- Synthesis of 1,6-Hexanediol from Cellulose Derived Tetrahydrofuran-Dimethanol with Pt-WOx/TiO2 Catalysts
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Cellulose-derived tetrahydrofuran-dimethanol (THFDM) can be converted over Pt-WOx/TiO2 catalysts to 1,6-hexanediol (1,6-HDO) with up to 70% yield. This reaction involves ring-opening of THFDM to 1,2,6-hexanetriol (HTO) and then hydrogenolysis of HTO to 1,6-HDO. Hydrogen atoms spill over from Pt sites onto WOx/TiO2 to reduce the W=O functional group and create Br?nsted acid sites. Similar catalytic activity for THFDM conversion can be been obtained with a physical mixture of Pt/TiO2 and WOx/TiO2 due to hydrogen spillover over spatially separate Pt and WOx when a reducible support (TiO2) is used.
- He, Jiayue,Burt, Samuel P.,Ball, Madelyn,Zhao, Dongting,Hermans, Ive,Dumesic, James A.,Huber, George W.
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Read Online
- Catalyst studies on the ring opening of tetrahydrofuran-dimethanol to 1,2,6-hexanetriol
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The metal catalyzed hydrogenolysis of the biomass-derived THF-dimethanol to 1,2,6-hexanetriol using heterogeneous catalysts was investigated. Bimetallic Rh-Re catalysts (4 wt% Rh and a Re/Rh (mol. ratio of 0.5) on a silica support gave the best performance and 1,2,6-hexanetriol was obtained in 84% selectivity at 31% conversion (120 C, 80 bar, 4 h); the selectivity reaches a maximum of 92% at 80 C. The product distribution at prolonged reaction times or higher temperatures or both shows the formation of diols and mono-alcohols, indicating that the 1,2,6-hexanetriol is prone to subsequent hydrodeoxygenation reactions. Different silica supports were investigated and optimal results were obtained with an amorphous silica featuring an intermediate surface area and an average mesopore size of about 6 nm. TPR and XPS surface analysis support the presence of mixed Rh and Re particles. The redox Reδ+/ReTotal surface ratio correlates with the conversion in a volcano type dependency. Both gas phase as well as Rh200Re1OH cluster DFT calculations support an acid-metal bifunctional mechanism and explain the products distribution.
- Buntara, Teddy,Melián-Cabrera, Ignacio,Tan, Qiaohua,Fierro, José L.G.,Neurock, Matthew,De Vries, Johannes G.,Heeres, Hero J.
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Read Online
- Process condition-based tuneable selective catalysis of hydroxymethylfurfural (HMF) hydrogenation reactions to aromatic, saturated cyclic and linear poly-functional alcohols over Ni-Ce/Al2O3
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The related immense versatility of a ceria-promoted transition metal catalyst, utilized for the hydrogenation of 5-hydroxymethylfurfural (HMF), is demonstrated in this research study. We reveal a strategy to achieve considerable selective yields of three important high-value HMF-derived compounds by simply modifying the analysed reaction conditions and/or water-containing process medium.
- Grilc, M.,Likozar, B.,Pomeroy, Brett
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supporting information
p. 7996 - 8002
(2021/11/01)
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- Reductive conversion of 5-hydroxymethylfurfural to 1,2,6-hexanetriol in water solvent using supported Pt catalysts
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One-pot conversion of biomass derived 5-hydroxymethylfurfural (HMF) to 1,2,6-hexanetriol (1,2,6-HT) in water solvent was performed using Pt catalysts supported on various acid-base metal oxides. Pt catalysts supported on hydrotalcite, MgO, and CeO2 showed better yield of 1,2,6-HT and 2,5-bis(hydroxymethyl)-tetrahydrofuran (BHF), while ring-rearranged cyclopentanol derivatives were predominant products on the other Pt catalysts. The product distribution with time course on Pt/hydrotalcite revealed that HMF is at first hydrogenated to BHF, then the following parallel reactions proceed; ring-rearrangement to cyclopentanol derivatives, ring-hydrogenation to BHF, and hydrogenolysis to 1,2,6-HT. When pure hydrotalcite, MgO and CeO2 were physically mixed with Pt/SiO2, the selectivity to 1,2,6-HT was almost zero or less than 10 %. It was suggested that the formation of 1,2,6-HT proceeds at metal-support interface. The effect of metal-support interface was examined by means of IR spectra of adsorbed methanol. It was indicated that both basic property of supports and surface monodentate alkoxide formation are essential for the production of 1,2,6-HT. The maximum yield of 1,2,6-HT (42 %) was obtained using Co-promoted Pt/CeO2 catalysts pre-reduced at 200 °C.
