488-44-8Relevant academic research and scientific papers
On the side-chain conformation of N-acetylneuraminic acid and its epimers at C-7, C-8, and C-7,8.
Christian,Schulz,Brandstetter,Zbiral
, p. 1 - 11 (1987)
The side-chain conformation of N-acetylneuraminic acid and analogs has been studied by n.m.r. spectroscopy. The results of the 1H-, 13C-n.m.r.-, and 1H-nuclear-Overhauser-enhancement measurements were used to distinguish between different local-minima conformations suggested by hard-sphere calculations. Attempts were made to correlate the major conformation determined for each compound with the behavior towards activation with N-acetylneuraminic acid-CMP-synthetase.
Production of hydrogen, alkanes and polyols by aqueous phase processing of wood-derived pyrolysis oils
Vispute, Tushar P.,Huber, George W.
, p. 1433 - 1445 (2009)
Pyrolysis oils are the cheapest liquid fuel derived from lignocellulosic biomass. However, pyrolysis oils are a very poor quality liquid fuel that cannot be used in conventional diesel and internal combustion engines. In this paper we show that hydrogen, alkanes (ranging from C1 to C6) and polyols (ethylene glycol, 1,2-propanediol, 1,4-butanediol) can be produced from the aqueous fraction of wood-derived pyrolysis oils (bio-oils). The pyrolysis oil was first phase separated into aqueous and non-aqueous fraction by addition of water. The aqueous phase of bio-oil contained sugars; anhydrosugars; acetic acid; hydroxyacetone; furfural and small amounts of guaiacols. The aqueous fraction was subjected to a low temperature hydrogenation with Ru/C catalyst at 125-175 °C and 68.9 bar. The hydrogenation step converts the various functionalities in the bio-oil (including aldehydes; acids; sugars) to corresponding alcohols. Undesired methane and light gases are also produced in this low-temperature hydrogenation step. Diols (ranging from C2 to C4) and sorbitol are obtained as major products in this step. After the low temperature hydrogenation step either hydrogen or alkanes can be produced by aqueous-phase reforming (APR) or aqueous-phase dehydration/hydrogenation (APD/H) respectively. APR was done with a 1 wt% Pt/Al2O3 catalyst at 265 °C and 55.1 bar. Hydrogen selectivities of up to 60% were observed. The hydrogen selectivity was a function of space velocity. A 4 wt% Pt/SiO2-Al 2O3 catalyst at 260 °C and 51.7 bar was used for alkane production by APD/H. The carbon conversion to gas phase products of 35% with alkane selectivity of 45% was obtained for a WHSV of 0.96 h-1 when hydrogen is produced in situ from bio-oil. Alkane selectivity can be improved by supplying hydrogen externally. Alkane selectivities as high as 97% can be obtained when HCl is added to the aqueous-phase of the bio-oil and hydrogen is supplied externally. Model compounds for further bio-oil conversion studies are suggested. The Royal Society of Chemistry 2009.
Selective and Scalable Synthesis of Sugar Alcohols by Homogeneous Asymmetric Hydrogenation of Unprotected Ketoses
Tindall, Daniel J.,Mader, Steffen,Kindler, Alois,Rominger, Frank,Hashmi, A. Stephen K.,Schaub, Thomas
supporting information, p. 721 - 725 (2020/10/19)
Sugar alcohols are of great importance for the food industry and are promising building blocks for bio-based polymers. Industrially, they are produced by heterogeneous hydrogenation of sugars with H2, usually with none to low stereoselectivities. Now, we present a homogeneous system based on commercially available components, which not only increases the overall yield, but also allows a wide range of unprotected ketoses to be diastereoselectively hydrogenated. Furthermore, the system is reliable on a multi-gram scale allowing sugar alcohols to be isolated in large quantities at high atom economy.
Seven undescribed steroids from the leaves of Datura metel L.
Liu, Yan,Tan, Jin-yan,Zou, Hai-dan,Qi, Zi-Tang,Naseem, Anam,Pan, Juan,Guan, Wei,Yang, Bing-you,Kuang, Hai-xue
, (2021/07/14)
Extraction of Datura metel L. leaves with ethanol as a solvent gave a group of steroids, including two unique 1,10-seco-withanolides (1, 4), an unusual nitrogen-containing withanolides (2), one undescribed saponin (3), two withanolides with a carbohydrate (5, 6), and one C21 steroid (7). These compounds' structures were identified based on HR-ESI-MS and 1H, 13C NMR data analyses, also compared with data from the document. Some compounds showed moderate inhibition on NO production in lipopolysaccharide-stimulated RAW 264.7 cells.
Boron oxide modified bifunctional Cu/Al2O3 catalysts for the selective hydrogenolysis of glucose to 1,2-propanediol
Liu, Chengwei,Shang, Yaning,Wang, Shen,Liu, Xin,Wang, Xianzhou,Gui, Jianzhou,Zhang, Chenghua,Zhu, Yulei,Li, Yongwang
, (2020/02/18)
A series of B2O3 modified Cu/Al2O3 catalysts were prepared for the hydrogenolysis of glucose. The catalysts were fully characterized by BET, ICP, N2O adsorptive decomposition, XRD, SEM, TG, H2-TPR, CO-FTIR, XPS, and NH3-TPD. The strong interaction between B2O3 and CuO could promote the dispersion of copper and inhibit the reduction of CuO, creating a proper mol ratio of Cuδ+/Cu0 for the hydrogenolysis of glucose to oxygen-containing chemicals. Furthermore, the doping of B2O3 also introduced more acid sites onto the CuB/Al2O3 catalysts, which is favorable for the cleavage of hydroxyl through dehydration. Therefore, the selective hydrogenolysis of glucose to 1,2-propanediol was dependent on the contribution of Cuδ+, Cu0, and acid sites. The catalytic activity and 1,2-propanediol selectivity were improved significantly by doping B2O3 into Cu/Al2O3. Among the catalysts, 1CuB/Al2O3 showed the highest selectivity for 1,2-propanediol, with the value of 49.5% at 96.6% conversion of glucose.
