- STUDY OF NITRATION EQUILIBRIUM IN THE GLYCERIN-AQUEOUS NITRIC ACID SYSTEM. 1. DEPENDENCE OF THE EQUILIBRIUM CONSTANTS OF NITRATION REACTIONS ON THE TEMPERATURE, ACIDITY OF THE MEDIUM, AND STRUCTURE OF THE NITRATED COMPOUND
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The equilibrium constants of seven sequential-parallel reactions of conversion of glycerin into glycerin trinitrate in aqueous HNO3 were measured.The effect of the acidity of the medium on the equilibrium nitration constants is correlated with processes of protonation of glycerin and its nitrates.The equilibrium nitration constants are higher for primary hydroxides than for secondary hydroxides, and they decrease in both series in going from glycerin to its dinitrates.
- Kazakov, A. I.,Lagodzinskaya, G. V.,Andrienko, L. P.,Yunda, N. G.,Korolev, A. M.,et al.
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- Reduction of nitroglycerin with elemental iron: Pathway, kinetics, and mechanisms
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Nitroglycerin (NG) is a nitrate ester used in dynamites, propellants, and medicines and is therefore a common constituent in propellant-manufacturing and pharmaceutical wastewaters. In this study we investigated the reduction of NG with cast iron as a potential treatment method. NG was reduced stepwise to glycerol via 1,2- and 1,3-dinitroglycerins (DNGS) and 1- and 2-mononitroglycerins (MNGs). Nitrite was released in each reduction step and was further reduced to NH4+. Adsorption of NG and its reduction products to cast iron was minimal. A reaction pathway and a kinetic model for NG reduction with cast iron were proposed. The estimated surface area-normalized reaction rate constants for NG and NO2- were (1.65 ± 0.30) × 10-2 (L·m -2·h-1) and (0.78 ± 0.09) × 10 -2 (L·m-2·h-1), respectively. Experiments using dialysis cell with iron and a graphite sheet showed that reduction of NG to glycerol can be mediated by graphite. However, reduction of NO2- mediated by graphite was very slow. NG and NO 2- were also found to reduce to glycerol and NH 4+ by Fe2+ in the presence of magnetite but not by aqueous Fe2+ or magnetite alone. These results indicate that in a cast iron-water system NG may be reduced via multiple mechanisms involving different reaction sites, whereas nitrite is reduced mainly by iron and/or adsorbed Fe2+. The study demonstrates that iron can rapidly reduce NG to innocuous and biodegradable end products and represents a new approach to treat NG-containing wastewaters.
- Oh, Seok-Young,Cha, Daniel K.,Kim, Byung J.,Chiu, Pei C.
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- A Kinetic Model for the Epoxidation of Allyl Alcohol with Hydrogen Peroxide on Titanium Silicate TS-1
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The kinetic regularities of the oxidation of allyl alcohol into glycidol in the presence of titanium silicate are studied at varied initial concentrations of the reagents, products, and temperature. The probable mechanism is used as the basis to develop a substantial kinetic model, which adequately describes the obtained experimental data.
- Sulimov,Danov,Ovcharova,Flid,Bruk
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- Permanganate oxidation of unsaturated alcohols in alkaline media
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A study was made on permanganate oxidation of olefinic and acetylenic alcohols in aqueous alkali media. Deprotonation constants of alcohols can be calculated from the kinetic data. The rate constant of alkoxide group oxidation exceeded that of the unsaturated bond. For oxidation of the alcoholic group a mechanism based on hydride ion transfer is proposed.
- Jaky, Miklos,Simon-Trompler, Edit
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- Removal of TBDMS protecting groups from carbohydrates using catalytic transfer hydrogenation
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Catalytic transfer hydrogenation provides a simple and convenient method for the cleavage of TBDMS ethers from both primary and secondary hydroxyl groups.
- Cormier
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- Dual mechanism of zinc-proline catalyzed aldol reactions in water
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The aldol reaction of acetone with aldehydes in aqueous medium under catalysis by zinc-proline (Zn(l-Pro)2) and secondary amines such as proline, (2S,4R)-4-hydroxyproline (Hyp) and (S)-(+)-1-(2-pyrrolidinomethyl) pyrrolidine (PMP) is shown to proceed by an enamine mechanism, as evidenced by reductive trapping of the iminium intermediate, while the aldol reaction of dihydroxyacetone (DHA) under catalysis by zinc-proline and by general bases such as N-methylmorpholine (NMM) is shown to occur under rate-limiting deprotonation of the α-carbon and formation of an enolate intermediate. The Royal Society of Chemistry 2006.
- Kofoed, Jacob,Darbre, Tamis,Reymond, Jean-Louis
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- Broadband laser-based mid-IR spectroscopy for analysis of proteins and monitoring of enzyme activity
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Laser-based infrared (IR) spectroscopy is an emerging key technology for the analysis of solutes and for real-time reaction monitoring in liquids. Larger applicable pathlengths compared to the traditional gold standard Fourier transform IR (FTIR) spectroscopy enable robust measurements of analytes in a strongly absorbing matrix such as water. Recent advancements in laser development also provide large accessible spectral coverage thus overcoming an inherent drawback of laser-based IR spectroscopy. In this work, we benchmark a commercial room temperature operated broadband external cavity-quantum cascade laser (EC-QCL)-IR spectrometer with a spectral coverage of 400 cm?1 against FTIR spectroscopy and showcase its application for measuring the secondary structure of proteins in water, and for monitoring the lipase-catalyzed saponification of triacetin. Regarding the obtained limit of detection (LOD), the laser-based spectrometer compared well to a research-grade FTIR spectrometer employing a liquid nitrogen cooled detector. With respect to a routine FTIR spectrometer equipped with a room temperature operated pyroelectric detector, a 15-fold increase in LOD was obtained in the spectral range of 1600–1700 cm?1. Characteristic spectral features in the amide I and amide II region of three representative proteins with different secondary structures could be measured at concentrations as low as 0.25 mg mL?1. Enzymatic hydrolysis of triacetin by lipase was monitored, demonstrating the advantage of a broad spectral coverage for following complex chemical reactions. The obtained results in combination with the portability and small footprint of the employed spectrometer opens a wide range of future applications in protein analysis and industrial process control, which cannot be readily met by FTIR spectroscopy without recurring to liquid nitrogen cooled detectors.
- Schwaighofer, Andreas,Akhgar, Christopher K.,Lendl, Bernhard
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- Lysophospholipases cooperate to mediate lipid homeostasis and lysophospholipid signaling
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Abstract Lysophospholipids (LysoPLs) are bioactive lipid species involved in cellular signaling processes and the regulation of cell membrane structure. LysoPLs are metabolized through the action of lysophospholipases, including lysophospholipase A1 (LYPLA1) and lysophospholipase A2 (LYPLA2). A new X-ray crystal structure of LYPLA2 compared with a previously published structure of LYPLA1 demonstrated near-identical folding of the two enzymes; however, LYPLA1 and LYPLA2 have displayed distinct substrate specificities in recombinant enzyme assays. To determine how these in vitro substrate preferences translate into a relevant cellular setting and better understand the enzymes’ role in LysoPL metabolism, CRISPR-Cas9 technology was utilized to generate stable KOs of Lypla1 and/or Lypla2 in Neuro2a cells. Using these cellular models in combination with a targeted lipidomics approach, LysoPL levels were quantified and compared between cell lines to determine the effect of losing lysophospholipase activity on lipid metabolism. This work suggests that LYPLA1 and LYPLA2 are each able to account for the loss of the other to maintain lipid homeostasis in cells; however, when both are deleted, LysoPL levels are dramatically increased, causing phenotypic and morphological changes to the cells.—Wepy, J. A., James J. Galligan, P. J. Kingsley, S. Xu, M. C. Goodman, K. A. Tallman, C. A. Rouzer, and L. J. Marnett. Lysophospholipases cooperate to mediate lipid homeostasis and lysophospholipid signaling.