- Kataoka, Hiroto,Kosuge, Daichi,Ogura, Keiji,Ohyama, Junya,Satsuma, Atsushi
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- Interface synergy between IrOx and H-ZSM-5 in selective C–O hydrogenolysis of glycerol toward 1,3-propanediol
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Site-selective deoxygenation of hydroxyl groups represents essential processes to access valuable functionalized bio-based compounds with industrial potential. One of the challenging tasks in this context is to convert biodiesel-derived glycerol in the presence of abundant water directly to 1,3-propanediol (1,3-PDO), a key component of the emerging polymer industry. Herein, a monometallic iridium supported on H-ZSM-5 in the absence of Re oxophilic metal oxides was prepared via grinding-assisted impregnation procedures and attempted as an effective and recyclable catalyst for the aqueous-phase selective hydrogenolysis of glycerol toward 1,3-PDO in the absence of acid additives. The results revealed the necessity to control the Ir domain dispersions, Ir0/Ir3+ ratio and the amounts of overall acid/Br?nsted acid sites. Activity depended linearly on the amount of overall and Br?nsted acid sites, and 1,3-PDO selectivity increased in the presence of Ir-induced Br?nsted acid sites, denoted as Ir-O(H)-H-ZSM-5. We speculate that Ir-O(H)-H-ZSM-5 are generated by the interfacial synergistic interaction between IrOx and H-ZSM-5 through hydrogen spillover and reverse hydrogen spillover according to the reported literatures. The reaction mechanism to elucidate the role of Ir-O(H)-H-ZSM-5 sites in glycerol hydrogenolysis was also postulated based on extensive characterization and catalytic reaction results.
- Wan, Xiaoyue,Zhang, Qi,Zhu, Mingming,Zhao, Yi,Liu, Yongmei,Zhou, Chunmei,Yang, Yanhui,Cao, Yong
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p. 339 - 350
(2019/07/03)
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- Mechanistic study on -C-O- and -C-C- hydrogenolysis over Cu catalysts: Identification of reaction pathways and key intermediates
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Important petro-based polyol compounds with a longer carbon chain, such as oligohydroxy hexanes (e.g. 1,2- and 1,6-hexanediol or 1,2,6-hexanetriol), require at least three to four synthesis steps. Replacing this complex chemistry by a one-pot reaction via -C-O- bond cleavage from sugars would be a significant breakthrough for the use of renewable feedstocks. Cu is known for its dehydroxylation (deoxygenation) properties, yielding the desired products from sugars. In this joint research between academic and industrial chemistry, we have identified so far unknown intermediate products and present the first mechanism that explains the selective cleavage of OH-groups over copper. Strong interactions between polyols, unsaturated species and the copper surface are observed. Stable five-membered rings are formed with Cu via two vicinal OH-groups of the polyol reactant that makes these OH-groups inert to -C-O- bond cleavage. Adjacent free OH-groups in close proximity to the catalyst are dehydroxylated (deoxygenated). We further show that degradation of polyols not only occurs via commonly cited retro-aldol reactions. The formation of acid intermediates with subsequent decarboxylation is validated as a new pathway for -C-C- bond cleavage to short-chain polyols and CO2. The proposed mechanisms for -C-O- and -C-C- bond cleavage elucidate why hydrogenolysis reactions require high hydrogen pressure (up to 200 bar) to suppress the degradation of sugars and obtain high yields of deoxy C6 products. With this knowledge, the improvement of a standard commercial Cu-RANEY catalyst under optimized reaction conditions was shown. In contrast to alumina-supported Cu, the Cu-Al alloy in a RANEY-type catalyst shows selective -C-O- bond cleavage properties while maintaining the C6 carbon chain. These new insights into the transformation of sugars to value added commodities show the potential for new approaches in future biorefinery concepts.
