Nickel-palladium bimetallic nanoparticles supported on multi-walled carbon nanotubes (Ni-Pd/MWCNTs) were prepared by dry mixing of the nickel and palladium salts using the mechanical energy of a ball-mill. These nanoparticles demonstrated remarkable catalytic activity in Sonogashira cross-coupling reactions with a wide range of functionalized aryl halides and terminal alkynes under ligand and copper free conditions using Monowave 50 heating reactor. The catalyst is air-stable and can be easily removed from the reaction mixture by centrifugation and reused several times with minimal loss of catalytic activity. Furthermore, the concentration of catalyst in Sonogashira reactions can be lowered to a minimum amount of 0.01 mol%while still providing a high conversion of the Sonogashira product with an excellent turnover number (TON) of 7200 and turnover frequency (TOF) of 21600 h. The Ni-Pd/MWCNTs nanoparticles were fully characterized by a variety of spectroscopic techniques including X-ray diffraction (XRD), transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy (XPS). The remarkable reactivity of the Ni-Pd/MWCNTs catalyst toward Sonogashira cross-coupling reactions is attributed to the high degree of the dispersion of Ni-Pdnanoparticles with small particle size of 5-10 nm due to an efficient grinding method. This work provides a facile, solventless and inexpensive method for large-scale preparation of Ni-Pd/MWCNTs to accomplish often-challenging Sonogashira cross-coupling reactions.
more »
« less
Nickel-Fe3O4 Magnetic Nanoparticles Supported on Multiwalled Carbon Nanotubes: Effective Catalyst in Suzuki Cross Coupling Reactions
Nickel-Fe3O4 nanoparticles supported on multi-walled carbon nanotubes (Ni-Fe3O4/MWCNTs) were synthesized by mechanical grinding of a sample of nickel salt, Fe3O4 and MWCNTs using a ball-mill mixer. The preparation method allows for bulk production of Ni-Fe3O4 nanoparticles at room temperature without the necessity of any solvent or chemical reagent. The nanoparticles prepared by this method exhibit small particles size of 5–8 nm with uniform dispersion of nickel nanoparticles on the surface of multi-walled carbon nanotubes. The Ni-Fe3O4/MWCNTs demonstrated remarkable catalytic activity for Suzuki cross coupling reactions of functionalized aryl halides and phenylboronic acids with excellent turnover number and turnover frequency (e.g., 76,000 h−1) using Monowave 50 conventional heating reactor at 120 °C within a very short reaction time of 15 min. The catalyst is air-stable and exhibits easy removal from the reaction mixture due to its magnetic properties, recyclability with no loss of activity, and significantly better performance than the other well-known commercial nickel catalyst. The Ni-Fe3O4/MWCNTs nanoparticles were fully characterized by a variety of spectroscopic techniques including X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). Since nickel offers similar properties to other more expensive transition metals including the most widely used palladium counterpart in cross coupling catalysis, this work demonstrates a promising lower-cost, air-moisture stable and efficient alternative catalyst based on nickel nanoparticles for cross coupling reactions.
more »
« less
- Award ID(s):
- 1719511
- PAR ID:
- 10376629
- Date Published:
- Journal Name:
- Catalysts
- Volume:
- 11
- Issue:
- 4
- ISSN:
- 2073-4344
- Page Range / eLocation ID:
- 495
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Nickel-palladium bimetallic nanoparticles supported on multi-walled carbon nanotubes (Ni-Pd/MWCNTs) were prepared by dry mixing of the nickel and palladium salts using the mechanical energy of a ball-mill. These nanoparticles demonstrated remarkable catalytic activity in Sonogashira cross-coupling reactions with a wide range of functionalized aryl halides and terminal alkynes under ligand and copper free conditions using Monowave 50 heating reactor. The catalyst is air-stable and can be easily removed from the reaction mixture by centrifugation and reused several times with minimal loss of catalytic activity. Furthermore, the concentration of catalyst in Sonogashira reactions can be lowered to a minimum amount of 0.01 mol%while still providing a high conversion of the Sonogashira product with an excellent turnover number (TON) of 7200 and turnover frequency (TOF) of 21600 h. The Ni-Pd/MWCNTs nanoparticles were fully characterized by a variety of spectroscopic techniques including X-ray diffraction (XRD), transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy (XPS). The remarkable reactivity of the Ni-Pd/MWCNTs catalyst toward Sonogashira cross-coupling reactions is attributed to the high degree of the dispersion of Ni-Pdnanoparticles with small particle size of 5-10 nm due to an efficient grinding method. This work provides a facile, solventless and inexpensive method for large-scale preparation of Ni-Pd/MWCNTs to accomplish often-challenging Sonogashira cross coupling reactions.more » « less
-
We have developed an efficient method to generate highly active nickel–palladium bimetallic nanoparticles supported on multi-walled carbon nanotubes (Ni–Pd/MWCNTs) by dry mixing of the nickel and palladium salts utilizing the mechanical energy of a ball-mill. These nanoparticles were successfully employed in Sonogashira cross-coupling reactions with a wide array of functionalized aryl halides and terminal alkynes under ligand and copper free conditions using a Monowave 50 heating reactor. Notably, the concentration of palladium can be lowered to a minimum amount of 0.81% and replaced by more abundant and less expensive nickel nanoparticles while effectively catalyzing the reaction. The remarkable reactivity of the Ni–Pd/MWCNTs catalyst toward Sonogashira cross-coupling reactions is attributed to the high degree of the dispersion of Ni–Pd nanoparticles with small particle size of 5–10 nm due to an efficient grinding method. The catalyst was easily removed from the reaction mixture by centrifugation and reused several times with minimal loss of catalytic activity. Furthermore, the concentration of catalyst in Sonogashira reactions can be reduced to a minimum amount of 0.01 mol% while still providing a high conversion of the Sonogashira product with a remarkable turnover number (TON) of 7200 and turnover frequency (TOF) of 21 600 h −1 . The catalyst was fully characterized by a variety of spectroscopic techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS).more » « less
-
NA (Ed.)Cross-coupling reactions are typically carried out under batch reaction conditions in which the reactants and catalyst are charged to a vessel that is then heated for a specified period of time followed by removal of the reaction product mixture However, it would be difficult to effectively take advantage of the elevated catalytic activity exhibited by the catalyst under batch reaction conditions given the short reaction times required to affect conversion to product. We have recently prepared nickel nanoparticles supported on multi-walled carbon nanotubes (Ni/MWCNTs) by dry mixing of the corresponding nickel salts and multi-walled carbon nanotubes using a mechanical shaking of the ball-mill. The method allows for bulk production of Ni/M WCNTs nanoparticles with small particle size of 5- 10 nm ideal for application in batch and continuous flow cross-coupling catalysis. As an alternative approach to batch reactions, we successfully evaluated the Ni/MWCNTs system for Suzuki cross-coupling reactions under continuous flow reaction conditions by which the reactants can be fed onto a catalyst bed at a specified feed rate and reaction temperature while the Suzuki product is continuously recovered. This approach has the additional advantage of a significantly greater surface-to-volume ratio which significantly reduces the catalyst contact time. Furthermore, various functionalized aryl halides and phenylboronic acids can be prepared under continuous flow conditions in high conversion %, a feature which allows for industrial and pharmaceutical applications of this method in future.more » « less
-
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.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/catal11040495