- Wepy, James A.,Galligan, James J.,Kingsley, Philip J.,Xu, Shu,Goodman, Michael C.,Tallman, Keri A.,Rouzer, Carol A.,Marnett, Lawrence J.
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- The structure and prebiotic activity of arabinogalactan from Ferula Kuhistаnica
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Acidic arabinogalactan with molecular weight 36 kDa was isolated from the aerial part of Ferula kuhistаnica, the monosaccharide composition of which is represented by galactose and arabinose in a ratio of 3.6:1. The chemical and spectral methods revealed a main polymer chain consisting of (1 → 6) β-galactopyranose residues, where in position of C-3 were the residues of α-arabinofuranose and its 1,5-linked oligomers, as well as β-GlcpA-4-OMe-(1 → 6)-β-Galp-(1→ fragments. In addition, a small part of the main chain carries monosaccharide residues of β-Galp-(1→ in position C-2. The effect of arabinogalactan on the growth of an associative culture of bifidobacteria and some mono-strains of lactobacilli was studied and it was shown that it exhibits more effective prebiotic activity.
- Rakhmanberdyeva,Shashkov,Bobakulov, Kh.M.,Azizov,Malikova, M.Kh.,Ogay
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- Influence of impurities on the epoxidation of allyl alcohol to glycidol with hydrogen peroxide over titanium silicate TS-1
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The epoxidation of allyl alcohol to glycidol by hydrogen peroxide over titanium silicate TS-1 ZSM-5 has been studied under conditions relevant for an industrial-scale process. In particular, the effects of different solvents, impurities and some side reactions known to occur due to those impurities have been examined. It was found that certain aldehydes (in particular, acrolein) are especially detrimental to glycidol yield. Conversely, some of the impurities added to the reaction mixture were found to promote the conversion of allyl alcohol. Possible mechanisms for this are discussed.
- Harvey, Luke,Kennedy, Eric,Dlugogorski, Bogdan Z.,Stockenhuber, Michael
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- Production of C3 platform chemicals from CO2 by genetically engineered cyanobacteria
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Platform chemicals can be readily converted into various value-added chemicals and fuels. Photosynthetic production of platform chemicals directly from CO2 by cyanobacteria, in the presence of sunlight, holds promise for addressing global energy and environmental concerns. Herein, we report the photosynthetic production of C3 platform chemicals using engineered Synechococcus elongatus PCC7942 as the kernel. The engineered S. elongatus strain YW1 expressing glycerol-3-phosphatase produced a C3 intermediate, glycerol, with a high concentration of 1.17 g L-1 and a maximum production rate of 7733 μg L-1 H-1. Strain YW1 could serve as the kernel for the production of various C3 chemicals. By extending heterologous pathways in the cyanobacterial kernel, the carbon flux was further channelled to produce two platform chemicals: dihydroxyacetone by introducing glycerol dehydrogenase and 3-hydroxypropionic acid by introducing glycerol dehydratase and aldehyde dehydrogenase. Co-cultivation of the cyanobacterial kernel and another microbe, Klebsiella pneumoniae, was also performed to convert the C3 intermediate produced from CO2 to 1,3-propanediol, an important monomer for biodegradable material production. Besides direct photosynthetic production and co-cultivation, we demonstrated that glycerol produced by the cyanobacterial kernel can be used as a fermentation feedstock after simple concentration. The production processes presented here display great potential for carbon capture and storage and for sustainable production of chemicals and fuels.
- Wang, Yu,Tao, Fei,Ni, Jun,Li, Chao,Xu, Ping
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- An Alkene-Forming Cascade Reaction en Route to 2,2'-Bi(glycerol)
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Synthesis of 2,3-bis(hydroxymethyl)butane-1,2,3,4-tetraol is of great interest because of its utility as a potential precursor to new dendrimers, in the preparation of unnatural lipids, and in the synthesis of open-framework coordination polymers. Synthesis of this new six-hydroxyl compound is achieved in four steps from commercially available starting materials. In this process, a new olefin-forming cascade reaction was discovered.
- Li, Xiaoxun,Livant, Peter D.,Chen, Jianjun
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- Molecular analysis of NAD+-dependent xylitol dehydrogenase from the zygomycetous fungus Rhizomucor pusillus and reversal of the coenzyme preference
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The zygomycetous fungus Rhizomucor pusillus NBRC 4578 is able to ferment not only D-glucose but also D-xylose into ethanol. Xylitol dehydrogenase from R. pusillus NBRC 4578 (RpXDH), which catalyzes the second step of D-xylose metabolism, was purified, and its enzymatic properties were characterized. The purified RpXDH preferred NAD+ as its coenzyme and showed substrate specificity for xylitol, D-sorbitol, and ribitol. cDNA cloning of xyl2 gene encoding RpXDH revealed that the gene included a coding sequence of 1,092 bp with a molecular mass of 39,185 kDa. Expression of the xyl2 in R. pusillus NBRC 4578 was induced by D-xylose, and the expression levels were increased with accumulation of xylitol. The xyl2 gene was expressed in Escherichia coli, and coenzyme preference of the recombinant RpXDH was reversed from NAD+ to NADP+ in the double mutant D205A/I206R by site-directed mutagenesis.
- Yamasaki-Yashiki, Shino,Komeda, Hidenobu,Hoshino, Kazuhiro,Asano, Yasuhisa
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- Transesterification of triacetin with methanol on various solid acid catalysts: A role of catalyst properties
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Present studies concentrated on a comparison of catalytic performance of number of solid acid catalysts, namely Amberlyst-15, Nafion-SAC-13, polyaniline-sulfate, silver and cesium salts of H3PW 12O40 in transesterifiaction of triglycerides with methanol. Reaction was studied for triacetin, the short triglyceride and for castor oil consisting of vegetable fatty acid esters under mild reaction conditions (atmospheric pressure, 50 °C). The catalysts were characterized by measuring textural (specific surface area, porosity, pore diameter) and acid (concentration and the strength of acid centers) properties. The affinity of catalyst to highly hydrophobic triglyceride reactant relative to that toward rather hydrophilic glycerol was also evaluated from the measurements of contact angles for droplets of triacetin, castor oil and glycerol on the surface of pressed tablet of catalyst. This affinity of catalysts was also evaluated from the drop of catalyst activity induced by glycerol added to the reaction mixture or by pre-treatment of catalyst with triacetin. Cs2HPW 12O40 salt was the most active catalyst, but it deactivated in the transesterification. The highest strength of acid sites and high affinity to glycerol was determined for this Cs salt. Thus, affinity of studied catalysts toward glycerol and the strength of acid sites seem to be decisive factors for their activity and in particular for deactivation due to polar reagents adsorption. Greater affinity toward glycerol and higher strength of acid sites, deactivation of catalysts would be easier.
- Zi?ba,Drelinkiewicz,Chmielarz,Matachowski,Stejskal
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- Synthesis and biological properties of dicationic arginine-diglycerides
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A novel family of dicationic arginine-diglyceride surfactants, 1,2-diacyl-3-O-(L-arginyl)-rac-glycerol·2HCl (XXR) with alkyl chain lengths in the range of C8-C14 was prepared. These new surfactants can be regarded as analogues of lecithins. They have two hydrophobic tails of identical fatty acid chains attached to the glycerol through ester bonds and a dicationic polar head from arginine instead of the zwitterionic on the lecithins. These new compounds can be classified as multifunctional surfactants with self-aggregation behaviour comparable to that of short-chain lecithins. They have antimicrobial activity similar to that of the conventional cationic surfactants and are as harmless as amphoteric betaines.
