Researchers of the Zelinsky Institute have studied the selective hydrogenation reaction catalyzed by the Pd/N-heterocyclic carbene system
Stereoselective hydrogenation of alkynes to alkenes is an important synthetic approach for the preparation of natural compounds, drugs, and intermediates in fine organic synthesis. Palladium catalysts are widely used in this process: they are compatible with many functional groups in the substrate, have high selectivity, and avoid the formation of side products of isomerization and complete hydrogenation. In recent years, the development of efficient palladium catalysts for transfer hydrogenation reactions has been actively conducted. They do not require an external source of hydrogen and run in a simple experimental setup without the need for special high pressure equipment.
Scientists from the Laboratory of Metal Complex and Nanoscale Catalysts of the ZIOC have studied the selective hydrogenation of diphenylacetylene catalyzed by the Pd/N-heterocyclic carbene (NHC) system. Most often, such systems work as homogeneous catalysts; however, the researchers of the Zelinsky Institute showed that in the hydrogenation reaction with their participation, homogeneous-heterogeneous catalysis was realized, and Pd/NHC species act as precursors of palladium nanoparticles. Presumably, compounds containing strong Pd-NHC bonds are rapidly converted into ligand-free complexes and then aggregate during the reaction to form palladium nanoparticles. The results obtained are quite important for understanding the mechanism of the hydrogenation reaction and determining the compounds responsible for the catalytic activity, which, in turn, is essential for the development of efficient catalytic systems.
Source:
Ekaterina A. Denisova, Alexander Yu. Kostyukovich, Artem N. Fakhrutdinov, Viktoria A. Korabelnikova, Alexey S. Galushko, Valentine P. Ananikov “Hidden” Nanoscale Catalysis in Alkyne Hydrogenation with Well-Defined Molecular Pd/NHC Complexes. ACS Catal., 2022, 12, 6980-6996. DOI: 10.1021/acscatal.2c01749.