cas 123-76-2, Levulinic acid | Articles data

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HReO4 as highly efficient and selective catalyst for the conversion of carbohydrates into value added chemicals
This work describes the first catalyst (HReO4) that promotes the efficient and selective conversion of several carbohydrates into four compounds, ethyl levulinate (EL), 5-ethoxymethylfurfural (EMF), 5-hydroxymethylfurfural (HMF) and levulinic acid (LA), through a one-pot reaction strategy adjusting the reaction conditions. The reaction of fructose in ethanol at 160 °C gave EL in 80% yield after 16 h and in a mixture of ethanol/THF at 140 °C produced EMF in 73% yield after 1 h. HMF and LA can also be obtained selectively with 100% yield from fructose at 140 °C after 1 h, in DMSO or 1,4-dioxane, respectively. EL, HMF, LA and EMF were also produced in moderate to good yields from other carbohydrates such as inulin and sucrose. The catalyst HReO4 can be used in gram scale for the production of EL, EMF, HMF and LA with good yields and in at least 8 catalytic cycles on the conversion of fructose into EL with no significant reduction in its activity.
Bernardo, Joana R.,Oliveira, M. Concei??o,Fernandes, Ana C.
p. 87 - 94
(2019)
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Efficient glucose dehydration to HMF onto Nb-BEA catalysts
The one-pot production of HMF from glucose was investigated in pure hot water and biphasic water/methylisobutylketone (MIBK) solvent using mesoporous Nb(0.02 and 0.05 mol%)-Beta zeolites obtained by a post synthesis methodology. The mesoporous Nb-Beta zeolites present residual framework Al-acid sites, extra-framework isolated Nb(V) and Nb2O5 pore-encapsulated clusters in which Nb(V)O-H exhibit moderate strength Br?nsted acidity. After optimization, the dehydration of glucose onto the Nb-modified Beta-zeolites occurred with a selectivity of 84.3% in HMF for a glucose conversion of 97.4%. This result has been obtained in a biphasic water/MIBK solvent and in the presence of NaCl, at 180 °C, after 12 h.
Candu, Natalia,El Fergani, Magdi,Verziu, Marian,Cojocaru, Bogdan,Jurca, Bogdan,Apostol, Nicoleta,Teodorescu, Cristian,Parvulescu, Vasile I.,Coman, Simona M.
p. 109 - 116
(2019)
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Direct production of levulinic acid in high yield from cellulose: Joint effect of high ion strength and microwave field
Cellulose without any pretreatment was directly converted into levulinic acid (LA) in a microwave-assisted acidic catalytic system with a high ionic strength. The highest LA yield could reach 67.3 mol% within 60 min even when the cellulose concentration was as high as 10 wt%. It is concluded that high ion strength and microwave irradiation were jointly responsible for the fast cellulose conversion and high LA yield, and a cooperative acceleration mechanism is finally proposed. The high ion concentration provided by alkali metal halides not only accelerated the cellulose hydrolysis but also facilitated glucose conversion into LA by shifting the weak acid ionization equilibria, and microwave irradiation further promoted this salt effect by its characteristic heating way of ion conduction. Such a one-pot catalytic system provides a possibility of practical application for direct highly efficient conversion of cellulose due to its green properties, low cost and efficient characteristics.
Qin, Kai,Yan, Yani,Zhang, Yahong,Tang, Yi
p. 39131 - 39136
(2016)
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Selective yields of furfural and hydroxymethylfurfural from glucose in tetrahydrofuran over Hβ zeolite
Several simple and effective solvents combined with Hβ zeolite were tested to selectively convert glucose into furfural and hydroxymethylfurfural in this work. The physicochemical properties of typically different polar aprotic solvents were compared. Tetrahydrofuran was found to be a suitable solvent in the selective conversion of glucose. The effect of reaction parameters, such as temperature, reaction time, water content, glucose dosage and protonic acid addition, on the product distribution were investigated in detail. Furfural and hydroxymethylfurfural could be selectively produced in this system, and the highest yields of furfural and hydroxymethylfurfural were up to 35.2% and 49.7% respectively. Furfural could be stable in a tetrahydrofuran medium when adding 5 wt% water in the absence of extra protonic acid. However, furfural production was extremely suppressed after addition of an acidic inorganic salt, which increased the yield of hydroxymethylfurfural. This investigation indicates a simple and feasible method to selectively produce furfural and hydroxymethylfurfural from renewable cellulosic carbohydrates.
Tan, Jin,Wang, Haiyong,Ma, Longlong,Wang, Chenguang,Liu, Qiying,Zhang, Qi,He, Minghong
p. 24534 - 24540
(2018)
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Microwave-assisted conversion of carbohydrates to levulinic acid: An essential step in biomass conversion
Degradation of non-edible carbohydrates to levulinic acid (4-oxopentanoic acid) was studied by using dielectric heating with microwave energy. Levulinic acid and its reduced and dehydrated derivative, γ-valerolactone (GVL), can be used for the production of small-molecule, functionalized hydrocarbons, which might be potential platform molecules for the chemical industry. First, simple model compounds (fructose, glucose, saccharose and cellobiose) were hydrolyzed in order to find the optimum reaction conditions (e.g. reagent, reaction temperature, acid concentration, time) for the degradation and transformation of polysaccharides (cellulose, chitin, chitosan) by using controlled microwave irradiation. Cellulose, a non-edible biopolymer of plant origin, was successfully converted to levulinic acid under the optimized conditions (2 M H2SO4, 170 °C, 50 min) with a yield of 34.2% in a mono-mode Multisynth microwave reactor. The reactions proceeded with hydrochloric acid catalysis as well, and a slightly better yield was achieved, however, using HCl (a chlorine containing catalyst) raises serious environmental concerns. The hydrolysis of glucosamine-based glycans (d-glucosamine, N-Ac-d-glucosamine, LMw-chitosan, MMw-chitosan, chitin) was also studied and optimized with sulfuric acid as a catalyst in a mono-mode Multisynth microwave reactor. The highest yield of levulinic acid was obtained with 2 M H 2SO4 at 190 °C for 30 min. N-Ac-d-glucosamine, d-glucosamine, LMw-chitosan and MMw-chitosan resulted in levulinic acid with yields between 20.6% and 32.7%, the larger molecular weight chitin was degraded to levulinic acid with a yield of 37.8%.
Szabolcs, Armin,Molnar, Mark,Dibo, Gabor,Mika, Laszlo T.
p. 439 - 445
(2013)
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Selective and recyclable depolymerization of cellulose to levulinicacid catalyzed by acidic ionic liquid
Cellulose depolymerization to levulinic acid (LA) was catalyzed by acidic ionic liquids (ILs) selectively and recyclably under hydrothermal conditions. The effects of reaction temperature, time, water amount and cellulose intake were investigated. Dilution effect becomes more pronounced at lower cellulose intake, dramatically improving the yield of LA to 86.1%. A kinetic model has been developed based on experimental data, whereby a good fit was obtained and kinetic parameters were derived. The relationships between IL structure, polymeric structure and depolymerization efficiency were established, shedding light on the in-depth catalytic mechanism of IL, inclusive of acidity and hydrogen bonding ability. The LA product can be readily separated through extraction by methyl isobutyl ketone (MIBK) and IL can be reused over five cycles without loss of activity. This environmentally friendly methodology can be applied to selective production of LA from versatile biomass feedstocks, including cellulose and derivatives, glucose, fructose and HMF.
Ren, Huifang,Girisuta, Buana,Zhou, Yonggui,Liu, Li
p. 569 - 576
(2015)
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One-pot catalytic conversion of microalgae (Chlorococcum sp.) into 5-hydroxymethylfurfural over the commercial H-ZSM-5 zeolite
Herein, we report a one-pot approach to produce HMF from aquatic microalgae (Chlorococcum sp.) with a yield up to 48.0% under mild reaction conditions (200 °C, 2 h) over the commercial cheap H-ZSM-5 catalyst. Conversion of microalgae to HMF involved three steps: (1) degradation of microalgae to carbohydrates; (2) hydrolysis of polysaccharides to glucose and mannose; (3) their isomerization to fructose on Lewis acid sites and its further dehydration to HMF over Br?nsted acid sites. Proteins and lipids in microalgal cells play an important role in stabilizing HMF in water. Ball-milling pretreatment or addition of another organic solvent enhanced the productivity of HMF from microalgae. Besides, this cheap H-ZSM-5 catalyst also demonstrated excellent stability, and a slight loss of its activity can be easily recovered by simple calcination treatment.
Wang,Tan,Zhu,Miao,Kong,Sun
p. 452 - 460
(2016)
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High conversion of glucose to 5-hydroxymethylfurfural using hydrochloric acid as a catalyst and sodium chloride as a promoter in a water/γ-valerolactone system
Biomass derived 5-hydroxymethylfurfural (HMF) is regarded as an important platform molecule for the synthesis of value-added chemicals and fuels, but the high production cost has always been a bottleneck for the industrial scale use of HMF. Different mineral acids (HCl and H2SO4) being used as the catalyst and different salts being used as the reaction promoter were evaluated. It was found that HCl, in combination with NaCl, in a water/γ-valerolactone system showed high selectivity and impressive efficiency for the synthesis of HMF from glucose. The optimal conditions to obtain the best HMF yield (62.45%) were 0.2 M HCl and 0.1 M NaCl at 140 °C with a residence time of 60 minutes. An 18.22% molar yield of LA was obtained as a by-product. The effect of different anions was also investigated, and it was determined that not only the hydrogen ions, but also the nature of the acid and the type of salt played a joint role in improving the HMF yield. In addition, a possible synthesis pathway was proposed for large scale production of HMF.
Li, Minghao,Li, Wenzhi,Lu, Yijuan,Jameel, Hasan,Chang, Hou-Min,Ma, Longlong
p. 14330 - 14336
(2017)
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Efficient green catalysis for the conversion of fructose to levulinic acid
Highly efficient and selective production of levulinic acid has been achieved from D-fructose in the presence of polystyrene-based sulphonic acid resin catalyst, Dowex 50?×?8-100, at mild reaction conditions of 120?°C, over 24?h in a 50:50 mixture of water/GVL resulting in 72?mol% yield under optimized reaction conditions. Optimization of the effect of reaction temperature, time, pressure, catalyst to substrate ratio, fructose concentration and solvent was performed. Various polystyrene-based sulfonic acid resins were also investigated for quantitative production of LA from 5-hydroxymethylfurfural (5-HMF) in pure water. Catalyst recycling was carried out up to 6 cycles. Significant mechanistic information was obtained for the formation of “humins”, which are the primary cause of catalyst fouling, by the identification of soluble by-products and polymerization presursors using Q-Tof mass spectrometry based on accurate masses.
Thapa, Indira,Mullen, Brian,Saleem, Ammar,Leibig, Cora,Baker, R. Tom,Giorgi, Javier B.
p. 70 - 79
(2017)
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An integrated effluent free process for the production of 5-hydroxymethyl furfural (HMF), levulinic acid (LA) and KNS-ML from aqueous seaweed extract
This paper demonstrates an integrated zero liquid discharge (ZLD) process for time-dependent recovery of 5-hydroxymethyl furfural (HMF), levulinic acid (LA) and potassium, nitrogen and sulphur rich mother liquor (KNS-ML) - manure from agar/agarose contain
Adimurthy, S.,Gangapur, Doddabhimappa R.,Kholiya, Faisal,Meena, Ramavatar,Rathod, Meena R.
(2020)
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Conversion of saccharides into levulinic acid and 5-hydroxymethylfurfural over WO3-Ta2O5 catalysts
Bimetallic oxide catalysts WO3-Ta2O5 are active in converting saccharides into 5-hydroxymethylfurfural (HMF) and levulinic acid (LA) in one-pot reactions. The product selectivity varies at different WO3 to Ta2O5 ratios. FTIR measurements indicate the presence of Lewis acid sites and the strength of the Lewis acid sites varies when the WO3 to Ta2O5 ratio changes. The result suggests that conversion of carbohydrates into HMF and LA can be realized using a single catalytic system by adjusting the catalyst's acidic properties.
Liu, Qishun,Yang, Fengli,Yin, Heng,Du, Yuguang
p. 49760 - 49763
(2016)
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Design of Br?nsted acidic ionic liquid functionalized mesoporous organosilica nanospheres for efficient synthesis of ethyl levulinate and levulinic acid from 5-hydroxymethylfurfural
Br?nsted acidic ionic liquids (BAILs) have brought new vitality in catalytic transformation of biomass to fuels and chemicals, but practical applications of BAILs suffer from drawbacks of slow diffusion and difficulty in separation. Chemical immobilization of BAILs is an effective way to circumvent these problems. Here, we demonstrate a series of monodispersed mesoporous organosilica nanosphere-immobilized BAIL catalysts, [C3PrIm][OTf]-MONSs (C3=PrSO3H, OTf = SO3CF3), by a quaternary ammonium surfactant micelle-directed liquid-interface assembly strategy followed by successive chemical modifications, and the particle size (180-360 nm) and pore morphology (periodic centrally radialized and 3D interconnected mesopores) of the catalysts are well-adjusted by changing the cations and/or anions of the surfactants as well as the preparation conditions. As-prepared [C3PrIm][OTf]-MONSs serve as nanoreactors to transform an important biomass-derived platform molecule, 5-hydroxymethylfurfural, in ethanol and water media to valuable chemicals, ethyl levulinate (EL) and levulinic acid (LA). By the combination of their superstrong Br?nsted acidic nature, outstanding open mesoporous spherical nanostructures and excellent textural properties, the [C3PrIm][OTf]-MONSs exhibit high ethanolysis and hydrolysis activity and selectivity. The particle size and pore morphology of the catalysts significantly influence the selectivity and thereby the yield of the products. The cetyltrimethylammonium tosylate-directed [C3PrIm][OTf]-MONSs catalyst with the smallest particle size (210 nm) and a wormhole-like interconnected mesostructure shows the highest yield of EL (93.6%) and LA (72.8%) under the optimum reaction conditions. The catalyst also displays good reusability in ethanolysis reaction, originating from chemical bonding [C3PrIm][OTf] within the hydrophobic silica framework.
