Improved catalytic performance by changing surface and textural properties of Ru supported bifunctional periodic mesoporous organosilicas in aerobic oxidation of alcohols

Abstract

The catalytic activity of several supported catalysts comprising perruthenate anions incorporated into the mesochannels of a series of plugged and unplugged bifunctional periodic mesoporous organosilicas (Ru@BFPMOs) was investigated in the...

Open Air Direct Oxidative Coupling of Alcohols and Amines to Imines Catalyzed by Ruthenium Nanoclusters Supported on a Mesoporous Carbon (CMK-8) in/on Water

“…Ruthenium-based catalysts are among the most active and effective metal-based catalysts in this field, catalyzing this dehydrogenative condensation reaction either with an oxidant (typically, O 2 or air) − or even in the absence of any oxidants under an inert atmosphere. − While the latter could largely avoid overoxidation of alcohols to carboxylic acids, it might also be faced with a significant decrease in reaction selectivity caused by the formation of amine byproducts as a result of the reaction of imine products with the hydride species generated during the dehydrogenation process. , Moreover, some of the catalytic systems presented for the coupling of alcohols with amines under inert conditions have drawbacks such as using large amounts of poorly accessible, expensive, complex, and yet nonrecyclable homogeneous catalysts, using additives, requiring high reaction temperatures, and needing to conduct the reactions under an Ar/N 2 atmosphere. − Therefore, it seems that the aerobic oxidative coupling of alcohols and amines, especially by employing heterogeneous and recoverable catalytic systems, is still an active and preferable approach to the synthesis of imines. However, while the utilization of various Ru catalysts, either in the form of homogeneous or heterogeneous catalytic systems, has been extensively established in the aerobic oxidation of alcohols and/or amines, − the use of Ru-based catalytic systems in the one-pot tandem synthesis of imines through the selective oxidative coupling of alcohols and amines is a multifaceted and relatively less explored process.…”