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1. Introduction One of the major research issues of the scientific community is the use of lignocellulosic biomass as a feedstock for the fermentative processing of biofuels and platform chemicals. The major research priority is to reduce the use of carbon energy by increasing the supply of renewable feedstock. Over the years, fermentable sugars could be produced from lignocellulosic biomass, using various approaches. Effective pretreatment of biomass can cause disruption of the crystalline structures of cellulose fibers and the removal of lignin. One of the successful and approved techniques for large-scale applications is dilute acid hydrolysis for that. Several inhibitors are produced during acid pretreatment including furanic aldehydes which inhibit pretreatment performance. Hydroxymethylfurfural (HMF) inhibitors among these are more harmful to the further fermenting species. Production and metabolism of microorganisms involved in the processes of fermentation often hindered by this furanic aldehyde.HMF is a breakdown product of fructose (one of the main sugars in honey) it forms slowly during storage and very quickly when honey is heated. HMF can be synthesized by dehydration of all types of C6 carbohydrates, including monomeric and polymeric carbohydrates, such as fructose, glucose, sucrose, starch, inulin, cellulose, and raw biomass. HMF represents a key intermediate for the conversion of biomass to biochemicals. Microorganisms are known for the furanic aldehyde degradation. HMF is a toxic substance and can be used as a chemical source to produce a variety of high value-added products such as 5-hydroxymethyl 2-furancarboxylic acid (HMFCA), 2,5-Furandicarboxylic acid (FDCA) and 2,5-diformylfuran (DFF). Every HMF derivative has its own properties as a biochemical capability. It is specifically FDCA that is called a compound derived from biomass. FDCA is an organic chemical compound consisting of two carboxylic acid groups attached to a central furan ring. FDCA has been found to be useful in many fields. The most important application of FDCA is that it can serve as a polymer building block to produce biobased polymers such as polyamides, polyesters, and polyeurethanes. The most attractive way is that FDCA can replace the petrochemicalderived terephthalic acid for the synthesis of biobased polyesters. Currently, FDCA is primarily generated by chemical routes and involves stoichiometric amounts of temperature, pressure and organic solvents, resulting in high energy consumption as well as tremendous contamination of the environment.In human urine and blood serum HMF is :metabolized into FDCA in a small amount. Mainly FDCA can be used for biochemical processing such as succinic acid, isodecylfuran-2, 5-dicarboxylate, isononyl furan-2, 5-dicarboxylate, dipentyl furan-2, 5-dicarboxylate, diheptyl furan-2, 5-dicarboxylate and poly (ethylene dodecanedioate-2, 5-furandicarboxylate) (PEDF). FDCA is also an essential component in the hexanoic acid, macrocyclic ligands, fungicides, corrosion inhibitors and thiolene films. FDCA derivatives, such as 2, 5-dihydroxymethylfuran 2, 5-bis (hydroxymethyl) tetrahydrofuran may be used as alcohol components in the production of new polyesters. FDCA's structurally furan rings are similar to fossil related TPA (Terepthalic Acid), one of today's commonly used plastic materials, and FDCA may be an environmentally safe choice for the development of modern bioplastics. It can also be used as an alternative for polybutylene terephthalate (PBT) and polyethylene terephthalate (PET) which are utilized in the production of film, fiber, packing materials and soft drink bottles. Unable to use the FDCA monomer as such in polymer processing. This must be paired with PEF (polyethylene furonate) and PBF (polybutylene furonate) synthesizing with ethylene glycol. FDCA diethyl esters have cocaine-like anaesthetic effects. It has a chelating ion activity (Ca2 , Cu2 , and Pb2 ) and has been used as a kidney stone reduction medication, synthesizing artificial vein transplant. This FDCA has eventually been identified as one of the 12 biochemical frameworks used for in-depth research into sustainable industrial production.Until now, microorganisms and enzymes have performed biotransformations of HMF into FDCA. Use advances in engineering such as media engineering, genetic engineering, and metabolic engineering, standard microbial HMF biotransformations and FDCA production rates are enhanced. The use of recombinant and wild enzymes has led to the development of new enzyme cascade systems with less time for higher tolerance of the substrates and product yield. Globally, these chemical and biological processes would need 4 metric tons of FDCA per year but have not yet reached its one fifth. Although several research activities are underway worldwide to produce FDCA, the green strategy to produce FDCA is not economic and not up to the industrial market level mark. It may take a long way from laboratory to industrial scale but in the coming years, the use of toxic chemical catalysts will give way to ' greener technology ' without any dangerous effects on the natural environment. Unless recent developments with some advances in microbial and enzyme processes resolve the challenges, this may lead to higher FDCA yield and soon hit global market level. 