Polymer immobilized [Mg@PS-anthra] complex: An efficient recyclable heterogeneous catalyst for the incorporation of carbon dioxide into oxiranes at atmospheric pressure and Knoevenagel condensation reaction under solvent free condition

Chemical fixation of CO2 conducted by Mg-based materials catalysts to produce cyclic carbonates: A comprehensive review

We are witnessing a surge in CO2 emissions into the atmosphere, leading to serious environmental issues for our planet. If we do not take action, it will harm humanity and the biosphere. Increased levels of CO2 in the atmosphere contribute to global warming, which results in climate upheavals that disrupt ecosystems, alter plant reproduction conditions, and cause numerous related problems. Consequently, the current CO2 levels in the atmosphere must be significantly lowered as soon as possible. CO2 is a plentiful C1 feedstock, and its chemical utilization has inspired chemists in recent years. The reaction of CO2 with epoxide to produce cyclic carbonate (CCs) is highly significant and actively pursued in laboratories worldwide. So, by chemically fixing CO2 into valuable cyclic carbonates, we can achieve two goals at once: reducing atmospheric CO2 and producing essential chemicals. However, CO2's low reactivity and high stability make fixation challenging, leading to the development of innovative heterogeneous catalytic systems to address this. Magnesium-based materials (Mg-based materials) have become an attractive choice for chemical catalysis of CO2 fixation reactions owing to their unique properties enabled by the polar structure of Mg(II) leads to their high CO2 affinity. This research deals with the introduction of Mg-based materials, synthesis methods, and their effect on the performance of the catalytic process in CO2 fixation reactions. Thus, this review can provide researchers with light horizons in utilizing the high potential of Mg-based materials in synthesizing efficient catalysts to achieve excellent yield, conversion, and selectivity in the cycloaddition of CO2 to epoxides into CCs.

Amine functionalized magnetic resorcinol formaldehyde as a green and reusable nanocatalyst for the Knoevenagel condensation

Herein, a novel amine-functionalized magnetic resorcinol-formaldehyde with a core-shell structure (Fe3O4@RF/Pr-NH2) is prepared through the chemical immobilization of (3-aminopropyl)trimethoxysilane over Fe3O4@RF composite. Characterization through FT-IR, EDX, PXRD, and TGA confirmed successful surface modification while preserving the crystalline structure of Fe3O4. The VSM analysis demonstrated excellent superparamagnetic properties, and SEM and TEM images revealed spherical particles for the designed nanocatalyst. The Fe3O4@RF/Pr-NH2 nanocomposite was employed as a robust nanocatalyst to promote the Knoevenagel condensation of benzaldehydes with ethyl cyanoacetate and malononitrile, resulting in the formation of substituted olefins. Various aromatic aldehydes were used as substrates in the presence of 0.01 g of Fe3O4@RF/Pr-NH2, achieving high to excellent yields (87-97%) within short reaction times (10-50 min) in EtOH at 60 °C. The high performance of Fe3O4@RF/Pr-NH2 is attributed to the hydrophobic nature of RF shell, which facilitates the accumulation of organic precursors around the catalytic active sites and enhances product yields. The designed magnetic catalyst could retain its high efficiency for at least ten runs. The metal-free, low-cost, and environmentally friendly attributes of the Fe3O4@RF/Pr-NH2 catalyst make it a promising alternative to traditional metal-based catalysts.

Constructing a metal-free 2D covalent organic framework for visible-light-driven photocatalytic reduction of CO2: a sustainable strategy for atmospheric CO2 utilization

A 2D polyimide-linked covalent organic framework (COF) with band gap energy of 2.2 eV is developed as a stable and efficient porous photocatalyst which shows CO2 reduction to formic acid, formaldehyde and methanol.