- Perez,Pinazo,Vinardell,Clapes,Angelet,Infante
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- Preparation of KF-La2O2CO3 solid base catalysts and their excellent catalytic activities for transesterification of tributyrin with methanol
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A series of 25% KF-La2O2CO3 catalysts (25-KF-LOC-x, x = 673, 723 and 773) were prepared at different calcination temperatures, which were tested as basic catalysts for the transesterification of tributyrin with methanol to produce methyl butyrate and characterized by means of XRD, SEM, CO2-TPD, FTIR, XPS and XRF. It was found that the calcination temperature greatly influences the catalytic activity, and its order is 25-KF-LOC-673 a very high activity, and the conversion of tributyrin is nearly 100%, the yield of methyl butyrate reaches 94% at 308 K. The activation energy of the 25-KF-LOC-773 catalyst is as low as 55.03 kJ mol-1. The excellent catalytic activity of the 25-KF-LOC-773 catalyst can be attributed to the largest amount of surface hydroxyl among these 25-KF-LOC-x catalysts. The results indicate that the Bronsted base is the main active site at low reaction temperature. The recycling use and stability have been investigated over the 25-KF-LOC-773 catalyst. The results indicate that the 25-KF-LOC-773 catalyst has a high stability after being stored for 90 days. The deactivation of the used 25-KF-LOC-773 catalyst at 308 K is due to the loss of hydroxyl on the surface. However, the conversion of tributyrin can reach 91%, and the yield of methyl butyrate also can achieve 64% when the transesterification reaction is performed at 338 K over the second used 25-KF-LOC-773 catalyst. It indicates that the second used 25-KF-LOC-773 catalyst still possesses good catalytic activity at the higher reaction temperature due to the unchanged strong Lewis basic sites provided with surface oxygen anions. the Partner Organisations 2014.
- Jiang, Wen,Niu, Xiaoyu,Yuan, Fulong,Zhu, Yujun,Fu, Honggang
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- Production and characterization of Escherichia coli glycerol dehydrogenase as a tool for glycerol recycling
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NAD+-dependent glycerol (Gro) dehydrogenase (GroDHase) catalyzes the conversion of Gro into dihydroxyacetone (DHA), the first step for fermentative Gro metabolism in Escherichia coli. In this work, we cloned the gldA gene that codes for the E. coli GroDHase and homologously expressed, purified, and kinetically characterized the recombinant protein. To achieve this, the enzyme was over-produced using Gro supplemented growth medium and lactose as the inducer. The enzyme was highly purified using either pseudo-affinity chromatography or a simple heat-shock treatment, which is potentially valuable for industrial production of GroDHase. We detected efficient oxidation of Gro derived from biodiesel production to DHA by gas chromatography. The results presented in this work support recombinant GroDHase production in a biorefinery setting as a relevant tool for converting Gro into DHA for future biotechnological applications.
- Piattoni, Claudia Vanesa,Figueroa, Carlos María,Asención Diez, Matías Damián,Parcerisa, Ivana Lorna,Antu?a, Sebastián,Comelli, Raúl Alberto,Guerrero, Sergio Adrián,Beccaria, Alejandro José,Iglesias, Alberto álvaro
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- Preparation, characterization, and catalytic testing of different Me–chitosan complexes for triglycerides transesterification
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A number of homogeneous and heterogenized chitosan complexes with different metals (Zn, Co, Ca, Ni, Sn, Pb) were synthesized and tested as catalysts in the reaction of transesterification of tributyrin simulating the process of biodiesel production from renewable natural feedstock (triglycerides, vegetable oils). It is found that chitosan complexes are effective catalysts for transformation of tributyrin into the corresponding esters. The comparative analysis of Me–chitosan (homogeneous), Me–chitosan (heterogeneous) and Me–chitosan/SiO2 catalysts testify that the efficiency of three-component egg-shell systems is close to that of homogeneous catalysts.
- Finashina,Kramareva,Kucherov,Tkachenko,Kustov
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- Polysaccharides from Peptostreptococcus anaerobius and structure of the species-specific antigen.
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The cell-envelope antigens of Peptostreptococcus anaerobius were extracted from intact cells by autoclave or alkaline treatment. The purified species-specific antigen (G) was identified among several polysaccharides obtained from the extracts by successive treatments with ribonuclease and pronase followed by ion-exchange and gel-filtration chromatography. G was investigated by 13C- and 31P-n.m.r. spectroscopy, titrimetry, elemental analysis, and gas-liquid chromatography. Oxidation of G with NaIO4 followed by reduction with NaBH4 and mild acid hydrolysis yielded the Smith degradation product of G (GS). Treatment of G and GS with 48% HF gave the respective dephosphorylated products GF and GSF. The structures of GS, GF, and GSF were investigated by 13C-n.m.r. spectroscopy, methylation analysis, and gas-liquid chromatography-mass spectrometry. The principal constituents of G were 2-acetamido-2-deoxy-D-glucose (D-GlcNAc), D-glyceric acid, and phosphate as a diester, in the ratio 2:1:1, and a minor amount of D-glucose (beta-D-Glcp). GS contained D-GlcNAc, D-glyceric acid, glycerol, and phosphate in a 1:1:1:1 ratio. GF and GSF contained D-GlcNAc and D-glyceric acid in the ratios 2:1 and 1:1, respectively. A structure for the principal repeating unit of polymeric G compatible with the analytical data consists of alpha-D-GlcpNAc-(1----3)-alpha-D-GlcpNAc-(1----2)-D-glyceric acid units linked through C-6'-C-6" phosphate diester bridges. This structure is novel for two reasons: (a) unsubstituted glyceric acid residues occur as aglycons in the repeating structure, and (b) phosphate diester bridges link nonanomeric glycose carbons in a non-nucleic acid polymer. The structural role of the minor amount of beta-D-Glcp in G remains unknown.
- Stortz,Cherniak,Jones,Treber,Reinhardt
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- The activating oxydianion binding domain for enzyme-catalyzed proton transfer, hydride transfer, and decarboxylation: Specificity and enzyme architecture
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The kinetic parameters for activation of yeast triosephosphate isomerase (ScTIM), yeast orotidine monophosphate decarboxylase (ScOMPDC), and human liver glycerol 3-phosphate dehydrogenase (hlGPDH) for catalysis of reactions of their respective phosphodianion truncated substrates are reported for the following oxydianions: HPO32-, FPO32-, S2O32-, SO42- and HOPO32-. Oxydianions bind weakly to these unliganded enzymes and tightly to the transition state complex (E?S?), with intrinsic oxydianion Gibbs binding free energies that range from -8.4 kcal/mol for activation of hlGPDH-catalyzed reduction of glycolaldehyde by FPO32- to -3.0 kcal/mol for activation of ScOMPDC-catalyzed decarboxylation of 1-β-D-erythrofuranosyl)orotic acid by HOPO32-. Small differences in the specificity of the different oxydianion binding domains are observed. We propose that the large -8.4 kcal/mol and small -3.8 kcal/mol intrinsic oxydianion binding energy for activation of hlGPDH by FPO32- and S2O32-, respectively, compared with activation of ScTIM and ScOMPDC reflect stabilizing and destabilizing interactions between the oxydianion -F and -S with the cationic side chain of R269 for hlGPDH. These results are consistent with a cryptic function for the similarly structured oxydianion binding domains of ScTIM, ScOMPDC and hlGPDH. Each enzyme utilizes the interactions with tetrahedral inorganic oxydianions to drive a conformational change that locks the substrate in a caged Michaelis complex that provides optimal stabilization of the different enzymatic transition states. The observation of dianion activation by stabilization of active caged Michaelis complexes may be generalized to the many other enzymes that utilize substrate binding energy to drive changes in enzyme conformation, which induce tight substrate fits. (Table Presented).
- Reyes, Archie C.,Zhai, Xiang,Morgan, Kelsey T.,Reinhardt, Christopher J.,Amyes, Tina L.,Richard, John P.
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- Selective Formation of Triose from Formaldehyde catalysed by Ethylbenzothiazolium Bromide
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Dihydroxyacetone was obtained selectively by condensation of formaldehyde using 3-ethylbenzothiazolium bromide as a catalyst in the presence of base.
