- Catalytic conversion of cellulose over mesoporous y zeolite
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Mesoporous Y zeolite (Meso-Y) was applied, for the first time, to the catalytic pyrolysis of cellulose which is a major constituent of lignocellulosic biomass, to produce high-quality bio-oil. A representative mesoporous catalyst Al-MCM-41 was also used t
- Park, Young-Kwon,Jun, Bo Ram,Park, Sung Hoon,Jeon, Jong-Ki,Lee, See Hoon,Kim, Seong-Soo,Jeong, Kwang-Eun
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- Mesoporous mixed CuCo oxides as robust catalysts for liquid-phase furfural hydrogenation
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A series of highly ordered mesoporous CuCo oxide catalysts with a controlled composition are successfully synthesized by nanocasting from mesoporous silica, KIT-6 template. Liquid-phase furfural (FAL) hydrogenation is carried out to find the optimal composition of the CuCo oxide catalysts to achieve the best catalytic performance. As-prepared mesoporous mixed CuCo oxides exhibit a high surface area (60?135 m2 g?1) and a well-defined ordered mesostructure with homogenous dispersion of Cu and Co. Among various compositions of CuxCoy oxides (x = 1–9, y = 1–x) studied, the Cu1Co5 oxide catalyst shows the highest conversion in the hydrogenation of FAL, which is superior to those achieved with mesoporous monometallic oxides, CuO and Co3O4. While 2-methylfuran is produced from furfuryl alcohol via aldehyde hydrogenation and subsequent hydrogenolysis, the formation of 2-methylfuran increased with a decrease in the Cu/Co ratio of the CuCo oxide catalyst. The mixed CuCo oxide catalyst is readily reduced under the reaction environment to produce metallic CuCo as the active species. The synergistic interactions between Cu and Co in the mixed CuCo oxide catalysts play an important role in the outstanding catalytic performance for FAL hydrogenation, which could not be achieved with either of the monometallic catalysts or their physical mixtures. The excellent stability and recyclability of mesoporous mixed CuCo oxide catalysts as well as the exceptionally high activity, surpassing those of the monometallic oxides, render them promising as a low-cost and efficient catalyst for the industrial upgrading of biomass-derived FAL.
- Nguyen-Huy, Chinh,Lee, Hojeong,Lee, Jihyeon,Kwak, Ja Hun,An, Kwangjin
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- Effects of thiol modifiers on the kinetics of furfural hydrogenation over Pd catalysts
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Thiolate self-assembled monolayers (SAMs) were used to block specific active sites on Pd/Al2O3 during the hydrogenation of furfural to elucidate site requirements for each process involved in this complex reaction network. Reactions were performed on uncoated, 1-octadecanethiol (C18) coated, and benzene-1,2-dithiol (BDT) coated catalysts. Selectivity among key reaction pathways was sensitive to the SAM modifier, with increasing sulfur density strongly suppressing furfural decarbonylation, less strongly suppressing furfural hydrogenation, and minimally affecting furfuryl alcohol hydrodeoxygenation to methylfuran. Diffuse reflectance infrared Fourier transform spectroscopy with CO was used to characterize site availability on the catalysts. The presence of a C18 modifier restricted the availability of Pd terrace sites, while accessibility to Pd edges and steps was practically unaffected with respect to the uncoated catalyst. The BDT modifier further restricted terrace accessibility but additionally restricted adsorption at particle edges and steps. Comparison between reaction rates and site availability suggested that decarbonylation occurred primarily on terrace sites, while hydrodeoxygenation occurred on particle steps and edges. Aldehyde hydrogenation, and its reverse process of alcohol dehydrogenation, was found to occur on both terrace or edge sites, with the dominant pathway dependent on surface coverage as determined by reaction conditions. The results of a detailed kinetic study indicate that in addition to changing the availability of specific sites, thiol monolayers can strongly affect reaction energetics and decrease the coverage of strongly adsorbed furfural-derived intermediates under reaction conditions. Ambient pressure X-ray photoelectron spectroscopy experiments indicated that the metal-sulfur bonds were not changed appreciably under reaction conditions. The results of this work show that HDO is not appreciably affected even with drastic decreases in the density of available sites as measured by CO adsorption, providing opportunities to design isolated catalyst sites for selective reaction.
- Pang, Simon H.,Schoenbaum, Carolyn A.,Schwartz, Daniel K.,Will Medlin
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- Maleimide-dimethylfuran exo adducts: Effective maleimide protection in the synthesis of oligonucleotide conjugates
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The reaction of maleimide-containing compounds with 2,5-dimethylfuran gives a mixture of exo and endo isomers from which the exo cycloadduct can be easily isolated taking advantage of its stability in concentrated aqueous ammonia. Bifunctional compounds incorporating a dimethylfuran-protected maleimide (exo adduct) have been attached to resin-linked oligonucleotide chains. Removal of protecting groups masking oligonucleotide functionalities followed by retro-Diels-Alder maleimide deprotection affords maleimido-oligonucleotides suitable for conjugation, as assessed by their reaction with different thiols.
- Sanchez, Albert,Pedroso, Enrique,Grandas, Anna
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- Factors affecting thermally induced furan formation
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Furan, a potential carcinogen, can be induced by heat from sugars, ascorbic acid, and fatty acids. The objective of this research was to investigate the effect of pH, phosphate, temperature, and heating time on furan formation. Heat-induced furan formation from free sugars, ascorbic acid, and linoleic acid was profoundly affected by pH and the presence of phosphate. In general, the presence of phosphate increased furan formation in solutions of sugars and ascorbic acid. In a linoleic acid emulsion, phosphate increased the formation of furan at pH 6 but not at pH 3. When an ascorbic acid solution was heated, higher amounts of furan were produced at pH 3 than at pH 6 regardless of phosphate's presence. However, in linoleic acid emulsion, more furan was produced at pH 6 than at pH 3. The highest amount of furan was formed from the linoleic acid emulsion at pH 6. In fresh apple cider, a product with free sugars as the major components (besides water) and little fatty acids, ascorbic acid, or phosphate, small or very low amounts of furan was formed by heating at 90-120 °C for up to 10 min. The results indicated that free sugars may not lead to significant amounts of furan formation under conditions for pasteurization and sterilization. Importantly, this is the first report demonstrating that phosphate (in addition to pH) plays a significant role in thermally induced furan formation.
- Fan, Xuetong,Huang, Lihan,Sokorai, Kimberly J. B.
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- Thermal Decomposition of 3′-Azidothymidine
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The kinetics of thermal decomposition of 3′-azidothymidine (AZT) in melt at 140-201°C were studied by the thermogravimetric and manometric methods. The process follows the first-order kinetics and is decribed by the Arrhenius equation: k = 1014.7±0.5
- Nedel'ko,Korsunskii,Chukanov,Larikova,Korchevskaya,Malin,Shcherbinin,Ostrovskii
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- Selective hydrogenation of furfuryl alcohol to tetrahydrofurfuryl alcohol over Ni/γ-Al2O3 catalysts
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A series of nickel-based catalysts (with 2O3, x represents the Ni loading amount) were synthesized by the impregnation method, which was successfully applied for the catalytic hydrogenation of furfuryl alcohol to tetrahydrofurfuryl alcohol. The effects of reaction time, reaction temperature, nickel loading amount, solvent, and hydrogen pressure on conversion of furfural alcohol as well as selectivity for tetrahydrofurfuryl alcohol were investigated systematically. The conversion of furfural alcohol over 15?wt% Ni/γ-Al2O3 was up to 99.8?% with a selectivity of 99.5?% toward tetrahydrofurfuryl alcohol, when the reaction was carried out at 353?K with an initial H2 pressure of 4.0?MPa and reaction time of 2?h. In addition, there was an increase of turnover frequency (TOF) value with the decrease of Ni particle size. The features of the Ni/γ-Al2O3 catalysts were investigated by characterization of XRD, TPR, BET, and SEM.
- Sang, Shengya,Wang, Yuan,Zhu, Wei,Xiao, Guomin
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- Structure-Reactivity Relations in Ruthenium Catalysed Furfural Hydrogenation
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Furfural is an abundant and low-cost bio-derived platform chemical, obtained by xylose dehydration, and an important precursor to furfuryl alcohol and furan resins. The liquid phase selective hydrogenation of furfural to furfuryl alcohol was systematically investigated over silica supported Ru nanoparticles to elucidate structure-reactivity relations and obtain mechanistic insight. Furfural hydrogenation to furfuryl alcohol is weakly structure sensitive for Ru nanoparticles spanning 2 to 25 nm, and the dominant reaction pathway reaching 95 % selectivity under our conditions (2 and 100–165 °C). In contrast, furfural decarbonylation to furan exhibits a strong structure sensitivity, being favoured over sub-10 nm particles. Increasing pH2 from 10 to 25 bar resulted in a modest increase in C=O hydrogenation, while higher temperatures promoted ring-opening of furfuryl alcohol.
- Durndell, Lee J.,Zou, Guchu,Shangguan, Wenfeng,Lee, Adam F.,Wilson, Karen
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- Selective Hydrogenation of Biomass-Derived Furfural: Enhanced Catalytic Performance of Pd?Cu Alloy Nanoparticles in Porous Polymer
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Here, the development of a new catalyst is reported for the selective furfural (FF) hydrogenation to furfuryl alcohol (FA) based on about 7 nm sized Pd?Cu alloy nanoparticles (NPs) formed in inexpensive, commercially available micro/mesoporous hypercrosslinked polystyrene (HPS). A comparison of the catalytic properties of as-synthesized and reduced (denoted “r”) catalysts as well as Pd?Cu alloy and monometallic palladium NPs showed a considerable enhancement of the catalytic performance of Pd?Cu/HPS-r compared to other catalysts studied, resulting in about 100 percent FF conversion, 95.2 percent selectivity for FA and a TOF of 1209 h?1. This was attributed to the enrichment of the NP surface with copper atoms, disrupting the furan ring adsorption, and to the presence of both zerovalent and cationic palladium and copper species, resulting in optimal hydrogen and FF adsorption. These factors along with exceptional stability of the catalyst in ten consecutive catalytic cycles make it highly promising in practical applications.
- Salnikova, Ksenia E.,Larichev, Yurii V.,Sulman, Esther M.,Bykov, Alexey V.,Sidorov, Alexander I.,Demidenko, Galina N.,Sulman, Mikhail G.,Bronstein, Lyudmila M.,Matveeva, Valentina G.
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- The Generation and Trapping of a Novel Dewar Furan
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2,4,7-Trimethyl-7-aza-3-oxatricyclo2,4>oct-1(5)-ene-6,8-dione (7), a derivative of the rarely observed Dewar furan ring-system, has been prepared by Zn-TiCl4 debromination of dibromide (6) and trapped in situ with furan.
- Pitt, Ian G.,Russel, Richard A.,Warrener, Ronald N.