Direct conversion of cellulose into isosorbide over Ni doped NbOPO4catalysts in water
Guo, Jiaxing,He, Minyao,Li, Cuiqing,Liu, ShanShan,Song, Yongji,Wang, Hong,Wang, Xincheng
supporting information, p. 10292 - 10299 (2020/07/14)
Isosorbide is a versatile chemical intermediate for the production of a variety of drugs, chemicals, and polymers, and its efficient production from natural cellulose is of great significance. In this study, bifunctional catalysts based on niobium phosphates were prepared by a facile hydrothermal method and used for the direct conversion of cellulose to isosorbide under aqueous conditions. NH3-TPD analysis showed that a high acid content existed on the catalyst surface, and pyridine infrared spectroscopic analysis confirmed the presence of both Lewis acid and Br?nsted acid sites, both of which played an important role in the process of carbohydrate conversion. XRD and H2-TPR characterization determined the composition and the hydrogenation centers of the catalyst. An isosorbide yield of 47% could be obtained at 200 °C for 24 h under 3 MPa H2 pressure. The Ni/NbOPO4 bifunctional catalyst retains most of its activity after five consecutive runs with slightly decreased isosorbide yield of 44%. In addition, a possible reaction mechanism was proposed that the synergistic effect of surface acid sites and hydrogenation sites was favorable to enhancing the cascade dehydration and hydrogenation reactions during the conversion of cellulose to isosorbide. This study provides as an efficient strategy for the development of novel multifunctional heterogeneous catalysts for the one-pot valorisation of cellulose. This journal is
Highly efficient catalytic conversion of cellulose into acetol over Ni-Sn supported on nanosilica and the mechanism study
Liu, Xiaohao,Liu, Xiaodong,Xu, Guangyue,Zhang, Ying,Wang, Chenguang,Lu, Qiang,Ma, Longlong
, p. 5647 - 5656 (2019/11/05)
Selective conversion of cellulose into high value-added C3 chemicals is a great challenge in biorefinery due to the complicated reaction process. In this work, 61.6% yield of acetol was obtained by one pot conversion of cellulose using Ni-Sn/SiO2 catalysts. A series of characterization methods including TEM, STEM-HAADF, EDS, AAS, XRD, XPS, H2-TPR, Py-FTIR, and CO2-TPD were carried out to explore the structure-activity relationship. The strong basicity of the catalysts was a key factor affecting the production of acetol. In addition, catalysts with the hydrothermally stable L-acid sites and no B-acid sites inhibited side reactions and ensured efficient conversion of cellulose into small molecules. Further studies showed that the formation of the Ni3Sn4 alloy significantly promoted the acetol production, and its weak hydrogenation activity inhibited further conversion of acetol. Noninteger valence tin species (Snδ+ and SnOx) were formed both in Ni3Sn4 and Sn/SiO2. These Sn species were the source of basic sites and the active sites for catalyzing cellulose to acetol. Under the synergistic catalysis of Sn/SiO2 and the Ni3Sn4 alloy, cellulose was efficiently converted into acetol. This work provides guidance for the selective conversion of cellulose into C3 products.
Role of the Strong Lewis Base Sites on Glucose Hydrogenolysis
Yazdani, Parviz,Wang, Bo,Gao, Feng,Kawi, Sibudjing,Borgna, Armando
, p. 3845 - 3853 (2018/07/31)
This work reports the individual role of strong Lewis base sites on catalytic conversion of glucose hydrogenolysis to acetol/lactic acid, including glucose isomerisation to fructose and pyruvaldehyde rearrangement/hydrogenation to acetol/lactic acid. Las
Hydrothermally Stable Ruthenium–Zirconium–Tungsten Catalyst for Cellulose Hydrogenolysis to Polyols
Lucas, Martin,Fabi?ovicová, Katarina,Claus, Peter
, p. 612 - 618 (2017/12/28)
In this work, we describe a catalytic material based on a zirconium–tungsten oxide with ruthenium for the hydrogenolysis of microcrystalline cellulose under hydrothermal conditions. With these catalysts, polyols can be produced with high yields. High and stable polyol yields were also achieved in recycling tests. A catalyst with 4.5 wt % ruthenium in total achieved a carbon efficiency of almost 100 %. The prepared Zr-W oxide is mesoporous and largely stable under hydrothermal conditions (493 K and 65 bar hydrogen). Decomposition into the components ZrO2 and WO3 could be observed at temperatures of 1050 K in air.
METHOD FOR PRODUCING ISOPROPANOL BY CATALYTIC CONVERSION OF CELLULOSE
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Page/Page column 14, (2017/07/13)
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℃.