- Matsumoto, Toshihiko,Inoue, Shohei
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- Functional investigation and applications of the acetylesterase activity of the Citrus sinensis (L.) Osbeck peel
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The hydrolysis of acetyl moieties on a set of commercially relevant substrates was performed by employing the whole tissue of Citrus sinensis (L.) Osbeck peel as an efficient biocatalyst in mild reaction conditions with high degree of regioselectivity. The reaction is done in aqueous media and the product is easily recovered. Optimal reaction conditions were deduced and two practical applications were investigated: the elaboration of acetylglicerols and the preparation of vitamin K1 precursor. Peel waste (flavedo and albedo) from orange juice manufacturing was successfully employed as a biocatalyst.
- Fontana, Gianfranco,Bruno, Maurizio,Maggio, Antonella,Rosselli, Sergio
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supporting information
p. 4502 - 4507
(2020/03/16)
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- Biochemical characterization of a recombinant acid phosphatase from Acinetobacter baumannii
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Genomic sequence analysis of Acinetobacter baumannii revealed the presence of a putative Acid Phosphatase (AcpA; EC 3.1.3.2). A plasmid construct was made, and recombinant protein (rAcpA) was expressed in E. coli. PAGE analysis (carried out under denaturing/ reducing conditions) of nickel-affinity purified protein revealed the presence of a nearhomogeneous band of approximately 37 kDa. The identity of the 37 kDa species was verified as rAcpA by proteomic analysis with a molecular mass of 34.6 kDa from the deduced sequence. The dependence of substrate hydrolysis on pH was broad with an optimum observed at 6.0. Kinetic analysis revealed relatively high affinity for PNPP (Km = 90 μM) with Vmax, kcat, and Kcat/Km values of 19.2 pmoles s-1, 4.80 s-1(calculated on the basis of 37 kDa), and 5.30 × 104 M-1s-1, respectively. Sensitivity to a variety of reagents, i.e., detergents, reducing, and chelating agents as well as classic acid phosphatase inhibitors was examined in addition to assessment of hydrolysis of a number of phosphorylated compounds. Removal of phosphate from different phosphorylated compounds is supportive of broad, i.e., 'nonspecific' substrate specificity; although, the enzyme appears to prefer phosphotyrosine and/or peptides containing phosphotyrosine in comparison to serine and threonine. Examination of the primary sequence indicated the absence of signature sequences characteristic of Type A, B, and C nonspecific bacterial acid phosphatases.
- Smiley-Moreno, Elizabeth,Smith, Douglas,Yu, Jieh-Juen,Cao, Phuong,Arulanandam, Bernard P.,Chambers, James P.
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- Well-defined Cp*Co(III)-catalyzed Hydrogenation of Carbonates and Polycarbonates
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We herein report the catalytic hydrogenation of carbonates and polycarbonates into their corresponding diols/alcohols using well-defined, air-stable, high-valent cobalt complexes. Several novel Cp*Co(III) complexes bearing N,O-chelation were isolated for the first time and structurally characterized by various spectroscopic techniques including single crystal X-ray crystallography. These novel Co(III) complexes have shown excellent catalytic activity to produce value added diols/alcohols from carbonate and polycarbonates through hydrogenation using molecular hydrogen as sole reductant or iPrOH as transfer hydrogenation source. To demonstrate the developed methodology's practical applicability, we have recycled the bisphenol A monomer from compact disc (CD) through hydrogenation under the established reaction conditions using phosphine-free, earth-abundant, air- and moisture-stable high-valent cobalt catalysts.
- Dahiya, Pardeep,Gangwar, Manoj Kumar,Sundararaju, Basker
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p. 934 - 939
(2020/12/15)
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- Product Control and Insight into Conversion of C6 Aldose Toward C2, C4 and C6 Alditols in One-Pot Retro-Aldol Condensation and Hydrogenation Processes
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Alcohols have a wide range of applicability, and their functions vary with the carbon numbers. C6 and C4 alditols are alternative of sweetener, as well as significant pharmaceutical and chemical intermediates, which are mainly obtained through the fermentation of microorganism currently. Similarly, as a bulk chemical, C2 alditol plays a decisive role in chemical synthesis. However, among them, few works have been focused on the chemical production of C4 alditol yet due to its difficult accumulation. In this paper, under a static and semi-flowing procedure, we have achieved the product control during the conversion of C6 aldose toward C6 alditol, C4 alditol and C2 alditol, respectively. About C4 alditol yield of 20 % and C4 plus C6 alditols yield of 60 % are acquired in the one-pot conversion via a cascade retro-aldol condensation and hydrogenation process. Furthermore, in the semi-flowing condition, the yield of ethylene glycol is up to 73 % thanks to its low instantaneous concentration.
- Gao, Lou,Hou, Wenrong,Hui, Yingshuang,Tang, Yi,Zhan, Yulu,Zhang, Yahong
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p. 560 - 566
(2021/06/25)
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- Novel method for producing 2-amino-1, 3-propylene glycol by JIT method
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The invention belongs to the field of fine chemical engineering, and relates to a novel method for producing 2-amino-1, 3-propylene glycol by a JIT method, the novel method is composed of a catalytic chlorination reaction and a catalytic amination reaction, glycerol is chlorinated by hydrogen chloride under the catalysis of zinc chloride to obtain 2-chloro-1, 3-propylene glycol, and the 2-chloro-1, 3-propylene glycol is subjected to a catalytic reaction by urotropin to obtain 2-chloro-1, 3-propylene glycol.
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Paragraph 0052-0054
(2021/11/26)
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- A mild and convenient approach for selective acetonide cleavage involved in carbohydrate synthesis using PPA-SiO2
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Here, we report a highly selective, efficient and rapid method for the selective cleavage of primary acetonide using silica supported polyphosphoric acid (PPA-SiO2) for various carbohydrate substrates. Corresponding diols were obtained in good to excellent yields within 30 min using PPA-SiO2. Overall, PPA-SiO2 was found to be a useful catalyst for selective acetonide cleavage in carbohydrate substrates which may expand its utility in organic synthesis.
- Nikam, Rahul R.,Gore, Kiran R.
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- Selective hydrogenolysis of biomass-derived sorbitol to propylene glycol and ethylene glycol on in-situ formed PdZn alloy catalysts
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Sorbitol hydrogenolysis to industrially important propylene glycol and ethylene glycol receives increasing attention, recently. Here, we developed an efficient and stable PdZn alloy catalyst, in-situ formed from a physical mixture of Pd/ZrO2 and ZnO, for the sorbitol hydrogenolysis with Mg3AlOx as a solid base, and obtained a 54.6% yield of the two target glycols (493 K and 5.0 MPa H2). The amounts of ZnO and Mg3AlOx strongly influenced the activity and selectivity, due to their effects on the formation of the PdZn alloys and the competitive metal-catalyzed dehydrogenation/hydrogenation and base-catalyzed retro-aldol condensation steps. The kinetic isotope effects, combined with the inhibiting effects of H2 pressure on the activity in a broad range (3.0–8.0 MPa), confirm that the sorbitol dehydrogenation to hexose intermediates is the kinetically-relevant step in the sorbitol hydrogenolysis. This study provides insights into the catalytic functions and reaction parameters for the hydrogenolysis of polyols to the target glycols.
- Jia, Yuqing,Liu, Haichao,Sun, Qianhui
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- Boron oxide modified bifunctional Cu/Al2O3 catalysts for the selective hydrogenolysis of glucose to 1,2-propanediol
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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.