Song, Daiyu,Liu, Jingyu,Zhang, Chaoyue,Guo, Yihang
p. 1827 - 1842
(2021)
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Direct Conversion of Cellulose into Ethyl Lactate in Supercritical Ethanol-Water Solutions
Biomass-derived ethyl lactate is a green solvent with a growing market as the replacement for petroleum-derived toxic organic solvents. Here we report, for the first time, the production of ethyl lactate directly from cellulose with the mesoporous Zr-SBA-15 silicate catalyst in a supercritical mixture of ethanol and water. The relatively strong Lewis and weak Br?nsted acid sites on the catalyst, as well as the surface hydrophobicity, were beneficial to the reaction and led to synergy during consecutive reactions, such as depolymerization, retro-aldol condensation, and esterification. Under the optimum reaction conditions, μ33 % yield of ethyl lactate was produced from cellulose with the Zr-SBA-15 catalyst at 260 C in supercritical 95:5 (w/w) ethanol/water.
Yang, Lisha,Yang, Xiaokun,Tian, Elli,Lin, Hongfei
p. 36 - 41
(2016)
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ON THE QUESTION OF CARBONYL OXIDE INTERMEDIATES IN THE OXYGEN TRANSFER BY FURAN ENDOPEROXIDES AND BICYCLIC OZONIDES: INTRAMOLECULAR TRAPPING EXPERIMENTS
On heating the furan endoperoxide (2) rearranges into the enol ester (4) and the bicyclic ozonide (3) affords instead the rearranged ozonide (7).The process (2)->(4) represents an intramolecular Baeyer-Villiger rearrangement presumably via the dioxirane (D-2), while the process (3)->(7) represents intramolecular trapping of the carbonyl oxide (C-3).
Adam, Waldemar,Rodriguez, Augusto
p. 3509 - 3512
(1981)
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Effects of Soluble Lignin on the Formic Acid-Catalyzed Formation of Furfural: A Case Study for the Upgrading of Hemicellulose
A comprehensive study is presented on the conversion of hemicellulose sugars in liquors obtained from the fractionation of Miscanthus, spruce bark, sawdust, and hemp by using formic acid. Experimental tests with varying temperature (130-170 ;°C), formic acid concentration (10-80 wt %), carbohydrate concentrations, and lignin separation were carried out, and experimental data were compared with predictions obtained by reaction kinetics developed in a previous study. The conversions of xylose and arabinose into furfural were inherently affected by the presence of polymeric soluble lignin, decreasing the maximum furfural yields observed experimentally by up to 24 %. These results were also confirmed in synthetic mixtures of pentoses with Miscanthus and commercial alkali lignin. This observation was attributed to side reactions involving intermediate stable sugar species reacting with solubilized lignin during the conversion of xylose into furfural.
Dussan, Karla,Girisuta, Buana,Lopes, Marystela,Leahy, James J.,Hayes, Michael H. B.
p. 492 - 504
(2016)
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Comprehensive Understanding of the Role of Br?nsted and Lewis Acid Sites in Glucose Conversion into 5-Hydromethylfurfural
The conversion of glucose and selectivity into 5-hydromethylfurfural (HMF) were investigated over various silica–alumina composite (AlSiO) catalysts. The type, amount, and strength of the acidic sites were characterized by using NH3 temperature-programmed desorption and FTIR spectroscopy and then correlated to the catalytic conversion of glucose into HMF to provide a quantitative relationship between the acidity and product selectivity. Lewis acid sites played an important role in glucose conversion, which can enhance the isomerization of glucose to fructose, whereas Br?nsted acid sites had a detrimental effect. HMF selectivity had an almost linear relationship with the weak/total Lewis acid ratio (L*/L), indicating that weak Lewis acids could promote formation of HMF. The medium-to-strong Lewis acid sites can enhance the formation of undesired byproducts (levulinic acid, humins). The Br?nsted to Lewis acid ratio (B/L) had an influence on the HMF selectivity; at similar L*/L ratios, volcano curves were obtained with the increase of the B/L ratio, but the influence was not as great as that of the L*/L ratio. Nb-doped AlSiO catalysts were prepared and used in the conversion of glucose into HMF, which also confirmed the above findings. Under the optimized conditions, the HMF selectivity can reach 71 % at 92.6 % conversion of glucose with no clear decline after four catalytic cycles.
Li, Xiangcheng,Peng, Kaihao,Liu, Xiaohui,Xia, Qineng,Wang, Yanqin
p. 2739 - 2746
(2017)
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The breakdown of reticent biomass to soluble components and their conversion to levulinic acid as a fuel precursor
A biphasic system consisting of THF and water was studied to achieve the integrated conversion of cellulose and hemicellulose in lignocellulosic biomass to levulinic acid. As compared to previous studies using GVL as solvent, the utilization of a lower boiling point solvent, THF, also achieves the simultaneous hydrolysis of C6 and C5 carbohydrates in lignocellulosic biomass, and the results of simultaneous hydrolysis are comparable. Furthermore, it offers an alternative operation procedure after the hydrolysis. A distillation process is not only used to achieve the effective separation of the solid residue from the desired products, but it also helps in the complete isolation of furfural and formic acid from levulinic acid. Consequently, the utilization of by-product formic acid in the hydrogenation of furfural to furfuryl alcohol is explored, and the process is achieved with both model substrates and the feed from the lignocellulosic biomass feedstock. The hydrolysis of furfuryl alcohol gave C5 carbohydrate-derived levulinic acid. We finally explored the integrated conversion with five biomass raw materials, and the total yield of levulinic acid was quite obviously promoted by the additional conversion of pentose. the Partner Organisations 2014.
Li, Jiang,Ding, Dao-Jun,Xu, Lu-Jiang,Guo, Qing-Xiang,Fu, Yao
p. 14985 - 14992
(2014)
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Catalytic conversion of glucose into levulinic acid using 2-phenyl-2-imidazoline based ionic liquid catalyst
Levulinic acid (LA) is an industrially important product that can be catalytically valorized into important value-added chemicals. In this study, hydrothermal conversion of glucose into levulinic acid was attempted using Br?nsted acidic ionic liquid catalyst synthesized using 2phenyl-2-imidazoline, and 2-phenyl-2-imidazoline-based ionic liquid catalyst used in this study was synthesized in the laboratory using different anions (NO3, H2 PO4, and Cl) and characterized using1 H NMR, TGA, and FT-IR spectroscopic techniques. The activity trend of the Br?nsted acidic ionic liquid catalysts synthesized in the laboratory was found in the following order: [C4 SO3 HPhim][Cl] > [C4 SO3 HPhim][NO3 ] > [C4 SO3 HPhim][H2 PO4 ]. A maximum 63% yield of the levulinic acid was obtained with 98% glucose conversion at 180? C and 3 h reaction time using [C4 SO3 HPhim][Cl] ionic liquid catalyst. The effect of different reaction conditions such as reaction time, temperature, ionic liquid catalyst structures, catalyst amount, and solvents on the LA yield were investigated. Reusability of [C4 SO3 HPhim][Cl] catalyst up to four cycles was observed. This study demonstrates the potential of the 2-phenyl-2-imidazoline-based ionic liquid for the conversion of glucose into the important platform chemical levulinic acid.
Kumar, Komal,Kumar, Mukesh,Upadhyayula, Sreedevi
(2021)
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New syntheses of haloketo acid methyl esters and their transformation to halolactones by reductive cyclization
A new method for haloketo acid methyl ester synthesis on the basis of the ring-opening of cyclic α,β-unsaturated ketones followed by halogenation under mild conditions is reported. Di- and tri-haloketo acid methyl esters are conveniently synthesized via the hydrolytic ring-opening reaction through this method. Halolactones were readily obtained from these haloketo acid methyl esters by reductive cyclization employing NaBH4 and trifluoroacetic acid. Derivatizations of the obtained halolactone utilizing the exo-halomethylene moiety were also demonstrated.
China, H.,Dohi, T.,Fujitake, M.,Kageyama, N.,Kikushima, K.,Yatabe, H.
p. 1804 - 1810
(2020)
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High yield production of 5-hydroxymethylfurfural from cellulose by high concentration of sulfates in biphasic system
A high 5-hydroxymethylfurfural (HMF) yield of 53 mol% was obtained by direct degradation of cellulose in a biphasic system with concentrated NaHSO4 and ZnSO4 as co-catalysts, with 96% of cellulose conversion in 60 min. The high concentration of catalysts in the aqueous solution and the high volume ratio of organic phase to aqueous phase were responsible for the excellent performance. The depolymerization of cellulose is the rate-determine step, and the formed glucose could be efficiently converted by concentrated catalysts in the aqueous solution, leading to low concentration of glucose in the solution and thus suppressing the side reactions such as humin and char formation.
Shi, Ning,Liu, Qiying,Zhang, Qi,Wang, Tiejun,Ma, Longlong
p. 1967 - 1974
(2013)
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Efficient dual acidic carbo-catalyst for one-pot conversion of carbohydrates to levulinic acid
Levulinic acid (LA) is an important platform intermediate for several high value renewable bioproducts. One-pot synthesis of LA from carbohydrates is disadvantaged by the lack of proximity of the active sites required for sequential isomerization, dehydration and rehydration reactions. Herein, we report an efficient one-pot conversion of C6 sugars to LA using a carbo-catalyst (ZrHyC), containing Lewis acidic zirconium and Br?nsted acidic carboxyl and hydroxyl sites. The proximity of the two acid sites on a hydrothermally prepared carbon support makes the catalyst highly effective enabling a maximum 73% LA yield from glucose conversion. Fructose conversion achieved a higher LA yield (89%) because of a facile reaction without involving an isomerization step. The effects of solvents, the glucose to catalyst ratio, and the reaction time on glucose conversion and LA yield are systemically examined. Detailed characterization of the catalyst using FTIR, Raman spectroscopy, XPS, XRD, FESEM and NH3-TPD techniques are presented to elucidate the presence of the two acid sites and zirconium in the +4 oxidation state.
Gupta, Dinesh,Kundu, Sabuj,Saha, Basudeb
p. 100417 - 100426
(2016)
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Selective dehydration of glucose to hydroxymethylfurfural and a one-pot synthesis of a 4-acetylbutyrolactone from glucose and trioxane in solutions of aluminium salts
Saturated water solutions of Al2(SO4)3 and AlCl3 were applied as solvent/matrices for dehydration of Glc to hydroxymethylfurfural (HMF). Addition of oxygen ligands: methanol, ethanol, THF, furan, dibutyl ether, ethyl orthoformate and trioxane influenced the yield and selectivity, the best being observed with ethanol. When Glc and trioxane were present together in reacting solution, formation of a 4-acetylbutyrolactone was observed. Copyright (C) 1999 Elsevier Science Ltd.
Tyrlik, Stanislaw K.,Szerszen, Dorota,Olejnik, Marian,Danikiewicz, Witold
p. 268 - 272
(1999)
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Efficient route to hydroxymethylfurans from sugars via transfer hydrogenation
Tandem catalysis, relying on formic acid as an acid catalyst and as a source of hydrogen, provides a promising route to highly pure furanylmethanols. The new approach exploits (i) the use of DMSO to mediate highly efficient routes to furfurals and (ii) the ability of transfer hydrogenation catalysts to effect the hydrogenation, with good tolerance for DMSO.
Thananatthanachon, Todsapon,Rauchfuss, Thomas B.
p. 1139 - 1141
(2010)
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Selective production of levulinic acid from furfuryl alcohol in THF solvent systems over H-ZSM-5
Furfuryl alcohol in high concentrations (1 M) was hydrolyzed to levulinic acid in high yields (>70%) using H-ZSM-5 zeolite as the catalyst in monophasic tetrahydrofuran (THF)-water solvent systems. Reaction kinetics studies using H-ZSM-5 were carried out, and combined with results obtained for other Br?nsted acid catalysts, we suggest that the structural properties of H-ZSM-5, in conjunction with increased reaction performance using the polar aprotic solvent THF, are effective for furfuryl alcohol hydrolysis to levulinic acid while inhibiting furfuryl alcohol polymerization reactions. In addition, on the basis of results obtained for a wide range of THF-H2O solvent systems (19:1-1:2 w/w), we suggest that the hydrophobic nature of H-ZSM-5 alters the internal solvent microenvironment within the zeolite framework, allowing for high levulinic acid yields, even at low THF solvent concentrations (e.g., 1:2 THF-H2O w/w).
Mellmer, Max A.,Gallo, Jean Marcel R.,Martin Alonso, David,Dumesic, James A.
p. 3354 - 3359
(2015)
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Suga
p. 569,576
(1958)