- Kühne, Benjamin,Vogel, Herbert,Meusinger, Reinhard,Kunz, Sebastian,Kunz, Markwart
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p. 755 - 767
(2018/02/14)
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- Direct conversion of carbohydrates to diol by the combination of niobic acid and a hydrophobic ruthenium catalyst
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Tetrahydro-2,5-furandimethanol (THFDM) was obtained directly from a wide variety of carbohydrates by the combination of niobic acid and a hydrophobic ruthenium catalyst. Fructose, glucose, and polysaccharides consisting of fructose or glucose could be converted to THFDM in one-step. The selectivity to THFDM was kept around 60% while the glucose conversion varied from 9% to 49%. The as-synthesized niobic acid was characterized by TEM, N2 adsorption/desorption, XRD, NH3-TPD and FT-IR spectra of adsorpted pyridine. The niobic acid was proved to have medium and strong acid sites with a high Br?nsted/Lewis ratio, which played a great role for keeping high THFDM selectivity using glucose as a substrate.
- Duan, Ying,Zhang, Jun,Li, Dongmi,Deng, Dongsheng,Ma, Lu-Fang,Yang, Yanliang
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p. 26487 - 26493
(2017/07/07)
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- METHOD FOR PRODUCING ISOPROPANOL BY CATALYTIC CONVERSION OF CELLULOSE
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This invention provides a method for producing isopropanol from cellulose, which is characterized by: cellulose is catalytically converted to isopropanol under existence of a Cu-Cr catalyst. In the method, the Cu-Cr catalyst contains an active phase of CuCr2O4 or further contains an active phase selected from a group consisting of CuO and Cr2O3; the mass ratio of cellulose and water is 15 wt% or below; and the temperature of catalytic reaction is 200-270℃.
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(2017/07/13)
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- SYNTHESIS OF R-GLUCOSIDES, SUGAR ALCOHOLS, REDUCED SUGAR ALCOHOLS, AND FURAN DERIVATIVES OF REDUCED SUGAR ALCOHOLS
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Disclosed herein are methods for synthesizing 1,2,5,6-hexanetetrol (HTO), 1,6 hexanediol (HDO) and other reduced polyols from C5 and C6 sugar alcohols or R glycosides. The methods include contacting the sugar alcohol or R-glycoside with a copper catalyst, most desirably a Raney copper catalyst with hydrogen for a time, temperature and pressure sufficient to form reduced polyols having 2 to 3 fewer hydoxy groups than the starting material. When the starting compound is a C6 sugar alcohol such as sorbitol or R-glycoside of a C6 sugar such as methyl glucoside, the predominant product is HTO. The same catalyst can be used to further reduce the HTO to HDO.
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- POROUS SHAPED METAL-CARBON PRODUCTS
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The present invention provides a porous metal-containing carbon-based material that is stable at high temperatures under aqueous conditions. The porous metal-containing carbon-based materials are particularly useful in catalytic applications. Also provided, are methods for making and using porous shaped metal-carbon products prepared from these materials.
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Paragraph 0228
(2017/05/17)
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- HYDROGENATION OF OXYGENATED MOLECULES FROM BIOMASS REFINING
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The present disclosure relates to methods, processes, and systems for utilizing the dehydrogenation of 2-butanol for hydrogen consuming reactions of biomass or biomass-derived molecules. The present invention relates to methods, processes, and systems for utilizing the dehydrogenation of 2-butanol for hydrogen consuming hydrogenation, hydrogenolysis, or hydrodeoxygenation reactions of biomass or biomass-derived molecules.