- Liu, Chengwei,Shang, Yaning,Wang, Shen,Liu, Xin,Wang, Xianzhou,Gui, Jianzhou,Zhang, Chenghua,Zhu, Yulei,Li, Yongwang
-
-
- Hydrogenolysis of biomass-derived sorbitol over la-promoted ni/zro2 catalysts
-
Ni/La2O3/ZrO2 catalysts were prepared by a step-by-step impregnation method through regulation of the contents of the active component and alkali. The introduction of an alkaline promoter not only enhanced the alkalinity of the catalyst but also improved the dispersion of Ni on the catalyst owing to the strong interaction between Ni2+ and alkali promoter. The synergistic effect between Ni and La2O3 was beneficial to selective hydrogenolysis of sorbitol. Under the optimal reaction conditions, sorbitol conversion reached nearly 100% and target products (ethylene glycol, 1,2-propanediol, and glycerol) selectivity reached 74.8%. Metal-alkali coordination mechanism and possible pathways for target products formation were proposed.
- Cai, Chiliu,Wang, Haiyong,Xin, Haosheng,Zhu, Changhui,Zhang, Qi,Zhang, Xinghua,Wang, Chenguang,Liu, Qiying,Ma, Longlong
-
p. 3993 - 4001
(2020/02/04)
-
- A mechanism study on the efficient conversion of cellulose to acetol over Sn-Co catalysts with low Sn content
-
Efficient conversion of renewable cellulose to high value-added C3 chemicals is a great challenge in the field of biomass valorization. In this work, we found that the combination of Co and Sn could significantly improve the efficiency of cellulose conversion to acetol. 54.4% yield of acetol and 66.6% total yield of C3 products were obtained when using 2%Sn-10%Co/SiO2 (2 wt% Sn content) as a catalyst. However, using the same Sn content of 2%Sn-10%Ni/SiO2, no acetol and only 7.1% yield of C3 products were produced. By studying the effects of different Sn and Co concentrations on cellulose conversion, it was found that the Sn species play an important role in catalyzing glucose conversion to C3 intermediates, while Co mainly played a role in hydrogenation, the same as Ni. The study demonstrated that Sn-Co/SiO2 with low Sn content can convert glucose to C3 intermediates more efficiently than the Sn-Ni/SiO2 catalyst. Moreover, Sn-Co/SiO2 could effectively convert C3 intermediates to acetol at a high temperature which is essential for acetol production from cellulose; but under the same conditions, the Sn-Ni/SiO2 catalyst tended to catalyze the polymerization of C3 intermediates. A series of characterization methods including AAS, TEM, HRTEM, EDS, XRD, ex situ XPS, in situ XPS, and CO2-TPD found that the combination of Sn and Co could significantly increase the noninteger valent SnOx species in the catalyst. These species increased the basicity of the catalyst and were beneficial in catalyzing the isomerization of glucose and the retro-aldol condensation of fructose. This journal is
- Liu, Xiaodong,Liu, Xiaohao,Ma, Longlong,Wang, Haiyong,Xiao, Tianci,Zhang, Ying
-
p. 6579 - 6587
(2020/11/16)
-
- Merits of photocatalytic and antimicrobial applications of gamma-irradiated Co: XNi1- xFe2O4/SiO2/TiO2; X = 0.9 nanocomposite for pyridine removal and pathogenic bacteria/fungi disinfection: Implication for wastewater treatment
-
In this paper, we report a layer-by-layer approach for the preparation of a concentric recyclable composite (CoxNi1-xFe2O4/SiO2/TiO2; x = 0.9) designed for wastewater treatment. The prepared composite was investigated by X-ray diffraction spectroscopy, high-resolution transmission electron microscopy and scanning electron microscopy (SEM) supported with energy dispersive X-ray (EDX) spectroscopy to analyze crystallinity, average particle size, morphology and elemental composition, respectively. The antimicrobial activities of the prepared composite have been investigated against multi-drug-resistant bacteria and pathogenic fungi using a variety of experiments, such as zone of inhibition, minimum inhibitory concentration, biofilm formation and SEM with EDX analysis of the treated bacterial cells. In addition, the effects of gamma irradiation (with different doses) and UV irradiation on the antibacterial abilities of the prepared composite have been evaluated. Moreover, the effect of gamma irradiation on the crystallite size of the prepared composite has been studied under varying doses of radiation (25 kGy, 50 kGy and 100 kGy). Finally, the photocatalytic efficiency of the prepared composite was tested for halogen-lamp-assisted removal of pyridine (artificial wastewater). Various parameters affecting the efficiency of the photocatalytic degradation, such as photocatalyst dose, pyridine concentration, pH, point of zero charge and the presence of hydrogen peroxide, have been studied. Our results show that the synthesized composite has a well-crystallized semi-spherical morphology with an average particle size of 125.84 nm. In addition, it possesses a high degree of purity, as revealed by EDX elemental analysis. Interestingly, the prepared composite showed promising antibacterial abilities against almost all the tested pathogenic bacteria and unicellular fungi, and this was further improved after gamma and UV irradiation. Finally, the prepared composite was very efficient in the light-assisted degradation of pyridine and its degradation efficiency can be tuned based on various experimental parameters. This work provides a revolutionary nanomaterial-based solution for the global water shortage and water contamination by offering a new wastewater treatment technique that is recyclable, cost effective and has an acceptable time and quality of water.
- Abd Elkodous, M.,El-Batal, Ahmed I.,El-Khawaga, Ahmed M.,El-Sayyad, Gharieb S.,Elsayed, Mohamed A.,Gobara, Mohamed
-
p. 5241 - 5259
(2020/02/19)
-
- Facile synthesis of digestible , rigid-and-flexible, bio-based building block for high-performance degradable thermosetting plastics
-
Plastics are indispensable in modern society, but are non-sustainable resources, releasing hazardous chemicals during their service life, and post-disposal issues make traditional plastics a risk. Herein, we report a digestible , rigid-and-flexible, bio-sourced building block for high-performance degradable plastics. This building block was synthesized from the bioresources vanillin (lignin derivative) and glycerol through solvent-free acetalization with a high conversion rate and high selectivity. It could be extremely rapidly degraded into non-toxic vanillin and glycerol under mild acidic conditions even at a similar pH and temperature to gastric juice in the human stomach ( digested ), resulting in the outstanding chemical degradability of its corresponding epoxy thermosets, which is beneficial for their recycling. By virtue of the benzene ring, heterocycle, and methoxyl group-related hydrogen bond, the degradable thermosetting plastic showed much higher mechanical properties (stronger and tougher) and comparable thermal properties relative to a commercial high-performance counterpart based on bisphenol A (BPA). This favorable performance combination has never been reported for plastics. Thus, this bio-derived building block exhibits great potential as a sustainable and upgraded alternative to petroleum-sourced aromatic chemicals such as BPA for high-performance plastics.
- Wang, Binbo,Ma, Songqi,Li, Qiong,Zhang, Hua,Liu, Junjie,Wang, Rong,Chen, Zhiquan,Xu, Xiwei,Wang, Sheng,Lu, Na,Liu, Yanlin,Yan, Shifeng,Zhu, Jin
-
supporting information
p. 1275 - 1290
(2020/03/11)
-
- Magnesium-catalyzed hydroboration of organic carbonates, carbon dioxide and esters
-
A low-valent magnesium(i) complex [(XylNacnac)Mg]2 was employed as a highly efficient precatalyst for the hydroboration of a variety of cyclic and linear organic carbonates, polycarbonates, CO2 and esters with HBpin under mild conditions. The resultant boronates can be used for the preparation of the corresponding value-added diols, triols or alcohols through hydrolysis.
