesized by ionothermal methodology followed by high temperature pyrolysis of functional cellulose (Cell-CN) and trimerization of nitrile groups in the presence of ZnCl2. A combination of different analysis such as FT-IR, Raman, XRD, FE-SEM, HRTEM, N2 adsorption-desorption isotherm and TGA confirm the successfully preparation of catalyst. The presence of ZnCl2 and also nitrile groups during pyrolysis process is proved to create a mesoporous structure with high specific surface area (1216.8 m2 g-1) which achieved from BET analysis. This heterogeneous catalyst represents a high stability and catalytic activity towards Heck cross-coupling reaction in optimized reaction condition.

A rapid and simple extraction of anti-depressant drugs by effervescent salt-assisted dispersive magnetic micro solid-phase extraction method using new adsorbent Fe3O4@SiO2@N3.

In this work, a rapid and simple method is applied using a newly synthesized nanoadsorbent for the extraction and preconcentration of the drugs Amitriptyline (AMT) and Nortriptyline (NRT), which are then determined using high performance liquid chromatography. We focus on the facile synthesis of Fe3O4@SiO2@N3, as a new and effective adsorbent, and the effervescent salt-assisted dispersive magnetic micro solid-phase extraction method. The applied method and modification of the surface of Fe3O4@SiO2 with the nitrogen-rich group lead to an increase in the interaction between the nanoadsorbent used and the analytes, and increase the extraction recovery. The accuracy of the synthesized nanoadsorbent is confirmed by the FT-IR, FE-SEM, XRD, and VSM analytical techniques. In order to obtain the best experimental conditions, optimization of the main variables involved is carried out using the central composite design method. Under the optimum experimental conditions, the limits of detection (LODs), linear dynamic ranges (LDRs), and relative standard deviations (RSDs for n = 5) for NRT and AMT were found to be as follow: LODs, 0.03 and 0.05 ng/mL; RSDs, 2.04 and 1.1 for NRT and AMT, respectively; and LDRs, 0.07-2000 ng/mL. Furthermore, the results obtained show that the nanoadsorbent can be used for five times with an extraction recovery more than 80% and 70% for AMT and NRT, respectively.

Diphenyl diselenide grafted onto a Fe3O4-chitosan composite as a new nanosorbent for separation of metal ions by effervescent salt-assisted dispersive magnetic micro solid-phase extraction.

Diphenyl diselenide was immobilized on chitosan loaded with magnetite (Fe3O4) nanoparticles to give an efficient and cost-effective nanosorbent for the preconcentration of Pb(II), Cd(II), Ni(II) and Cu(II) ions by using effervescent salt-assisted dispersive magnetic micro solid-phase extraction (EA-DM-µSPE). The metal ions were desorbed from the sorbent with 3M nitric acid and then quantified via microflame AAS. The main parameters affecting the extraction were optimized using a one-at-a-time method. Under optimum condition, the limits of detection, linear dynamic ranges, and relative standard deviations (for n = 3) are as following: Pb(II): 2.0 ng·mL-1; 6.3-900 ng·mL-1; 1.5%. Cd(II): 0.15 ng·mL-1; 0.7-85 ng·mL-1, 3.2%; Ni(II): 1.6 ng·mL-1,.6.0-600. ng·mL-1, 4.1%; Cu(II): 1.2 ng·mL-1, 3.0-300 ng·mL-1, 2.2%. The nanosorbent can be reused at least 4 times. Graphical abstract Fe3O4-chitosan composite was modified with diphenyl diselenide as a sorbent for separation of metal ions by effervescent salt-assisted dispersive magnetic micro solid-phase extraction.

A Simple and One-pot Synthesis of Tetrahydrobenzo[b]pyrans and Spirooxindoles Catalyzed by H-Fe3O4@DA-SO3H as an Efficient, Light and Reusable Nanocatalyst.