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MFI Acid Catalysts with Different Crystal Sizes and Porosity for the Conversion of Furanic Compounds in Alcohol Media
Solid acid catalysts possessing MFI topology and different crystal sizes and porosities were explored for the conversion of carbohydrate-biomass-derived α-angelica lactone and 5-(hydroxymethyl)furfural, in 1-butanol at T=120–170 °C, to give levulinate esters and furanic ethers. Micro/mesoporous microcrystalline catalysts were prepared by post-synthesis base/acid treatments of ZSM-5 zeolite; the influence of the desilication (base) conditions on the material properties was investigated. A nanocrystalline ZSM-5 sample was synthesised by using hydrothermal, dynamic conditions and used as a reference material. A comparison of the catalytic performances of materials featuring different morphological, textural, and acid properties highlights a complex interplay between the acid and textural properties. The best-performing catalyst (MZS0.6) was obtained by post-synthesis-treatment; fairly good catalytic stability was confirmed by catalyst recycling, contact tests, and characterisation of the spent catalyst. MZS0.6 was compared with the macrorecticular ion-exchange resin Amberlyst-15, chosen as a benchmark solid acid catalyst, in the two reaction systems.
Antunes, Margarida M.,Lima, Sérgio,Fernandes, Auguste,Magalh?es, Ana L.,Neves, Patrícia,Silva, Carlos M.,Ribeiro, Maria F.,Chadwick, David,Hellgardt, Klaus,Pillinger, Martyn,Valente, Anabela A.
p. 2747 - 2759
(2017)
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Catalytic air oxidation of biomass-derived carbohydrates to formic acid
An efficient catalytic system for biomass oxidation to form formic acid was developed. The conversion of glucose to formic acid can reach up to 52 % yield within 3 h when catalyzed by 5 mol % of H5PV2Mo 10O40 at only 373 K using air as the oxidant. Furthermore, the heteropolyacid can be used as a bifunctional catalyst in the conversion of cellulose to formic acid (yield=35 %) with air as the oxidant. Copyright
Li, Jiang,Ding, Dao-Jun,Deng, Li,Guo, Qing-Xiang,Fu, Yao
p. 1313 - 1318
(2012)
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The effect of different Br?nsted acids on the hydrothermal conversion of fructose to HMF
The hydrothermal dehydration of fructose to 5-hydroxymethylfurfural (HMF), a promising platform chemical from renewable resources, is commonly known to be Br?nsted acid catalysed. However, it is not clear whether the acids used as catalysts may have an additional effect on the reaction, besides the donation of protons. In this work, we studied the effect of different Br?nsted acids on the hydrothermal conversion of fructose to HMF. In particular, phosphoric acid, if present in a high concentration, leads to a significantly stronger acceleration of the reaction than would be expected from the pH value, calculated under hydrothermal conditions. Acetic acid, on the other hand, seems to evoke an alternative reaction mechanism. The maximal HMF yield however is essentially unaffected by the pH value or the type of acid used.
K?rner, Paul,Jung, Dennis,Kruse, Andrea
p. 2231 - 2241
(2018)
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Kinetics and reaction engineering of levulinic acid production from aqueous glucose solutions
We have developed a kinetic model for aqueous-phase production of levulinic acid from glucose using a homogeneous acid catalyst. The proposed model shows a good fit with experimental data collected in this study in a batch reactor. The model was also fitted to steady-state data obtained in a plug flow reactor (PFR) and a continuously stirred tank reactor (CSTR). The kinetic model consists of four key steps: (1) glucose dehydration to form 5-hydroxymethylfurfural (HMF); (2) glucose reversion/degradation reactions to produce humins (highly polymerized insoluble carbonaceous species); (3) HMF rehydration to form levulinic acid and formic acid; and (4) HMF degradation to form humins. We use our model to predict the optimal reactor design and operating conditions for HMF and levulinic acid production in a continuous reactor system. Higher temperatures (180-200 °C) and shorter reaction times (less than 1 min) are essential to maximize the HMF content. In contrast, relatively low temperatures (140-160 °C) and longer residence times (above 100 min) are essential for maximum levulinic acid yield. We estimate that a maximum HMF carbon yield of 14 % can be obtained in a PFR at 200 °C and a reaction time of 10 s. Levulinic acid can be produced at 57 % carbon yield (68 % of the theoretical yield) in a PFR at 149 °C and a residence time of 500 min. A system of two consecutive PFR reactors shows a higher performance than a PFR and CSTR combination. However, compared to a single PFR, there is no distinct advantage to implement a system of two consecutive reactors. Copyright
Weingarten, Ronen,Cho, Joungmo,Xing, Rong,Conner, William Curtis,Huber, George W.
p. 1280 - 1290
(2012)
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The role of salts and Bronsted acids in lewis acid-catalyzed aqueous-phase glucose dehydration to 5-hydroxymethylfurfural
The effect of salts and Bronsted acids on the Lewis acid (CrCl3·6-H2O)-catalyzed glucose dehydration to 5-hydroxymethylfurfural (HMF) in aqueous media are described. We show that the reaction with bromide salts in place of chlorides leads to higher HMF yields. The influence of salts can be attributed to the anions in solution, specifically to the bromide anions enhancing the fructose dehydration step. Additionally, we demonstrate that the reaction kinetics are governed strongly by acidity. Although the fructose dehydration step is accelerated by the addition of Bronsted acids, even on a catalytic scale, a significant retardation of the glucose conversion rate results in a substantial drop in HMF yields. The suppression in glucose-to-fructose isomerization rate with increasing acidity is ascribed to the restrained formation of the chromium-glucose chelate complex during the reaction. Glucose to HMF with CrCl3·6-H2O: Bromide salts in place of chlorides improve the dehydration of glucose to 5-hydroxymethylfurfural (HMF) in aqueous solution by enhancing the fructose dehydration step. The addition of Bronsted acid to the reaction, even in catalytic scale, is not beneficial for HMF yields. This is attributed to the deceleration in the glucose-to-fructose isomerization rate although fructose dehydration is significantly accelerated.
Wrigstedt, Pauli,Keskiv?li, Juha,Leskel?, Markku,Repo, Timo
p. 501 - 507
(2015)
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Assessment of ion exchange resins as catalysts for the direct transformation of fructose into butyl levulinate
The transformation of fructose into butyl levulinate in aqueous 1-butanol (initial molar ratio 1-butanol/fructose 79, and butanol/water 1.19) has been studied in a discontinuous reactor at 80?120 °C and 2.0 MPa over 8 sulfonic polystyrene-DVB ion exchange resins as catalysts (catalyst loading 0.85–3.4 %). Resins swell greatly in the reaction medium and the reaction takes place mainly in the swollen gel-phase. Swollen resins in water have been characterized by analysis of ISEC data, and spaces originated in the gel phase upon swelling are described in terms of zones of different polymer density. A relationship has been found between the morphology of swollen resins and ester production. Swollen resins with low polymer density show the highest butyl levulinate yield. Dowex 50Wx2 was the most effective because it creates the largest and widest spaces in the gel-phase when swelling. Consequently, it better accommodates the proton-transfer-reaction mechanisms.
Ramírez, Eliana,Bringué, Roger,Fité, Carles,Iborra, Montserrat,Tejero, Javier,Cunill, Fidel
(2021)
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Sustainable pathway to furanics from biomass: Via heterogeneous organo-catalysis
An organic sulfonated graphitic carbon nitride is synthesized and its application has been demonstrated in the conversion of carbohydrates into furanics and related value-added products. The most important feature of the material is the stability and acidity, which could be utilized at elevated temperatures for cleaving carbohydrates and converting them into biologically important scaffolds and platform chemicals.
Verma, Sanny,Baig, R. B. Nasir,Nadagouda, Mallikarjuna N.,Len, Christophe,Varma, Rajender S.
p. 164 - 168
(2017)
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Conversion of cellulose to glucose and levulinic acid via solid-supported acid catalysis
Cellulose is hydrolyzed to glucose, which is further converted to levulinic acid in the presence of surface-supported Br?nsted and Lewis acid catalysts. Nafion catalysts, in particular, have the potential to be recycled or applied to a continuous flow reactor for the synthesis of these biofuel precursors.
Hegner, Jessica,Pereira, Kyle C.,DeBoef, Brenton,Lucht, Brett L.
p. 2356 - 2358
(2010)
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Efficient utilization of potash alum as a green catalyst for production of furfural, 5-hydroxymethylfurfural and levulinic acid from mono-sugars
In present work, we have explored potash alum (PA) as an efficient and green catalyst for production of high value platform chemicals such as 5-hydroxymethylfurfural (HMF) furfural from bio-renewable feedstocks in a biphasic reaction medium. Maximum 64% and 49% HMF yields were obtained from the dehydration reactions of fructose and glucose, respectively, at 140 °C over a 6 h reaction time. Similarly, 55% furfural yield was obtained from xylose at 190 °C in 6 h period. Products obtained have been analyzed by 1H-NMR spectra and a detailed mechanistic understanding of the dehydration reactions has been developed. This is first report highlighting a strategy for the utilization of cost effective and non-hazardous potash alum as catalyst for the conversion of glucose, fructose, and xylose to respective furans.
Gupta, Dinesh,Ahmad, Ejaz,Pant, Kamal K.,Saha, Basudeb
p. 41973 - 41979
(2017)
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Formation of C-C bonds for the production of bio-alkanes under mild conditions
It is of crucial importance to form C-C bonds between biomass-derived compounds for the production of bio-alkanes from biomass. In this study, it was found that C-C bonds can be formed between angelica lactones, key intermediates derived from biomass, through free radical reactions under mild conditions without using a noble catalyst or solvent, which gave elongated carbon chains of di/trimers with 10 or 15 carbons, with complete conversion and 100% selectivity. The di/trimers produced serve as a novel feedstock for the carbon backbones of bio-alkanes. Hydrogenation of the di/trimers produced C6-C13 hydrocarbons suitable for use as transportation fuels. This journal is the Partner Organisations 2014.
Xin, Jiayu,Zhang, Suojiang,Yan, Dongxia,Ayodele, Olubunmi,Lu, Xingmei,Wang, Jianji
p. 3589 - 3595
(2014)
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Development of Betaine-Based Sustainable Catalysts for Green Conversion of Carbohydrates and Biomass into 5-Hydroxymethylfurfural
Renewable and sustainable betaine-based catalysts (BX) derived from the betaine sugar industry or ChCl were developed for the production of 5-hydroxymethylfurfural (HMF) from various carbohydrates. The HMF yields in the BX-based media reached up to 88 %, 66 %, 37 % and 53 %, for the conversion of fructose, glucose, cellulose, and lignocellulosic biomass, respectively. In addition, choline-O-sulfate was synthesized and demonstrated to be an efficient catalyst for the conversion of fructose to HMF. From the perspective of green and sustainable chemistry, this work demonstrates benefits not only in the preparation of sustainable catalysts but also the green production of HMF from biomass.
Feng, Yunchao,Li, Mengzhu,Gao, Zhebang,Zhang, Xin,Zeng, Xianhai,Sun, Yong,Tang, Xing,Lei, Tingzhou,Lin, Lu
p. 495 - 502
(2019)
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Sulfonated polyaniline as a solid organocatalyst for dehydration of fructose into 5-hydroxymethylfurfural
The rehydration of 5-hydroxymethylfurfural (HMF), an important bio-based chemical building block, to levulinic acid (LA) and formic acid (FA) over Br?nsted acid catalysts is the key block to the effective production of HMF from hexose. In this work, we develop a novel acidic solid organocatalyst, sulfonated polyaniline (SPAN), for the effective dehydration of fructose into HMF in the low-boiling water/1,4-dioxane cosolvent. The highest HMF yield of 71% is obtained from fructose with complete restriction of HMF rehydration to LA. We demonstrate that hydrogen bonds form between the ring-attached sulfonic acid group and the quinoid imine nitrogen as a result of internal doping, which confines the Br?nsted acidity of the SPAN catalyst. The H-bonded sulfonic acid species is active for fructose-to-HMF dehydration and complete suppression on HMF rehydration. The chemical bonding of sulfonic acid groups on the backbone of the PAN chain allows stable recyclability of the polymer catalyst. This work highlights the potential importance of confining Br?nsted acidity on a solid organocatalyst via H-bonding for transforming renewable carbohydrates into fine chemicals.
Dai, Jinhang,Zhu, Liangfang,Tang, Dianyong,Fu, Xing,Tang, Jinqiang,Guo, Xiawei,Hu, Changwei
p. 1932 - 1939
(2017)
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Enhanced yields of furfural and other products by simultaneous solvent extraction during thermochemical treatment of cellulosic biomass