Base-Free Synthesis and Photophysical Properties of New Schiff Bases Containing Indole Moiety

Schiff bases represent an essential class in organic chemistry with antitumor, antiviral, antifungal, and antibacterial activities. The synthesis of Schiff bases requires the presence of an organic base as a catalyst such as piperidine. Base-free synthesis of organic compounds using a heterogeneous catalyst has recently attracted more interest due to the facile procedure, high yield, and reusability of the used catalyst. Herein, we present a comparative study to synthesize new Schiff bases containing indole moieties using piperidine as an organic base catalyst and Au@TiO2 as a heterogeneous catalyst. In both methods, the products were isolated in high yields and fully characterized using different spectral analysis techniques. The catalyst was reusable four times, and the activity was slightly decreased. The presence of Au increases the number of acidic sites of TiO2, resulting in C=O polarization. Yields of the prepared Schiff bases in the presence of Au@TiO2 and piperidine were comparable. However, Au@TiO2 is an easily separable and recyclable catalyst, which would facilitate the synthesis of organic compounds without applying any hazardous materials. Furthermore, the luminescence behavior of the synthesized Schiff bases exhibited spectral shape dependence on the substituent group. Interestingly, the compounds also displayed deep-blue fluorescence with Commission Internationale de l'Éclairage (CIE) coordinates of y < 0.1. Thus, these materials may contribute to decreasing the energy consumption of the emitting devices.

An Overview of Metal-free Sustainable Nitrogen-based Catalytic Knoevenagel Condensation Reaction ‎

Knoevenagel condensation reaction counts as a vital condensation in organic chemistry due to the synthesis of valuable intermediates, ‎heterocycles, and fine chemicals from commercially available reactants through forming new C=C...

Zn(II)-Functionalized COF as a Recyclable Catalyst for the Sustainable Synthesis of Cyclic Carbonates and Cyclic Carbamates from Atmospheric CO2

A simple covalent organic framework (COF) bearing β-ketoenamine units as a potential heterogeneous ligand for ZnII-catalyzed fixation and transformation of CO2 into value-added chemicals is reported. Catalytic investigations convincingly demonstrated...

Ag2CO3 containing magnetic nanocomposite as a powerful and recoverable catalyst for Knoevenagel condensation

In this paper, the synthesis, characterization and catalytic application of a novel magnetic silica-supported Ag2CO3 (MS/Ag2CO3) with core-shell structure are developed. The MS/Ag2CO3 nanocomposite was prepared through chemical modification of magnetic MS nanoparticles with AgNO3 under alkaline conditions. The structure, chemical composition and magnetic properties of MS/Ag2CO3 were investigated by using VSM, PXRD, FT-IR, EDX and SEM techniques. The MS/Ag2CO3 nanocomposite was used as an effective catalyst for the Knoevenagel condensation under solvent-free conditions at 60 °C in an ultrasonic bath. The recovery and leaching tests were performed to study the nature of the MS/Ag2CO3 catalyst under applied conditions.

Macroporous polystyrene degraded and functionalized chromium MPS-Cr(iii)-alen complex as a sustainable porous catalyst for CO2 fixation under atmospheric pressure and selective oxidation of aromatic alkenes

The benign synthesis of porous polystyrene supported chromium(iii) catalyst has been carried out for the production of cyclic carbonates via CO₂ fixation under atm. pressure and for the selective oxidation of aromatic alkenes under mild conditions.

Highly efficient FeNP-embedded hybrid bifunctional reduced graphene oxide for Knoevenagel condensation with active methylene compounds

Novel hybrid bifunctional FeNPs/PPD@rGO for Knoevenagel condensation reaction with 100% conversion and yield.

Catalytic synthesis of benzimidazoles and organic carbamates using a polymer supported zinc catalyst through CO2 fixation

Zinc metal is attached to the organically modified polystyrene and the obtained catalyst is well characterized. The catalyst is very efficient for the formation of benzimidazoles and organic carbamates through carbon dioxide fixation.

Polymer-incarcerated palladium-catalyzed facile in situ carbonylation for the synthesis of aryl aldehydes and diaryl ketones using CO surrogates under ambient conditions

A palladium-incorporated heterogeneous catalyst, Pd@(Merf-FA), was designed for the synthesis of aryl aldehydes and diaryl ketones using carbonylative surrogates.