- Cao, Xu,Lu, Kai,Ma, Mengtao,Wang, Weifan,Xue, Fei,Yao, Weiwei
-
supporting information
p. 2776 - 2780
(2020/03/13)
-
- Catalytic Hydrogenolysis of Solketal on Bifunctional Catalysts with Production of High Octane Components of Motor Fuels
-
The possibility of implementing the concept of converting bioglycerin into a blend of oxygenates, potentially applicable as components of gasoline by ketalization with acetone (T = 30°C–40°C, atmospheric pressure), accompanied by mild hydrogenolysis of ketal [T = 100°C–140°C, p(H2) = 2 MPa] to obtain a mixture of of glycerol and solketal isopropyl ethers was demonstrated. Results showed that the preferred method of conversion was the separate performing of ketalization and hydrogenolysis, since when these stages are combined, the side reaction of the formation of free isopropyl alcohol was highly selective. The regularities in the influence of the composition of the catalytic system (Pd/C + para-toluenesulfonic acid) on its activity were observed in the reaction of catalytic hydrogenation of solketal to a mixture of glycerol and solketal isopropyl ethers (optimal ratio of Pd/para-toluenesulfonic acid = 0.811 mol). The addition of 4%–5% glycerol to raw materials increased the yield of target hydrogenation products from 25% to 36%. Using a flow unit, the catalytic hydrogenation of solketal was optimized. In the optimal mode [T = 170°C, p(H2) = 4 MPa, v = 0.5 h?1, H2/feedstock = 660 nL L?1], the conversion of solketal to a mixture of target products (glycerol monoisopropyl ether, glycerol diisopropyl ethers, and solketal isopropyl ether) reached 98%. The possibility of carrying out the reaction on heterogeneous bifunctional catalysts of the Pd/sulfonated coal type was shown.
- Goncharova, A. V.,Knyazeva, M. I.,Maksimov, A. L.,Ni, D. S.,Ramazanov, D. N.,Samoilov, V. O.
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p. 108 - 117
(2020/03/27)
-
- ELECTROCHEMICAL METHODS AND SYSTEMS FOR PRODUCING MONOSACCHARIDES
-
The present disclosure is related to electrochemical methods of forming monosaccharides, and systems for generating the same. A benefit of the methods and systems disclosed herein can include the sustainable production of monosaccharides in an automated process. A benefit of the methods and systems herein can be the generation of monosaccharides from renewable source materials. An additional benefit of the methods and systems herein can include the use of abundant feedstocks, such as carbon dioxide, for the efficient generation of select monosaccharides for use as nutrients and for other useful applications. Another benefit of the methods and systems disclosed herein can include reduction of excess carbon dioxide from the environment.
- -
-
Paragraph 0067-0068
(2020/07/15)
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- Lipase-Powered Mesoporous Silica Nanomotors for Triglyceride Degradation
-
We report lipase-based nanomotors that are capable of enhanced Brownian motion over long periods of time in triglyceride solution and of degrading triglyceride droplets that mimic “blood lipids”. We achieved about 40 min of enhanced diffusion of lipase-modified mesoporous silica nanoparticles (MSNPs) through a biocatalytic reaction between lipase and its corresponding water-soluble oil substrate (triacetin) as fuel, which resulted in an enhanced diffusion coefficient (ca. 50 % increase) at low triacetin concentration (10 mm). Lipase not only serves as the power engine but also as a highly efficient cleaner for the triglyceride droplets (e.g., tributyrin) in PBS solution, which could yield potential biomedical applications, for example, for dealing with diseases related to the accumulation of triglycerides, or for environmental remediation, for example, for the degradation of oil spills.
- Wang, Lei,Hortel?o, Ana C.,Huang, Xin,Sánchez, Samuel
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p. 7992 - 7996
(2019/05/21)
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- Practical Cleavage of Acetals by Using an Odorless Thiol Immobilized on Silica
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A practical, efficient and general method was developed for the deprotection of a variety of aromatic and aliphatic acetals to their corresponding catechol or diol derivatives using thiol immobilized on silica gel. This is an application for the well-known commercial solid-supported thiol (SiliaMetS Thiol). The procedure is mild and amenable to scale-up. It does not require inert atmosphere and clean conversions were observed. This method is applicable to substituted 1,3-benzodioxole and aliphatic acetals with different functionalities. It offers the advantage of a general route with high yield, which can be undertaken at ambient temperature.
- de Léséleuc, Mylène,Kukor, Andrew,Abbott, Shaun D.,Zacharie, Boulos
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p. 7389 - 7393
(2019/12/03)
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- Reduction of Cyclic and Linear Organic Carbonates Using a Readily Available Magnesium Catalyst
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Efficient reduction of cyclic and linear organic carbonates catalyzed by a readily available earth alkaline catalyst has been achieved. The described homogenous reaction based on a ligand-free magnesium catalyst provides an indirect route for the conversion of CO2 into valuable alcohols. The reaction proceeds with high yields under mild reaction conditions, with low catalyst loading and short reaction times, and shows a broad applicability toward various linear and cyclic carbonates. Additionally, it can be applied for the depolymerization of polycarbonates.
- Szewczyk, Marcin,Magre, Marc,Zubar, Viktoriia,Rueping, Magnus
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p. 11634 - 11639
(2019/12/02)
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- SUGAR HYDROGENOLYSIS WITH MOLYBDENUM CO-CATALYST SELECTIVE FOR PRODUCING GLYCOLS
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A hydrogenolysis process is disclosed for directly converting a sugar feed comprised of a high fructose feedstock, a high sucrose feedstock, or a combination of these to a mixed lower polyols product including both propylene glycol and ethylene glycol. The process provides greater propylene glycol selectivity than ethylene glycol selectivity such that the propylene glycol is present to a greater extent than the ethylene glycol in the mixed lower polyols product. The sugar feed and a source of hydrogen are supplied to a reaction vessel and reacted in the presence of a hydrogenolysis catalyst comprising molybdenum (Mo) and ruthenium (Ru).
- -
-
Paragraph 44-49
(2019/08/29)
-
- Selective Conversion of Cellulose to Hydroxyacetone and 1-Hydroxy-2-Butanone with Sn–Ni Bimetallic Catalysts
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The high-value-added chemicals hydroxyacetone (HA) and 1-hydroxy-2-butanone (HB) were produced from agricultural waste over a Ni3Sn4-SnOx catalyst. The Sn–Ni intermetallic compound and SnOx acted as the active sites for HA and HB production by selectively cleaving the target C?C and C?O bonds. Approximately 70 % of the total HA and HB yield was obtained by selective hydrogenolysis of cellulose. This strategy expands the application of cellulose towards renewable production of high-value C3 and C4 keto-alcohols from cellulosic biomass.
- Wang, Haiyong,Zhu, Changhui,Liu, Qiying,Tan, Jin,Wang, Chenguang,Liang, Zheng,Ma, Longlong
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p. 2154 - 2160
(2019/03/21)
-
- Visible-light-driven selective oxidation of glucose in water with H-ZSM-5 zeolite supported biomimetic photocatalyst
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A new iron tetra(2,3-bis(butylthio)maleonitrile)porphyrazine (FePz(SBu)8)has been synthesized, then it was loaded on H-ZSM-5 zeolite to obtain a supported biomimetic photocatalyst H-ZSM-5/FePz(SBu)8. Using H2O2 as oxidant, the photocatalytic selective oxidation of glucose in water under visible light (λ ≥ 420 nm)irradiation was carried out in presence of H-ZSM-5/FePz(SBu)8. Under such conditions, the glucose can be efficiently converted into value-added chemicals such as glucaric acid, gluconic acid, arabinose, glycerol and formic acid. More importantly, in comparison with pure FePz(SBu)8 and pure H-ZSM-5 zeolite, the H-ZSM-5/FePz(SBu)8 exhibited a higher photocatalytic activity for glucose oxidation and the formation of glucaric acid was observed only when H-ZSM-5/FePz(SBu)8 was used, deriving from the synergistic effect between FePz(SBu)8 and H-ZSM-5 zeolite. Some reaction parameters of glucose oxidation catalyzed by the H-ZSM-5/FePz(SBu)8 were discussed, such as loading amount of FePz(SBu)8, H2O2:glucose ratio, glucose concentration, and so on. It was demonstrated that the Soret-band of FePz(SBu)8 contributed more to the visible light photocatalytic activity than the Q-band during the photocatalytic process. The stability of H-ZSM-5/FePz(SBu)8 during the photocatalytic process was further evaluated by the reusability test. In addition, the generation of reactive oxygen species was determined by electron spin resonance (ESR)technology and scavenger experiments. A possible reaction pathway of glucose oxidation was also discussed.
