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ISSN : 1225-0112(Print)
ISSN : 2288-4505(Online)
Applied Chemistry for Engineering Vol.30 No.3 pp.280-289
DOI : https://doi.org/10.14478/ace.2019.1036

Efficient Synthetic Routes of Biomass-derived Platform Chemicals

Mobina Irshad, Seongwoo Lee, Eunju Choi, Jung Won Kim†
Department of Chemical Engineering, Kangwon National University, Samcheok 25913, Republic of Korea
§

These authors contributed equally to this work.


Corresponding Author: Kangwon National University, Department of Chemical Engineering, Samcheok 25913, Republic of Korea Tel: +82-33-570-6543 e-mail: jwemye@kangwon.ac.kr
May 16, 2019 ; May 23, 2019 ; May 27, 2019

Abstract


5-hydroxymethylfurfural (HMF) and its derivatives, 2,5-furandicarboxylic acid (FDCA) or 2,5-diformylfuran (DFF), are regarded as the “sleeping giants” owing to their wide range of applications and a good alternative source for the production of significant chemicals in almost all kind of industries. This mini-review briefly covers the aspects related to the syntheses, transformation, and applications for the biomass-derived platform chemicals from past to most recent. Many scientific efforts have continuously been made to find out the environmental benign applicable ways in order to achieve the full advantage of these renewable materials because of not only to protect the globe but also shield the future of new generations. One of the best solutions could be the development and utilization of platform chemicals from the natural biomass.


5-hydroxymethylfurfural (HMF) , 2,5-furandicarboxylic acid (FDCA) , 2,5-diformylfuran (DFF) , Biomass-derived , Platform chemicals

바이오매스 유래 플랫폼 케미컬들에 대한 효과적인 합성 방법들

이 르샤드 모비나, 이 성우, 최 은주, 김 정원†
강원대학교 에너지공학부(에너지화학공학전공)

초록


5-Hydroxymethylfurfural (HMF) 및 그 유도체들인 2,5-furandicarboxylic acid (FDCA)와 2,5-diformylfuran (DFF)는 넓은 응 용 범위와 중요한 화학 물질 생산을 위한 좋은 대체 자원으로 인해 “잠자는 거인”으로 인식되고 있다. 본 미니-리뷰 논문은 과거부터 최근까지 이러한 바이오매스 유래 케미컬 플랫폼들에 대한 합성, 전환과 적용에 관해 간략히 소개한 다. 많은 과학적 노력들이 자연 환경과 새로운 미래 세대를 보호하기 위해서 재생 가능한 재료들의 최대한 활용을 위한 자연친화적-적용가능한 방법들을 찾기 위한 노력이 지속적으로 행해지고 있다. 최선의 해결책 중 하나는 자연 바이오매스로부터 플랫폼 케미컬을 개발하고 활용하는 것이다.


    1. Introduction

    Biomass is a never-ending source of nature that can be utilized in multiple ways as a feedstock to produce a variety of chemicals and valuable products. The threatening changes in the global climate because of the immense use of fossil fuels has shifted the concern of scientists and researchers to look for the alternate renewable sources that can not only prevent the depletion of the existing resources but also put a stop or at least minimize the rapid changes in the environment[ 1]. Moreover, the cost of the management of biomass waste can also be reduced if this biomass residue could be converted into handy materials which are otherwise burdensome to waste management practices[ 2]. Currently, only 10% of the crude oil is used for the manufacturing of industrial chemicals while the rest of the crude oil goes to fulfill the needs of transportation fuels. This is the sole reason that the concern has turned towards the biomass considering it as a potential source for the production of values added chemicals. The challenge to keep the biomass conversion processes “green” and cost-effective has always been a big point to ponder for the researchers[3]. From the viewpoint of green chemistry, the most valuable renewable feedstock derived from the plant-based biomass is the carbohydrates[4]. Among the carbohydrates, hexoses are of significant interest as they can be converted into the compounds containing five-membered furan ring after some chemical treatment. Fructose which is obtained by the isomerization of glucose contains this furan ring that can be easily converted into hydroxymethylfurfural (HMF)[5].

