Efficient Production of Nitrones via One-Pot Reductive Coupling Reactions Using Bimetallic RuPt NPs
Xiaomin Ren, Jianmin Lü, Maodi Wang, Miao Guo, He Li, Xiaoli Pan, Lin Li, Alexis Munyentwali, Qihua Yang
Abstract
The H2-assisted catalytic one-pot cascade reductive coupling of nitroarenes with aldehydes for the production of nitrones is extremely attractive but still faces the difficulty of selectivity control due to the complex reaction pathways. Herein, we reported the selective production of nitrones under ambient conditions (35 °C, 1 atm H2) via catalytic cascade reactions using supported RuPt nanoparticles (NPs) with finely tuned surface geometric and electronic structures. Under optimized conditions, 94% yield of nitrone was obtained with Ru3Pt1 bimetallic core–shell NPs in the reductive coupling of nitrobenzene and benzaldehyde, while Pt NPs were deactivated after nitrone yield approached 42% and no activity was observed for Ru NPs. The microcalorimetric adsorption measurement and density functional theory (DFT) calculations showed that the strong adsorption of nitrones compared to that of H2 is the main reason for the deactivation of Pt NPs. The combination of Pt with Ru could increase the surface electronic density of Pt as well as induce Pt isolation by Ru, which, in turn, affects the adsorption strength of nitrone and H2. Ru3Pt1 achieved a high nitrone yield in comparison with other RuPt samples, which is possibly related to the strong adsorption and activation ability toward H2 and weak adsorption toward nitrone. Our findings open an avenue for a rational design of catalysts for complex cascade reactions via precise tuning of the adsorption strength of reactants and products.