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  1. NA (Ed.)
    The advancement of metal-catalyzed carbon-carbon bond forming reactions represents one of the most significant contributions to contemporary organic synthesis. Innovations in the area of palladium catalyzed homogeneous cross-coupling catalysis have dominated this area of chem. and are playing an increasingly important role in the area of pharmaceutical drug discovery and development. However, the use of these catalysts under homogeneous conditions has limited their com. viability due to product contamination as a direct result of inability to effectively sep. the catalyst from the reaction product. Ligand-free heterogeneous catalysis presents a promising option to address this problem as evidenced by the significant increase in research activity in this area. We have recently developed a simple, one-step method for the preparation of bimetallic nickel-palladium nanoparticles supported on multi-walled carbon nanotubes (Ni-Pd/MWCNTs) under mech. shaking in a ball- mill. The preparation method is very fast and straightforward which does not require any chems., solvents, or addnl. ligands. Notably, the concentration of palladium can be lowered to a min. amount of 1% and replaced by more abundant and less expensive nickel nanoparticles while effectively catalyzing the reaction. The as-prepared nanoparticles demonstrated remarkable catalytic activities in cross-coupling catalysis such as Suzuki and Sonoga shira reactions with functionalized substrates in batch with high turnover number in a single catalytic reaction. Batch operations have several inherent limitations that include reproducibility, scalability, and reactor productivity. Continuous flow chem. has been considered as an alternative approach in academic and industrial processes due to its efficient and innovative synthetic design. The low palladium loading and excellent recyclability of the catalyst make this an affordable and clean option for cross-coupling catalysis under continuous flow conditions, a feature that enables the large-scale industrial and pharmaceutical applications of this method in the future. 
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    Free, publicly-accessible full text available March 20, 2025
  2. NA (Ed.)
    Metal catalyzed carbon-carbon bond forming reactions have rapidly become one of the most effective tools in organic synthesis for the assembly of highly functionalized molecules. These reactions have typically been carried out under homogeneous reaction conditions, which require the use of ligands to solubilize the catalyst and broaden its window of reactivity. However, the use of these catalysts under homogeneous conditions has limited their commercial viability due to product contamination as a direct result of inability to effectively separate the catalyst from the reaction product. Ligand-free heterogeneous catalysis presents a promising option to address this problem as evidenced by the significant increase in research activity in this area. We have recently developed a simple, one-step method for the preparation nickel nanoparticles supported on multi-walled carbon nanotubes (Ni/MWCNTs) under mechanical shaking in a ball-mill. The preparation method is very fast and straightforward which does not require any chemicals, solvents, or additional ligands. The as-prepared nanoparticles demonstrated remarkable catalytic activities in Suzuki cross-coupling reactions of the functionalized aryl halides and phenylboronic acids in batch with high turnover number in a single catalytic reaction. Batch operations have several inherent limitations that include reproducibility, scalability, and reactor productivity. Continuous flow chemistry has been considered as an alternative approach in academic and industrial processes due to its efficient and innovative synthetic design. Due to the low level of leaching observed in batch reactions as well as remarkable recyclability, the Ni/MWCNTs nanoparticles demonstrated remarkable catalytic activity in Suzuki coupling reactions with a diverse range of functionalized aryl halides and phenyl boronic acids under continuous flow conditions. Further optimization of the method including the reaction time, temperature, required solvents, flow rate, and minimum residence time will be discussed in this presentation. 
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