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Paragraph 0137-0141
(2017/04/12)
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- PROCESS FOR PRODUCING 1,6-HEXANEDIOL
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Disclosed herein are processes for producing 1,6-hexanediol. In one embodiment, the process comprises a step of contacting 3,4-dihydro-2H-pyran-2-carbaldehyde, a solvent, and hydrogen in the presence of a catalyst at a reaction temperature between about 0° C. and about 120° C. at a pressure and for a reaction time sufficient to form a product mixture comprising 1,6-hexanediol. In one embodiment, the catalyst comprises a metal M1, a metal M2 or an oxide of M2, and a support, wherein M1 is Rh, Ir, Ni, Pd, or Pt, and M2 is Mo, W, or Re; or M1 is Cu and M2 is Ni, Mn, or W.
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Page/Page column 0025; 0096; 0097
(2016/06/28)
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- PROCESS FOR THE TRANSFORMATION OF LIGNOCELLULOSIC BIOMASS INTO MONO- OR POLY-OXYGENATED MOLECULES
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The invention concerns a process for the transformation of lignocellulosic biomass or cellulose into mono- or poly-oxygenated compounds, in which the lignocellulosic biomass or the cellulose is brought into simultaneous contact with a catalytic system comprising a combination of one or more homogeneous catalysts and one or more heterogeneous catalysts, in the same reaction chamber, in the presence of at least one solvent, said solvent being water alone or as a mixture with at least one other solvent, in a reducing atmosphere, and at a temperature in the range 80° C. to 250° C. and at a pressure in the range 0.5 MPa to 20 MPa.
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Paragraph 0122-0126
(2016/05/09)
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- Synthesis of 1,6-hexanediol from HMF over double-layered catalysts of Pd/SiO2 + Ir-ReOx/SiO2 in a fixed-bed reactor
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1,6-Hexanediol (1,6-HDO) was effectively prepared from 5-hydroxymethylfurfural (HMF) over double-layered catalysts of Pd/SiO2 + Ir-ReOx/SiO2 in a fixed-bed reactor. Under optimal reaction conditions (373 K, 7.0 MPa H2, in solvent mixtures of 40% water and 60% tetrahydrofuran (THF)), 57.8% yield of 1,6-HDO was obtained. The double-layered catalysts loaded in double-layered beds showed much superior performance compared to that of a single catalyst of Pd-Ir-ReOx/SiO2, even when the same amount of active components were used in the catalysts. The reaction solvent significantly affected product distributions, giving a volcano-shape plot for the 1,6-HDO yield as a function of the ratio of water to THF. Br?nsted acidic sites were generated on the catalyst in the presence of water which played determining roles in 1,6-HDO formation. A high pressure of H2 contributed to 1,6-HDO formation by depressing the over-hydrogenolysis of reaction intermediates and products to form hexane and hexanol. The reaction route was proposed for HMF conversion to 1,6-HDO on the basis of conditional experiments.
- Xiao, Bin,Zheng, Mingyuan,Li, Xinsheng,Pang, Jifeng,Sun, Ruiyan,Wang, Hua,Pang, Xiaoli,Wang, Aiqin,Wang, Xiaodong,Zhang, Tao
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p. 2175 - 2184
(2016/04/19)
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- The effect of heterogeneous acid-base catalysis on conversion of 5-hydroxymethylfurfural into a cyclopentanone derivative
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The effect of heterogeneous acid-base catalysis on conversion of 5-hydroxymethylfurfural (HMF) to 3-hydroxymethylcyclopentanone (HCPN) was investigated. It was demonstrated that acidic metal oxides, in particular Ta2O5, significantly enhanced the yield of HCPN due to their moderate Lewis acidity.