Furfural derived from pentose sugars is one of the key reactive intermediates for production of hydrocarbons from cellulosic biomass for use as drop-in fuels. Simultaneous extraction into a solvent immiscible in water can substantially enhance furfural yields by removing it from the aqueous environment where the yield would otherwise be limited by its rapid degradation to chars and other carbon rich compounds that are loosely termed humins. Thus, in this study, the effectiveness of the organic solvent methyl isobutyl ketone (MIBK) in improving furfural yields from maple wood was determined for reactions of 5 wt% solids in 0.1 M sulfuric or hydrochloric acid at 170°C over a range of reaction times. For comparison, pure xylose, glucose, and Avicel cellulose were also reacted under the same conditions. Various process configurations based on simultaneous hydrolysis and dehydration were compared to acid hydrolysis followed by dehydration to furfural with and without simultaneous extraction. Without MIBK extraction, the maximum furfural yields were less than 65% when maple wood was reacted for about 40-45 min with either sulfuric or hydrochloric acid. However, the yield increased significantly to about 85.3% when MIBK extraction was employed in combination with sulfuric acid catalysis for 50 min, while combining MIBK extraction with hydrochloric acid catalysis only increased the yield to ～67.0%. Simultaneous extraction with MIBK also improved yields of other products such as 5-HMF and levulinic acid, compared to results from the acids alone.
Zhang, Taiying,Kumar, Rajeev,Wyman, Charles E.
p. 9809 - 9819
(2013)
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Importance of the synergistic effects between cobalt sulfate and tetrahydrofuran for selective production of 5-hydroxymethylfurfural from carbohydrates
In this study, an effective catalytic system (CoSO4·7H2O/THF) for selective conversion of fructose to 5-hydroxymethylfurfural (HMF; yield: 88%) was developed. The synergistic effects among Co2+, SO42-, crystal water and tetrahydrofuran (THF) were crucial for achieving selective dehydration of fructose to HMF. Co2+ worked as a Lewis acid for catalyzing mainly dehydration of fructose to HMF but not the further decomposition of HMF to levulinic acid. THF could help to retain HMF while CoSO4 could coordinate with HMF, enhancing the thermal stability of HMF in THF. The crystal water in cobalt sulfate could help to coordinate with fructose, which facilitated the conversion of fructose via dehydration reactions. The CoSO4·7H2O/THF catalytic system could also catalyze the conversion of inulin and cellulose into HMF. The main advantages of the CoSO4·7H2O/THF catalytic system are the low cost, the easy recycling of the CoSO4·7H2O catalyst and the easy separation of HMF from volatile THF.
Dong, Dehua,Hu, Xun,Li, Qingyin,Li, Xueli,Shao, Yuewen,Sun, Kai,Wang, Yi,Ye, Zhengmao,Zhang, Lijun,Zhang, Shu
p. 2293 - 2302
(2020)
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Efficient microwave-assisted synthesis of 5-hydroxymethylfurfural from concentrated aqueous fructose
Studies on the HCl-catalysed microwave-assisted dehydration of highly concentrated aqueous fructose (27 wt %) to 5-hydroxymethylfurfural (HMF) revealed a significant increase in the fructose conversion rate over the conventional heated systems. Water, bei
Hansen, Thomas S.,Woodley, John M.,Riisager, Anders
p. 2568 - 2572
(2009)
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Effects of water and alcohols on the polymerization of furan during its acid-catalyzed conversion into benzofuran
Furan, an important product from catalytic pyrolysis of biomass, has the potential to be further converted into value-added chemicals or biofuels. This study investigated the conversion of furan into benzofuran over a Br?nsted acid catalyst (Amberlyst 70) at 140-190°C in various solvents. With water as the solvent, furan could barely make its way to benzofuran as its polymerization dominated. With methanol as the solvent, the polymerization of furan was suppressed and benzofuran formation was enhanced substantially. This is because in methanol, the reactive intermediates (i.e., aldehydes) were stabilized and their involvement in polymerization reactions was suppressed. Other alcohols showed similar effects on suppressing polymerization. In dimethyl sulfoxide (DMSO), the polymerization of furan was also effectively suppressed. However, furan was not converted to benzofuran but to levulinic acid via a distinct reaction route.
Hu, Xun,Jiang, Shengjuan,Kadarwati, Sri,Dong, Dehua,Li, Chun-Zhu
p. 40489 - 40501
(2016)
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THE FLUORIDE ION EFFECT IN THE REACTIONS OF SINGLET OXYGEN WITH ENOLS
The fluoride ion effect in the reaction of enolic systems with singlet oxygen has been investigated. β-Dicarbonyl compounds yielded 1,2,3-tricarbonyl derivatives, some of which underwent further hydration, whereas α-diketones suffered oxidative decarboxylation to give open-chain aldehydo-acids or keto-acids.
Wasserman, Harry H.,Pickett, James E.
p. 2155 - 2162
(1985)
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Insights into the interplay of lewis and Br?nsted acid catalysts in glucose and fructose conversion to 5-(hydroxymethyl)furfural and levulinic acid in aqueous media
5-(Hydroxymethyl)furfural (HMF) and levulinic acid production from glucose in a cascade of reactions using a Lewis acid (CrCl3) catalyst together with a Br?nsted acid (HCl) catalyst in aqueous media is investigated. It is shown that CrCl3 is an active Lewis acid catalyst in glucose isomerization to fructose, and the combined Lewis and Br?nsted acid catalysts perform the isomerization and dehydration/rehydration reactions. A CrCl3 speciation model in conjunction with kinetics results indicates that the hydrolyzed Cr(III) complex [Cr(H2O)5OH]2+ is the most active Cr species in glucose isomerization and probably acts as a Lewis acid-Br?nsted base bifunctional site. Extended X-ray absorption fine structure spectroscopy and Car-Parrinello molecular dynamics simulations indicate a strong interaction between the Cr cation and the glucose molecule whereby some water molecules are displaced from the first coordination sphere of Cr by the glucose to enable ring-opening and isomerization of glucose. Additionally, complex interactions between the two catalysts are revealed: Br?nsted acidity retards aldose-to-ketose isomerization by decreasing the equilibrium concentration of [Cr(H2O)5OH]2+. In contrast, Lewis acidity increases the overall rate of consumption of fructose and HMF compared to Br?nsted acid catalysis by promoting side reactions. Even in the absence of HCl, hydrolysis of Cr(III) decreases the solution pH, and this intrinsic Br?nsted acidity drives the dehydration and rehydration reactions. Yields of 46% levulinic acid in a single phase and 59% HMF in a biphasic system have been achieved at moderate temperatures by combining CrCl3 and HCl.
Choudhary, Vinit,Mushrif, Samir H.,Ho, Christopher,Anderko, Andrzej,Nikolakis, Vladimiros,Marinkovic, Nebojsa S.,Frenkel, Anatoly I.,Sandler, Stanley I.,Vlachos, Dionisios G.
p. 3997 - 4006
(2013)
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Diterpenes based on the dolabellane skeleton from dictyota dichotoma
From a variety of Dictyota dichotoma we have isolated, in addition to previously reported dolabellane (6-8) and perhydroazulene diterpenes (9,10), four new diterpenoids (2-5). Their structure have been elucidated by spectral analysis and chemical degradation. All the new dolabellane derivatives possess antimicrobial activity against gram-positive and gram-negative organisms.
Amico,Oriente,Piattelli,Tringali,Fattorusso,Magno,Mayol
p. 1409 - 1414
(1980)
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Cellulose conversion to biofuel precursors using conjugated ionic liquid catalyst: An experimental and DFT study?
In this study, an efficient catalytic system has been developed for the single step conversion of microcrystalline cellulose into 5-hydroxymethyl furfural and levulinic acid using Br?nsted acidic ionic liquid (IL) catalysts which have large conjugated structure. The IL catalysts used in this study comprising of different anions ([CF3SO3]?, [HSO4]?, [CF3COO]?, and [Cl]?) with a common cation 1-butyl sulfonic acid-2-phenylimidazolinium ([2-PhIm-SO3H]+), were synthesized in laboratory and characterized. The MCC conversion was carried out in a biphasic reaction medium and yields of 70 % for 5-HMF and 23 % for LA were achieved at 150 °C and 5 h reaction time. Furthermore, density functional theory (DFT) was performed to identify the key interactions in the stable configurations of the ion-pairs of ILs. The electronic properties and chemical reactivity of the individual ions and ion-pairs of ILs were investigated by performing natural bond orbital (NBO) and second order perturbation theory analysis.
Kashyap, Hemant K.,Khatri, Vikas,Kumar, Komal,Upadhyayula, Sreedevi
(2021)
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Butenolide Derivatives of Biobased Furans: Sustainable Synthetic Dyes
The dye and pigment manufacturing industry is one of the most polluting in the world. Each year, over one million tons of petrochemical colorants are produced globally, the synthesis of which generates a large amount of waste. Naturally occurring, plant-based dyes, on the other hand, are resource intensive to produce (land, water, energy), and are generally less effective as colorants. Between these two extremes would be synthetic dyes that are fully sourced from biomass-derived intermediates. The present work describes the synthesis of such compounds, containing strong chromophores that lead to bright colors in the yellow to red region of the visible spectrum. The study was originally motivated by an early report of an unidentified halomethylfurfural derivative which resulted from hydrolysis in the presence of barium carbonate, now characterized as a butenolide of 5-(hydroxymethyl)furfural (HMF). The method has been generalized for the synthesis of dyes from other biobased platform molecules, and a mechanism is proposed.
Saska, Jan,Li, Zheng,Otsuki, Andrew L.,Wei, Jiahui,Fettinger, James C.,Mascal, Mark
p. 17293 - 17296
(2019)
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One-Pot Transformation of Cellobiose to Formic Acid and Levulinic Acid over Ionic-Liquid-based Polyoxometalate Hybrids
Currently, levulinic acid (LA) and formic acid (FA) are considered as important carbohydrates for the production of value-added chemicals. Their direct production from biomass will open up a new opportunity for the transformation of biomass resource to valuable chemicals. In this study, one-pot transformation of cellobiose into LA and FA was demonstrated, using a series of multiple-functional ionic liquid-based polyoxometalate (IL-POM) hybrids as catalytic materials. These IL-POMs not only markedly promoted the production of valuable chemicals including LA, FA and monosaccharides with high selectivities, but also provided great convenience of the recovery and the reuse of the catalytic materials in an environmentally friendly manner. Cellobiose conversion of 100 %, LA selectivity of 46.3 %, and FA selectivity of 26.1 % were obtained at 423 K and 3 MPa for 3 h in presence of oxygen. A detailed catalytic mechanism for the one-pot transformation of cellobiose was also presented.
Li, Kaixin,Bai, Linlu,Amaniampong, Prince Nana,Jia, Xinli,Lee, Jong-Min,Yang, Yanhui
p. 2670 - 2677
(2014)
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Complete chemical hydrolysis of cellulose into fermentable sugars through ionic liquids and antisolvent pretreatments
This work describes a relatively simple methodology for efficiently deconstructing cellulose into monomeric glucose, which is more easily transformed into a variety of platform molecules for the production of chemicals and fuels. The approach undertaken herein first involves the dissolution of cellulose in an ionic liquid (IL), followed by a second reconstruction step aided by an antisolvent. The regenerated cellulose exhibited strong structural and morphological changes, as revealed by XRD and SEM analyses. These changes dramatically affect the hydrolytic reactivity of cellulose with dilute mineral acids. As a consequence, the glucose yield obtained from the deconstructed-reconstructed cellulose was substantially higher than that achieved through hydrolysis of the starting cellulose. Factors that affect the hydrolysis reaction include the type of cellulose substrate, the type of IL used in pretreatment, and the type of acid used in the hydrolysis step. The best results were obtained by treating cellulose with IL and using phosphotungstic acid (0.067 molL-1) as a catalyst at 413 K. Under these conditions, the conversion of cellulose was almost complete (> 99 %), with a glucose yield of 87% after only 5 h of reaction.
Morales-delaRosa, Silvia,Campos-Martin, Jose M.,Fierro, Jose L. G.
p. 3467 - 3475
(2014)
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Oxidation of cyclohexanone and/or cyclohexanol catalyzed by Dawson-type polyoxometalates using hydrogen peroxide
The oxidation of cyclohexanone, cyclohexanol or cyclohexanone/cyclohexanol mixture using as catalyst, Dawson-type polyoxometalates (POMs) of formula, α- and β-K6P2W18O62, α-K6P2Mo6W12O62 and α1-K7P2Mo5VW12O62 and hydrogen peroxide, carried out at 90 °C with a reaction time of 20 h, led to a high number of mono- and di-acids which were identified by GC-MS. Levulinic, 6-hydroxyhexanoic, adipic, glutaric and succinic acids, major products were evaluated by HPLC. Regardless of the substrate nature, all POMs exhibited high catalytic activity with 94–99% of conversion, whereas the formation of the different products is sensitively related to both the composition and symmetry of the POMs and the substrate nature. The main products are adipic acid in the presence of α-K6P2Mo6W12O62 and α1-K7P2Mo5VW12O62, levulinic acid in the presence of α1-K7P2Mo5VW12O62 and β-K6P2W18O62 and 6-hydroxyhexanoic acid in the presence of α- and β-K6P2W18O62. Graphical abstract: High catalytic activity was observed with?α- and?β-K6P2W18O62, α-K6P2Mo6W12O62 and α1-K7P2Mo5VW12O62 Dawson-type for the oxidation of cyclohexanone, cyclohexanol or cyclohexanone/cyclohexanol mixture, in the hydrogen peroxide presence, to several oxygenated products. Adipic, levulinic and 6-hydroxyhexanoic acids are the main products. The peroxo- species formed in situ could be the active sites.[Figure not available: see fulltext.]
Dermeche, Leila,Idrissou, Yasmina,Mazari, Tassadit,Moudjahed, Mohammed,Rabia, Cherifa
(2022/03/07)