    HMF is among one of the significant platform chemicals which are obtained from the renewable biomass[6]. U.S. Department of energy has added HMF and its derivatives, particularly furfural and FDCA in the list of potential chemicals for future[7] because it can not only be obtained readily from different sources but also used as a starting material in the production of other compounds[8]. The furan ring-containing compounds that can be derived from HMF are shown in Figure 1. These include 2,5-diformylfuran (DFF), 2,5-furandicarboxylic acid (FDCA), 2,5-bis(hydroxymethyl)-furan (BHMF), 2,5-dimethylfuran (DMF), and levulinic acid. All of these compounds are interlinked to each other and can be produced by one process or the other in the transformation reactions. For example, FDCA and DFF are not only produced by the oxidation of HMF but obtained as a secondary product in the chemical conversion of hexoses. FDCA has been employed in a number of applications such as fungal control agent, melting agent, photography, pharmaceuticals, rust controlling and as a monomer in particular applications[6,9,10]. Furthermore, FDCA is an excellent alternative for the terephthalic acid which is widely used in polyester manufacturing[11] and can also be used as a raw material for the production of succinic acid that is utilized on the large scale in chemical industries. Moreover, DFF, another important derivative of HMF has its applications in the fields of polymerization, as intermediate, as a fungicide, ligands preparation, and as a cross-linking agent[12]. This mini-review focuses on the overview of various methods which has been employed since long for the conversion of biomass to HMF and then transformation of HMF to its derivatives particularly FDCA and DFF. Additionally, the potential applications of FDCA and DFF have also been outlined to provide the researchers a complete insight into these innovative compounds at one place.

    2. 5-Hydroxymethylfurfural - Synthetic Routes

    The first paper on the synthesis of HMF by dehydration of sugar in the acidic environment was published in 1875[13]. Until the middle of the 20th century, the field of biomass conversion didn’t capture much interest. In 1951, a review on the topic of furan formation from hexoses was published and gradually this domain caught the attention of researchers. Since then, the research in the area of conversion of biomass into valued products has gone through several stages from single phase conventional methods to advanced biphasic and green catalytic systems. An overview of all these developmental changes with time can be seen in Figure 2. From past to present, a number of routes have been proposed for the synthesis of HMF from plants derived biomass especially carbohydrates. Despite, the method chosen for the conversion, it has been determined that some factors are influential towards the rate of transformation of HMF. These factors were first given by Kuster[14] and are as follows:

    • Degree of hydrolysis and type of starting material

    • Amount and nature of the catalyst

    • Reaction conditions (time, temperature, etc.)

    • Rate and concentration of the polymerization

    • Stability of HMF in the given solvent

    A number of good reviews have been written[5,8,15,16] constituting the synthesis of HMF from biomass and each review has its own point of focus. The current mini-review only summarizes all the possible formation systems of HMF that have been employed in different reaction conditions. Starting from the biomass which needs some pretreatments either physical or chemical, the formation systems of biomass to HMF can broadly be classified in two major categories: autocatalytic systems and catalytic systems. Autocatalytic systems are defined as the systems in which a product acts as catalysts to promote the further reaction and no aid is provided in the form of the external catalyst[15]. These systems take account of various solvents such as polar protic solvents, polar aprotic solvents, and the solvents which function as the reaction promoters. Different mechanisms are involved which make a solvent exhibiting such a performance in a reaction system such as high solubility of the product, complex formation with solvent, or enhanced activity of a specific tautomer[17,18]. Dehydration of carbohydrates by using catalysts dated back almost a century and since then a lot of work has been done for the development of sustainable and economically favorable catalysts. Catalytic systems are generally divided into homogeneous catalysts, heterogeneous catalysts, metal salt catalysts, and bi-functional catalysts. Figure 3 provides a general overview of the till used synthetic routes for the transformation of biomass into 5-hydroxymethylfurfural.

