Sonogashira cross coupling reactions have a wide range of applications in pharmaceutical industry for drug discovery and organic synthesis of natural products and pharmaceutical compounds. These reactions typically involve the coupling of aryl halides with terminal alkynes in the presence of palladium catalyst under appropriate reaction conditions. Most Sonogashira reactions have been carried out with homogeneous Pd catalysis, in which the catalyst is soluble in the reaction mixture. There are many disadvantages to this method including the difficulty to remove the catalyst from the sample and recyclability. Heterogeneous catalysis is an alternative approach to address the issues associated with homogeneous system mainly due to facile and clean removal of the catalyst and minimum metal residual contamination. Herein, we report the preparation of nickel-palladium nanoparticles supported on multi-walled carbon nanotubes (Ni-Pd/MWCNTs) as an effective heterogeneous catalyst for Sonogashira coupling reactions. The catalyst was prepared by mixing the appropriate ratio of nickel-palladium salts with multi-walled carbon nanotubes using a mechanical power of a ball mill. The nanoparticles prepared by this method were successfully used to catalyze Sonogashira coupling reactions of various substituted aryl halides and terminal alkynes using an equal amount of water and ethanol as an environmentally benign solvent system. This project provides a facile and effective method for largescale preparation of Ni-Pd/MWCNTs to catalyze Sonogashira cross-coupling reactions. The recyclability of the catalyst makes this an affordable and clean option for pharmaceutical and industrial applications.
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This content will become publicly available on March 20, 2025
Bimetallic nickel-palladium nanoparticles supported on multi-walled carbon nanotubes for Suzuki and Sonogashira cross-coupling reactions in continuous flow
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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- Award ID(s):
- 2101126
- PAR ID:
- 10528543
- Editor(s):
- NA
- Publisher / Repository:
- ACS; American Chemical Society (CAS)
- Date Published:
- ISSN:
- AN: 2024:1125479
- Format(s):
- Medium: X
- Location:
- ACS Spring 2024, New Orleans, LA, United States
- Sponsoring Org:
- National Science Foundation
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