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- CHARACTERISTICS OF THE CATALYTIC HYDROGENATION OF 5-METHYLFURFURAL
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The hydrogenation of 5-methylfurfural in the vapor and liquid phases was studied in the presence of catalysts: Pd/C (KDF), Pd/Al2O3, copper-chromite (GIPKh-105) and Raney-Ni.The chief characteristics of the conversion of the aldehyde group of 5-methylfurfural depending on the nature of the catalyst and the reaction conditions were established.The greater reactivity of 5-methylfurfural in the hydrogenation reaction, compared with furfural, was revealed.
- Stonkus, V. V.,Yuskovets, Zh. G.,Shimanskaya, M. V.
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- A magnetic CoRu-CoO: X nanocomposite efficiently hydrogenates furfural to furfuryl alcohol at ambient H2 pressure in water
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A one-pot synthesized CoRu-CoOX nanocomposite was reported as a magnetically recoverable catalyst for selective hydrogenation of furfural to furfuryl alcohol in water at ambient H2 pressure.
- Cao, Qiue,Fang, Wenhao,Lu, Yaowei,Wang, Yongxing
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- Production of renewable oleo-furan surfactants by cross-ketonization of biomass-derived furoic acid and fatty acids
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Synthesis of 2-dodecanoyl furan is a crucial step in the formulation of oleo-furan sulfonates as bio-surfactants from biomass-derived furans and vegetable-oil-derived molecules. Herein, cross-ketonization of 2-furoic acid and lauric acid is proposed to produce the bio-surfactant precursor. Among the commonly reported metal oxide ketonization catalysts, the inexpensive and abundant iron oxides are demonstrated as effective and recyclable catalysts, enabling up to 77% selectivity to 2-dodecanoyl furan at 56% lauric acid conversion. Catalyst characterization by X-ray diffraction, H2temperature-programmed reduction, and X-ray photoelectron spectroscopy indicates that Fe3O4is the catalytically active and stable phase.13C isotopic tracing experiments suggest that cross-ketonization on Fe3O4proceedsviaa β-keto acid intermediate.
- Fu, Jiayi,Moglia, David,Nguyen, Hannah,Orazov, Marat,Vlachos, Dionisios G.,Wang, Yunzhu,Zheng, Weiqing
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- Pd-catalyzed decarbonylation of furfural: Elucidation of support effect on Pd size and catalytic activity using in-situ XAFS
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Palladium (Pd) clusters on zirconia (ZrO2) and single Pd atoms on ceria (CeO2) exhibited high catalytic activity and selectivity for decarbonylation of furfural to furan without additives in the liquid phase. To study the active size of Pd and changes in chemical states or structures during the reaction, in-situ X-ray absorption fine structure (XAFS) measurements were conducted. The size of Pd clusters consisting of less than 10 Pd atoms was maintained on ZrO2 during the reaction. In contrast, single Pd atoms were aggregated during heating and only Pd clusters consisting of 13 atoms were present after the reaction. According to the in-situ XAFS results, the size of Pd particles did not gradually increase to Pd13 clusters. Instead, Pd13 clusters were partly formed from the beginning of the reaction, and the proportion of Pd13 clusters increased with time while keeping the size of Pd13 clusters. This result suggests that a single Pd atom is inactive, but Pd clusters are active for decarbonylation. Ab-initio calculation revealed that ZrO2 (1 1 1) surface had lower adsorption and migration energies than CeO2 (1 1 1), implying that Pd was easily diffused on the surface and stabilized as small Pd clusters.
- Ishida, Tamao,Honma, Tetsuo,Nakada, Kengo,Murayama, Haruno,Mamba, Tetsuya,Kume, Kurumi,Izawa, Yusuke,Utsunomiya, Masaru,Tokunaga, Makoto
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- Infrared Study of the Adsorption of But-1-ene, Buta-1,3-diene, Furan and Maleic Anhydride on the Surface of Anhydrous Vanadyl Pyrophosphate
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Broensted-acidic hydroxy groups on the surface of vanadyl pyrophosphate act as catalytically active sites for the isomerisation of but-1-ene to but-2-enes.Progressive poisoning of the reaction is attributed to the tormation of alkyl species, possibly alkoxy groups, on the (VO)2P2O7 surface.Adsorbed alkyl groups also result from buta-1,3-diene adsorption.Furan adsorbs on (VO)2P2O7 through coordinative interactions with Lewis-acidic surface sites.The presence of oxygen promotes the oxidation of furan to maleic anhydride.
- Puttock, Simon J.,Rochester, Colin H.
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- Highly selective synthesis of oxabicycloalkanes by indium tribromide-mediated cyclization reactions of epoxyalkenes
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The cyclization of epoxyalkenes to oxabicycloalkanes is catalyzed by stoichiometric quantities of indium tribromide which exhibits excellent selectivity giving the oxabicyclic product in high yield in preference to other cyclized or rearrangement products. The Royal Society of Chemistry.
- Smith, Brendan M.,Skellam, Elizabeth J.,Oxley, Samantha J.,Graham, Andrew E.
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- Structure-dependent catalytic properties of mesoporous cobalt oxides in furfural hydrogenation
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As the development of noble metal free catalysts became important in the biomass conversion, catalytic hydrogenation of furfural (FAL) is investigated over ordered mesoporous cobalt oxide (m-Co3O4). When m-Co3O4 is reduced at 350 and 500 °C in hydrogen, the original crystal structure of Co3O4 is changed to CoO and Co, respectively. Here we examine the effect of the structure, porosity, and oxidation state of m-Co3O4 to identify catalytically active species for hydrogenation of FAL. Among cobalt oxide catalysts having different crystal structures and symmetry, m-CoO having p6mm symmetry exhibits the highest activity. In product selectivity, the CoO phase induces FAL hydrogenolysis by selective production of 2-methyl furan (MF), while the Co3O4 and Co phases promote preferential hydrogenation of side chain (carbonyl group) of FAL to furfuryl alcohol. Density functional theory calculations also reveal that the adsorption of FAL on CoO(111) is higher than Co(111). Overall, these studies demonstrate that CoO as the most active phase is responsible for the high FAL conversion and the distinct pathway of FAL to MF.
- Nguyen-Huy,Lee, Jihyeon,Seo, Ji Hui,Yang, Euiseob,Lee, Jaekyoung,Choi, Keunsu,Lee,Kim, Jae Hyung,Lee, Man Sig,Joo, Sang Hoon,Kwak, Ja Hun,Lee, Jun Hee,An, Kwangjin
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- Facile synthesis of inorganic–organic Fe2W18Fe4@NiO@CTS hybrid nanocatalyst induced efficient performance in oxidative desulfurization of real fuel
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In this work, a new nanocatalyst, Fe2W18Fe4@NiO@CTS, was synthesized by the reaction of sandwich-type polyoxometalate (Fe2W18Fe4), nickel oxide (NiO), and chitosan (CTS) via sol–gel method. The assembled nanocatalyst was systematically characterized by FT-IR, UV–vis, XRD, SEM, and EDX analysis. The catalytic activity of Fe2W18Fe4@NiO@CTS was tested on oxidative desulfurization (ODS) of real gasoline and model fuels. The experimental results revealed that the levels of sulfur content and mercaptan compounds of gasoline were lowered with 97% efficiency. Also, the Fe2W18Fe4@NiO@CTS nanocatalyst demonstrated an outstanding catalytic performance for the oxidation of dibenzothiophene (DBT) in the model fuel. The major factors that influence the desulfurization efficiency and the kinetic study of the ODS reactions were fully detailed and discussed. The probable ODS pathway was proposed via the electrophilic mechanism on the basis of the electrophilic characteristic of the metal-oxo-peroxo intermediates. The prepared nanocatalyst could be reused for 5 successive runs without any appreciable loss in its catalytic activity. As a result, the current study suggested the potential application of the Fe2W18Fe4@NiO@CTS hybrid nanocatalyst as an ideal candidate for removal of sulfur compounds from fuel.
- Rezvani, Mohammad Ali,Maleki, Zeynab
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- Real-time product switching using a twin catalyst system for the hydrogenation of furfural in supercritical CO2
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"Vending machine" chemistry: A tandem flow-reactor setup can be used to generate a choice of five products in high yield from a single biorenewable feedstock, furfural (1). "Real-time" switching to any of the products can be achieved rapidly by simply changing the reactor conditions.
- Stevens, James G.,Bourne, Richard A.,Twigg, Martyn V.,Poliakoff, Martyn
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- Photoisomerization and photochemistry of matrix-isolated 3-furaldehyde
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3-Furaldehyde (3FA) was isolated in an argon matrix at 12 K and studied using FTIR spectroscopy and quantum chemistry. The molecule has two conformers, with trans and cis orientation of the O=C-C=C dihedral angle. At the B3LYP/6-311++G(d,p) level of theory, the trans form was computed to be ca. 4 kJ mol-1 more stable than the cis form. The relative stability of the two conformers was explained using the natural bond orbital (NBO) method. In fair agreement with their calculated relative energies and the high barrier of rotamerization (ca. 34 kJ mol-1 from trans to cis), the trans and cis conformers were trapped in an argon matrix from the compound room temperature gas phase in proportion ~7:1. The experimentally observed vibrational signatures of the two forms are in a good agreement with the theoretically calculated spectra. Broad-band UV-irradiation (λ > 234 nm) of the matrix-isolated compound resulted in partial trans → cis isomerization, which ended at a photostationary state with the trans/cis ratio being ca. 1.85:1. This result was interpreted based on results of time-dependent DFT calculations. Irradiation at higher energies (λ > 200 nm) led to decarbonylation of the compound, yielding furan, cyclopropene-3-carbaldehyde, and two C3H4 isomers: cyclopropene and propadiene.
- Kus, Nihal,Reva, Igor,Fausto, Rui
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- Understanding the Role of M/Pt(111) (M = Fe, Co, Ni, Cu) Bimetallic Surfaces for Selective Hydrodeoxygenation of Furfural
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Selectively cleaving the C=O bond of the aldehyde group in furfural is critical for converting this biomass-derived platform chemical to an important biofuel molecule, 2-methylfuran. This work combined density functional theory (DFT) calculations and temperature-programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS) measurements to investigate the hydrodeoxygenation (HDO) activity of furfural on bimetallic surfaces prepared by modifying Pt(111) with 3d transition metals (Cu, Ni, Fe, and Co). The stronger binding energy of furfural and higher tilted degree of the furan ring on the Co-terminated bimetallic surface resulted in a higher activity for furfural HDO to produce 2-methylfuran in comparison to that on either Pt(111) or Pt-terminated PtCoPt(111). The 3d-terminated bimetallic surfaces with strongly oxophilic 3d metals (Co and Fe) showed higher 2-methylfuran yield in comparison to those surfaces modified with weakly oxophilic 3d metals (Cu and Ni). The effect of oxygen on the HDO selectivity was also investigated on oxygen-modified bimetallic surfaces, revealing that the presence of surface oxygen resulted in a decrease in 2-methylfuran yield. The combined theoretical and experimental results presented here should provide useful guidance for designing Pt-based bimetallic HDO catalysts.
