HMF is a very important building block for a wide range of applications. In this paragraph applications in the areas of polymers, fine chemicals, and fuels are sum­marized. When HMF is produced at high efficiency follow-up products will become an attractive option to replace petrochemical analogs. An interesting molecule that can be derived from HMF is FDCA. It can be obtained via the oxidation of HMF; several oxidation methods have been described in literature (Van Putten et al., 2013a). FDCA was identified by the US Department of Energy (Bozell and Petersen, 2010) to be a key bio­derived platform chemical, which in itself is the building block for polyesters, polyamides and plasticizers but FDCA can also serve as starting point for several other interesting molecules, including succinic acid, FDCA dichloride, and FDCA dimethyl ester. In addition to FDCA, other platform chemicals can be produced as well. 5-Hydroxymethylfuroic acid, 2,5-diformyl furan, the 2,5-diamino-methylfuran, and 2,5-bishydroxymeth — ylfuran are most versatile intermediate chemicals of high industrial potential because they are six-carbon monomers that could replace, for example, adipic acid, alkyldiols, or hexamethylenediamine in the production of polymers (Van Putten et al., 2013a). 2,5-Furandi — carboxaldehyde and 2,5-hydroxymethylfuroic acid can be considered intermediates to FDCA in the oxidation of HMF. De Vries, Heeres and coworkers (Buntara et al., 2011) have shown an interesting route to convert HMF into caprolactam, the monomer for nylon-6. In addition to applications in the polymer field HMF can also be used in many fine chemicals applications. In view of the rigid furan structure and the two substituents that can be easily modified, HMF has been used in quite a number of pharmaceutical studies (Van Putten et al., 2013a). HMF-derived 5-amino-levulinic acid (Binder et al., 2010) and its derivatives are herbicides. A synthesis route was published by Descotes in collaboration with Sudzucker (Schinzer et al., 2004).

The Maillard reaction between reducing carbohy­drates and amino acids is undoubtedly one of the most important reactions in the flavor and fragrance world, leading to the development of the unique aroma and taste as well as the typical browning, which contribute to the sensory quality of thermally processed foods, such as cooked or roasted meat, roasted coffee or cocoa.

Although numerous studies have addressed the struc­tures and sensory attributes of the volatile odor-active compounds, the information available on nonvolatile, sensory-active components generated during thermal food processing is scarce but HMF derivatives play an essential role (Van Putten et al., 2013a). HMF has also been linked to natural products, sugar derivatives (e. g. glucosylated HMF) and spiroketals (Van Putten et al., 2013a). HMF can also be a precursor of fuel components. HMF is a solid at room temperature with very poor fuel blend properties; therefore, HMF cannot be used and has not been considered as a fuel or a fuel additive. The Small Medium-sized Enterprise (SME) company Avantium is developing chemical, catalytic routes to produce furan derivatives "furanics" for a range of biofuel applications (de Jong et al., 2012a, b). Avantium targets biofuels with advantageous qualities, both over existing biofuels such as bioethanol and biodiesel as well as over tradi­tional transportation fuels. Another major goal is mini­mizing the H2 demand for their production. These C5-derived furanic monoethers and C6-derived furanic diethers have a relatively high energy density, and good chemical and physical characteristics, no difference in the engine operation was observed and strongly decreased smoke and particulates emissions. The use of furans, such as HMF and furfural, as precursors of liquid hydrocarbon fuels is also an option for the production of linear alkanes in the molecular weight range appropriate for diesel or jet fuel. The group of Dumesic has researched and evaluated the different strategies possible for upgrading HMF to liquid fuels (531 Alonso et al., 2010). HMF can be transformed by hydrogenolysis to 2,5-dimethyl furan. To form larger hydrocarbons, HMF and other furfural products can be upgraded by aldol condensation with ketones, such as acetone, over a basic catalyst (NaOH) already at room temperatures (West et al., 2008). Also several levulinic acid derivatives have been proposed for fuel applications, for instance ethyl levulinate, g-valerolactone, and MTHF (Geilen et al., 2010). The conversion of HMF to fuels has recently been reviewed (Maki-Arvela et al., 2012).