Renewable bio-based routes to γ-valerolactone in the presence of hafnium nanocrystalline or hierarchical microcrystalline zeotype catalysts
Different renewable bio-based routes leading to the versatile bioproduct γ-valerolactone (GVL) were studied in integrated fashions, starting from furfural (Fur), α-angelica lactone (AnL) and levulinic acid (LA), in the presence of multifunctional hafnium-
Antunes, Margarida M.,Fernandes, Auguste,Pillinger, Martyn,Ribeiro, Filipa,Silva, Andreia F.,Valente, Anabela A.
p. 56 - 71
(2022/01/19)

Ethanolysis of selected catalysis by functionalized acidic ionic liquids: An unexpected effect of ILs structural functionalization on selectivity phenomena
A series of functionalized hydrogen sulfate imidazolium ILs were synthesized and applied as catalysts in the reaction of glucose, xylose and fructose with ethanol. In this research, an unexpected selectivity phenomenon was observed. It showed that in this reaction functionalized ILs should be considered as a special type of catalyst. Functionalization of alkyl imidazolium ILs, especially the addition of electronegative OH groups, causes a clear and unexpected effect manifested via visible changes in the selectivity of the reaction studied. In the case of fructose, an increase in the number of OH groups affects an increase in the selectivity towards ethyl levulinate from 14.2% for [bmim]HSO4 to 20.1% for [glymim]HSO4 with an additional increase in selectivity to 5-hydroxymethyfurfural. In turn, for xylose, the introduction of OH groups to the alkyl chain was manifested by a decrease in selectivity to furfural as its ethyl acetal and an increase in selectivity to ethylxylosides. This journal is
Nowakowska-Bogdan, Ewa,Nowicki, Janusz
p. 1857 - 1866
(2022/02/05)

Acylative Kinetic Resolution of Cyclic Hydroxamic Acids
Racemic cyclic hydroxamic acids bearing an aryl substituent adjacent to the hydroxyl group undergo effective acylative kinetic resolution promoted by benzotetramisole (BTM).
Yin, Jingwei,Straub, Matthew R.,Liao, Julian D.,Birman, Vladimir B.
supporting information
p. 1546 - 1549
(2022/03/01)

Catalytic wet air oxidation of D-glucose by perovskite type oxides (Fe, Co, Mn) for the synthesis of value-added chemicals
The conversion of common biomasses derived, as D-glucose, into value-added chemicals has received highest attention in the last few years. Among all processes, the catalytic wet air oxidation (CWAO) of derived biomasses using noble metal-based heterogeneo
Geobaldo, Francesco,Pirone, Raffaele,Russo, Nunzio,Scelfo, Simone
(2022/03/15)

Application of biimidazole-based ionic liquid in catalysis of biomass to preparation of levulinic acid
The invention discloses application of biimidazole-based ionic liquid in catalysis of biomass to preparation of levulinic acid. When the biimidazole-based ionic liquid is used for catalyzing biomass to prepare levulinic acid, on one hand, the catalyst can be recycled, on the other hand, the reaction rate can be effectively increased, the reaction time can be shortened, the product yield can be increased, and the highest product yield can reach about 76.5%; the method effectively overcomes the problems of equipment corrosion, waste acid pollution and the like when inorganic acid is used as a catalyst.
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Paragraph 0122-0124

(2021/05/12)

Direct conversion of cellulose to levulinic acid using SO3H-functionalized ionic liquids containing halogen-anions
The conversion of cellulose to levulinic acid (LA) and other platform chemicals is a promising route to solve the energy crisis. For this purpose, a series of new SO3H-functionalized ionic liquids (ILs), containing different halogen-anions were synthesized and applied for catalytic conversion of cellulose to LA. The structure, thermal stability, and acidity of SO3H-functionalized ILs were characterized by Nuclear magnetic resonance (NMR) spectra, Fourier-transform infrared (FT-IR), High resolution mass spectrometry (HRMS), thermogravimetric analysis (TGA), and Hammet acidity method. The results revealed that as the size of halogen anions increased, the Hammett acidity gradually increased from SO3H-functionalized ILs containing fluorine- to chlorine- and then to bromine-anions. When SO3H-functionalized ILs were used as a catalyst for the production of LA from cellulose, the yield of LA gradually increased as the size of halogen-anions increased from fluorine- to chlorine- and then to bromine-anions. Among the SO3H-functionalized ILs, 1,1-bis(3-(4-sulfobutyl)imidazolium-1-yl)butylene bromine ([BSim]Br) exhibited the best catalytic activity with 76.5% yield of LA in cellulose/[BSim]Br/H2O (m/m/m = 1:9:8) reaction system at 180 °C for 20 min, which was the highest yield compared to previous literature reports using ILs as catalyst. Besides, the [BSim]Br was easily recovered and showed high catalytic activity after five cycles. The efficient catalyst, [BSim]Br is then proposed to have a great potential for mass production of LA from biomass.
Gao, Lijing,Oderinde, Olayinka,Shi, Shengbin,Wu, Yuanfeng,Xiao, Guomin,Zhang, Mengting,Zhang, Zongqi
(2021/08/24)

Conversion of glucose to levulinic acid and upgradation to γ-valerolactone on Ru/TiO2catalysts
Combining glucose dehydration and the subsequent hydrogenation in one pot is a preferable approach for process development as such a method allows in situ generation of the reactive intermediate to undergo further reaction without extra energy-intensive separation. Herein, phosphotungstic acid and various types of titania (anatase, rutile, P25) supported Ru-based catalysts were considered as the dehydration and hydrogenation catalysts, respectively. Modulating the different reactant media (N2, H2), various products were obtained with GBL-H2O as the solvent. A considerable yield (42%) of levulinic acid (LA) and γ-valerolactone (GVL) (40%) were obtained in nitrogen and subsequent hydrogen. Ru/TiO2 (rutile) was the favorable hydrogenation catalyst among the three types of Ru/TiO2. Meanwhile, a certain amount of sorbitol (36%) was obtained in pure hydrogen. The hydrogenation of glucose is more likely to occur than the glucose dehydration. The physicochemical properties of the catalysts were characterized by XRD, BET, TPR, STEM and in situ CO/FT-IR, and the results show that well-dispersed Ru particles are located on the rutile crystallites, which facilitated the hydrogenation of LA. A strong metal support interaction (SMSI) was responsible for the various microstructure properties and the different hydrogenation reactivity. This work allows a better understanding of the reaction paths of glucose conversion.
Ding, Guoqiang,Liu, Yubo,She, Haohao,Yang, Yong,Zhao, Guoping,Zhu, Yulei
p. 14406 - 14413
(2021/08/23)

Formic acid enabled selectivity boosting in transfer hydrogenation of 5-hydroxymethylfurfural to 2,5-furandimethanol on highly dispersed Co-Nxsites
Catalytic transfer hydrogenation (CTH) reaction is considered as a potential route for upgrading bio-based carbonyl compounds to their corresponding alcohols. Herein, ordered mesoporous N-doped carbon confined Co-Nx(Co-NC) was adopted as a catalyst for converting cellulose-derived 5-hydroxymethylfurfural (HMF) to 2,5-furandimethanol (FDM) using formic acid (FA) as a hydrogen donor. Different catalysts and preparation methods were screened, by varying cobalt phases and template removal procedures. It is found that highly dispersed N-confined Co species (Co-Nx) other than naked Co NPs acted as catalytic species for the CTH of HMF with FA, which gave 86% yield of FDM at 100% HMF conversion. Kinetic experiments revealed that, compared with molecular hydrogen, Co-NC could effectively accelerate HMF hydrogenation and suppress as-formed FDM hydrogenolysis in the presence of FA, which is ascribed to its superior activity toward hydrogen transfer from FA and fast desorption toward FDM. Mechanism studies indicated that C-H dissociation of FA could be the rate-determining step in the CTH reaction, and the hydrogenation of HMF could proceed through an intermolecular hydride transfer route. This work shows that the bifunctional nature of the catalyst is critical in the efficient CTH of biomass-derived carbonyl compounds and provides insights toward the rational design of such catalysts.
Xu, Ling,Nie, Renfeng,Chen, Xujie,Li, Yanchen,Jiang, Yuxi,Lu, Xiuyang
p. 1451 - 1457
(2021/03/14)

Method for continuously preparing gamma-valerolactone from furfuryl alcohol by one-step method
The invention discloses a method for integrally and continuously producing gamma-valerolactone from furfuryl alcohol through hydration and hydrogenation, which comprises the steps of by using furfuryl alcohol as a reaction raw material, hydrating furfuryl alcohol into levulinic acid under the action of a solid acid catalyst and a metal catalyst, and then hydrogenating to obtain gamma-valerolactone. According to the method, side reactions such as furfuryl alcohol hydrogenation or polymerization are reduced or avoided through sectional assembly of the catalyst; and meanwhile, gamma-valerolactone is used as a reaction solvent to improve the actual utilization concentration of furfuryl alcohol. The method is mild in reaction condition, separation and purification of the product from the solvent and separation of the catalyst from the product are avoided, the technological process can be effectively shortened, and the operation cost is saved.
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Paragraph 0057-0062; 0079

(2021/04/26)

PREPARATION OF HMF CATALYZED BY A MIXTURE OF SALT AND ACID
The present invention relates to a method for the production of 5-hydroxymethylfurfural (HMF), which converts a fructose-containing component using a catalyst system comprising a solution of a salt and acid mixture at a temperature of 90 to 200° C. and leads to obtaining an HMF-containing product mixture, wherein advantageously a high HMF selectivity with significantly lower by-product formation is achieved at the same time.
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Paragraph 0174-0194

(2021/07/17)

5-(Chloromethyl)furfural production from glucose: A pioneer kinetic model development exploring the mechanism
Conversion of glucose to 5-(chloromethyl)furfural (CMF) is one of the well-known high yield unit processes in lignocellulosic biomass valorization. A kinetic modeling study was not reported for the reaction, owing to the complexity in quantification of CMF. Herein we have successfully developed a rapid, sensitive, and specific HPLC method (reverse phase) to quantify the generated CMF (range: 10–650?μg/mL) in a dichloroethane solvent. The Box–Behnken design of experiment method employed for the statistical optimization. A kinetic model was developed based on the homogeneous first-order kinetic model, and the results are in good agreement with the experiment data. The formation of CMF, 5-(hydroxymethyl)furfural, formic acid, levulinic acid, and humins from glucose and HCl were modeled using a serial parallel reaction mechanism. The apparent activation energy (Ea) for glucose decomposition and CMF formation is 99 and 31 kJ/mol.
Antonyraj, Churchil A.,Chennattussery, Amal J.,Haridas, Ajit
p. 825 - 833
(2021/03/18)