- Jiang, Zhifeng,Wan, Weiming,Lin, Zhexi,Xie, Jimin,Chen, Jingguang G.
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- In-situ hydrogenation of furfural conversion to furfuryl alcohol via aqueous-phase reforming of methanol
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It is a promising pathway to reduce the dependence on fossil fuels and obtain the bio-fuels or chemicals production from biomass derivatives. The conversion from furfural (FFR) to furfuryl alcohol (FFA) is an important industrial technology using the liquid-phase hydrogenation method with external hydrogen gas. However, the natural environment is threatened by the security of external hydrogen gas, toxicant catalyst, and the high energy consumption. Recently, in-situ hydrogenation is a novel method to converse FFR to FFA at mild reaction conditions to replace the dangerous external hydrogen gas. In this paper, we reported an efficient in-situ hydrogenation method via aqueous-phase reforming of methanol using Pt loading MgTiO3 (perovskite-type material) at mild conditions. Pt nanoparticles were high dispersion on the nano-MgTiO3-450 surface, and CH3OH and H2O were reformed to produce hydrogen gas on the catalyst surface through the action of Pt nanoparticles. A part of active hydrogen could be involved in the reduction of Pt2+ to Pt0, resulting in the perfect recyclability of the Pt@MT-450 catalyst. The other part of active hydrogen were participated in the hydrogenation of FFR conversion to FFA under the interaction of Pt and Mg elements. The in-situ hydrogenation of FFR to FFA using Pt@MT-450 is an effectively pathway to reduce the reaction conditions than that with external hydrogen gas.
- Zhang, Shiqiu,Yang, Xue,Zheng, Kui,Xiao, Ruihao,Hou, Qidong,Liu, Bangjun,Ju, Meiting,Liu, Le
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- Experimental and theoretical study of the homogeneous, unimolecular gas-phase elimination kinetics of 2-furoic acid
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The kinetics of the gas-phase elimination kinetics of CO2 from furoic acid was determined in a static system over the temperature range 415-455°C and pressure range 20-50 Torr. The products are furan and carbon dioxide. The reaction, which is carried out in vessels seasoned with allyl bromide and in the presence of the free-radical suppressor toluene and/or propene, is homogeneous, unimolecular, and follows a first-order rate law. The observed rate coefficient is expressed by the following Arrhenius equation: log k1 (s-1) = (13.28 ± 0.16) - (220,5 ± 2.1) kJ mol-1 (2.303 RT)-1. Theoretical studies carried out at the B3LYP/6-31++G** computational level suggest two possible mechanisms according to the kinetics and thermodynamic parameters calculated compared with experimental values.
- Ramirez, Beatriz C.,Dominguez, Rosa M.,Herize, Armando,Tosta, Maria,Cordova, Tania,Chuchani, Gabriel
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- A study of furfural decarbonylation on K-doped Pd/Al2O 3 catalysts
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Vapor-phase decarbonylation of furfural to furan was performed on K-doped Pd/Al2O3 catalysts in a fixed-bed reactor. A series of K-doped catalysts were prepared by impregnation method with various potassium salt precursors and different potassium content. The catalyst evaluation results revealed that the doping of K not only promoted the furfural decarbonylation, but also suppressed the hydrogenation side reaction. Among the investigated catalysts, Pd-K2CO3/Al2O3 (K% = 8 wt.%) presented the best performance and achieved the furan yields up to 99.5% at 260 °C. The selectivity of 2-methylfuran would approach zero at high K content (K% > 4 wt.%). Furthermore, the catalysts were characterized by BET, SEM, ICP, H2-TPR, H2-TPD, H2-chemisorption, CO-FTIR, furfural-TPSR, and furfural-FTIR experiments. It was shown that the dopant phase had a remarkable effect on the precursor Pd2+ and the reduced Pd metal particles. Furfural-TPSR and furfural-FTIR exhibited that K-doped catalysts enhanced the furfural adsorption and promoted the decarbonylation reaction, which was due to the different adsorption mode and intensity of furfural on K-doped and undoped samples. Besides, the decrease of C-O adsorption of furfural (η2(C,O)-furfural) by K doping is the main reason for suppressing the furfural hydrogenation.
- Zhang, Wei,Zhu, Yulei,Niu, Shasha,Li, Yongwang
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- Furfural hydrodeoxygenation on iron and platinum catalysts
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Furfural can be converted into a wide range of high-octane products like 2-methylfuran (2-MF) through hydrodeoxygenation (HDO). Iron-based catalyst (Fe/SiO2), has shown high selectivity for gas phase conversion of furfural to 2-MF at atmospheric pressure and 573 K. However, it showed rapid deactivation. Furfural is the main coke precursor, although coke is also formed when 2-MF and furan are used as reactants, but in lower quantities. Coke profiles along the catalytic bed suggest that tetra-hydrofuran is an important coke precursor. The addition of a second metal like platinum, even in very low proportions, generates hydrogen spillover leading to an important improvement in the stability of the catalyst. The Fe/Pt ratio on the surface regulates the amount of coke deposited because it modifies the iron particle sizes, the interaction with the support and the amount of hydrogen available for the reactions. These phenomena influence the reaction, coke formation and regeneration mechanisms.
- Zanuttini, M. Soledad,Gross, Martin,Marchetti, Gustavo,Querini, Carlos
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- Deuterium kinetic isotope effects in butadiene epoxidation over unpromoted and Cs-promoted silver catalysts
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The kinetic isotope effects (KIE) in the epoxidation of butadiene over both unpromoted and Cs-promoted catalysts were studied using selectively deuterium-labeled isotopomers of 1,3-butadiene (CD2CDCDCD2, CD2CHCHCD2, and CH2CDCDCH2) as feed reactants. On unpromoted silver catalysts, 3,4-epoxy-1-butene formation was characterized by an inverse KIE that results from a primary effect in total oxidation to CO2. These KIE were only significant for butadiene isotopomers that are D-labeled in the 1- and 4-positions, indicating that combustion was initiated by cleavage of a terminal C-H bond. In analogous fashion to previous KIE studies for the epoxidation of ethylene, the observed KIE could be explained by a reaction scheme in which partial and total oxidation products were generated from a common C4H6(ads) surface intermediate. This scheme was also consistent with previous surface science experiments, suggesting that the C4H6O(ads) intermediate could be a surface oxametallacycle. The results of KIE experiments performed over Cs-promoted silver catalysts were in accord with the proposed reaction scheme and showed that the function of the Cs promoter could be to lower the activation energy for epoxy-butene formation from the C4H6O(ads) species.
- Barteau,Monnier,Medlin
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- Dye-Sensitized Photooxygenation of 2,3-Dihydrofurans: Competing Cycloadditions and Ene Reactions of Singlet Oxygen with a Rigid Cyclic Enol Ether System
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Singlet oxygen reacts with 2,3-dihydrofuran (1), 5-methyl (7), 4,5-dimethyl- (13), and 4-carbomethoxy-5-methyl-2,3-dihydrofuran (20), 5,6-dimethyl-3,4-dihydro-2H-pyran (26), and 3-methoxy-2-methyl-2-butene (32) in nonpolar and polar aprotic solvents to yield dioxetanes and allylic hydroperoxides, except 32, which gives only allylic hydroperoxides.The dioxetanes were isolated, but decompose slowly with weak chemiluminescence at room temperature to yield the corresponding dicarbonyl compounds.The allylic hydroperoxides produced by the cyclic enol ethers could not be isolated or separated by high vacuum distillation or by chromatography; the endocyclic allylic hydroperoxides arising from the dihydrofurans eliminate H2O2 to yield the corresponding furans while the exocyclic allylic hydroperoxides gives unknown products.Allylic hydroperoxides 28 and 29 and the dioxetane 27 obtained from 26 yield the same dicarbonyl compound 31.The proportion of dioxetanes to allylic hydroperoxides depends on ring size and substitution of the enol ethers and on solvent polarity.Smaller ring size, greater electron-donor substitution, and solvent polarity favor the formation of dioxetanes at the expense of allylic hydroperoxides.It is noteworthy that enol ether 20, an α,β-unsaturated ester, forms appreciable amounts of a dioxetane in polar solvents (44 percent in acetonitrile).Kinetic results show that the rate and product distribution of the ene reaction are independent of solvent polarity, whereas the rate of dioxetane formation increases with solvent polarity.It is suggested that cycloadditions and ene reactions occur via different transition states and intermediates, zwitterions and perepoxides, respectively.Furthermore, the remarkable propensity to dioxetane formation of dihydrofurans compared to that of dihydropyrans and the other enol ethers seems to be due to the rigidity of the five-membered ring in the transition state and intermediate zwitterion.
- Gollnick, Klaus,Knutzen-Mies, Karen
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- Effect of hydrogen donor on liquid phase catalytic transfer hydrogenation of furfural over a Ru/RuO2/C catalyst
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The effect of alcohol hydrogen donor on methyl furan production through catalytic transfer hydrogenation of furfural in the liquid phase has been investigated over a mildly calcined Ru/C catalyst in the temperature range of 110-200 °C. It has been found that several parameters contribute to furfural hydrogenolysis, including alcohol dehydrogenation activity, solvent properties, as well as side reactions such as etherification between the intermediate, furfuryl alcohol, and the hydrogen donor. Methyl furan yield increases from 0 to 68% at 180 °C following the order of 2-methyl-2-butanol tert-butanol ethanol 1-propanol ~ 1-butanol 2-propanol 2-butanol ~ 2-pentanol, which correlates well with the alcohol dehydrogenation activity. In ethanol, 1-propanol, 2-propanol and 2-pentanol, furfuryl alcohol hydrogenolysis to methyl furan is significantly retarded at low temperatures due to furfuryl alcohol etherification with the corresponding alcohol solvent. We find that methyl furan yield decreases with increasing alcohol polarity. An optimum methyl furan yield of 76% is attained after 10 h of reaction at 180 °C, using 2-butanol and 2-pentanol as hydrogen donors. This is the highest reported yield in the liquid phase at temperatures below 200 °C.
- Panagiotopoulou, Paraskevi,Martin, Nickolas,Vlachos, Dionisios G.
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- Flash vacuum pyrolysis of 2-diazo-8-oxabicyclo[3.2.1]oct-6-en-3-ones. A new method for the preparation of propadienones
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When diazoketones 3a and 3b are pyrolysed at 430°C and 10-4 torr, they undergo loss of N2 followed by Wolff rearrangement and loss of furan by retro Diels-Alder reaction to yield the desired propadienones 1(a,b). If argon is added to the pyrolysate mixture, these reactive compounds can be trapped under matrix isolation conditions at 22 K and observed by FTIR. Upon photolysis, 1b yields carbon monoxide and 2-butyne.