2. Chemical oxidative production of 2,5- FDCA from HMFVarious reaction systems were used to oxidize HMF with air, oxygen, or other oxidizing agents (H2O2, KMnO4 etc.). The chemical conversion requires high conditions of reaction (temperature and pressure) and additives, while using biological catalysts bioconversion proceeds through a mild process environment. Usually, the incremental development of FDCA from biomass requires the following steps: (1) glucose hydrolysis of lignocellulosic cellulose; (2) chemical and thermochemical conversion of glucose to biochemical platforms, i.e. dehydration of glucose to HMF; (3) catalytic oxidation of HMF to FDCA. In this process, cellulose is generally first separated by pretreatment from hemicellulose and lignin, then converted to glucose by chemical or biological approaches, followed by isomerization of the glucose obtained to form fructose. Direct use of glucose as feedstock proceeds via in situ isomerization of glucose to fructose followed by dehydration to produce HMF, and FDCA further yields oxidation of HMF. The conversion of HMF to FDCA can proceed through preferred aldehyde group oxidation to 5-hydroxymethyl-2-furan carboxylic acid, or the alcoholic group oxidation to 2, 5-furan dicarboxaldehyde, depending on the device applied. These intermediate processes are then oxidized to FFCA which is transformed as the final product into FDCA.3. Historical Method FDCA production was performed as early as 1876 when Fittig produced FDCA from mucic acid catalytically in 48 per cent aqueous hydrogen bromide (HBr) solution. Mucic acid dehydration continues with different dehydrating agents to effectively form FDCA. However, due to its high cost, long reaction time (> 20 hours), and relatively high reaction temperature (120 C), the mucic acid method failed to achieve scientific progress. This was accompanied by an analysis of the FDCA synthesis using different starting materials in different media. An alternate raw material for FDCA production could be xylose-derived furfural. In this process, inorganic oxidants (e.g. HNO3) may initially be used for furfural oxidation, followed by esterification of the generated2-furoic acid with methanol to form an intermediate, which is eventually converted to FDCA through several subsequent steps.4. One-pot production of FDCA from biomassDirect conversion of fractions of biomass and biomass into the products needed is always a fascinating and economical alternative for industrial application. The conversion of HMF to FDCA is theoretically feasible but faces cost, stability and availability challenges. HMF also has many other potentials and more economical uses that barricade its oxidation in order to manufacture FDCA. HMF is a biomass-derived product, so the FDCA's direct synthesis of carbohydrates such as fructose, glucose, cellulose, and lignocellulosic biomass has long been studied. This conversion process is called a one-pot synthesis and is usually performed with multifunctional catalysts combined from the acid and metal sites. Competitive carbohydrate oxidation is a major obstacle to the direct development of FDCA from carbohydrates but it can be partially overcome by adding molecular sieves or polymeric membranes in biphasic systems. The desired carbohydrate oxidation is vetoed by the use of polytetrafluoroethylene membrane (pore size = 0.45 μm and exchange area = 70 cm2) as a water and MIBK system reactor divisor. HMF is produced on a solid acid catalyst (Lewatit SPC 108) through the dehydration of fructose passed through the membrane towards the MIBK solution and oxidized to FDCA over metal base catalysts. Single phase conversion in MIBK only produces DFF, so that the presence of water is needed to convert the alcoxy group to FDCA. A higher yield (25 per cent) of levulinic acid and its membrane diffusion leads to lower yield of FDCA. Though this one-pot yield is very small and demanding, it unwraps a new research arena along with difficulties in purification.A bifunctional catalyst (Co(acac)3 encapsulation in solgel silica) improved the conversion of fructose and product selectivity, which was further enhanced by a two-step single-pot process. In the HClcatalyzed isopropanol mixture, fructose was dehydrated to HMF, and then oxidized to FDCA in the second step. This particular process has the advantages of recovering high overall yield (83 per cent) and effective solvent (isopropanol). FDCA's water extraction from the product mixture has a quantitative effect on product yield, and water extraction followed by oxidation over the Au / HT catalyst is the most economical purification process with maximum yield (98 per cent). By comparison, the total yield is reduced by replacing the catalyst with solid polybenzylic ammonium chloride. With the introduction of tetraethylammonium bromide (TEAB) as phase I, MIBK as phase II and water as phase III, the biphasic system was then modified to the triphasic system. Phase I promotes the oxidation of sugars (fructose or glucose) into HMF in this triphasic system, which is then collected, processed, and transferred through a funnel to phase III (phase II). The Au / HT catalyst used in phase III improved oxidation of the HMF. When using fructose as a feedstock, the FDCA yield was high (78 per cent) but reduced with glucose to 50 per cent. The one-pot one-step process can be converted into a two-step one-pot process to boost yield and selectivity. This method promotes the recovery and recycling of the catalysts for economic expansion to mass production. Using t-BuOOH as an oxidant, the nanocatalyst (Fe3O4CoOx) effectively oxidizes HMF to FDCA. HMF was derived from fructose over an acid catalyst (Fe3O4SiO2SO3H in DMSO) followed by oxidation of the nano-Fe3O4CoOx catalyst to FDCA with t-BuOOH. The catalyst can be isolated by an external magnet before oxidation with