    3. Transformation of HMF into Value-added Chemicals

    The structure of HMF is said to be the only one of its kind which makes it the most capable and tempting backbone chemical for the production of a large number of innovative compounds[19-21]. This groundbreaking chemical activity of HMF lies in its unique structure which is the combination of three highly active functional groups such as -OH group, -CHO group, and a furan ring. By controlling different reaction conditions, these functional groups can be derivatized into number of conventional and innovative compounds which are further used to produce premium fuels for instance, 2,5-dimethylfuran (DMF) [22-25], 5-ethoxymethylfurfural (EMF)[26-29], and ethyl levulinate (EL)[30-32], long chain liquid alkanes (LLA)[33,34], and industrially valuable chemicals for example levulinic acid (LA)[35-37], 2,5-diformylfuran (DFF)[38-41] and 2,5-furandicarboxylic acid (FDCA) [42-45]. The synthetic route for the production of DFF and FDCA is represented in Figure 4. The innovation has been created in the synthesis of new compounds by various pre-existing methodologies 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), and 3-hydroxymethylcyclopetanone (HMCPN) have been prepared by the hydrogenation of HMF in the presence of diverse catalysts. Similarly, maleic anhydride (MA), 5-hydroxy- 5-(hydroxymethyl)furan-2(5H)-one (HHMFO), and 2,5-furandimethylcarboxylate (FDMC) are the products of catalytic oxidation of HMF. The catalytic conversion of HMF via etherification results in the formation of 5-alkoxymethylfurfural (AMF), and 5,5-oxy-(bismethylene)- 2 furaldehyde (OBMF). The amination of HMF in the presence of catalysts produces 5-arylaminomethyl-2-furanmethanol (AAMFM), 1-alkyl-5-hydroxy-2(hydroxymethyl) pyridinium (AHHMP), and 2,5- furandiamidine dihydrochloride (FDADHC). The catalytic condensation products of HMF are 5,5-bis(hydroxymethyl)furoin (BHMF), and 5- (dialkyloxymethyl)-2-furanmethanol (DAMFM). Furthermore, 5-chloromethylfurfural (CMF), 5-alkanoyloxymethylfurfural (AOOMF) and furfuryl alcohol (FFA) are synthesized by the catalytic halogenation, esterification and decarbonylation of HMF respectively, under different reaction conditions.

    3.1. Conversion of 5-Hydroxymethylfurfural to 2,5-furandicarboxylic acid (FDCA)

    FDCA was found for the first time in the human urine and later in the blood plasma. The visual confirmation of the presence of the FDCA was determined by the Millard reaction indicated by the change of color (brown) as can be seen in some fruits when exposed to air. FDCA is a highly stable compound with a melting point of 342 ℃ and almost insoluble in common solvents except for DMSO. The extraordinary stability of FDCA is attributed to the intermolecular hydrogen bonding. Various methods have been proposed since now for the synthesis of FDCA but they are broadly classified into three sections[46]:

    • Hexose derivatives undergo dehydration to give FDCA

    • 2,5-disubstituted furans oxidize to produce FDCA

    • Different furan derivatives under catalytic conversion reactions form FDCA

    All these methods are dated back to the 18th century and the middle of the 19th century. Many of them were found to be insufficient to apply at the industrial level because of non-selectivity, low yields of desired products, the formation of many side products, and severe reaction conditions[46]. A number of new methods for the synthesis of FDCA from HMF have been introduced in the late 20th century and in the 21st century and are reviewed by different researchers[21,47,48]. Oxidation of HMF in the presence of ruthenium catalysts and in the absence of base was found to be quantitative under moderate conditions. Different Ru-catalysts were introduced with different supports though some of them were not of much use because of metal leaching problems[42,49]. Better results were obtained with the catalyst produced by incorporating Mg on the surface of carbon and then platinum coating on the carbon surface. This catalyst demonstrated much higher selectivity towards the desired product, i.e. FDCA but the problem was the same with Mg metal leaching[50]. Furthermore, Pt@CNTs and Pt nanoparticles were also employed for the oxidative transformation of HMF to FDCA and it was observed that the transformation rate can be enhanced if the O-containing groups are present on the surface of CNTs[51,52]. Gold nanoparticles with various supports were used in the base free conditions and high yields (99%) were obtained[53,54]. Efforts have been made to carry out the oxidation of HMF to FDCA using earth-abundant metals such as Fe or Co and cheap metals, for example, a ternary mixture of oxides of Mn/Ce/Cu, in the presence of additives and optimized reaction conditions[55,56].