- Brahms,Dailey
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- TERTIARY BUTYLATION OF FIVE MEMBERED HETEROCYCLES. A UPS STUDY
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The reaction of 2-chloromercuryfuran and t-butylbromide was studied by UV photoelectron spectroscopy.During the reaction the formation of t-butylfuran, 2,5-di-t-butylfuran, t-butylchloride, isobutylene and furan were found.In accordance with the experimental observations a novel reaction mechanism has been proposed.The first fast and the second slow step of the reaction has been interpreted.The corresponding thiophene derivative gave similar results.
- Nyulaszi, L.,Gyuricza, A.,Veszpremi, T.
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- Visible light induced enhanced photocatalytic degradation of organic pollutants in aqueous media using Ag doped hollow TiO2 nanospheres
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The silver doped hollow TiO2 (Ag-h-TiO2) nanoparticles were synthesized by a sacrificial core (AgBr) method. The Ag doping and the core removal was done simultaneously during the dissolution of the core in (NH4)OH solution. The mean particle size of synthesized Ag-h-TiO2 nanoparticles is 17.76 ± 2.85 nm with a wall thickness of ~2.5 nm. The hollow structured nanoparticles have 103.2 m2 g-1 more specific surface area compared to solid TiO2 nanoparticles. The suitability of these synthesized hollow nanoparticles as photocatalyst were tested for the photocatalytic degradation of three important different classes of organic compounds such as nitrobenzene (NB), metronidazole (MTZ) antibiotic, and methylene blue dye (MBD) in aqueous solution under irradiation of visible light. Photodegradation studies show there is a significant enhancement of the degradation efficiency of the TiO2 after the hollow structure formation and silver doping. The recycling tests of the catalysts show only ~10% decrease in efficiency for NB and MTZ degradation after sixth cycle of reuse. The light emission capacity in terms of quantum yield (QY) is enhanced by 18.7% for Ag-h-TiO2 than that of pure TiO2 nanoparticles.
- Boxi, Siddhartha Sankar,Paria, Santanu
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- Carbon efficiency and the surface chemistry of the actinides: Direct formation of furan from acetylene over β-UO3
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Uranium oxide is a very good catalyst for oxidation reactions, and bare U atoms are very active for carbon-carbon coupling reactions. The direct oxidative coupling of two molecules of acetylene to furan (C4H4O) over the surface of pure polycrystalline β-UO3 was presented. For comparison, only traces of furan were formed over α-U3O8 and none on UO2 surfaces. Comparison to the reactions of other C2 compounds (ethanol, acetaldehyde, and ethylene) over β-UO3 showed the presence of two routes for making furan from C2 compounds, i.e., via aldolization and via oxidative coupling.
- Idriss,Madhavaram
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- INFRARED STUDY OF CROTONALDEHYDE OXIDATION BY 12-MOLYBDOPHOSPHORIC ACID
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IR spectra of H3PMo12O40 (HPA) with adsorbed crotonaldehyde disclosed that HPA is reduced by crotonaldehyde only in the presence of water, giving furan as the oxidation product.Water is evidentially involved in the reaction path of crotonaldehyde oxidation, being consistent with water-enhanced catalytic oxidation of crotonaldehyde on HPA.
- Tsai, Thian-hsi,Maruya, Ken-ichi,Ai, Mamooru,Ozaki, Atsumu
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- Ex situ catalytic upgrading of lignocellulosic biomass components over vanadium contained H-MCM-41 catalysts
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H-V-MCM-41 catalysts containing 5, 10, and 30 wt% of vanadium were synthesized and applied to the ex situ catalytic pyrolysis (CP) of three polymeric components of lignocellulosic biomass for the first time. Characterization of the catalysts was performed using N2 adsorption-desorption, XRD, FT-IR, and NH3-TPD. The results of XRD analysis showed that 5 wt% and 10 wt% H-V-MCM-41 catalysts maintained the mesoporous structure, whereas the mesoporous structure was destroyed in 30 wt% H-V-MCM-41 with considerable amount of small V2O5 crystalline outside the framework. NH3-TPD showed that H-V-MCM-41 has mostly weak acid sites and that 10 wt% H-V-MCM-41 had the largest quantity of acid sites due to framework vanadium. In the case of CP of cellulose using Py-GC/MS, 10 wt% H-V-MCM-41 showed the highest catalytic activity for the production of valuable furanic compounds such as furfural because of the enhanced deoxygenation over the acid sites formed on framework vanadium. In the case of CP of xylan as well, 10 wt% H-V-MCM-41 led to the largest yield of mono-aromatics. The production of acetic acid was also promoted by H-V-MCM-41 catalysts. The CP of lignin over H-V-MCM-41 catalysts promoted substantially the production of important feedstock chemicals for the petrochemical industry: phenolics and mono-aromatics.
- Kim, Beom-Sik,Jeong, Chang Seok,Kim, Ji Man,Park, Su Bin,Park, Sung Hoon,Jeon, Jong-Ki,Jung, Sang-Chul,Kim, Sang Chai,Park, Young-Kwon
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- AN IMPROVED METHOD TO PREPARE CATALYSTS FOR THE SELECTIVE DECARBONYLATION OF FURAN-2 CARBOXALDEHYDE INTO FURAN
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We are able to produce pure furan and pure carbon monoxide from furan-2 carboxaldehyde using an improved catalyst.This new catalyst (Pd/C-K2CO3) is activated by UV irradiation at 254 nm for 1 h.
- Lejemble, Philippe,Maire, Yolande,Gaset, Antoine,Kalck, Philippe
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- Study on the reaction pathway in decarbonylation of biomass-derived 5-hydroxymethylfurfural over Pd-based catalyst
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An extensive product distribution is firstly examined in the process of 5-hydroxymethylfurfural (HMF) decarbonylation over Pd-based catalysts and some interesting results are obtained. The main side reactions are due to the high activity of the furan ring-branched hydroxymethyl, which could go through hydrogenolysis, dehydrogenation and etherification. The H2 source was carefully explored and determined to be the hydroxymethyl dehydrogenation. The reactivity of the main intermediates was separately investigated and their evolution pathway was obtained. Noticeably, it is demonstrated that the elimination of the furanic ring-branched hydroxymethyl (in HMF or furfuryl alcohol) is completed by sequential dehydrogenation and decarbonylation via the intermediate of aldehyde (2, 5-diformylfuran or furfural). A comprehensive reaction pathway for HMF decarbonylation is proposed, which is significant for designing highly selective decarbonylation catalysts.
- Meng, Qingwei,Zheng, Hongyan,Zhu, Yulei,Li, Yongwang
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- Thermolysis Improvements in Retro-Diels-Alder Reactions of Benzylamino Alcohols under Microwave Irradiation
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Microwave activation under solvent-free conditions is shown to be the best procedure for performing retro-Diels-Alder reactions.
- Bortolussi, Michel,Bloch, Robert,Loupy, Andre
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- Study of the vacuum pyrolysis of 11-oxatricyclo[6.2.1.02,7]undeca-2,9-diene. The HeI ultraviolet photoelectron spectrum of 1,2-cyclohexadiene
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A newly developed ultraviolet photoelectron spectrometer - CO2 laser apparatus that utilizes a 50-watt CW CO2 laser as a directed heat source is used to study the vacuum pyrolysis of 11-oxatricyclo[6.2.1.02.7]undeca-2,9-diene (4). We report the HeI photoelectron spectrum of the strained cyclic allene 1,2-cyclohexadiene (1) that correlates with the HAM/3 ionization energies calculated with the optimized C2 equilibrium structure obtained with AM1 and the molecular orbital energies of the optimized C2 equilibrium structure calculated at the ab initio HF/6-31G** level of theory.
- Werstiuk,Roy,Ma
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- Sustainable hydrocarbon production via simultaneous condensation-hydrodeoxygenation of propionic acid with furfural over red mud-supported noble metal catalysts
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A new catalytic system for single-step alkane synthesis from furans and carboxylic acids was investigated using noble metals-supported red mud (RM) catalysts. Maximum alkane selectivities were 100%, 87%, and 56% over Pt/RM, Pd/RM, and Ru/RM respectively. Potassium doping prolonged the catalyst life by suppressing methanation reaction, decreased coking, and enhancing the stability of noble metals towards oxidation. Five functionalities were accomplished on the modified catalysts: partial reduction of propionic acid on noble metals; moderating coking reactions on K, suppressing methanation on K, ketonization of acid on RM, and condensation-hydrodeoxygenation reaction on RM. Magnetite played significant role in catalyzing ketonization reaction.
- Castille, Antonie,Bessette, Claudie,Thomas, Francois,Etemad, Mania
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- Hydroprocessing of furfural over in situ generated nickel phosphide based catalysts in different solvents
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The present work is dedicated to the nickel phosphide based catalysts, containing particles, generated in situ in the reaction medium from the different catalytic systems. The present catalytic systems exhibited high activity in the hydroprocessing of furfural. Full conversion of furfural depending on conditions was reached after 0.5?3 hours of reaction at 250?350 °C. 2-methylfuran was obtained as a main product in toluene with the highest selectivity of 77 %. Ethyl levulinate and 2-methylfuran with selectivity of 40 % and 38 % respectively were obtained as main products in ethanol under different conditions. Different reaction medium and nickel phosphide precursors had an influence on the obtained phases of catalysts. Ni12P5 and Ni2P were obtained in toluene from oil-soluble precursors and Ni12P5 was obtained in ethanol from water-soluble precursors.
- Golubeva, Maria A.,Maximov, Anton L.
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- Promotional effect of Fe on the performance of supported Cu catalyst for ambient pressure hydrogenation of furfural
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A noble-metal free FeCu based bimetallic catalyst system prepared by facile co-impregnation method was found to be highly admirable for vapour phase selective hydrogenation of furfural to furfuryl alcohol at ambient pressure. Monometallic Cu/γ-Al2O3, Fe/γ-Al2O3 and bimetallic FeCu/γ-Al2O3 catalysts with different Fe loadings were prepared. Structural and morphological features of the catalysts were thoroughly investigated by several physico-chemical characterization techniques. The influence of various reaction parameters, such as Fe loading, reaction temperature and flow of reactants was examined with respect to furfural conversion and furfuryl alcohol yield. The results clearly showed that an optimum amount of Fe is necessary to enhance the catalytic activity of monometallic Cu/γ-Al2O3 for the selective hydrogenation of furfural. The catalyst FC-10 with 10 wt% Fe exhibited excellent activity which led to high furfural conversion (>93%) and furfuryl alcohol selectivity (>98%) under mild reaction conditions. The higher activity of bimetallic FeCu/γ-Al2O3 compared to monometallic Cu/γ-Al2O3 is ascribed to the formation of FeCu bimetallic particles and the existence of oxygen vacancies in the Fe oxide system. The superior activity after Fe loading on the Cu-based catalyst was attributed to the synergy between Cu and Fe. A plausible mechanism is proposed to explain the promoting effect of Fe, which involves synergism between Fe sites with strong oxophilic nature and Cu sites with a high ability for hydrogen activation. Based on the activity results, prolonged catalytic activity and spent catalyst analysis, the developed FeCu/γ-Al2O3 catalyst is inexpensive, eco-benign and robust, which makes it a promising candidate for the efficient conversion of biomass-derived substrates to fine chemicals and drop-in biofuels.