- Chen, Rui,Yang, Changjun,Zhang, Quanquan,Zhang, Bingguang,Deng, Kejian
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p. 297 - 305
(2019/05/24)
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- METHOD FOR THE PRODUCTION OF GLYCOLS FROM SORBITOL
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Implementations of the disclosed subject matter provide a process for producing ethylene glycol and propylene glycol from a sorbitol feed which may include contacting the sorbitol feed with hydrogen in a reactor in the presence of a solvent and a bi-functional catalyst system. The bi-functional catalyst system may include a first catalyst comprising a copper compound, a zinc compound, and an additional metal compound and a second catalyst comprising sodium carbonate.
- -
-
Paragraph 0038-0043; 0044-0046; 0047-0055
(2019/08/02)
-
- Laminaria digitata and palmaria palmata seaweeds as natural source of catalysts for the cycloaddition of CO2 to Epoxides
-
Seaweed powder has been found to act as an effective catalyst for the fixation of CO2 into epoxides to generate cyclic carbonates under solvent free conditions. Model background reactions were performed using metal halides and amino acids typically found in common seaweeds which showed potassium iodide (KI) to be the most active. The efficacy of the seaweed catalysts kelp (Laminaria digitata) and dulse (Palmaria palmata) was probed based on particle size, showing that kelp possessed greater catalytic ability, achieving a maximum conversion and selectivity of 63.7% to styrene carbonate using a kelp loading of 80% by weight with respect to epoxide, 40 bar of CO2, 120?C for 3 h. Maximizing selectivity was difficult due to the generation of diol side product from residual H2O found in kelp, along with a chlorinated by-product thought to form due to a high quantity of chloride salts in the seaweeds. Data showed there was loss of organic matter upon use of the kelp catalyst, likely due to the breakdown of organic compounds and their subsequent removal during product extraction. This was highlighted as the likely cause of loss of catalytic activity upon reuse of the Kelp catalyst.
- Comerford, James W.,Gray, Thomas,Lie, Yann,Macquarrie, Duncan J.,North, Michael,Pellis, Alessandro
-
-
- Synergistic effect between copper and different metal oxides in the selective hydrogenolysis of glucose
-
Copper catalysts have been extensively applied in saccharide hydrogenolysis for their high selectivity to C-O bond cleavage. The hydrogenolysis of glucose contains many reaction procedures, which need the synergistic effect of different active sites. A series of Cu catalysts supported on metal oxides with different surface physicochemical properties were prepared. The metal oxide supports not only influence the properties of Cu, such as dispersion and the electronic state, but also affect the activity of C-C and C-O bond cleavage in glucose. Furthermore, the coordination of a large amount of Lewis acid sites and hydrogenation sites on a Cu/γ-Al2O3 catalyst can promote C-C and C-O bond cleavage, leading to the selective conversion of glucose to glycol (selectivity of 66.6%). A Cu/MgO catalyst with a large amount of basic sites and metal sites could accelerate the retro-aldol condensation and isomerization reactions simultaneously, resulting in the main products of C2, C3, and C4 polyols. A study of the synergistic effect between other transition metals and γ-Al2O3 showed that Pd had high activity for central C-C bond cleavage in glucose. Ru provided extremely strong activity for C-C bond cleavage at the terminal of the carbon chain in glucose, with the main product being methane (selectivity of 66.4%).
- Liu, Chengwei,Zhang, Zhaonan,Zhai, Xuefeng,Wang, Xianzhou,Gui, Jianzhou,Zhang, Chenghua,Zhu, Yulei,Li, Yongwang
-
p. 3733 - 3742
(2019/03/05)
-
- Cu/C-catalyzed Hydrogenolysis of Sorbitol to Glycols–On the Influence of Particle Size and Base
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Herein, a series of Cu catalysts supported on activated carbon with increasing particle size was tested for the conversion of sorbitol to glycols including 1,2-propanediol and ethylene glycol in the presence of Ca(OH)2. Activity measurements reveal a distinct correlation between TOF and particle size, which increases until 14 nm (N2O chemisorption based) after which a plateau is reached. However, variation of the particle size has no apparent effect on the selectivity for C3/C3 and C2/C4 cleavage. In contrast, variation of the Ca(OH)2 equivalence has a profound impact on selectivity. The ratio of C3/(C2+C4) products reaches an optimum at 0.45 equiv. of Ca(OH)2. Notably, the time course of the reaction demonstrates that the by-products lactic acid and glycerol are in-situ converted to the desired product 1,2-propanediol, contributing to the unprecedented combined glycol selectivity of 84.5 % at 513 K, 5 MPa H2 and 0.3 equiv. of Ca(OH)2. Furthermore, recycling tests reveal a rapid deactivation which is attributed to aggregation of Cu observed in TEM.
- Wang, Xinde,Beine, Anna Katharina,Hausoul, Peter J. C.,Palkovits, Regina
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p. 4123 - 4129
(2019/05/27)
-
- DEHYDRATION AND CRACKING OF ALPHA-, BETA-DIHYDROXY CARBONYL COMPOUNDS TO LACTIC ACID AND OTHER PRODUCTS
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Processes are disclosed for the synthesis of a cracked product from a starting substrate having a carbonyl functional group (C=O), with hydroxy-substituted carbon atoms at alpha and beta positions, relative to the carbonyl functional group. In one embodiment, an alpha-, beta-dihydroxy carboxylic acid or carboxylate is dehydrated to form a dicarbonyl intermediate by transformation of the alpha-hydroxy group to a second carbonyl group and removal of the beta-hydroxy group. The dicarbonyl intermediate is cracked to form the cracked product in which the first and second carbonyl groups are preserved. Either or both of (i) the cracked product and (ii) a second cracked product generated from cleavage of a carbon-carbon bond of the dicarbonyl intermediate, may be hydrogenated to form additional products.
- -
-
Paragraph 51-52
(2019/11/04)
-
- Versatile and scalable synthesis of cyclic organic carbonates under organocatalytic continuous flow conditions
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The benchmark route for the preparation of cyclic organic carbonates starts from toxic, volatile and unstable epoxides. In this work, cyclic organic carbonates are prepared according to alternative sustainable and intensified continuous flow conditions from the corresponding 1,2-diols. The process utilizes dimethyl carbonate (DMC) as a low toxicity carbonation reagent and relies on the organocatalytic activity of widely available and cheap organic ammonium and phosphonium salts. Glycerol is selected as a model substrate for preliminary optimization with a library of homogeneous ammonium and phosphonium salts. The nature of the anion dramatically influences the catalytic activity, while the nature of the cation does not impact the reaction. Upon optimization, glycerol carbonate is obtained in 95% conversion and 79% selectivity within 3 min residence time at 180 °C (11 bar) with 3.5 mol% of tetrabutylammonium bromide as the organocatalyst. A straightforward liquid-liquid extraction procedure enables both the purification of glycerol carbonate and the recycling of the homogeneous catalyst. The conditions are amenable to refined and crude bio-based glycerol, although conversions are lower in the latter case. Control experiments suggest that water present in the crude samples induces significant hydrolysis of glycerol carbonate. The reaction conditions are then successfully applied on a wide variety of substrates, affording the corresponding cyclic carbonates in overall good to excellent yields (20 examples, 45-95%). The substrate scope notably encompasses bio-based starting materials such as glycerol ethers and erythritol-derived diols. In-line NMR is featured as a qualitative analytical tool for real-time reaction monitoring. The scalability of this carbonation procedure on glycerol is assessed in a commercial pilot-scale silicon carbide continuous flow reactor of 60 mL internal volume. Glycerol carbonate is obtained in 76% yield, corresponding to a productivity of 13.6 kg per day.