- Ohyama,Kanao,Ohira,Satsuma
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p. 676 - 680
(2016/02/12)
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- Upgrading biomass-derived furans via acid-catalysis/hydrogenation: The remarkable difference between water and methanol as the solvent
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In methanol 5-hydroxymethylfurfural (HMF) and furfuryl alcohol (FA) can be selectively converted into methyl levulinate via acidcatalysis, whereas in water polymerization dominates. The hydrogenation of HMF, furan and furfural with the exception of FA is
- Hu, Xun,Westerhof, Roel J. M.,Wu, Liping,Dong, Dehua,Li, Chun-Zhu
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p. 219 - 224
(2018/04/16)
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- Biphasic catalytic conversion of fructose by continuous hydrogenation of HMF over a hydrophobic ruthenium catalyst
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The production of chemicals directly from sugars is an important step in biomass conversion. Herein, tetrahydro-2,5-furandimethanol (THFDM), obtained from fructose, is formed by using a combination of acid and hydrophobic Ru/SiO2 in a water/cyclohexane biphasic system. Two key factors enable the high selectivity towards THFDM: modifying the hydrogenation catalyst so that it has hydrophobic properties, and the continuous hydrogenation of generated 5-(hydroxymethyl)furfural in the cyclohexane phase. Moreover, the selectivity towards THFDM is found to depend strongly on the acid catalyst used. Divide and conquer: A method for direct catalytic conversion of fructose to tetrahydro-2,5-furandimethanol (THFDM) via 5-(hydroxymethyl)furfural (HMF) is reported. High selectivity towards THFDM is achieved by using a catalyst combination of acid and a hydrophobic ruthenium catalyst (Ru/SiO2-TM) in a water/cyclohexane biphasic system by continuous hydrogenation of generated HMF. The use of the hydrophobic Ru/SiO2-TM is the key, as it prevents hydrogenation of fructose to mannitol and sorbitol in the water phase.
- Yang, Yanliang,Du, Zhongtian,Ma, Jiping,Lu, Fang,Zhang, Junjie,Xu, Jie
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p. 1352 - 1356
(2014/06/09)
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- PROCESS FOR PREPARING 1, 6-HEXANEDIOL
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Disclosed are processes for preparing 1, 6-hexanediol and synthetic intermediates useful in the production of 1, 6-hexanediol from renewable biosources. In one embodiment, a process comprises contacting levoglucosenone with hydrogen in the presence of a first hydrogenation catalyst at a first temperature to form product mixture (I); and heating product mixture (I) in the presence of hydrogen and a second hydrogenation catalyst at a second temperature to form product mixture (II) which comprises 1, 6-hexanediol.
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- The selective hydrogenation of biomass-derived 5-hydroxymethylfurfural using heterogeneous catalysts
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The products produced by hydrogenation of biomass-derived 5-hydroxymethylfurfural (HMF) are potential sustainable substitutes for petroleum-based building blocks used in the production of chemicals. We have studied the hydrogenation of HMF over supported Ru, Pd, and Pt catalysts in monophasic and biphasic reactor systems to determine the effects of the metal, support, solution phase acidity, and the solvent to elucidate the factors that determine the selectivity for hydrogenation of HMF to its fully hydrogenated form of 2,5-di-hydroxy-methyl-tetrahydrofuran (DHMTHF). We show that the selectivity to DHMTHF is affected by the acidity of the aqueous solution containing HMF. The major by-products observed are C6-polyols formed from the acid-catalyzed degradation and subsequent hydrogenation of 2,5-dihydroxymethylfuran (DHMF), an intermediate hydrogenation product of HMF to DHMTHF. The highest yields (88-91%) to DHMTHF are achieved using Ru supported on materials with high isoelectric points, such as ceria, magnesia-zirconia, and γ-alumina. Supported catalysts containing Pt and Pd at the same weight percent as Ru are not as active for the selective hydrogenation to DHMTHF.
- Alamillo, Ricardo,Tucker, Mark,Chia, Mei,Pagan-Torres, Yomaira,Dumesic, James
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experimental part
p. 1413 - 1419
(2012/06/15)
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- Preparation of caprolactone, caprolactam, 2,5-tetrahydrofuran dimethanol, 1,6-hexanediol or 1,2,6-hexanetriol from 5-hydroxymethyl-2-furfuraldehyde
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The present invention relates to a method for preparing caprolactone, comprising converting 5-hydroxymethyl-2-furfuraldehyde by hydrogenation into at least one intermediate compound selected from the group of 2,5-tetrahydrofuran dimethanol, 1,6-hexanediol and 1,2,6-hexanetriol,and preparing caprolactone from said intermediate compound. Further, the invention relates to a method for preparing 1,2,6 hexanetriol comprising preparing 5-hydroxymethyl-2-furfaldehyde from a renewable source, converting 5-hydroxymethyl-2-furfaldehyde into 2,5-tetrahydrofuran dimethanol and converting 2,5-tetrahydrofuran dimethanol into 1,2,6 hexanetriol. Further, the invention relates to a method for preparing 1,6 hexanediol from 1,2,6-hexanetriol, wherein 1,2,6-hexanetriol is subjected to a ring closure reaction, thereby forming 2-hydropyranyl-methanol, and the 2-hydropyranyl-methanol is hydrogenated, thereby forming 1,6 hexane diol.