- Manikandan, Marimuthu,Venugopal, Ashok Kumar,Nagpure, Atul S.,Chilukuri, Satyanarayana,Raja, Thirumalaiswamy
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- Unusual hydroxyl effect on fulvene endoperoxide decompositions
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The thermal decomposition of fulvene endoperoxides ordinarily proceeds via an allene oxide intermediate affording oxepin-2(3H)-one derivatives. We have now uncovered new, unusual pathways in these decompositions where the presence of a hydroxyl group on the alkyl or aryl attached to the fulvene exocyclic double bond has a profound effect on the fate of the reactive intermediates derived from the unstable endoperoxides. Computational work supports the proposed mechanistic pathways.
- Erden, Ihsan,Basada, John,Poli, Daniela,Cabrera, Gabriel,Xu, Fupei,Gronert, Scott
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- Infrared Multiphoton Dissociation in Two-Channel Systems. Pulse-Duration Effects
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Both ethyl vinyl ether (EVE) and dihydrofuran (DHF) dissociate by two reaction channels which differ by ca. 25 kcal mol-1 in activation energies.In DHF, the branching ratio between these channels produced by IR-multiphoton-induced dissociation shows no power dependence, by contrast to previous work with EVE.In view of the similarity of the Arrhenius activation parameters in the two systems, this is surprising.Therefore, a comparison of peak-power dependence of the branching ratio in the two systems has been studied at hνCO2 = 1076 cm-1 where the average energy absorbed is the same in both molecules.Results on the power dependence of branching ratio and yield suggest that differences in absorption coefficients (pumping rates) in the quasicontinuum may account for the differences in power dependence.
- Brenner, D. M.
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- Selective aqueous-phase hydrogenation of furfural to cyclopentanol over PdRu/C catalyst
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The bimetallic PdRu catalyst supported on carbon nanotubes were found ot provide an efficient synthesis of cyclopentanol in aqueous-phase hydrogenation of furfural. Under the chosen reaction conditions (temperature of 473 K, total pressure of 8 MPa), the selectivity towards cyclopentanol reaches 77% at a complete conversion of furfural. A high activity of this catalyst can be associated with changes in the electronic state and dispersion of the supported metals caused by their mutual interaction and formation of PdRu alloy.
- Mironenko,Belskaya,Lavrenov,Likholobov
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- Concurrent formation of furan-2,5- and furan-2,4-dicarboxylic acid: Unexpected aspects of the Henkel reaction
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The concurrent formation of furan-2,5- and furan-2,4-dicarboxylic acid under solvent free conditions via a disproportionation reaction is described. By reacting potassium-2-furoate at 260 °C in the presence of 22 mol% of (Lewis acidic) catalysts like CdI2 or ZnCl2, potassium-2-furoate is disproportionated to furan and furandicarboxylic acids. Besides furan and furan-2,5-dicarboxylic acid (2,5-FDCA) as the main products, furan-2,4-dicarboxylic acid (2,4-FDCA) is also formed as a by-product. Experimental evidence has been obtained that, under the reaction conditions applied, 2,5-FDCA and 2,4-FDCA are formed by separate reaction pathways. Selectivity towards the different FDCA isomers is affected by the type of catalyst used. Single-crystal X-ray analysis shows that 2,4-FDCA has a more 'linear' character compared to 2,5-FDCA and hence is structurally more comparable to terephthalic acid (TA), making it an interesting monomer for synthetic polyesters.
- Thiyagarajan, Shanmugam,Pukin, Aliaksei,Van Haveren, Jacco,Lutz, Martin,Van Es, Daan S.
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- Biomass to drugs: Green production of salicylic acid from 2-furoic acid in two steps
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Salicylic acid, generally produced by chemical synthesis based on petrochemical products, is a vital organic acid and widely used in the pharmaceutical synthesis. This work developed a new and green route for the production of salicylic acid from biomass-derived 2-furoic acid in two steps. Firstly, 2 mmol 2-furoic acid was creatively converted to 2,3-benzofuran using HZSM-5 (Si/Al=130) at 280 °C for 1.5 h under 100 psi N2; and then the oxidation of 2,3-benzofuran to salicylate was conducted with tert?butyl hydroperoxide under basic condition without metal catalyst at 120 °C for 1 h. The stability of the catalyst for the first step and the possible reaction pathway for the second step based on the control experiments was properly envisioned. Regardless of limited salicylic acid yield (16%) from 2-furoic acid, this work paves a potentially feasible pathway for the preparation of drugs from biomass.
- Jiang, Jun,Li, Teng,Sun, Guangyu,Wang, Yantao,Xiong, Lu,Yang, Weiran,Yu, Pengxin,Zheng, Boying
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- Interfacial effect of Pd supported on mesoporous oxide for catalytic furfural hydrogenation
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Highly dispersed Pd is loaded onto different types of mesoporous oxide supports to investigate the synergetic metal-support effect in catalytic furfural (FAL) hydrogenation. Ordered mesoporous Co3O4, MnO2, NiO, CeO2, and Fe2O3 are prepared by the nanocasting and the supported Pd on mesoporous oxide catalysts are obtained by the chemical reduction method. It is revealed that mesoporous oxides play an important role on Pd dispersion as well as the redox behavior of Pd, which determines the final FAL conversion. Among the catalysts used, Pd/Co3O4 shows the highest conversion in FAL hydrogenation and distinct product selectivity toward 2-methylfuran (MF). While FAL is converted via two distinct pathways to produce either furfuryl alcohol (FA) via aldehyde hydrogenation or MF via hydrogenolysis, MF as a secondary product is derived from FA via the hydrogenolysis of C–O over the Pd/Co3O4 catalyst. It is revealed that FAL is hydrogenated to FA preferentially on the Pd surface; then the secondary hydrogenolysis to MF from FA is further promoted at the interface between Pd and Co3O4. We confirm that the reaction pathway over Pd/Co3O4 is totally different from other catalysts such as Pd/MnO2, which produces FA dominantly. The characteristics of the mesoporous oxides influence the Pd-oxide interfaces, which determine the activity and selectivity in FAL hydrogenation.
- Lee, Hojeong,Nguyen-Huy, Chinh,Jeong Jang, Eun,Lee, Jihyeon,Yang, Euiseob,Lee, Man Sig,Kwak, Ja Hun,An, Kwangjin
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p. 291 - 300
(2020/03/05)
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- Furfural hydrodeoxygenation (HDO) over silica-supported metal phosphides – The influence of metal–phosphorus stoichiometry on catalytic properties
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The gas-phase hydrodeoxygenation (HDO) of furfural, a model compound for bio-based conversion, was investigated over transition metal phosphide catalysts. The HDO activity decreases in the order Ni2P ≈ MoP > Co2P ≈ WP ? Cu3P > Fe2P. Nickel phosphide phases (e.g., Ni2P, Ni12P5, Ni3P) are the most promising catalysts in the furfural HDO. Their selectivity to the gasoline additives 2-methylfuran and tetrahydro-2-methylfuran can be adjusted by varying the P/Ni ratio. The effect of P on catalyst properties as well as on the reaction mechanism of furfural HDO were investigated in depth for the first time. An increase of the P stoichiometry weakens the furan-ring/catalyst interaction, which contributes to a lower ring-opening and ring-hydrogenation activity. On the other hand, an increasing P content does lead to a stronger carbonyl/catalyst interaction, i.e., to a stronger η2(C, O) adsorption configuration, which weakens the C1[sbnd]O1 bond (Scheme 1) in the carbonyl group and enhances the carbonyl conversion. Phosphorus species can also act as Br?nsted acid sites promoting C1[sbnd]O1 (Scheme 1) hydrogenolysis of furfuryl alcohol, hence contributing to higher production of 2-methylfuran.
- Lan, Xuefang,Pestman, Robert,Hensen, Emiel J.M.,Weber, Thomas
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p. 181 - 193
(2021/02/27)
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- Heterolytic Oxidative Addition of sp2and sp3C-H Bonds by Metal-Ligand Cooperation with an Electron-Deficient Cyclopentadienone Iridium Complex
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Oxidative addition reactions of C-H bonds that generate metal-carbon-bond-containing reactive intermediates have played essential roles in the field of organometallic chemistry. Herein, we prepared a cyclopentadienone iridium(I) complex 1 designed for oxidative C-H bond additions. The complex cleaves the various sp2 and sp3 C-H bonds including those in hexane and methane as inferred from their H/D exchange reactions. The hydroxycyclopentadienyl(nitromethyl)iridium(III) complex 2 was formed when the complex was treated with nitromethane, which highlights this elementary metal-ligand cooperative C-H bond oxidative addition reaction. Mechanistic investigations suggested the C-H bond cleavage is mediated by polar functional groups in substrates or another iridium complex. We found that ligands that are more electron-deficient lead to more favorable reactions, in sharp contrast to classical metal-centered oxidative additions. This trend is in good agreement with the proposed mechanism, in which C-H bond cleavage is accompanied by two-electron transfer from the metal center to the cyclopentadienone ligand. The complex was further applied to catalytic transfer-dehydrogenation of tetrahydrofuran (THF).
- Higashi, Takuya,Kusumoto, Shuhei,Nozaki, Kyoko
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supporting information
p. 12999 - 13004
(2021/08/16)
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- Transition-metal-free decarboxylation of D-glucaric acid to furan catalyzed by SnCl4 in a biphasic system
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As a useful chemical, furan can be produced from bio-based chemicals, such as furfural and furoic acid (FA). There were few reports on the preparation of furan from bio-based C6 aldaric acids. Herein, a new method was developed to produce furan from D-glucaric acid (GA) without transition metals, and nearly 80% yield of furan was produced in the water/toluene biphasic system with SnCl4 at 200 °C in 2 h. 3-Hydroxy-2-pyrone (3-HP) and FA were proved to be the key intermediates in the formation of furan from GA, and the reaction pathway was proposed to be GA→ 3-HP→ FA→ furan based on the kinetic study, model substrate reaction, and isotope labeling experiments. SnCl4 gave the highest furan yield among the common acid catalysts, and the contrast experiments suggested that H+, Cl? and Sn4+ all have promoting effect on GA conversion to furan. This method was also applicable with other C6 aldaric acids.
