Abstract
In contrast to the nonrenewable fossil resources, biomass, the only renewable resource of organic carbon in the nature, is considered as a special kind of inexhaustible feedstocks, which can be used for the synthesis of numerous valuable products in a sustainable manner. Among many biomass-derived products, 5-hydroxymethylfurfural (HMF) is identified to be a crucially important versatile compound due to its marvelous structure that is composed of an aldehyde group, a hydroxyl group and a furan ring. Hence, HMF possesses a very strong chemical reactivity, and it can be further transformed into a wide variety of value-added derivatives. In recent years, the synthetic methods, physicochemical properties and commercial prospects of HMF-based conventional derivatives such as 2,5-dimethylfuran (DMF), 5-ethoxymethylfurfural (EMF), ethyl levulinate (EL), long chain alkane (LLA), levulinic acid (LA), 2,5-diformylfuran (DFF) and 2,5-furandicarboxylic acid (FDCA) have been intensively reviewed by many researchers. However, up to now, the preparation of HMF-based innovative derivatives such as 2,5-dihydroxymethylfuran (DHMF), 2,5-dihydroxymethyltetrahydrofuran (DHMTHF), 1,2,6-hexanetriol (HTO), 1,6-hexanediol (HDO), 1-hydroxyhexane-2,5-dione (HHD), 3-hydroxymethylcyclopetanone (HMCPN), furan-2,5-dimethylcarboxylate (FDMC), maleic anhydride (MA), 5-hydroxy-5-(hydroxymethyl)furan-2(5H)-one (HHMFO), 5-alkoxymethylfurfural (AMF), 5,5-oxy-(bismethylene)-2-furaldehyde (OBMF), 5-arylaminomethyl-2-furanmethanol (AAMFM), 2,5-furandiamidine dihydrochloride (FDADHC), 1-alkyl-5-hydroxy-2-(hydroxymethyl)pyridinium (AHHMP), 5,5-bis(hydroxymethyl)furoin (BHMF), 5-(dialkyloxymethyl)-2-furanmethanol (DAMFM), 5-chloromethylfurfural (CMF), 5-alkanoyloxymethylfurfural (AOOMF) and furfuryl alcohol (FFA) has not yet been comprehensively summarized. In order to fill this gap, the latest studies and advancements on the preparation of HMF-based innovative derivatives via various catalytic approaches such as hydrogenation, oxidation, etherification, amination, condensation, halogenation, esterification and decarbonylation are systematically outlined and discussed in this review. Furthermore, a few potential research trends in the future studies are also proposed to provide some useful ideas for the further preparation of HMF-based innovative derivatives in a much more green, simple, efficient and economical way.