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Page/Page column 9
(2011/12/12)
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- Caprolactam from renewable resources: Catalytic conversion of 5-hydroxymethylfurfural into caprolactone
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Renewable nylon: 5-Hydroxymethylfurfural (HMF), which can be obtained from renewable resources such as D-fructose, was converted into caprolactone with very good overall selectivity in only three steps. The new route involves two hydrogenation steps to obtain 1,6-hexanediol, which was oxidatively cyclized to caprolactone, and then converted into caprolactam. Copyright
- Buntara, Teddy,Noel, Sebastien,Phua, Pim Huat,Melian-Cabrera, Ignacio,De Vries, Johannes G.,Heeres, Hero J.
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p. 7083 - 7087
(2011/09/30)
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- PREPARATION OF CAPROLACTONE, CAPROLACTAM, 2,5-TETRAHYDROFURAN-DIMETHANOL, 1,6-HEXANEDIOL OR 1,2,6-HEXANETRIOL FROM 5-HYDROXYMETHYL-2-FURFURALDEHYDE
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The present invention relates to a method for preparing caprolactone, comprising converting 5-hydroxymethyl-2-furfuraldehyde by hydrogenation into at least one intermediate compound selected from the group of 2,5-tetrahydrofuran-dimethanol, 1,6-hexanediol and 1,2,6-hexanetriol,and preparing caprolactone from said intermediate compound. Further, the invention relates to a method for preparing 1,2,6-hexanetriol comprising preparing 5-hydroxymethyl-2-furfaldehyde from a renewable source, converting 5- hydroxymethyl-2-furfaldehyde into 2,5-tetrahydrofuran-dimethanol and converting 2,5-tetrahydrofuran-dimethanol into 1,2,6-hexanetriol. Further, the invention relates to a method for preparing 1,6-hexanediol from 1,2,6- hexanetriol, wherein 1,2,6-hexanetriol is subjected to a ring closure reaction, thereby forming (tetrahydro-2H-pyran-2-yl)methanol, and the (tetrahydro-2H-pyran-2- yl)methanol is hydrogenated, thereby forming 1,6-hexane diol.
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- Hydroxymethylfurfural Reduction Methods and Methods of Producing Furandimethanol
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A method of reducing hydroxymethylfurfural (HMF) where a starting material containing HMF in a solvent comprising water is provided. H2 is provided into the reactor and the starting material is contacted with a catalyst containing at least one metal selected from Ni, Co, Cu, Pd, Pt, Ru, Ir, Re and Rh, at a temperature of less than or equal to 250° C. A method of hydrogenating HMF includes providing an aqueous solution containing HMF and fructose. H2 and a hydrogenation catalyst are provided. The HMF is selectively hydrogenated relative to the fructose at a temperature at or above 30° C. A method of producing tetrahydrofuran dimethanol (THFDM) includes providing a continuous flow reactor having first and second catalysts and providing a feed comprising HMF into the reactor. The feed is contacted with the first catalyst to produce furan dimethanol (FDM) which is contacted with the second catalyst to produce THFDM.
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Page/Page column 7-8
(2008/06/13)
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- Selective cleavage of acetals with ZnBr2 in dichloromethane
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A selective cleavage of acetals of 1,2- and 1,3-diols has been achieved under mild conditions using ZnBr2 in dichloromethane at room temperature. Acetal types cleavable by this procedure include benzylidene, isopropylidene and cyclohexylidene acetals. This method is compatible with several other types of hydroxyl protecting groups such as Bn, Bz, TBDPS, TIPS and TBDMS.