- Duan, Yaqi,Jiang, Jun,Li, Teng,Sun, Guangyu,Wang, Yantao,Xiong, Lu,Yang, Weiran,Yu, Rui,Zheng, Boying
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- H2-Free Selective Dehydroxymethylation of Primary Alcohols over Palladium Nanoparticle Catalysts
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The dehydroxymethylation of primary alcohols is a promising strategy to transform biomass-derived oxygenates into hydrocarbon fuels. In this study, a novel, highly efficient, and reusable heterogeneous catalyst system was established for the H2-free dehydroxymethylation of primary alcohol using cerium oxide-supported palladium nanoparticles (Pd/CeO2). A wide range of aliphatic and aromatic alcohols including biomass-derived alcohols were converted into the corresponding one-carbon shorter hydrocarbons in high yields in the absence of any additives, accompanied by the production of H2 and CO. Pd/CeO2 was easily recovered from the reaction mixture and reused, retaining its high activity, thus, providing a simple and sustainable methodology to produce hydrocarbon fuels from biomass-derived oxygenates.
- Yamaguchi, Sho,Kondo, Hiroki,Uesugi, Kohei,Sakoda, Katsumasa,Jitsukawa, Koichiro,Mitsudome, Takato,Mizugaki, Tomoo
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p. 1135 - 1139
(2020/12/29)
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- Microwave-Assisted Decarbonylation of Biomass-Derived Aldehydes using Pd-Doped Hydrotalcites
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Catalytic decarbonylation is an underexplored strategy for deoxygenation of biomass-derived aldehydes owing to a lack of low-cost and robust heterogeneous catalysts that can operate in benign solvents. A family of Pd-functionalized hydrotalcites (Pd-HTs) were synthesized, characterized, and applied to the decarbonylation of furfural, 5-hydroxymethylfurfural (HMF), and aromatic and aliphatic aldehydes under microwave conditions. This catalytic system delivered enhanced decarbonylation yields and turnover frequencies, even at a low Pd loading (0.5 mol %). Furfural decarbonylation was optimized in a benign solvent (ethanol) compatible with biomass processing; HMF selectively afforded an excellent yield (93 %) of furfuryl alcohol without humin formation; however, a longer reaction favored the formation of furan through tandem alcohol dehydrogenation and decarbonylation. Yields of the substituted benzaldehydes (37–99 %) were proportional to the calculated Mulliken charge of the carbonyl carbon. Activity and selectivity reflected loading-dependent Pd speciation. Continuous-flow testing of the best Pd-HT catalyst delivered good stability over 16 h on stream, with near-quantitative conversion of HMF.
- An, Nan,Ainembabazi, Diana,Reid, Christopher,Samudrala, Kavya,Wilson, Karen,Lee, Adam F.,Voutchkova-Kostal, Adelina
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p. 312 - 320
(2019/11/13)
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- Structural evolution of ZIF-67-derived catalysts for furfural hydrogenation
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Zeolitic imidazolate framework-67 (ZIF-67) can be converted to metallic Co nanoparticles supported on N-doped carbon (Co/NC) through reduction. However, its unique properties, including extremely high surface area, isoreticular pore structure, and regular metal–organic network, disappear after high-temperature (>500 °C) reduction. Aggregated CoOx particles reduce the number of surface-active sites, resulting in poor catalytic activity. If the original ZIF-67 structure is maintained after the high-temperature reduction, promoting the uniform distribution of active sites in the porous carbon, the catalytic performance can be further improved. Herein, the correlation between the catalytic furfural hydrogenation performance, Co/NC morphology, and oxidation state of Co was investigated as a function of the H2 reduction temperature and time. The reduction of ZIF-67 at 400 °C for 6 h yields a highly dispersed Co/NC catalyst, while preserving the overall morphology. The resulting Co/NC-400-6 catalyst exhibits the highest activity, promoting high selectivity toward 2-methylfuran. The product selectivity can be further altered by incorporating Cu into ZIF-67 to produce furfuryl alcohol. With proper H2 treatment to minimize the damage to the intrinsic surface area and pore structure, metal–organic frameworks can be utilized as high-performance heterogeneous catalysts by maximizing the distribution of active sites.
- An, Kwangjin,Lee, Jae Hwa,Lee, Jun Gyeong,Moon, Hoi Ri,Song, Kyung,Yang, Euiseob,Yoon, Sinmyung
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p. 302 - 312
(2020/11/20)
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- Chromium-free Cu?Mg/γ-Al2O3-an active catalyst for selective hydrogenation of furfural to furfuryl alcohol
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Development of a chromium (Cr)-free hydrogenation catalyst is very important to replace the existing hazardous Cr based catalyst used in the furfural hydrogenation to furfuryl alcohol. Herein, we report synthesis of well-dispersed copper nanoparticles supported on hydrothermally stable magnesium doped alumina (Cu?Mg/γ-Al2O3) for selective hydrogenation of furfural to furfuryl alcohol. The prepared catalyst was characterized by X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES), Powder X-ray Diffraction (PXRD), Surface Area Analysis (SAA), High Resolution-Transmission Electron Microscopy (HR-TEM), Temperature Programmed Reduction/Desorption (TPR/TPD) and Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) to understand textural properties of the catalyst. The prepared catalyst was found to be highly active and selective with 99% conversion of furfural and 94% selectivity for furfuryl alcohol under solvent free conditions at 443.15 K and 2 MPa of hydrogen pressure. It was also observed that the Cu?Mg/γ-Al2O3 catalyst is reusable (up to six runs) while maintaining its high activity and selectivity (≥94%) in the hydrogenation of furfural to furfuryl alcohol. This journal is
- Arundhathi, Racha,Newalkar, Bharat L.,Reddy, Panyala Linga,Samanta, Chanchal
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p. 41120 - 41126
(2020/11/23)
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- Integrating Biomass into the Organonitrogen Chemical Supply Chain: Production of Pyrrole and d-Proline from Furfural
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Production of renewable, high-value N-containing chemicals from lignocellulose will expand product diversity and increase the economic competitiveness of the biorefinery. Herein, we report a single-step conversion of furfural to pyrrole in 75 % yield as a key N-containing building block, achieved via tandem decarbonylation–amination reactions over tailor-designed Pd?S-1 and H-beta zeolite catalytic system. Pyrrole was further transformed into dl-proline in two steps following carboxylation with CO2 and hydrogenation over Rh/C catalyst. After treating with Escherichia coli, valuable d-proline was obtained in theoretically maximum yield (50 %) bearing 99 % ee. The report here establishes a route bridging commercial commodity feedstock from biomass with high-value organonitrogen chemicals through pyrrole as a hub molecule.
- Di, Lu,Fung Kin Yuen, Vincent,Song, Song,Sun, Qiming,Yan, Ning,Zhou, Kang
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supporting information
p. 19846 - 19850
(2020/09/02)
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- Nickel-Catalyzed Electrosynthesis of Aryl and Vinyl Phosphinates
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A mild and useful nickel-catalyzed electrochemical phosphonylation of aryl and vinyl bromides is described. We show that alkyl H-phenylphosphinates can be coupled electrochemically with functionalized aryl and vinyl bromides using very simple conditions (Fe/Ni anode, bench-stable nickel pre-catalyst, undivided cell, galvanostatic electrolysis) to furnish the corresponding aryl and vinyl phosphinates in satisfactory to good yields. Couplings can also be applied to heteroaromatic bromides with some limitations like increased propensity to hydro-dehalogenation.
- Daili, Farah,Ouarti, Abdelhakim,Pinaud, Marine,Kribii, Ibtihal,Sengmany, Stéphane,Le Gall, Erwan,Léonel, Eric
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supporting information
p. 3452 - 3455
(2020/05/25)
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- Efficient one-pot conversion of furfural into 2-methyltetrahydrofuran using non-precious metal catalysts
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2-methyltetrahydrofuran, a biomass-derived chemical, is an important solvent with broad applications in organic chemistry. In this study, one-pot conversion of furfural into 2-methyltetrahydrofuran over non-precious metal catalysts was achieved by two-stage packing in a single reactor. The first stage converted furfural into 2-methylfuran over Co-based catalysts, and the second stage converted 2-methylfuran into 2-methyltetrahydrofuran over Ni-based catalysts. In order to reveal the reaction pathway and mechanism of this process, the hydrogenation reactions of 2-methylfuran, furfuryl alcohol, and tetrahydrofurfuryl alcohol were also carefully investigated. It is discovered that the conversion of furfural into 2-methylfuran could be catalyzed by Lewis acid sites, which was confirmed by a correlation between 2-methylfuran production rate and Lewis acid site density. Also, a mechanism on the direct conversion of furfural into 2-methylfuran without forming furfuryl alcohol as the intermediate is proposed. The experimental results of 2-methylfuran, furfuryl alcohol, and tetrahydrofurfuryl alcohol hydrogenation/hydrodeoxygenation over various catalysts provided valuable information on the future design of 2-methyltetrahydrofuran catalyst.
- Jia, Xinxin,Li, Cuiqing,Liu, Ping,Song, Yongji,Sun, Luyang,Wang, Hong,Zhang, Chen,Zhang, Wei
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- GREEN, COPPER-CATALYZED DISPROPORTIONATION OF AROMATIC AND HETEROAROMATIC CARBOXYLATES TO DICARBOXYLATES
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The present application relates to a process for preparation of a compound of Formula (I) and Formula (IV): wherein is as described herein; and wherein and R are as described herein.
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Paragraph 0121
(2020/06/08)
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- Synthesis of thioethers, arenes and arylated benzoxazoles by transformation of the C(aryl)-C bond of aryl alcohols
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Transformation of aryl alcohols into high-value functionalized aromatic compounds by selective cleavage and functionalization of the C(aryl)-C(OH) bond is of crucial importance, but very challenging by far. Herein, for the first time, we report a novel and versatile strategy for activation and functionalization of C(aryl)-C(OH) bonds by the cooperation of oxygenation and decarboxylative functionalization. A diverse range of aryl alcohol substrates were employed as arylation reagents via the cleavage of C(aryl)-C(OH) bonds and effectively converted into corresponding thioether, arene, and arylated benzoxazole products in excellent yields, in a Cu based catalytic system using O2 as the oxidant. This study offers a new way for aryl alcohol conversion and potentially offers a new opportunity to produce high-value functionalized aromatics from renewable feedstocks such as lignin which features abundant C(aryl)-C(OH) bonds in its linkages.
