A novel and capable supported phenylazophenylenediamine-based nano-adsorbent for removal of the Pb, Cd, and Ni ions from aqueous solutions

Synthesis of pyrano-pyrimidines: recent advances in catalysis by magnetically recoverable nanocatalysts

The widespread use of catalysts in chemistry in the current century, especially in multicomponent reactions, has led researchers to design catalysts with high catalytic power and which can be recycled. In recent years, most scientists and researchers of chemical science have become interested in magnetic nanocatalysts and used them to perform chemical reactions. Due to the magnetic property of this nanocatalyst, it can be separated and collected from the reaction mixture by a magnet after the reaction is complete and reused. Pyrano-pyrimidines are a group of heterocyclic compounds and important pharmaceutical compounds. Pyrano-pyrimidine derivatives are of great interest due to the wide role they play in biological activities. During the past years, various methods for the synthesis of pyrano-pyrimidines based on the use of magnetic nanocatalysts have been reported. In this review article, for the first time, we would like to focus on the reported non-magnetic materials as magnetically recoverable nanocatalysts for the synthesis of pyrano-pyrimidine derivatives. Considering the wonderful features of magnetic nanocatalysts such as simple separation and preparation, high catalytic activity and stability, we expect more articles on the synthesis of heterocycles using this type of catalyst to be published in the near future.

Application of MIL-101(Cr) for biofuel dehydration and process optimization using the central composite design method

Nowadays, researchers from various fields are aiming to replace petro-based and other fossil fuels with green and renewable alternatives. One of the potential candidates, requiring a highly pure reactant, is biofuel. The use of alcohol-containing water as a reactant can lead to different types of problems including the generation of side reactions, hydrolysis, equilibrium shifts, catalyst deactivation and process complexity. A metal-organic framework, MIL-101(Cr), was successfully synthesized using the hydrothermal method and subsequently employed for the dehydration of a standard biofuel. With this goal in mind, we aimed to optimize the effects of operational parameters-specifically, initial water concentration, adsorbent dosage, and temperature-using the central composite design (CCD) method, while also analyzing their behaviors by applying variance analysis. To predict the process behavior, we propose a refined quadratic equation under various conditions, achieving an R 2 value of 95.26. The results showed that the process was more influenced by temperature variations than the other two parameters. The optimal conditions were predicted with an initial concentration of 1.41, catalyst dosage of 0.14, and a temperature of 302.5 K, resulting in a capacity of 1349.72 and a desirability value of 0.95. Additionally, the synthesized MIL-101(Cr) was characterized using XRD, SEM, DSC/TGA, and N2 physisorption techniques. The results indicated that the particles possessed microporous windows and mesoporous cages, exhibiting a uniform octahedral shape with an average size ranging between 200 and 500 nm.

An Fe3O4 supported O-phenylenediamine based tetraaza Schiff base-Cu(ii) complex as a novel nanomagnetic catalytic system for synthesis of pyrano[2,3-c]pyrazoles

In this research, we present a post-synthetic method for synthesizing a novel nanomagnetic Cu(II) Schiff base complex and investigate its efficiency in catalytic organic conversion reactions. Various spectroscopic analyses were employed to characterize the physiochemical characteristics of the resulting nanocomposite. The experimental results successfully demonstrate the catalytic application of the prepared Cu-complex in the preparation of pyrano[2,3-c]pyrazole heterocycles. This synthesis involved a one-pot three-component condensation reaction, wherein hydrazine hydrate, ethyl acetoacetate, malononitrile, and aromatic aldehydes were combined under reflux conditions using water as the solvent. Notably, the heterogenized complex exhibited exceptional catalytic performance, achieving remarkable conversion rates and selectivity, all accomplished using only 12 mg of the catalyst. Furthermore, thorough stability assessments of this catalyst were conducted through reusability and hot filtration tests, which confirmed its non-leaching properties and demonstrated excellent results over the course of five consecutive runs.

Synthesis of a bistriazolyl-phenanthroline-Cu(ii) complex immobilized on nanomagnetic iron oxide as a novel green catalyst for synthesis of imidazoles via annulation reactions

We designed and prepared a novel N-heterocycle-based nanocatalyst by a post synthetic method, namely the [Fe3O4@DAA-BTrzPhen-Cu(ii)] composite. In this method, bistriazolyl-phenanthroline groups were stepwise synthesized on an Fe3O4 substrate and used as a tetradentate nitrogenous ligand for coordinating to copper ions. The obtained nanocomposite was well characterized using FT-IR, PXRD, TGA, EDAX, ICP-OES, EDX-mapping, SEM, TEM, VSM and BET analyses, which confirm the formation of a thermostable crystalline spherical particle morphology with the particle size in the range of 17 nm to 25 nm and a magnetization value of 42 emu g-1. Also, the catalytic activity of [Fe3O4@DAA-BTrzPhen-Cu(ii)] as a novel and magnetically separable heterogeneous nanocatalyst was evaluated in preparing various tetrasubstituted imidazole derivatives from one-pot four-component condensation of anilines, aldehydes, 1,2-diketones and ammonium acetate, and favorable products were produced with excellent yields. The stability, low Cu leaching, and heterogenous nature of the nanocatalyst were confirmed by hot-filtration and leaching tests. The copper based nanocatalyst could be easily recovered by magnetic field separation and recycled at least 8 times in a row without noticeable loss in its catalytic activity.