- Ribes, Celia,Falomir, Eva,Murga, Juan
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p. 1239 - 1244
(2007/10/03)
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- DERMATOLOGICAL COMPOSITIONS AND METHODS
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Disclosed are methods and compositions for regulating the melanin content of mammalian melanocytes; regulating pigmentation in mammalian skin, hair, wool or fur; treating or preventing various skin and proliferative disorders; by administration of various compounds, including alcohols, diols and/or triols and their analogues.
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- Treatment of neurodegenerative diseases
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Disclosed are methods for increasing the differentiation of mammalian neuronal cells for purposes of treating neurodegenerative diseases or nerve damage by administration of various compounds including alcohols, diols and/or triols and their analogues.
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- Treatment of diseases mediated by the nitric oxide/cGMP/protein kinase G pathway
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Disclosed are methods and compositions for stimulating cellular nitric oxide (NO) synthesis, cyclic guanosine monophosphate levels (cGMP), and protein kinase G (PKG) activity for purposes of treating diseases mediated by deficiencies in the NO/cGMP/PKG signal transduction pathway, by administration of various compounds including alcohols, diols and/or triols and their analogues.
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- Microwave thermolysis V : A rapid and selective method for the cleavage of THP ethers, acetals and acetonides using clay supported ammonium nitrate 'Clayan' in dry media
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The deprotection of a variety of tetrahydropyranyl ethers (THP), acetonides and acetals into their parent compounds using clay supported ammonium nitrate 'Clayan' under microwave irradiation is described. The ecofriendly nature of the reagent and non solvent conditions are the important features of the procedure.
- Meshram,Sumithra,Reddy,Ganesh,Yadav
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p. 2807 - 2815
(2007/10/03)
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- Separation of methylene chloride from tetrahydrofuran by extractive distillation
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Methylene chloride is difficult to separate from tetrahydrofuran by conventional distillation or rectification because of the proximity of their vapor pressures. Methylene chloride can be readily separated from tetrahydrofuran by extractive distillation. Effective agents are 1-pentanol, 1,2-butanediol and 3-nitrotoluene.
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- Synthetic lubricating oil
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A synthetic lubricating oil contains an esterification product obtained from a hydroxycarboxylic acid polyol ester (A) and at least one aliphatic monocarboxylic acid (B), and optionally either an aliphatic carboxylic acid having two or more carboxyl groups (C) or a combination of an aliphatic carboxylic acid having two or more carboxyl groups (C) and an aliphatic polyhydric alcohol (D).
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- Method of preparing bioerodible polymers having pH sensitivity in the acid range and resulting product
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Biodegradible polymers are provided which may contain a biologically active substance, e.g. a drug such as insulin, which is released over a period of time as the polymer erodes when in contact with a body fluid. The polymer contains an amine functionality whereby it erodes faster at low acid pH's than at higher acid pH's. As an example, the polymer may contain insulin and may contain or may have an encapsulating hydrogel containing glucose oxidase. As the blood sugar level of a diabetic person rises, e.g., afte a meal, glucose diffuses into the polymer or hydrogel and is converted to gluconic acid which lowers the pH, and accelerates erosion and the release of insulin.
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- Dimethylboron Bromide and Diphenylboron Bromide: Cleavage of Acetals and Ketals
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The cleavage of various acetal and ketal derivatives by the use of dialkyl- and diarylboron halides is described.Acetals and ketals readily react with dimethylboron bromide or diphenylboron bromide at -78 deg C to give the corresponding carbonyl compounds in excellent yield.Under similar reaction conditions MEM, MOM, and MTM ethers are smoothly converted to alcohols.Acetonides are also cleaved with dimethylboron bromide while THP and THF ethers and methyl glycosides react at room temperature.Mechanistic considerations of the cleavage reactions are presented.The chemoselective virtues of dimethylboron bromide are summarized.
- Guindon, Yvan,Yoakim, Christiane,Morton, Howard E.
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p. 3912 - 3920
(2007/10/02)
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