HMF. Although the observed yield of FDCA is small (59.8 per cent), the added advantages are the ease of separation and effective recycling. Glucose dehydration with FDCA over iPrOH / H2O or THF / H2O in comparatively less time induces quantitative yield. In the one-pot two-step synthesis of FDCA from glucose, the green Pd / CC catalyst produced by the carbonisation of biomass-derived glucose works efficiently. It has been stated that a more efficient, green and commercial process would produce FDCA with a yield of 64 per cent without separation and purification requirements. Deep separation and recycling efficiency with extended stability were demonstrated by the developed catalyst. The Pt / C catalyst performed efficiently (91 percent FDCA yield) with high initial concentrations of fructose (15 W percent) in water (GVL / H2O) co-solvent system of -valerolactone (GVL). Use the separate FDCA drug solution as the acid catalyst, fructose can be dehydrated to HMF in 50 per cent GVL aqueous solution, followed by oxidation over Pt/C catalyst. This process has industrial potential because crystallization makes it easy to isolate the developed FDCA. For economical reasons, the clean solution can be recycled to the stage of fructose dehydration. This effective recycling of the spent liquor, together with the removal of the separation step, eliminates the need for an external acid catalyst and minimizes the waste, thus conforming to the green chemical. To date, FDCA's one-pot production has focused primarily on using fructose as a feedstock. The FDCA yield with glucose as the feedstock by the one-pot process is usually lower than with fructose because it requires isomerization of glucose to fructose. Much lower yield for one-pot processing of the lignocellulosic biomass is achieved mainly because of the difficulty of releasing glucose from the matrix of the cell wall. While being a new trend in the research arena, the one-pot cycle has the barriers of low FDCA yield with less competitive and economic constraints. The one-pot process needs further development in terms of yield, selectivity and economics. The development of new transition metal catalysts is therefore important for this principle to be economically utilized. Elimination of side reactions and increase of FDCA yields can be improved by the isolation of several catalytic sites. Thus, for preferred carbohydrate adsorption the formed catalyst must have hydrophilic acidic sites. In a hydrophobic environment, active oxidative sites that boost the adsorption of the available HMF, which will enhance its conversion to FDCA. A simultaneous method would increase the yield and selectivity of the process to make the onepot process more feasible, efficient, effective, and competitive in cost. FDCA's extensive use in the synthesis of renewable-sourced polyesters is accounted for by its demand as the monomer replaces terephthalic acid. The biodegradability and biocompatibility properties make FDCA the preferred material for producing polyesters such as PET and PBT. Biomass-derived FDCA is a promising feedstock for a range of downstream chemical manufacturing. Consequently, FDCA's competitive manufacturing and marketing will not only play a vital role in the manufacture of biodegradable polymers but will also reap huge financial benefits. Numerous processes to produce FDCA from HMF or directly from carbohydrates derived from biomass (one-pot synthesis) have been studied extensively in laboratories, and some processes are now increasing industrially. Such processes include processes which are catalytic (both chemical and biological), non-catalytic, and electrochemical.6. References Tharangattumana Krishnan, Godan R O, Rajesh Loreni, Phukon Rai, Amit Sahoo, Dinabandhu Pandey, Ashok Parameswaran, Binod. (2019). Biotransformation of 5-hydroxymethylfurfural by Acinetobacter oleivorans S27 for the synthesis of furan derivatives. Bioresource Technology. 282. 10.1016/j.biortech.2019.02.125. R O, Rajesh Tharangattumana Krishnan, Godan Raveendran, Sindhu Pandey, Ashok Parameswaran, Binod. (2019). Bioengineering advancements, innovations and challenges on green synthesis of 2, 5 - furan dicarboxylic acid. Bioengineered. 11. 10.1080/21655979.2019.1700093. Serrano, A., Calvio, E., Carro, J. et al. Complete oxidation of hydroxymethylfurfural to furandicarboxylic acid by aryl-alcohol oxidase. Biotechnol Biofuels 12, 217 (2019). https://doi.org/10.1186/s13068-019-1555-z Peng Zhou and Zehui Zhang (2016) One-pot catalytic conversion of carbohydrates into furfural and 5-hydroxymethylfurfural. Catal. Sci. Technol., 2016, 6, 3694 S. M. McKenna,a P. Mines,b P. Law,b K. Kovacs-Schreiner,b W. R. Birmingham, c N. J. Turner, c S. Leimkhlerd and A. J. Carnell * (2017). The continuous oxidation of HMF to FDCA and the immobilisation and stabilisation of periplasmic aldehyde oxidase (PaoABC). Green Chem., 2017, 19, 4660 Muhammad Sajid, a,b Xuebing Zhao *a and Dehua Liu* (2018) \. Production of 2,5-furandicarboxylic acid (FDCA) from 5-hydroxymethylfurfural (HMF): recent progress focusing on the chemical-catalytic routes. DOI: 10.1039/c8gc02680g https://en.wikipedia.org/wiki/2,5-Furandicarboxylic_acid Zehui Zhang* and Kejian Deng (2015). Recent Advances in the Catalytic Synthesis of 2,5-Furandicarboxylic Acid and Its Derivatives. ACS Catal. 2015, 5, 11, 6529-6544. https://doi.org/10.1021/acscatal.5b01491 Siew Ping Teong, Guangshun Yi and Yugen Zhang* (2015) Hydroxymethylfurfural production from bioresources: past, present and future. Green Chem., 2014, 16, 2015. DOI: 10.1039/c3gc42018c
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