Platform molecules glucose

Selective isomerization of glucose to fructose in aqueous medium Sn-p zeolite Fructose is easier to transform in suitable platform molecules than the abundant glucose. Hence, to find selective catalysts for this transformation is a critical key in the lignocellulosic biomass conversion [74]... 

This chapter is an overview of architectures adopted for the catalytic/biocatalytic composites used in wide applications like the biomass valorization or fine chemical industry. On this perspective, the chapter updates the reader with the most fresh examples of construction designs and concepts considered for the synthesis of such composites. Their catalytic properties result from the introduction of catalytic functionalities and vary from inorganic metal species e.g., Ru, Ir, Pd, or Rh) to well-organized biochemical structures like enzymes e.g., lipase, peroxidase, (3-galactosidase) or whole cells. Catalytic/biocatalytic procedures for the biomass conversion into platform molecules e.g., glucose, GVL, Me-THF, sorbitol, succinic acid, and glycerol) and their further transformation into value-added products are detailed in order to make understandable the utility of these complex architectures and to associate the composite properties to their performances, versatility, and robustness. 

Another practical example is glucose isomerase. It is connected to 5-HMF, another platform molecule, that has been synthesized using a chemo-enzymatic route [95]. Accordingly, glucose isomerase immobilized on a solid support catalyzed the glucose isomerization into fructose followed by the catalytic dehydration (oxalic acid catalyst) step to the target compound (5-HMF). The reaction was carried out in seawater since high salt concentration enhanced the efficiency of the whole process. 5-HMF product is continuously extracted from the reaction medium into... 

Early efforts for the efficient conversion of biomass into monomers were concentrated on the acidic transformation and on the fermentation of sugars obtained from sucrose, or from glucose after depolymerization of starch materials (potato, com). During the last two decades, however, more attention has been focused on other constituents of plant materials, such as cellulose and lignocellulosic residues. The current trend is indeed to avoid competition with food, offering new routes to C6 and C5 carbohydrates, for further transformation into value-added platform molecules. 

Figure 9 Compounds relevant to biomass conversion. Common monosaccharides glucose, fructose, and xylose are shown in their pyranose forms in the top row. Platform molecules furfural and 5-hydroxyfurfural (5-HMF) are shown in the bottom row.

In a future, ideal enzyme biosensor, the enzymes would be immobilised in such a way that aU the enzyme molecules react with enzyme substrate diffusing easily from solution into the enzyme layer and the products of the enzyme reaction reach the sensor transducer surface without any diffusion limitations, which leads to efficiencies approaching 100 %. Ideally, there should be no redox mediator and direct electron transfer occurs. Two recent examples are a biosensor platform based on lactate oxidase where characterisation was done by AFM and SECM [65] and glucose oxidase using functionalised nanotubes within a dihexadecylphos-phate film (DHP) [66]— in this latter case, SEM shows clearly CNTs distributed homogeneously in the DCP film. Fig. 6.8. 

---