CuZSM-5@HMS composite as an efficient micro-mesoporous catalyst for conversion of sugars into levulinic acid
In the present work, the formulation and performance of the silica-aluminosilicate-based composites were studied for catalytic conversion of sugars to levulinic acid. Tailoring the acidity, surface area and the porosity of the catalysts were the main goal of the work. The acidities of the catalysts were provided by ZSM-5 zeolite and were modulated by microwave assisted solid state ion-exchange with copper. The high surface area and porosity of the catalysts were guaranteed by mesopores silica type HMS. The composites of HMS and CuZSM-5 with different contents of 30%, 50%, 60% and 70% were synthesized and the morphological and textural features and acidity of the materials were assessed using XRD, EDX, SEM, TEM, N2-physisorption, and FTIR, FTIR with pyridine and NH3-TPD. CuZ(60%)@H composite acted as the best catalyst with production of 45% yield and 30% yield of LA from glucose and cellulose conversion, respectively. High surface area, large pore size and volume of HMS in the best composite structure favored mass transfer of the substrates and products and higher performance of the catalyst especially in cellulose hydrolysis. In addition, tuned and balanced concentration, strength and type of CuZSM-5 acidity in the composite promoted the desired pathway, favored formation of levulinic acid and suppressed humins formation.
Cruciani, Giuseppe,Di Michele, Alessandro,Ghedini, Elena,M?ki-Arvela, P?ivi,Menegazzo, Federica,Murzin, Dmitry Yu.,Peurla, Markus,Signoretto, Michela,Taghavi, Somayeh,Zendehdel, Mojgan
(2021/12/10)

Sulfonated magnetic carbon nanoparticles from eucalyptus oil as a green and sustainable catalyst for converting fructose to 5-HMF
Sulfonated magnetic carbon nanoparticles (SMCNs) were synthesized from eucalyptus oil via co-pyrolysis with ferrocene and sulfonation by H2SO4. Catalytic performance of SMCNs for conversion of fructose to 5-hydroxymethylfurfural was examined within a designated range of reaction temperature (120–180 °C) and time (30–240 min). 84% conversion of fructose and 51.6% yield of 5-hydroxymethylfurfural could be achieved with catalyst-to-fructose mass ratio of 0.167 at 180 °C and the reaction time of 30 min. The magnetic property of SMCNs also facilitated recovery and recycling of the spent catalyst. Additionally, more than 50% yield of 5-hydroxymethylfurfural could be achieved after three cycles.
Arunaditya, Kantapong,Chaipojjana, Kawisa,Charinpanitkul, Tawatchai,Faungnawakij, Kajornsak,Le, Giang T. T.,Panichpol, Jamekorn,Rodruangnon, Tanapat,Thongratkaew, Sutarat
(2020/11/27)

Effect of Ni Metal Content on Emulsifying Properties of Ni/CNTox Catalysts for Catalytic Conversion of Furfural in Pickering Emulsions
Ni/CNTox catalysts with variable metal content have been prepared to investigate their emulsifying and catalytic properties for the liquid-phase conversion of furfural. The solid catalysts and emulsions were analyzed by several characterization techniques. The catalytic activity linearly increased with increasing Ni content (up to 10 wt.%) before dropping down again for a Ni content of 15 wt.%. The loss of catalytic activity was attributed to larger emulsion droplets formed by the inhibition of hydrophilic sites. All Ni/CNTox catalysts were highly selective to cyclopentanone as a main product, while several changes regarding secondary products were observed. Ni/CNTox catalysts with a Ni content up to 10 wt.% favor the formation of levulinic acid, while catalysts with a Ni content of 15 wt.% were selective to tetrahydrofurfuryl alcohol. This was attributed to an inhibition of the acid sites thus favoring the catalyst's hydrogenation capacity.
Herrera,Pinto-Neira,Fuentealba,Sepúlveda,Rosenkranz,García-Fierro,González,Escalona
p. 682 - 694
(2020/12/01)

Ru Nanoparticles on a Sulfonated Carbon Layer Coated SBA-15 for Catalytic Hydrogenation of Furfural into 1, 4-pentanediol
Furfural (FFR) is one of the most important biomass-derived chemicals. Its large-scale availability calls for the exploration of new transformation methods for further valorization. Herein, we demonstrate that Ru nanoparticles (Ru NPs)-supported on a sulfonated carbon layer coated SBA-15 can be employed as an efficient bi-functional catalyst for one step conversion of FFR into 1,4-pentanediol (1,4-PeDO). The optimum bi-functional catalyst can afford the full the conversion of FFR and 86% selectivity to 1,4-PeDO. The catalysts have been characterized thoroughly by using a complementary combination of powder X-ray diffraction, N2 adsorption–desorption, scanning/transmission electron microscopy, Fourier transform infrared spectroscopy, elemental analysis, and X-ray photoelectron spectroscopy. The characterization revealed that acidic groups (–SO3H) have been introduced on the surface of the carbon layer coated SBA-15 support after sulfonation with 98% H2SO4 and the surface acidity can be tuned facilely by the sulfonating time. Meantime, Ru(0) sites was highly dispersed via an impregnation and sequential reduction and directly adjacent to the surface –SO3H group. There existed an electronic interaction between Ru(0) sites and sulfonic groups, in which the electronic transfer from sulfonic sites to Ru(0) sites occurred. Br?nsted acid sites (–SO3H) have a significant influence on the FFR conversion and the selectivity to 1,4-PeDO. The ordered mesoporous structure, the appropriate density of acid sites and the electron-rich Ru(0) sites accounted for the the excellent performance of the catalyst for an efficient production of 1,4-PeDO from FFR. Graphic Abstract: [Figure not available: see fulltext.].
Cui, Kai,Qian, Wei,Shao, Zhengjiang,Zhao, Xiuge,Gong, Honghui,Wei, Xinjia,Wang, Jiajia,Chen, Manyu,Cao, Xiaoming,Hou, Zhenshan
p. 2513 - 2526
(2021/02/05)

γ-Valerolactone synthesis from α-angelica lactone and levulinic acid over biobased multifunctional nanohybrid catalysts
The selective chemical conversion of biomass components to useful bioproducts may contribute to a renewable resource-based economy. The selective production of target bioproducts may be accomplished using heterogeneous catalysts operating under relatively moderate reaction conditions. In this work, carbohydrate biomass derived α-angelica lactone (AnL) and levulinic acid (LA) were converted to the versatile bioproduct γ-valerolactone (GVL), in the presence of nanohybrid catalysts (M-FDCA) and the microcrystalline metal-organic framework CAU-28, all of which were synthesized from bio-based 2,5-furandicarboxylic acid (FDCA) and a metal (M = Zr or Hf) precursor. The nanohybrids were prepared in a simple fast (FT) fashion, and, for comparison, via a conventional solvothermal (S) procedure. The M-FDCA catalysts stood on a higher footing than CAU-28 in the conversion of AnL and LA to GVL. The superior results for the M-FDCA catalysts may be partly due to their higher ratio Sext:SBET and nano-features, which may advantageously enhance active sites accessibility. In particular, the Hf-FDCA catalysts were stable and performed superiorly to the Zr-FDCA ones. Experimental mechanistic studies shed light on the multifunctional behavior of the hybrid catalysts in the one-pot conversion of AnL-to-GVL, which involved acid and reduction chemistry.
Antunes, Margarida M.,Fernandes, Auguste,Silva, Andreia F.,Valente, Anabela A.
(2021/09/20)

On the chemical interactions of the biomass processing agents γ-valerolactone (GVL) and: N -methylmorpholine- N -oxide (NMMO)
In new biorefinery processes, NMMO/water is used for the pre-treatment of biomass to increase the efficiency of subsequent digestion processes, while GVL/water is used for organosolv fractionation of biomass. The combination of both methods, GVL digestion after pre-activation by NMMO, appears to be reasonable, but has not been successful. In the present study, we examine the reason for this failure and investigate the chemical processes in the ternary system NMMO/GVL/water and in the quaternary system NMMO/GVL/water/ biomass . The consumption kinetics of NMMO and GVL at different temperatures, water contents and NMMO/GVL ratios were recorded. The respective degradation and reaction products were identified for the first time, by combining nuclear magnetic resonance (NMR) spectroscopy, and gas chromatography-mass spectrometry (GC-MS) techniques and synthesis of authentic compounds for comparison. Decomposition products of NMMO and GVL on their own as well as reaction products of both components together (α-morpholinomethyl-GVL (7), α-methylene-GVL (8), and 4-hydroxyvaleric acid morpholide (13)) were observed among the main degradation products. At temperatures of 150 °C and at a water content a significant extent. While the biomass component cellulose was largely unreactive, lignin was the main culprit that caused degradation reactions in the system. The formation of NMM (5) from NMMO and the resulting ring opening of GVL to 4-hydroxyvaleric acid (3), which is immediately oxidized by NMMO to levulinic acid (4), were the initial reactions that triggered the subsequent, more complex decomposition pathways. The chemical structures of all degradation products were fully analytically confirmed. Due to the instability of the NMMO/GVL system, the combination of NMMO biomass pre-treatment and GVL biomass digestion is prohibited, unless a careful removal of NMMO is carried out beforehand. Besides these practical conclusions with regard to biomass processing in biorefineries, the present study provides hopefully helpful insights into the chemistry of NMMO and GVL and the underlying reaction mechanisms.
Bacher, Markus,Hettegger, Hubert,Jusner, Paul,Lê, Huy Quang,Potthast, Antje,Rosenau, Thomas,Sixta, Herbert
p. 5832 - 5848
(2021/08/23)

Zeolite-Tailored Active Site Proximity for the Efficient Production of Pentanoic Biofuels
Biofuel production can alleviate reliance on fossil resources and thus carbon dioxide emission. Hydrodeoxygenation (HDO) refers collectively to a series of important biorefinery processes to produce biofuels. Here, well-dispersed and ultra-small Ru metal nanoclusters (ca. 1 nm), confined within the micropores of zeolite Y, provide the required active site intimacy, which significantly boosts the chemoselectivity towards the production of pentanoic biofuels in the direct, one-pot HDO of neat ethyl levulinate. Crucial for improving catalyst stability is the addition of La, which upholds the confined proximity by preventing zeolite lattice deconstruction during catalysis. We have established and extended an understanding of the “intimacy criterion” in catalytic biomass valorization. These findings bring new understanding of HDO reactions over confined proximity sites, leading to potential application for pentanoic biofuels in biomass conversion.
Chen, Shaohua,Chen, Tiehong,Chu, Shengqi,Gu, Qingqing,He, Jiang,Liu, Yuanshuai,Luo, Wenhao,Wang, Aiqin,Weckhuysen, Bert M.,Wu, Zhijie,Yang, Bing,Zhang, Tao,Zhang, Yafeng
supporting information
p. 23713 - 23721
(2021/09/22)

Conversion of glucose into levulinic acid in continuous segmented turbulent flow with enhanced chemical reaction
Fine chemicals derived from renewable carbon feedstocks can be potentially used as various platform chemicals in the production of fuel additives, polymers, green solvents, foods, and cosmetics. Batch reactions are widely used for the conversion of lignocellulosic biomass into fine chemicals, which possess several drawbacks. Therefore, we investigated the conversion of glucose into various fine chemicals using a segmented (plug) flow reaction system with different segment lengths. The highest conversion of glucose (67.3%) and reaction yield of formic acid (75.1%), levulinic acid (68.9%), and 5-hydroxyl methylfurfural (0.49%) were obtained using reaction conditions of 1 g/L glucose solution and 0.25 M H2SO4 at 150 °C for a short segment reaction. Higher glucose conversion was observed with shorter segments as the result of internal mixing, which enhanced the chemical reactions.
Chia, Chin Hua,Chin, Siew Xian,Jaafar, Sharifah Nabihah Syed,Lau, Kam Sheng
(2021/08/25)

Catalytic C-C coupling of furanic platform chemicals to high carbon fuel precursors over supported ionic liquids
Imidazolium-based ionic liquid (IL) catalysts with different anions (Cl-, HSO4-, and CF3SO3-) were covalently anchored to the surface of fibrous silica (FS) by using alkyl chains as a linker. The prepared catalysts were applied for the C-C coupling reactions of 2-methylfuran (2-MF) with levulinic acid (LA), angelica lactone (AL), and ethyl levulinate (EL) to synthesize high carbon fuel precursors. The hydrophilic nature of FS supported IL catalyst having bisulfate anion was suitable for the self C-C coupling reaction of 2-MF and the reaction of 2-MF with LA. FS supported IL catalyst having triflate anion (FS-ILCF3SO3) exhibited high conversion and selectivity for the target fuel precursors from the C-C coupling reaction of 2-MF with AL and EL. The increased solubility, tunable acidity, and hydrophilicity/hydrophobicity of FS-ILHSO4 and FS-ILCF3SO3 promise a sustainable catalyst system. Supported ILs make the transformation processes greener and more efficient for large-scale production of biomass-derived fuel precursors.
Gebresillase, Mahlet N.,Seo, Jeong Gil
(2021/11/11)

