Super-paramagnetic polymer composite-supported dendrimer-Mn catalyst: Fabrication, characterization and catalytic evaluation in selective aerobic oxidation of ethylbenzene and oximes derivatives

Design of strategy and catalytic for oxidation ethylbenzene, toxic petroleum, to high value-added via hy-drogen-atom-transfer process is lately attracting a renewed interest from both environmentally and economic view. Herein, novel manganese-based dendritic catalysts supported on the polymer-magnetic core-shell were synthesized, fully identified and evaluated with initiator NDHPI for selective and easy-to-handle aerobic oxidation of ethylbenzene (EB) and oximes to acetophenone (ACP) & carbonyl compounds (AH/KO), respectively. Besides mild condition reaction, the supported dendrimer-encapsulated Mn NPs also exhibited out-standing catalytic performance, such as selective oxidation of ethylbenzene and oximes using O-2 as green and cheaper oxidant with excellent reactivity, selectivity, stability, and magnetic recyclability. Additionally, the effect of operating parameters such as the amount of catalyst, nature of solvent, temperature and reaction time, and role of several N-hydroxyimides were studied in the catalytic efficiency of the synthesized dendritic catalyst. The results illustrated that the enhanced catalytic efficiency of the catalyst is derived from the magnetic dendritic structures, high Mn(II) content, hydrophobic arm of dendrimers, and interaction of Mn and the dendritic framework. Finally, the reaction pathway for EB and oxime has been deduced, and the crucial role of dendritic catalyst, NDPHI, and electronic effect has been elucidated. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

The design of a novel manganese-based dendritic catalyst for the selective oxidation of ethylbenzene and oximes has attracted renewed interest due to its mild reaction conditions, excellent catalytic performance, and magnetic recyclability. The study also investigated the effect of operating parameters and N-hydroxyimides on the catalytic efficiency of the synthesized dendritic catalyst.