    Gold-based catalysts were widely studied with different supports and their reactivity was described as depending on the structure of the catalyst and ratio of the gold nanoparticles with the other metals or support[ 57-61]. Carbon and zirconia were also employed as a support with the ruthenium metal[62] and Kerdi et al. explained the pore diameter and the surface properties of the carbon-based Ru catalyst for the aqueous phase oxidation of HMF to FDCA[63]. Platinum and palladium supported catalysts also gained interest and demonstrated good results in various reaction conditions but the consideration of cost-effectiveness has always been urging the scientists to go deeper finding the green processes[52,64-68]. Iron-based catalysts and other non-expensive metals such as cobalt, manganese, vanadium, and copper have been found a good alternative for the precious metals but their use is accompanied with the non-selectivity and relatively low product yield [43,45,55,56,69-71]. Gao, Tianyu et al. have proposed recently numerous methods to bring about the base free aerobic oxidation of 5-HMF to 2,5-FDCA in water[72-75]. In all protocols, 100% conversion of HMF were observed yielding > 99% of the desired product FDCA. Some other research groups performed the HMF conversion reaction with different metal supported catalysts and reported good results [51,76-78]. In the last few years, a great deal of research has been observed in proposing different catalytic systems with environmentally friendly conditions for the HMF conversion into added value products. These include resins as support, biocatalysts, earth-abundant metals, precious metals, photo-catalytic irradiation methods and so on [5,48,79-98]. Moreover, FDCA undergoes all the reaction which are common for carboxylic acids and therefore can be derivatized further into different chemicals. One of the most important reactions of FDCA is polymerization. In addition to these its use is extensive in pharmaceutical industries, as an anti-bacterial, antifungal agent, and complxing agent. Some derivatives of FDCA are shown in Figure 5.