Tin, molybdenum and tin-molybdenum oxides: Influence of Lewis and Bronsted acid sites on xylose conversion
In this study, tin oxide (SnO2), molybdenum oxide (MoO3) and a mixed oxide based on tin and molybdenum (respectively, Sn100, Mo100 and SnMo25, synthesized by the impregnation method) were applied in xylose conversion. The best results were obtained employing Mo100 and SnMo25. In the presence of SnMo25, after 0.5 h, xylose conversions of 39.5%, 34.1% and 63.4% were obtained, respectively, at 110, 130 and 150 °C. For Mo100, conversions of 49.6%, 71.8% and 85.3% were attained under the same reaction conditions, showing that Mo100 provided the best conversion results. However, with the use of this catalyst there was an increase in the amount of soluble and insoluble polymeric material. In terms of the soluble products formed from xylose, depending on the reaction condition were detected xylulose (X), lyxose (L) and furfural (FUR), glyceraldehyde (GL), pyruvaldehyde (PYR), glycoaldehyde (GLYC), dihydroxyacetone (DHA), lactic acid (AL), levulinic acid (LA) and acetic acid (AA). However, with the use of Sn100 or without a catalyst (systems with low conversions) there was mainly the formation of lyxose. The use of Mo100 and SnMo25 (systems which exhibit high acidity) leads mainly to isomerization, epimerization and dehydration reactions, as in the case of the retro-aldol pathway and furfural conversion, highlighting the importance of Lewis and Bronsted acid sites in relation to modulating the selectivity of the systems.
Meneghetti, Mario R.,Meneghetti, Simoni M. P.,Pryston, Dhara B. A.,da Silva Avelino, Débora Olimpio,dos Santos, Thatiane V.
(2021/11/16)

Dibromo-BODIPY as an Organic Photocatalyst for Radical-Ionic Sequences
A new dibrominated 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) is reported as a new metal-free photocatalyst. This BODIPY showed similar optoelectronic, electrochemical, and performance properties to those of Ru(bpy)3Cl2, one of the most common photocatalysts in a known radical-ionic transformation, such as the formation of 1,4-dicarbonyl compounds. Moreover, additional sequences in which the generated oxonium ion is trapped by an internal nucleophile were developed using this BODIPY photocatalyst. These new sequences allowed the straightforward preparation of ?3-alkoxylactones, monoprotected 1,4-ketoaldehydes, and dihydrofurans. This new catalyst, the methodology, and the forged functional groups could be important tools in organic synthesis.
Garciá-Santos, William H.,Ordó?ez-Hernández, Javier,Farfán-Paredes, Mónica,Castro-Cruz, Hiram M.,Maciás-Ruvalcaba, Norma A.,Farfán, Norberto,Cordero-Vargas, Alejandro
p. 16315 - 16326
(2021/11/18)

A practical and concise homogeneous nickel catalyst for efficient solvent-free synthesis of γ-valerolactone
Here, we report an inexpensive nickel-phosphine complex that can catalyse neat levulinic acid (LA) to γ-valerolactone (GVL) without additive at 1 atm H2, and the catalyst can be reduced to 0.01 molpercent at 30 atm. 5.8 kg LA was successfully converted to GVL in a yield of 94percent with 0.1 molpercent catalyst. DFT calculations andin situAPXPS indicate that L-Ni+-H species are the key active intermediates.
Deng, Jin,Fu, Yao,Liu, Jiao,Wang, Bing,Zada, Bakht,Zhu, Rui
supporting information
p. 3427 - 3432
(2020/07/30)

Influence of the ammonium salts used in the Br?nsted acid catalyzed hydrothermal decomposition of d-glucose towards 5-HMF
In this work, we compare the effect of two ammonium salts (ammonium sulfate and ammonium acetate) used as promoters in the hydrothermal decomposition of d-glucose with the results obtained in the presence of sulfuric acid. For the first time, we demonstrate that ammonium acetate is not a good promoter due to the low conversion of d-glucose. Conversely, ammonium sulfate appears as a much more promising promoter. Indeed, even if a large amount of humins is observed, 5-HMF is obtained in good yield with a fast conversion of d-glucose. After isolation and characterization of the liquid and solid phases, the role of ammonium sulfate was thoroughly investigated. Structural characterization of the humins obtained from d-glucose and ammonium salts is also proposed. In addition, we demonstrated that with an ammonium-containing promoter, part of the nitrogen atoms is inserted in the humin structure as pyrrole derivatives.
Maruani, Victor,Framery, Eric,Andrioletti, Bruno
supporting information
p. 4171 - 4176
(2020/03/19)

Flame-made amorphous solid acids with tunable acidity for the aqueous conversion of glucose to levulinic acid
Solid acids of amorphous silica-alumina (a-SA) and amorphous silica-alumina-phosphate (a-SAPO) were prepared by flame spray pyrolysis (FSP). Careful tuning of the acidity of the solid acids was enabled by capitalizing on the advantage of FSP in preserving the metal stoichiometry (i.e., Si, Al, P) in the product nanoparticles. Although the amount of acids on these non-porous solid acids is an order of magnitude lower than the well-recognized strong acidic ZSM-5 zeolite, both exhibit comparable acid strengths. The a-SA and a-SAPO were characterized by a mixture of Br?nsted (B) and Lewis (L) acids, and the B/L ratios were composition-tunable. The highest B/L ratios were recorded for a-SA (Al/(Al + Si) = 0.4) and a-SAPO (Si/(P + Si) = 0.25), giving the highest yields of levulinic acid (≥40% carbon yield) from the conversion of glucose in the aqueous phase without requiring the addition of liquid acids or metal halides. Under the same conditions, the almost exclusive Br?nsted acid ZSM-5 yielded only 17% levulinic acid. The FSP-made solid acid catalyst exhibited good reusability over at least 4 consecutive runs.
Beh, Gein Khai,Wang, Chang Ting,Kim, Kyungduk,Qu, Jiangtao,Cairney, Julie,Ng, Yun Hau,An, Alicia Kyoungjin,Ryoo, Ryong,Urakawa, Atsushi,Teoh, Wey Yang
supporting information
p. 688 - 698
(2020/02/25)

Selective conversion of chitin to levulinic acid catalyzed by ionic liquids: Distinctive effect of: N-acetyl groups
Selective and green conversion of chitin to levulinic acid (LA) has been realized by the catalysis of the ionic liquid (IL) 1-methyl-3-(3-sulfopropyl)imidazolium hydrogen sulfate ([C3SO3Hmim]HSO4) up to a yield of 67.0%. The relationship between the structure of IL and the yield of LA was investigated, demonstrating that both acidity and the hydrogen bonding ability of IL dictate its catalytic activity. Furthermore, by means of NMR, IR, SEM, GPC analyses and determination of the degree of acetylation (DA), two approaches of deacetylation-depolymerization to glucosamine (GlcN) and direct depolymerization to N-acetylglucosamine (GlcNAc) were proposed as chitin hydrolysis mechanisms, which occur only at the outer surface while leaving the interior crystalline chitin intact. The N-acetyl groups in chitin construct strong intramolecular and intermolecular hydrogen bond networks that contribute to the integration of the crystalline structure and building up of barriers to shield the accessibility of glycosidic linkages with the acidic catalyst.
Hou, Wuxin,Zhao, Qingyang,Liu, Li
supporting information
p. 62 - 70
(2020/01/13)

Conversion of saccharides in enteromorpha prolifera to furfurals in the presence of FeCl3
In this work, the conversion of saccharides in Enteromorpha prolifera (E. prolifera) in the presence of a series of metal chloride was studied. FeCl3, was found the best precursor of catalyst for obtaining furfural products, with 8.9 wt% 5-hydroxymethylfurfural (HMF), 14.9 wt% 5-methylfurfural (5-MF), and 4.2 wt% 2-formylfuran (FF) without levulinic acid (LA) formation, under the optimized reaction conditions (190 °C, 60 min and 0.0125 mol/L FeCl3 loading). In H2O-THF-NaCl bi-solvent system catalyzed by FeCl3 derived species, the highest yields of furfurals (20.0 wt% HMF, 19.8 wt% 5-MF, and 5.2 wt% FF) could be obtained when 2 wt% NaCl was added. With the help of THF by in situ extraction, nearly 90 % of the furfural products was enriched in the THF phase, while H2O had a great contribution to the dissolution and hydrolysis of polysaccharides. The catalytic activity and product selectivity of FeCl3 for the conversion of other saccharide model compounds were also studied comparatively. In the presence of FeCl3, the hexose model compounds were converted to LA, whereas those in E. prolifera to HMF. It was found that FeCl3 might interact with the saccharides from E. prolifera to form new species, which could catalyze the conversion of hexose to HMF without LA generation. The new species was considered as a kind of complexes containing Fe(II), which suppressed the rehydration decomposition of HMF. This work provided an effective method for the production of value-added chemicals from E. prolifera.
Chen, Yaguang,Zhou, Yingdong,Zhang, Rui,Hu, Changwei
(2019/12/24)

Reductive amination of levulinic acid to N-substituted pyrrolidones over RuCl3 metal ion anchored in ionic liquid immobilized on graphene oxide
Reductive amination of biomass derived Levulinic acid (LA) for the synthesis of N-substituted pyrrolidones is one of the highly attractive routes for biomass valorization. The supported homogeneous metal precursor into the solid surface is an important context in the field of catalysis because these types of catalysts provide the heterogeneous nature and meet the needs of recyclability. Herein, we have reported a synthesis of catalyst with ruthenium ion supported on ionic liquid immobilized into graphene oxide (Ru?GOIL) and its application for reductive amination reaction. Synthesized catalyst is characterized using different analytical techniques such as FT-IR, XRD, XPS, TGA, FEG-SEM, TEM and EXAFS analysis. The prepared Ru?GOIL found to be highly effective for reductive amination of LA and under these optimized conditions various N-substituted pyrrolidones derivatives were synthesized in excellent yield (78–93%). Ru?GOIL catalyst demonstrated great catalytic performance for reductive amination reaction of LA giving good turnover frequency (TOF = 62 h?1) value in comparison with other catalysts. The Ru?GOIL catalyst was recycled for six reaction runs with slight drop-in activity after 4th cycle. Practical applicability of the developed catalyst was successfully demonstrated by direct transformation of biomass waste (rice husk and wheat straw) derived LA to N-substituted pyrrolidones.
Raut, Amol B.,Shende, Vaishali S.,Sasaki, Takehiko,Bhanage, Bhalchandra M.
p. 206 - 214
(2020/02/15)

Catalytic conversions of isocyanate to urea and glucose to levulinate esters over mesoporous α-Ti(HPO4)2·H2O in green media
We have described a facile solvothermal synthesis of a sheet-like α-Ti(HPO4)2·H2O nanomaterial. The material comprises 10.7 nm nanoparticles along with ordered mesopores throughout its hexagonal building blocks. The material possesses a bandgap of 3.86 eV and works as an efficient catalyst for the selective synthesis of ureas from a broad range of isocyanates in the presence of H2O at room temperature with a high product yield (up to 93%) and a TOF value up to 15.25 h-1. The α-Ti(HPO4)2·H2O nanomaterial also catalytically converts glucose to levulinic acid (LA) and subsequently LA to alkyl levulinates in the presence of different alcohols with a high product yield (up to 98%) and a TOF value up to 43.00 h-1. Furthermore, all the reactions are performed under green and facile catalytic conditions without using any hazardous solvent. The α-Ti(HPO4)2·H2O catalyst material was also found to be reusable for manifold cycles for all the reactions, keeping its catalytic efficiency along with its structural and morphological characteristics unaffected, supporting its industrial relevance.
Hazra Chowdhury, Arpita,Hazra Chowdhury, Ipsita,Biswas, Surajit,Chakrabortty, Pekham,Islam, Sk. Manirul
p. 16452 - 16460
(2020/10/14)

A TiO2/Nb2O5·: N H2O heterojunction catalyst for conversion of glucose into 5-hydroxymethylfurfural in water
A series of water-Tolerant Lewis acidic TiO2/Nb2O5·nH2O heterojunction catalysts with different Ti : Nb ratios have been prepared and investigated in the conversion of glucose into HMF in water. Under optimized conditions (i.e. 150 °C, 300 min), 5-hydroxymethylfurfural (HMF) was obtained in 42% yield together with formic acid (FA) in 17% yield. Extending the reaction time, the yield of FA can be increased to over 60%, albeit at the expense of HMF which is reduced to a slight decrease in activity.
Chen, Lu,Dyson, Paul J.,Fei, Zhaofu,Huang, Fangmin,Jiang, Tianying,Laurenczy, Gabor,Xu, Xincheng
p. 7857 - 7864
(2020/12/31)

