Manganese catalyzed transfer hydrogenation of biomass-derived aldehydes: Insights to the catalytic performance and mechanism

Manganese catalyzed transfer hydrogenation (CTH) of aldehydes is an attractive method for the synthesis of alcohols. Here, we report a novel and efficient MnO@C-N catalyst for the CTH of biomass-derived 5-hydroxymethylfurfural and other aldehydes to alcohols in high yields. Catalytic experimental studies showed that the MnO and nitrogen-doping are responsible for the high selectivity and high conversion, respectively. Isotopic labelling experiments demonstrated that the CTH of aldehydes to alcohols over MnO@C-N is via a route by direct hydrogen transfer. Kinetic studies revealed that the N-doping can improve the reaction rate and reduce the activation energy of the aldehydes conversion. DFT calculations also indicated that both pyridine N and pyrrolic N doping can reduce the energy barrier for acetone desorption by the interaction between N and hydroxyl-H of alcohol. Furthermore, MnO@C-N showed good recyclability for at least five reaction cycles. We anticipate that these results can drive progress in the manganese catalyzed transfer hydrogenation reaction. (C) 2020 Elsevier Inc. All rights reserved.