Efficient heterogenization of palladium by citric acid on the magnetite nanoparticles surface (Nano-Fe3O4@CA-Pd), and its catalytic application in C-C coupling reactions

Recyclable LaF3·Pd nanocatalyst in Suzuki coupling: green synthesis of biaryls from haloarenes and phenylboronic acids

Herein we prepared the novel LaF3·Pd nanocatalyst characterized by XRD and TEM analysis. The nanocatalyst was applied in Suzuki coupling reaction for the synthesis of biaryls in aqueous medium from readily available aryl halides (bromides and iodides) and substituted phenylboronic acids in the presence of K2CO3 as the base at 70 °C. The present method is capable of giving the C-C coupled product in good to excellent yields (up to 97%). The reactions were conducted under green conditions in aqueous medium and the nanocatalyst used in this study was recyclable. The recyclability and reusability of the catalyst was checked for seven consecutive cycles without significant loss in reactivity.

Efficient and biocompatible new palladium-supported boehmite nanoparticles: synthesis, characterization and application in Suzuki-Miura and Mizoroki-Heck coupling reactions

Palladium complex-supported on boehmite (Pd(0)-SMTU-boehmite) nanoparticles were synthesized and characterized by using XRD, SEM, EDS, TGA, BET, ICP and FT-IR techniques. When applied as a new catalyst for C-C coupling reactions of Suzuki-Miyaura and Mizoroki-Heck in PEG-400 solvent, the Pd(0)-SMTU-boehmite nanoparticles showed excellent activity and recyclability. The study of palladium leaching by the ICP-OES technique and hot filtration led to the catalyst exhibiting excellent stability and recyclability.

Selective photo-reduction of NO2- to N2 in the presence of Fe2+ and citric acid

The photo-reduction of NO₂^- has received increasing attention due to its high photo-activity. However, the intermediate products of NO₂^- photo-reduction might contain NO_x, which are also toxic pollutants. Herein, a novel strategy to selectively photo-reduce NO₂^- to N₂ was proposed using Fe²⁺ and citric acid (H₃Cit) as assistant to eliminate the formation of NO_x. In this strategy, NO₂^- was firstly reduced to NO by the combination of photon, Fe²⁺ and H₃Cit; the generated NO was then immediately captured by Fe²⁺-H₃Cit to form Fe²⁺-H₃Cit-NO complex; finally, H₃Cit was activated by Fe³⁺ and •OH in Fe²⁺/H₃Cit/UV/NO₂^- system to produce carbon dioxide anion radical (CO₂•^-), which could reduce the NO in Fe²⁺-H₃Cit-NO complex to N₂ with high efficiency and selectivity. The removal efficiencies of NO₂^- and TN were 98.6% and 87.5%, respectively, and the selectivity of N₂ was 81.6% in Fe²⁺/H₃Cit/UV/NO₂^- system after 60-min reaction at initial pH of 2.2, Fe²⁺ dosage of 3.0 mmol·L^-1 and H₃Cit dosage of 3.0 mmol·L^-1. Based on the experimental results and spectral analysis, the mechanism of NO₂^- selective reduction in Fe²⁺/H₃Cit/UV/NO₂^- system was proposed. Our finding provides a new way for wastewater denitrification and water purification.

Two Schiff-base Complexes of Copper and Zirconium Oxide Fabricated on Magnetic Nanoparticles as Practical and Recyclable Catalysts in C-C Coupling Reaction

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Fe3O4 magnetic nanoparticles (MNPs) were prepared via a chemical co-precipitation method. Then, the surface of Fe3O4 MNPs was modified by (3-Chloropropyl)trimethoxysilane and then two Schiff-base complexes of zirconium oxide and copper were stabilized on modified Fe3O4 MNPs. These catalysts were characterized using SEM, EDS, WDX, FTIR, XRD, TGA, VSM and AAS techniques. The catalytic activity of these catalysts was described in the carbon-carbon coupling reaction. VSM analysis of these catalysts indicate the high magnetic performance, therefor these catalysts can be recovered by an external magnet and reused for several times without missing in the amount of catalysts. Reusability, excellent yields and high TON values indicate the high efficiency of these catalysts. Leaching of these catalysts was studied by AAS which leaching of copper or zirconium was not observed. Also, the stability of these catalysts was confirmed by characterization of recovered catalysts and comparing with fresh catalysts.

Magnetic MCM-41 nanoparticles as a support for the immobilization of a palladium organometallic catalyst and its application in C–C coupling reactions

An organometallic catalyst of palladium has been immobilized on magnetic MCM-41 nanoparticles and used for C–C coupling reactions. The products were obtained in high yields and good TOF values which were indicate the high efficiency of this catalyst.