- Chen, Bingfeng,Han, Buxing,Liu, Mingyang,Meng, Qinglei,Song, Jinliang,Zhang, Pei,Zhang, Zhanrong
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p. 7634 - 7640
(2020/08/14)
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- METHOD FOR THE HYDRODEOXYGENATION OF OXYGENATED COMPOUNDS TO UNSATURATED PRODUCTS
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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 12-13
(2021/01/23)
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- N,N,O-Coordinated tricarbonylrhenium precatalysts for the aerobic deoxydehydration of diols and polyols
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Rhenium complexes are well known catalysts for the deoxydehydration (DODH) of vicinal diols (glycols). In this work, we report on the DODH of diols and biomass-derived polyols using L4Re(CO)3as precatalyst (L4Re(CO)3= tricarbonylrhenium 2,4-di-tert-butyl-6-(((2-(dimethylamino)ethyl)(methyl)amino)methyl)phenolate). The DODH reaction was optimized using 2 mol% of L4Re(CO)3as precatalyst and 3-octanol as both reductant and solvent under aerobic conditions, generating the active high-valent rhenium speciesin situ. Both diol and biomass-based polyol substrates could be applied in this system to form the corresponding olefins with moderate to high yield. Typical features of this aerobic DODH system include a low tendency for the isomerization of aliphatic external olefin products to internal olefins, a high butadiene selectivity in the DODH of erythritol, the preferential formation of 2-vinylfuran from sugar substrates, and an overall low precatalyst loading. Several of these features indicate the formation of an active species that is different from the species formed in DODH by rhenium-trioxo catalysts. Overall, the bench-top stable and synthetically easily accessible, low-valent NNO-rhenium complex L4Re(CO)3represents an interesting alternative to high-valent rhenium catalysts in DODH chemistry.
- Klein Gebbink, Robertus J. M.,Li, Jing,Lutz, Martin
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p. 3782 - 3788
(2020/06/22)
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- Method and System for Hybrid Catalytic Biorefining of Biomass to Methylated Furans and Depolymerized Technical Lignin
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A method is disclosed for converting biomass into a fuel additive, the method comprising: liquefying the biomass to form a liquor; neutralizing the liquor; precipitating lignin out of the liquor; extracting furfural (FF) and 5-hydroxymethylfurfural (HMF) from the liquor; and hydrodeoxygenating (HDO) the extracted furfurals over a Cu—Ni/TiO2 catalyst. The catalyst for hydrodeoxygenating (HDO) furfural (FF) and 5-hydroxymethylfurfural (HMF) to methylated furans comprises copper-nickel (Cu—Ni) particles supported on titanium dioxide (TiO2), and wherein the copper-nickel particles form core-shell structures in which copper (Cu) is enriched at a surface of the catalyst.
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- Highly Electrophilic Titania Hole as a Versatile and Efficient Photochemical Free Radical Source
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Photogenerated holes in nanometric semiconductors, such as TiO2, constitute remarkable powerful electrophilic centers, capable of capturing an electron from numerous donors such as ethers, or nonactivated substrates like toluene or acetonitrile, and constitute an exceptionally clean and efficient source of free radicals. In contrast with typical free radical precursors, semiconductors generate single radicals (rather than pairs), where the precursors can be readily removed by filtration or centrifugation after use, thus making it a convenient tool in organic chemistry. The process can be described as an example of dystonic proton coupled electron transfer.
- Hainer, Andrew,Marina, Nancy,Rincon, Stefanie,Costa, Paolo,Lanterna, Anabel E.,Scaiano, Juan C.
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supporting information
p. 4531 - 4535
(2019/03/19)
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- Ruthenium(II) Porphyrin Quinoid Carbene Complexes: Synthesis, Crystal Structure, and Reactivity toward Carbene Transfer and Hydrogen Atom Transfer Reactions
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Reactivity study of novel metal carbene complexes can offer new opportunities in catalytic carbene transfer reactions as well as in other synthetic protocols. Metal complexes with quinoid carbene (QC) ligands are assumed to be key intermediates in a variety of metal-catalyzed QC transfer reactions using diazo quinones, which demands development of the chemistry of QC transfer of well characterized metal-QC complexes. Herein we report the isolation and QC transfer of ruthenium porphyrins [Ru(Por)(QC)] which contribute the first examples of (i) structurally characterized metal-QC complex (by X-ray crystallography) and (ii) isolated metal-QC complex that undergoes QC transfer reaction. The complexes [Ru(Por)(QC)] were prepared from reaction of [Ru(Por)(CO)] with diazo quinones and exhibited dual reactivity, i.e., hydrogen atom transfer (HAT) as well as QC transfer. The stoichiometric QC transfer reactions from these Ru-QC complexes to nitrosoarenes (ArNO) afforded nitrones in up to 90% yield, and the corresponding catalytic reactions were also developed. Both the stoichiometric and catalytic reactions for a series of QC ligands bearing electron-donating and -withdrawing substituents showed a reverse substituent effect on the QC transfer reactivity. Complexes [Ru(Por)(QC)] are also reactive toward C-H and X-H (X = N, S) bonds and can catalyze aerobic oxidation of 1,4-cyclohexadiene; their stoichiometric HAT reactions with unsaturated hydrocarbons gave product yields of up to 88%. The unique dual reactivity and electronic feature of [Ru(Por)(QC)] were studied by spectroscopic means and density functional theory (DFT) calculations.
- Wang, Hai-Xu,Wan, Qingyun,Wu, Kai,Low, Kam-Hung,Yang, Chen,Zhou, Cong-Ying,Huang, Jie-Sheng,Che, Chi-Ming
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supporting information
p. 9027 - 9046
(2019/06/13)
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- Importance of Zeolite Wettability for Selective Hydrogenation of Furfural over Pd@Zeolite Catalysts
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The metal-catalyzed selective hydrogenation of biomass-derived molecules is in great demand but is challenging due to the complex reaction pathways. Herein, we report a persuasive example for achieving selective hydrogenation of furfural over Pd catalysts by controllable sorption of molecules in zeolite micropores. The key to this success is fixation of Pd nanoparticles inside of silicalite-1 zeolite with controllable wettability (Pd@S-1-OH) by functionalizing silanol groups into the zeolite framework. In the hydrogenation of furfural as a model reaction, the Pd@S-1-OH catalyst with appropriate hydrophilicity exhibits extraordinary selectivity for the formation of furan, giving furan selectivity as high as >99.9% with a complete conversion of furfural, outperforming the conventional Pd nanoparticles supported on zeolite crystals (Pd/S-1) and S-1 zeolite fixed Pd catalysts without an artificially functionalized silanol group (Pd@S-1). The extraordinary performance of Pd@S-1-OH is reasonably attributed to the controllable diffusion of molecules within the hydrophilic zeolite micropores, which favors the adsorption of furfural and a series of byproducts but promotes the desorption of furan. Very importantly, Pd@S-1-OH is stable and gives the furan productivity of ~583.3 g gPd-1 day-1 in a continuous test.
- Wang, Chengtao,Liu, Zhiqiang,Wang, Liang,Dong, Xue,Zhang, Jian,Wang, Guoxiong,Han, Shichao,Meng, Xiangju,Zheng, Anmin,Xiao, Feng-Shou
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p. 474 - 481
(2018/01/17)
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- Accelerated decarbonylation of 5-hydroxymethylfurfural in compressed carbon dioxide: A facile approach
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Herein, decarbonylation of biomass-based 5-hydroxymethylfurfural (HMF) in compressed CO2 with an unexpected acceleration of the reaction rate and excellent catalytic activity is reported. Without any additive, CO surrogates, or any organic solvents, via the developed method, an excellent conversion of 99.8% and highest selectivity of furfuryl alcohol (99.6%) in 4 h at 145 °C were achieved using an alumina-supported Pd catalyst (Pd/Al2O3). The superior activity is due to the unique characteristics (miscibility of reactant gases and high diffusivity) of compressed CO2 and the synergy between CO2 and Pd/Al2O3, where CO2 plays an interesting role in accelerating the reaction by enhancing the diffusion of CO and furfuryl alcohol (both products have high solubilities in CO2), consequently shifting the equilibrium to the forward direction. Characterisation of the catalyst suggested its direct interaction with the substrate and provided an indication of the possible reaction path. Thus, a mechanism was outlined. Compared to the results obtained using organic solvents, the results obtained using compressed CO2 were superior in terms of activity, selectivity, and reaction rate. This strategy highlights easy product separation, improved catalyst life, and a simple sustainable process. The efficiency of this protocol is confirmed by its potential application to a series of aldehydes with various substituents to produce decarbonylated products in good to excellent yields.
- Chatterjee, Maya,Ishizaka, Takayuki,Kawanami, Hajime
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p. 2345 - 2355
(2018/06/01)
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- A one-pot conversion furfural, 5 - hydroxymethyl furfural furan
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A one-pot conversion furfural, 5 - hydroxymethyl furfural furan method, characterized by comprising the following steps: the furfural, 5 - hydroxymethyl furfural, catalyst, solvent are added in the reactor with a condensation device, in an inert atmosphere, in the 80 - 250 °C reaction temperature, stirring, reaction 0.5 - 30 h, ice water bath cooling. The invention will be furfural, 5 - hydroxymethyl furfural two substrates through a pot conversion of furan, simplify operation process, avoiding the loss of the material and the step of, maximum utilization of resources; in suitable process conditions, greatly shortens the reaction time, the production cost is reduced, thereby improving the production efficiency; in the normal pressure on the temperate conditions, high expectations for production equipment, in accordance with the principles of safe production; and forming the lignin is suitable for pre-treatment of wood cellulose acid or catalytic generation of furfural, 5 - hydroxymethyl furfural mixture one-pot conversion of furan, to proceed from the biomass resources for producing tetrahydrofuran.
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Paragraph 0028-0029; 0033
(2021/05/12)
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- Palladium-metalated porous organic polymers as recyclable catalysts for chemoselective decarbonylation of aldehydes
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A novel palladium nanoparticle (NP)-metalated porous organic ligand (Pd NPs/POL-xantphos) has been prepared for the chemoselective decarbonylation of aldehydes. This heterogenous catalyst not only has excellent catalytic activity and chemoselectivity, but also holds high activity after 10 runs of reuse. The effective usage of this method is demonstrated through the synthesis of biofuels such as furfuryl alcohol (FFA) via the highly chemoselective decarbonylation of biomass-derived 5-hydroxy-methylfurfural (HMF) with a TON up to 1540. More importantly, 9-fluorenone could be obtained in one step through the decarbonylation of 2-bromobenzaldehyde by using this heterogeneous catalyst.
- Li, Wen-Hao,Li, Cun-Yao,Li, Yan,Tang, Hai-Tao,Wang, Heng-Shan,Pan, Ying-Ming,Ding, Yun-Jie
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supporting information
p. 8446 - 8449
(2018/08/28)
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- Stable Carbocation Generated via 2,5-Cyclohexadien-1-one Protonation
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Protonation of a substituted cyclohexadien-1-one (1) leads to the generation of carbocation [3]+, capable of effecting hydride abstraction and oxidation reactions. The molecular structure of [3]+ shows it to be structurally similar to [(p-MeO-C6H4)Ph2C]+. The ability to easily access [3]+ from stable and available precursors, such as 1 and commercially available acids, may allow a wider application of the growing number of trityl-based reactions in organic syntheses.
- Fraser, Craig,Young, Rowan D.