METHOD FOR THE HYDRODEOXYGENATION OF OXYGENATED COMPOUNDS TO UNSATURATED PRODUCTS
The invention relates to methods of hydrodeoxygenation of oxygenated compounds into compounds with unsaturated carbon-carbon bonds, comprising the steps of: a) providing a reaction mixture comprising, an oxygenated compound containing one or more of a hydroxyl, keto or aldehyde group, an ionic liquid, a homogeneous metal catalyst, and carbon monoxide or a carbon monoxide releasing compound, b) reacting said reaction mixture under a H2 atmosphere at acidic conditions at a temperature between 180 and 250 °C and a pressure between 10 and 200 bar.
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Page/Page column 18

(2021/01/23)

Catalytic production of 1,4-pentanediol from furfural in a fixed-bed system under mild conditions
Furfural is one of the most important biomass-derived chemicals. Its large-scale availability calls for the exploration of new transformation methods for further valorization. Here we report on the direct, one-step conversion of furfural into 1,4-pentanediols (1,4-PeDs) using a combination of Amberlyst-15 and Ru-FeOx/AC catalysts. It is interesting to find that the introduction of a suitable amount of FeOxresults in a great improvement in the dispersion of Ru and a decrease in the Lewis acidity. Both XPS and H2-TPR show that there is electron transfer from Ru to Fe, and the electronic interaction facilitates the reduction of both Ru and Fe species. When used in combination with Amberlyst-15, the Ru-6.3FeOx/AC catalyst afforded the best performance with a 1,4-PeD yield of 86%; by contrast, Ru/AC free of FeOxonly gave levulinic acid as the major product, demonstrating the key role of the acid/metal balance in the one-pot conversion of furfural to 1,4-PeD. Moreover, such a dual catalyst exhibited excellent durability within 175 h time-on-stream.
Liu, Fei,Liu, Qiaoyun,Qiao, Botao,Su, Yang,Wang, Aiqin,Zhang, Leilei,Zhang, Tao
supporting information
p. 3532 - 3538
(2020/08/28)

Production of 5-(formyloxymethyl)furfural from biomass-derived sugars using mixed acid catalysts and upgrading into value-added chemicals
In this work, 5-(formyloxymethyl)furfural (FMF) has been produced from biomass-derived hexose sugars within a biphasic reaction mixture consisting of aqueous formic acid (85%), a strong Br?nsted acid catalyst, and 1,2-dichloroethane as an organic extractant. Using a combination of aqueous hydrobromic acid and formic acid, under optimized condition (80 °C, 8 h, 10 wt% substrate loading), 68% isolated yield of FMF was obtained from fructose. FMF has been demonstrated as a renewable chemical building block for the synthesis of renewable chemicals of commercial significance such as 5-methylfurfural, 2,5-diformylfuran, and 2,5-furandicarboxylic acid in good to excellent isolated yields.
Dutta, Saikat
(2020/10/02)

Tin oxide-coated transition metal oxide molecular wires for biomass conversion
Catalytic conversion of cellulosic biomass to levulinic acid is interesting and important to utilize biomass for the production of raw chemicals. Herein, Sn oxide-coated transition metal oxide molecular wires, tin tellurotungstate and tin selenotungstate, were synthesized as catalysts for the abovementioned conversion. The characterization results showed that Sn oxide was successfully formed and coated on the external surfaces of the tellurotungstate and selenotungstate molecular wires and the structures of the molecular wires were retained. These materials were used as acid catalysts for the conversion of cellulose in an aqueous solution to form levulinic acid. The Sn oxide-coated catalysts showed superior catalytic activity to that of metal oxide molecular wire catalysts under the same reaction conditions.
Zhang, Zhenxin,Tateno, Haruka,Hara, Michikazu,Ueda, Wataru
supporting information
p. 5147 - 5151
(2020/04/09)

Evolution Process and Controlled Synthesis of Humins with 5-Hydroxymethylfurfural (HMF) as Model Molecule
Elucidation of the chemical structure and formation mechanism of humins is a requisite to further improve the efficiency of acid-catalyzed biomass conversion. Through a low-temperature approach, the key intermediates resulting in the formation of 5-hydroxymethylfurfural (HMF)-derived humins were captured, revealing multiple elementary reactions such as etherification, esterification, aldol condensation, and acetalization. Through humin characterization, it was found out that the aldol condensation moiety between aldehyde group and levulinic acid is critical to justify the characteristic IR peaks (1620 and 1710 cm?1) and aromatic fragments from pyrolysis GC–MS. Based on the investigations by means of HPLC–MS/MS, IR, pyrolysis GC–MS, and SEM, the structural models of humins at different temperatures were proposed, which are comprised of the elementary reaction types confirmed by the key intermediates. Humin structures with varying content of aldol condensation could be controllably synthesized under different reaction conditions (temperature and time), demonstrating the evolution process of HMF-derived humins.
Shen, Haiyan,Shan, Haozhe,Liu, Li
p. 513 - 519
(2019/12/24)

5-HMF production from glucose using ion exchange resin and alumina as a dual catalyst in a biphasic system
5-HMF is a platform chemical that can be used in many applications such as biofuels, monomers, industrial feed stocks, etc. In this work 5-HMF was synthesized from glucose in a biphasic system using a batch reactor. Aluminium oxide and ion exchange resin were used as catalysts in this system. The organic solvent and aqueous solvent were methyl isobutyl ketone (MIBK) and 1-methyl-2-pyrrolidinone (NMP). The effect of operating conditions for synthesis of 5-HMF on the yield and selectivity of 5-HMF was studied including aqueous-to-organic phase ratio, NMP-to-water ratio, catalyst dosage, ratio of catalyst, and reaction time. The optimal conditions were at the reaction temperature of 120 °C and reaction time of 480 min, aqueous-to-organic phase ratio of 7 : 3, NMP-to-water ratio of 4 : 1, 0.3 g of catalyst, and the catalyst ratio of 1 : 2. The conversion of glucose, yield of 5-HMF, and selectivity of 5-HMF were 94.036%, 84.92%, and 90.48%, respectively.
Jaree, Attasak,Kaewchada, Amaraporn,Pumrod, Supakrit,Roddecha, Supacharee
p. 9492 - 9498
(2020/03/19)

Highly efficient oxidation of alcohols to carboxylic acids using a polyoxometalate-supported chromium(iii) catalyst and CO2
Direct catalytic oxidation of alcohols to carboxylic acids is very attractive, but economical catalysis systems have not yet been well established. Here, we show that a pure inorganic ligand-supported chromium compound, (NH4)3[CrMo6O18(OH)6] (simplified as CrMo6), could be used to effectively promote this type of reaction in the presence of CO2. In almost all cases, oxidation of various alcohols (aromatic and aliphatic) could be achieved under mild conditions, and the corresponding carboxylic acids can be achieved in high yield. The chromium catalyst 1 can be reused several times with little loss of activity. Mechanism study and control reactions demonstrate that the acidification proceeds via the key oxidative immediate of aldehydes.
Han, Sheng,Wang, Ying,Wei, Yongge,Wu, Zhikang,Yu, Han
p. 3150 - 3154
(2020/06/19)

Sugar dehydration to 5-hydroxymethylfurfural in mixtures of water/[Bmim]Cl catalyzed by iron sulfate
Ionic liquids (ILs) as additives were used in the selective conversion of bio-based carbohydrates to 5-hydroxymethylfurfural (HMF) in this work. The effect of adding various imidazole-based ionic liquids with different anion structures on the production of HMF from fructose was firstly investigated in aqueous media. The presence of 15 wt% 1-butyl-3-methylimidazole chloride ([Bmim]Cl) ionic liquids in water with Fe2(SO4)3 as the homogeneous catalyst provided a more effective HMF synthesis compared to that without [Bmim]Cl addition. The enhanced HMF yield was mainly attributed to the fact that [Bmim]Cl might play a vital role in stabilizing the HMF molecule, which could thereby suppress side reactions involving HMF (e.g., its rehydration to levulinic acid or/and polymerization to humins). NMR and FTIR analyses suggested that such a stabilization effect stemmed from the interaction of [Bmim]Cl with the hydroxyl and aldehyde groups of HMF through hydrogen bonding. By performing the operation in a biphasic system (i.e., with the biomass-derived THF solvent as the organic phase and the addition of NaCl salt into water for improving HMF partition), the HMF yield over the Fe2(SO4)3 catalyst in the presence of the [Bmim]Cl additive could be further improved. The catalyst and ionic liquids were quite stable, and could be reused for more than five cycles with a consistent activity. A similar enhancement effect of [Bmim]Cl was also demonstrated in HMF synthesis with better yields from other biomass feedstocks or derivatives (including glucose, sucrose, cellobiose, inulin and starch) in aqueous media.
Song, Xiangbo,Wang, Chenguang,Chen, Lungang,Liu, Qiying,Liu, Jianguo,Zhu, Yuting,Yue, Jun,Ma, Longlong
p. 16877 - 16890
(2020/10/27)

Method for preparing levulinic acid from fructose and separating levulinic acid
The invention belongs to the field of biomass catalytic conversion, and particularly relates to a method for preparing levulinic acid from fructose and separating levulinic acid. Aiming at the problems of low sugar concentration, low production efficiency, difficulty in product separation, difficulty in system recycling and the like in the existing reaction system for preparing levulinic acid fromfructose, one part of reaction substrate fructose and choline chloride are directly utilized to form a fructose-choline chloride eutectic solvent, and then an organic solvent is added, and levulinicacid is obtained under the effect of astrong acid catalyst. The method is simple to operate, the product is easy to separate, the economy is good, the production efficiency is high, and the eutectic solvent is environment-friendly and recyclable.
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Paragraph 0029-0048

(2020/12/30)

Production of 5-HMF from glucose using TiO2-ZrO2 catalysts: Effect of the sol-gel synthesis additive
Different TiO2-ZrO2 (50/50 wt%) mixed metal oxide catalysts were synthesized by the sol-gel method after varying the synthesis additive (e.g., CH3COOH, HNO3, NH4OH and NaOH) to study its effect on the production yield of 5-HMF from the conversion of glucose at 175 °C and 30 bar (Ar) (batch reaction system). Various characterization techniques such as BET, XRD, FTIR, 1HNMR, NH3-TPD, TPO, SEM and TEM were employed to study the physicochemical properties of the synthesized materials and to correlate them with the reaction product yields. Highest HMF yield (76%) was obtained over the TiO2-ZrO2-C2H4O2 catalyst in a biphasic reaction system with a glucose concentration of 2 wt% and a glucose/catalyst mass ratio of 2.5. From the NH3-TPD results, highest amount of total acid sites was observed for the TiO2-ZrO2 (50/50 wt%) prepared by the sol-gel method using the acetic acid additive, and acidity value was 3 and 2.5 times higher than that of TiO2 and ZrO2 alone, respectively. It was concluded that total acid sites density is an important parameter to obtain high 5-HMF product yields. A higher number density of sites can be obtained using the complexing additive of acetic acid in the Sol-Gel method among the other additives investigated.
Silahua-Pavón, Adib A.,Espinosa-González, Claudia G.,Ortiz-Chi, Filiberto,Pacheco-Sosa, J. Gpe,Pérez-Vidal,Arévalo-Pérez, J. Carlos,Godavarthi, Srinivas,Torres-Torres
(2019/06/18)

Solvent Effects on Degradative Condensation Side Reactions of Fructose in Its Initial Conversion to 5-Hydroxymethylfurfural
The degradative condensation of hexose, which originates from the C?C cleavage of hexose and condensation of degraded hexose fragment, is one of the possible reaction pathways for the formation of humins in hexose dehydration to 5-hydroxymethylfurfural (HMF). Herein, the impacts of several polar aprotic solvents on the degradative condensation of fructose to small-molecule carboxylic acids and oligomers (possible precursors of humins) are reported. In particular, a close relationship between the tautomeric distribution of fructose in solvents and the mechanism of degradative condensation is demonstrated. Typically, α-fructofuranose in 1,4-dioxane and acyclic open-chain fructose in THF favor the conversion of fructose to formic acid and oligomers; α-fructopyranose in γ-valerolactone or N-methylpyrrolidone favors levulinic acid and oligomers, whereas β-fructopyranose in 4-methyl-2-pentanone favors acetic acid and corresponding oligomers. This close correlation highlights a general understanding of the solvent-controlled formation of oligomers, which represents an important step toward the rational design of effective solvent systems for HMF production.
Fu, Xing,Hu, Yexin,Zhang, Yanru,Zhang, Yucheng,Tang, Dianyong,Zhu, Liangfang,Hu, Changwei
(2019/11/13)