Ru nanoclusters supported on a bimodal N,S-doped mesoporous carbon: an efficient and reusable catalyst for selective aerobic oxidation of alcohols and amines

Abstract

We present the preparation of a novel heterogeneous catalyst based on Ru [Ru(III)@IBOMC] prepared by the immobilization of ruthenium species on carbonaceous support and its utilization for the selective oxidation of alcohols and amines to their corresponding aldehydes/ketones and nitriles under an O₂ atmosphere and additive-free conditions. IBOMC (Ionic liquid derived Bimodal cubic Ordered Mesoporous Carbon) has been synthesized by the carbonization of a homogeneous mixture of an imidazolium-based ionic liquid and guanine as carbon precursors inside the mesochannels of KIT-6 as a hard template, followed by the subsequent template removal. The Ru(III)@IBOMC catalyst displayed excellent catalytic activity for the oxidation of various benzylic, heterocyclic, and aliphatic substrates of both alcohols and amines, giving exclusively the respective aldehydes/ketones and nitriles in high yields and selectivity. The catalyst exhibited excellent robustness and integrity, and can be recycled and reused several times in both alcohol and amine oxidation systems without any significant loss in its performance or leaching of the supported metal. The extraordinary activity, selectivity, and stability of this catalyst are assumed to originate from its ordered bimodal mesoporous structure as well as its homogeneous and stable decoration with heteroatoms and consequently with Ru nanoparticles.