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p. 505 - 509
(2018/02/19)
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- Zeolite-Encapsulated Pt Nanoparticles for Tandem Catalysis
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Encapsulation of metal nanoparticles in a zeolite matrix is a promising route to integrate multiple sequential reactions into a one-pot and one-step tandem catalytic reaction. We report a cationic polymer-assisted synthetic strategy to encapsulate Pt nanoparticles (NPs) into MFI zeolites. Degrees of encapsulation of Pt NPs in the synthesized catalysts exceeding 90% were demonstrated via kinetic studies of model reactions involving substrates with different molecular dimensions. HZSM-5 zeolite-encapsulated Pt NPs are able to selectively mediate the tandem aldol condensation and hydrogenation of furfural and acetone to form hydrogenated C8 products with a combined yield of 87%. In contrast, hydrogenation and decarbonylation of furfural dominate on Pt NPs supported on HZSM-5 at otherwise identical conditions. The high selectivity toward the tandem reaction on the encapsulated catalyst is attributed to the distribution of metal and acid sites, which limits the access of furfural to Pt sites and promotes the acid-catalyzed aldol condensation. This is the first demonstration that the product distribution in a tandem reaction is manipulated by tailoring the architecture of catalytic materials via encapsulation.
- Cho, Hong Je,Kim, Doyoung,Li, Jing,Su, Dong,Xu, Bingjun
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supporting information
p. 13514 - 13520
(2018/10/20)
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- Reductive Cleavage of Aromatic and Heteroaromatic Ester Functions via Copper-Catalyzed Proto-Decarbomethoxylation
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An unprecedented catalytic reductive cleavage of aromatic and heteroaromatic methyl ester functions was successfully achieved with a cheap, nontoxic, and air-stable Cu(OAc)2 catalyst. This reaction is fast, features good functional group tolerance, does not require inert atmosphere or anhydrous solvent, and can be scaled up to 1 g. Moreover, carboxylic acids and t-butyl esters also reacted smoothly under these conditions.
- Fichez, Jeanne,Prestat, Guillaume,Busca, Patricia
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supporting information
p. 2724 - 2727
(2018/05/22)
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- Palladium–Ruthenium Catalyst for Selective Hydrogenation of Furfural to Cyclopentanol
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Bimetallic Pd–Ru/C catalyst was shown to be much more active in the aqueous-phase hydrogenation of furfural (473 K, 8 MPa) in comparison with both Pd/C and Ru/C catalysts. The enhanced hydrogenation activity manifested itself as an increased yield of cyclopentanol (77%) at a complete conversion of furfural. The observed synergistic effect between palladium and ruthenium in the tested reaction can be related to changes in the electronic state and particle size of supported metals upon interaction with each other and the Pd–Ru alloy formation.
- Mironenko,Belskaya,Lavrenov,Likholobov
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p. 339 - 346
(2018/06/11)
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- A Cptt-Based Trioxo-Rhenium Catalyst for the Deoxydehydration of Diols and Polyols
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Trioxo-rhenium complexes are well known catalysts for the deoxydehydration (DODH) of vicinal diols (glycols). In this work, we report on the DODH of diols and biomass-derived polyols using CpttReO3 as a new catalyst (Cptt=1,3-di-tert-butylcyclopentadienyl). The DODH reaction was optimized using 2 mol % of CpttReO3 and 3-octanol as both reductant and solvent. The CpttReO3 catalyst exhibits an excellent activity for biomass-derived polyols. Specifically, glycerol is almost quantitatively converted to allyl alcohol and mucic acid gives 75 % of muconates at 91 % conversion. In addition, the loading of CpttReO3 can be reduced to 0.1 mol % to achieve a turn-over number as high as 900 per Re when using glycerol as substrate. Examination of DODH reaction profiles by NMR spectroscopy indicates that catalysis is related to Cp-ligand release, which raises questions on the nature of the actual catalyst.
- Li, Jing,Lutz, Martin,Otte, Matthias,Klein Gebbink, Robertus J. M.
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p. 4755 - 4760
(2018/10/02)
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- Nickel Phosphide/Silica Catalysts for the Gas-Phase Hydrogenation of Furfural to High–Added–Value Chemicals
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A series of Ni2P-based catalysts supported on a commercial silica with a metallic Ni loading of 5–20 wt. % and an initial P/Ni molar ratio of 0–3 was prepared by incipient wetness impregnation. Catalyst precursors were reduced and characterized by using XRD, CO chemisorption, NH3 temperature-programmed desorption, N2 adsorption–desorption at ?196 °C, and X-ray photoelectron spectroscopy and then tested in the gas-phase hydrogenation of furfural. Almost full furfural conversion and a 2-methylfuran yield of 73 % can be achieved with the Ni2P-based catalyst with a Ni content of 15 wt. % at 190 °C after 5 h of time on stream. The high selectivity towards 2-methylfuran is attributed to both the high hydrogenating capacity of the metallic sites to lead to furfuryl alcohol and the presence of reduced P species that favor the hydrogenolysis process. However, catalysts undergo deactivation along the catalytic test because of the formation of carbonaceous deposits in the form of coke and adsorption of reactants and/or products.
- Jiménez-Gómez, Carmen P.,Cecilia, Juan A.,Moreno-Tost, Ramón,Maireles-Torres, Pedro
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p. 2881 - 2889
(2017/07/28)
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- Method for catalytic conversion of furfural
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The invention relates to a method for catalytic conversion of furfural, which comprises taking furfural and a methanol aqueous solution as raw materials and heating to carry out a reduction reaction on the furfural in the presence of a loaded type nickel-based catalyst, so as to prepare a furfural converted product comprising furan and/or methyl furan as main components. As the methanol aqueous solution is adopted as a solvent and a hydrogen supply reagent of the reaction, the situation that a series of cost and security problems of transportation, storage and operation are caused due to great consumption of external hydrogen can be avoided, methods of catalyst preparation and furfural conversion are simple, the used reagent is non-toxic, operation conditions are mild, the cost reduction and the production benefit improvement can be facilitated, and thus the method has good industrial prospects.
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Paragraph 0053-0054
(2017/08/26)
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- A new synthon for the synthesis of aminoinositol derivatives
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The regio- and stereoselective synthesis of a new synthon, trans-3,8-dioxatricyclo[3.2.1.02,4]octane-6,7-diamine, from 7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate is reported. Transformation of the acid functionalities to acyl azides followed by Curtius rearrangement gave the corresponding trans-diisocyanate, which was reacted with HCl to produce a trans-diamino compound that is a potentially important synthon for the versatile synthesis of aminocyclitols.
- Cokol, Nalan Korkmaz,Kaya, Serdal,Balci, Metin
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p. 2732 - 2735
(2017/06/23)
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- Nickel-Catalyzed Decarbonylation of Aromatic Aldehydes
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We report here the first systematic study of nickel-catalyzed decarbonylation of aromatic aldehydes under relatively mild conditions. Aldehydes with electron donating groups at para and ortho positions are generally successful with our method. For aldehydes with electron-withdrawing groups, significantly higher yields were achieved for ortho-substituted substrates than para ones, probably due to the effects of steric hindrance or electron donors at the ortho position to suppress the Tishchenko reaction, an undesirable side reaction toward homocoupled esters.
- Ding, Keying,Xu, Shi,Alotaibi, Rajeh,Paudel, Keshav,Reinheimer, Eric W.,Weatherly, Jessie
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supporting information
p. 4924 - 4929
(2017/05/12)
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- Palladium-Catalyzed Deformylation Reactions with Detailed Experimental and in Silico Mechanistic Studies
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A facile, efficient, and general deformylation reaction with a wide-ranging functional group compatibility has been developed with palladium acetate as a precatalyst under exogenous ligand-free conditions. The mechanistic details of the palladium-catalyzed deformylation reaction have been outlined on the basis of a combination of experimental and computational studies. The heterogeneous pathway is predominant for the deformylation, and homogeneous catalysis occurs to a lesser extent. This ligand-free catalytic cycle is proposed to undergo oxidative addition, migratory extrusion, and reductive elimination as the key steps. Kinetic studies reveal a first-order rate dependency with respect to the aldehyde. Furthermore, kinetic isotope effects, competition experiments, and Hammett studies suggest that the migratory extrusion step is the rate-determining step. For the homogeneous pathway, the experimental findings are also supported by DFT studies.
- Modak, Atanu,Rana, Sujoy,Phukan, Ashwini K.,Maiti, Debabrata
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supporting information
p. 4168 - 4174
(2017/08/07)
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- Structure, activity, and selectivity of bimetallic Pd-Fe/SiO2 and Pd-Fe/Γ-Al2O3 catalysts for the conversion of furfural
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The conversion of furfural has been investigated in vapor and liquid phases over a series of supported monometallic Pd and bimetallic Pd-Fe catalysts. Over the monometallic Pd/SiO2 catalyst, the decarbonylation reaction dominates, yielding furan as the main product. By contrast, over the bimetallic Pd-Fe/SiO2 catalyst a high yield of 2-methylfuran is obtained with much lower yield to furan. Interestingly, changing the catalyst support affects the product distribution. For instance, using γ-Al2O3 instead of SiO2 as support of the bimetallic catalyst changed the dominant product from 2-methylfuran to furan. That is, Pd-Fe/γ-Al2O3 behaves more like monometallic Pd/SiO2 than bimetallic Pd-Fe/SiO2. A detailed characterization of the catalysts via XPS, XRD, and TEM indicated that a Pd-Fe alloy is formed on the SiO2 support but not on the γ-Al2O3 support. Theoretical density functional theory calculations suggest that on the Pd-Fe alloy binding of the furan ring to the surface is weakened compared to on pure Pd. This weakening disfavors the ring hydrogenation and decarbonylation paths, while the oxophilic nature of Fe atoms enhances the interaction of the C[dbnd]O and the OH groups with the metal surface, which favors the C[dbnd]O hydrogenation and C–O bond cleavage paths. The presence of the solvent has a less pronounced effect, but clearly has a stronger inhibition on C–C bond cleavage (decarbonylation to furan) than on C–O bond cleavage (hydrogenolysis to methylfuran).
- Pino, Natalia,Sitthisa, Surapas,Tan, Qiaohua,Souza, Talita,López, Diana,Resasco, Daniel E.
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- Method of manufacturing dihydrobenzofuran compd. (by machine translation)
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PROBLEM TO BE SOLVED: dihydrobenzofuran compd. furtural compd. in manufacturing, furancarboxylic compd. to improve productivity, to avoid the production of furfuryl alcohol compound, and the activity of the catalyst deterioration with the lapse of time by suppressing, to convert the stable furtural compd., high efficiency and to provide a method of manufacturing a bisfuran compound. SOLUTION: furtural compd., and hydrogen in a pressurized state is brought into contact with a catalyst in the presence, in the method for manufacturing a bisfuran compound, the molar ratio of hydrogen to furtural compd., exceeds 0 0. 2 or less, and therefore, improving the productivity and amt. dihydrobenzofuran, furfuryl compd. product is reduced. Selected drawing: no (by machine translation)
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Paragraph 0108; 0110
(2016/11/09)
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