AIM AND OBJECTIVE: One of the principles of green chemistry is using inexpensive reagents and catalysts to design green route for synthesis of organic compounds. Recently magnetic nanoparticles have provided a considerable merits. In this study, hollow Fe3O4@Dopamine-SO3H has been successfully applied for the green synthesis of tetrahydrobenzo[b]pyrans and spirooxindoles via one-pot multi-component reaction. MATERIALS AND METHODS: Chemical reagents were purchased from Merck and Aldrich. Melting points were determined using an Electrothermal 9100. Fourier transform infrared and NMR spectra were recorded with a Shimadzu 8400 spectrometer and Bruker spectrometer, respectively. RESULTS: The reaction between benzaldehyde, malononitrile and dimedone was selected as the model for synthesis of tetrahydrobenzo[b]pyran. The obtained results showed that the best amount of catalyst is 0.01 g and the reaction has occurred in solvent free condition at 70°C. The results showed that both electron-withdrawing and electron-donating substituents have an acceptable yield in the reaction. After that the scope of this method was evaluated in one-pot synthesis of spirooxindole derivatives through three-component reaction of isatin derivatives, malononitrile or ethyl cyanoacetate and 1,3-cycllic diketone. The optimum condition was 0.01 g catalyst using H2O under reflux condition. Then other derivatives produced in excellent yields during short reaction times. CONCLUSION: Tetrahydrobenzo[b]pyran and spirooxindole derivatives in the presence of this catalyst were synthesized. The ease of preparation and handling of the catalyst and operational simplicity are some of the main advantages of this work. In addition, the catalyst could be recycled and reused at least six times without notable reduction in its catalytic activity.

Magnetic chitosan composite as a green support for anchoring diphenyl diselenide as a biocatalyst for the oxidation of sulfides.

Development of efficient, inexpensive and recyclable catalysts for a reaction under mild and green reaction conditions is still a very marvelous topic. In this work, diphenyl diselenide stabilized on magnetic chitosan as a novel, highly efficient, ecologically safe, cost-effective and magnetically recoverable heterogeneous nano-biocatalyst was prepared and characterized by different techniques, such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM) and vibrating sample magnetometer (VSM). Then, the catalytic activity of resultant nano-biocatalyst was effectively appraised for the chemoselective oxidation of sulfides to sulfoxides using H2O2 as a green oxidant at ambient temperature with a good to high yields without use any organic solvents. Additionally, the easily preparation from cheap and commercially available reagent, carrying out the reactions in the eco-friendly and mild conditions, short reaction times, easy separation from reaction mixture, recoverability and reusability of catalyst for four consecutive cycles without a significant degradation in catalytic activity, are some prominent advantages of this novel catalyst. These advantages make it a potential candidate to address the industrial needs and economic and environmental concerns.

Diphenyl diselenide immobilized on magnetic nanoparticles: A novel and retrievable heterogeneous catalyst in the oxidation of aldehydes under mild and green conditions.

In the present study diselenide stabilized on silica coated Fe3O4 magnetic nano particles asa novel, highly efficient and magnetically retrievable heterogeneous catalyst was designed, synthesized and introduced. Full characterization of the newly prepared magnetic nanocatalyst was authenticated using several physico-chemical characterization techniques such as Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction patterns (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM). Thereafter, the catalytic performance of this (Fe3O4@SiO2-Se)2 nanocatalyst was investigated in oxidation of aldehydes using H2O2 as the clean oxidant under aqueous conditions. Under the title conditions, a range of both aromatic and aliphatic aldehydes can be converted into the corresponding carboxylic acid products with excellent yields. Additionally, the magnetic nanoparticles could be conveniently recovered using an external magnetic field and reused four times without discernible decrease of efficiency. Some of the other outstanding features of this methodology are short reaction times, simple and easy work-up procedure, eco-friendly nature and cost effectiveness that make it economic, sustainable and in agreement with some green chemistry protocols.