Recent Progress in Metal-Catalyzed Selective Oxidation of 5-Hydroxymethylfurfural into Furan-Based Value-Added Chemicals.

5-hydroxymethylfurfural (HMF), one of the most significant biomass-derived renewable resources, has been widely utilized to create furan-based value-added chemicals such as 2,5-diformylfuran (DFF), 5-hydroxymethyl-2-furancarboxylic acid (HMFCA), 5-formyl-2-furancarboxylic acid (FFCA), and 2,5-furan dicarboxylic acid (FDCA). Indeed, DFF, HMFCA and FFCA are key intermediate products during the oxidation of HMF to FDCA. Herein, this review aims to demonstrate the recent advances in metal-catalyzed oxidation of HMF into FDCA via two different reaction routes (HMF-DFF-FFCA-FDCA and HMF-HMFCA-FFCA-FDCA). All the four furan-based compounds are comprehensively discussed by the selective oxidation of HMF. Additionally, various metal catalysts, reaction conditions, and reaction mechanisms used to obtain the four different products are systematically reviewed. It is anticipated that this review will provide related researchers with new perspectives and speed up the development of this field.