    3.2. Conversion of 5-hydroxymethylfurfural to 2,5-diformylfuran (DFF)

    2,5-diformylfuran (DFF) is another significant platform compound that is derived from HMF and can be converted further into a precursor to many innovative compounds. Some of the important applications of DFF have been reported in the first half of this mini-review already. Herein, various synthetic routes for the formation of DFF from HMF are addressed including catalytic and non-catalytic methods ranging from old to most recent. Ed de Jong et al. reviewed the till date employed methods in detail for the synthesis of DFF in 2013[21]. Later on, the use of water as a solvent in the formation of DFF from HMF was reported by many authors and reviewed by Michele Aresta et al. in 2017[48]. More recent advances in this domain are still in progress and we have tried to gather them at one place for the sake of ease of readers. Zhang, H. et al. reported the Photo-catalytic selective oxidation of HMF to DFF on WO3/g-C3N4 composite under irradiation of visible light[94,99]. When it comes to oxidation reactions, ruthenium has always been a very reliable metal to carry out this conversion. Therefore, much literature is available on the oxidation of HMF to DFF using supported ruthenium catalysts[39,40,62,100-106]. Most of the time, the selective oxidation of HMF to DFF has been studied in the presence of molecular oxygen and toluene as a solvent. The prepared catalysts were easily recoverable and showed recyclability over 5 cycles for the oxidation of HMF with more than 95% conversion and selectivity of HMF and DFF, respectively. In the same way, manganese oxide supported heterogeneous catalysts have been proved very consistent and mechanically strong catalysts. Mn has been found as effective in all forms such as nanoparticles, embedded with other metals, molecular sieves, or hollow spheres[107-114]. Vanadium oxide, iron, and copper have been used in numerous ways to produce benign heterogeneous catalysts and employed for the transformation of HMF into DFF in various solvents and additives[43,69,115-125]. Several other complex catalytic systems have also been introduced in recent years, for example, TEMPO which is a well-known catalyst for the oxidation reactions and have been used since long in homogeneous catalysis. In current research work, 4-acetamido-TEMPO was used in the presence of ethyl acetate solvent to synthesize DFF and Fe(NO3)3 and NaCl as co-catalysts[126]. TEMPO and its analogs have low solubility in ethyl acetate making the separation of the catalyst convenient after the reaction. At 40 ℃ in 2 hrs, 100% conversion of HMF was obtained with 89% product yield with a substrate concentration of 0.125 mol/L. In another study, thermally treated partially reduced and exfoliated graphene oxide was used for the DFF synthesis in the presence of TEMPO as co-catalyst and the oxygen as the terminal oxidant. The actual oxidant in this reaction was found to be GO with its reduced carboxyl groups which can activate the oxygen to continue the oxidation reaction. The proposed mechanism explained that the high reactivity is due to the synergistic effect of -COOH groups and unpaired electrons at GO edge defects. Under 1atm air pressure and 80 wt% GO loading, 100% HMF conversion was obtained with 99.6% DFF yield[38]. Liu, Xianxiang et al. proposed a benign method for the formation of DFF at room temperature[127]. In this conversion, NaNO2 has been used as an oxidant. The solvent was found to have a crucial effect for this reaction and after testing numerous solvents, trifluoroacetic acid gave the best results. Though the conversion of HMF was not 100%, a high DFF yield was obtained within one hour. Direct and one-pot synthesis of DFF from carbohydrates such as fructose, glucose, inulin, and sucrose has been introduced lately by Jun Wang et al. through a promising atom-effective heterogeneous catalyst derived from the partial carbonization of polyoxometalate based mesoporous poly(ionic liquid)[128]. Incomplete carbonization spectacularly improved the acid and oxidation properties, depicting the wholly strengthened activity in both the degradation of fructose into 5-hydroxymethylfurfural (HMF) and oxidation of HMF into DFF with 87.3% yield and turn-over number (TON) of 77.7.

    4. Conclusion and Prospect

    In conclusion, the plant-based biomass especially carbohydrates can be transformed into HMF autocatalytic and catalytic systems. HMF thus obtained can be further derivatized into a wide range of added value chemicals via different routes such as transition metal catalysts, biocatalysts, and homogeneous metal salt catalysts. Among the variety of chemicals, synthesis of FDCA and DFF from past to recent years has been discussed in this mini-review and it has been realized that regarding lots of potential applications, HMF and its derivatives can be a tremendous outlet for the chemical industry in future. No doubt, commercialization of these products is still under trials but things can be smoothened if the relation between reaction system and work-up procedure is focused. Countless work is in progress in this domain and a number of promising results have also been attained in environmentally benign solvents but the shortcomings of using high amounts of base and high reaction temperatures still need to be solved.

    Acknowledgement

    This work was supported by 2016 Research Grant from Kangwon National University (No. 620160135) and the National Research Foundation (NRF) of Korea Grant funded by the Korean Government (MSIP) (No. 2016R1D1A3B03934797).

    Figures

    ACE-30-3-280_F1.gif
    5-Hydroxymethylfurfural and its derivatives.
    ACE-30-3-280_F2.gif
    Historical background of HMF production.
    ACE-30-3-280_F3.gif
    Summary of conversion systems of biomass to HMF.
    ACE-30-3-280_F4.gif
    Synthesis route of DFF and FDCA from biomass based HMF.
    ACE-30-3-280_F5.gif
    Derivatives of FDCA.

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