- Gérardy, Romaric,Estager, Julien,Luis, Patricia,Debecker, Damien P.,Monbaliu, Jean-Christophe M.
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p. 6841 - 6851
(2019/12/24)
-
- Utilization of hexabromoacetone for protection of alcohols and aldehydes and deprotection of acetals, ketals, and oximes under UV irradiation
-
Hexabromoacetone (HBA) was efficiently used for the protection of alcohols and aldehydes and deprotection of benzaldehyde dimethyl acetal, solketal, and other acetals and ketals. In only 10?min, the protection of glycerol yielded 90% of solketal and protection of benzaldehyde gave 95% of benzaldehyde dimethyl acetal. The deprotection of benzaldehyde dimethyl acetal under UV irradiation gave over 90% yield of benzaldehyde within 15?s using only 2.5?mol% of HBA. HBA was also successfully used for deoximation. Solvent was found to play an important role in the efficiency of HBA for these reactions.
- Chaiseeda, Kittichai,Chantharadet, Ladawan,Chavasiri, Warinthorn
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p. 1305 - 1323
(2017/10/30)
-
- Kinetics of the Formation of Solketal in the Presence of Sulfuric Acid
-
The kinetics of reversible solketal synthesis in the presence of sulfuric acid as a catalyst is studied. The parameters of kinetic equations describing direct and reverse reactions are found.
- Dmitriev,Terekhov,Zanaveskin,Maksimov,Khadzhiev
-
p. 504 - 508
(2018/08/17)
-
- Technologies for Processing of Crude Glycerol from Biodiesel Production: Synthesis of Solketal and Its Hydrolysis to Obtain Pure Glycerol
-
Information on the volume of production of biodiesel and crude glycerol is discussed. The possibility of using crude glycerol as a feedstock for preparing solketal is demonstrated. The specific features of the solketal synthesis from crude glycerol and of separation of the reaction products are described. A catalytic process is suggested for selective decomposition of solketal to glycerol to obtain purified glycerol of any required concentration up to 99.8 wt.%. A flowsheet is provided for processing of crude glycerol to obtain solketal and subsequently converting it to obtain pure glycerol.
- Dmitriev,Zanaveskin,Terekhov,Samoilov,Kozlovskii,Maksimov
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p. 1478 - 1485
(2018/12/11)
-
- Selective production of glycols from xylitol over Ru on covalent triazine frameworks-suppressing decarbonylation reactions
-
Ru on covaltent triazine frameworks (CTF) are highly active and selective catalysts for the conversion of xylitol to glycols (80% C-yield) in basic media. With increasing N-content decarbonylation reactions are suppressed leading to high glycol selectivit
- Beine, Anna Katharina,Krüger, Andreas J. D.,Artz, Jens,Weidenthaler, Claudia,Glotzbach, Christoph,Hausoul, Peter J. C.,Palkovits, Regina
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p. 1316 - 1322
(2018/03/26)
-
- Formation of Chiral Structures in Photoinitiated Formose Reaction
-
The possibility to synthesize biologically important sugars and other chiral compounds without any initiators in the UV-initiated reaction of formaldehyde in aqueous solution has been shown for the first time. An optically active condensed phase due to an
- Stovbun,Skoblin,Zanin,Tverdislov,Taran,Parmon
-
p. 108 - 116
(2018/04/05)
-
- Isolation, purification, characterization and antioxidant activity of polysaccharides from the stem barks of Acanthopanax leucorrhizus
-
A novel water-soluble polysaccharide (named ALP-1) was successfully isolated from the stem barks of Acanthopanax leucorrhizus by hot-water extraction, and further purified by Cellulose DEAE-52 and Sephadex G-100 chromatography. The structure of ALP-1 was characterized by HPLC, HPGPC, partial acid hydrolysis, periodate oxidation, Smith degradation, methylation, together with UV, IR and NMR spectral analysis. The antioxidant activities also were evaluated in vitro. Structural analysis revealed that ALP-1 was a homogeneous galactan with the average molecular weight of 169 kDa, composed of galactose, glucose, mannose and arabinose in a molar ratio of 6.1:2.1:1.1:1.0, owning a backbone structure of 1,6-linked α-D-Galp residues with some branches of α-D-Manp-(1 → 3)-α-L-Araf residues at O-3 and α-D-Galp residues at O-4 of 1,6-linked α-D-Galp. Antioxidant assay showed that ALP-1 exhibited strong DPPH[rad] and HO[rad] scavenging activities, as well as ferric-reducing antioxidant power. These results provide a scientific basis for the further use of polysaccharides from A. leucorrhizus.
- Hu, Hao-Bin,Liang, Hai-Peng,Li, Hai-Ming,Yuan, Run-Nan,Sun, Jiao,Zhang, La-La,Han, Ming-Hu,Wu, Yun
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p. 359 - 367
(2018/05/29)
-
- Catalytic Hydrogenation of Cyclic Carbonates using Manganese Complexes
-
Catalytic hydrogenation of cyclic carbonates to diols and methanol was achieved using a molecular catalyst based on earth-abundant manganese. The complex [Mn(CO)2(Br)[HN(C2H4PiPr2)2] 1 comprising commercially available MACHO ligand is an effective pre-catalyst operating under relatively mild conditions (T=120 °C, p(H2)=30–60 bar). Upon activation with NaOtBu, the formation of coordinatively unsaturated complex [Mn(CO)2[N(C2H4PiPr2)2)] 5 was spectroscopically verified, which confirmed a kinetically competent intermediate. With the pre-activated complex, turnover numbers up to 620 and 400 were achieved for the formation of the diol and methanol, respectively. Stoichiometric reactions under catalytically relevant conditions provide insight into the stepwise reduction form the CO2 level in carbonates to methanol as final product.
- Kaithal, Akash,H?lscher, Markus,Leitner, Walter
-
supporting information
p. 13449 - 13453
(2018/09/25)
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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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- Ordered Mesoporous NiCeAl Containing Catalysts for Hydrogenolysis of Sorbitol to Glycols
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Cellulose-derived sorbitol is emerging as a feasible and renewable feedstock for the production of value-added chemicals. Highly active and stable catalyst is essential for sorbitol hydrogenolysis. Ordered mesoporous M–xNiyCeAl catalysts with different loadings of nickel and cerium species were successfully synthesized via one-pot evaporation-induced self-assembly strategy (EISA) and their catalytic performance were tested in the hydrogenolysis of sorbitol. The physical chemical properties for the catalysts were characterized by XRD, N2 physisorption, H2-TPR, H2 impulse chemisorption, ICP and TEM techniques. The results showed that the ordered mesopores with uniform pore sizes can be obtained and the Ni nanoparticles around 6 nm in size were homogeneously dispersed in the mesopore channels. A little amount of cerium species introduced would be beneficial to their textural properties resulting in higher Ni dispersion, metal area and smaller size of Ni nanoparticles. The M–10Ni2CeAl catalyst with Ni and Ce loading of 10.9 and 6.3 wt % shows better catalytic performance than other catalysts, and the yield of 1,2-PG and EG can reach 56.9% at 493 K and 6 MPa pressure for 8 h after repeating reactions for 12 times without obvious deterioration of physical and chemical properties. Ordered mesoporous M–NiCeAl catalysts are active and stable in sorbitol hydrogenolysis.
- Zhou, Zhiwei,Zhang, Jiaqi,Qin, Juan,Li, Dong,Wu, Wenliang
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p. 456 - 465
(2018/03/21)
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- Hydrogenolysis of sorbitol into valuable C3-C2 alcohols at low H2 pressure promoted by the heterogeneous Pd/Fe3O4 catalyst
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The hydrogenolysis of sorbitol and various C5-C3 polyols (xylitol; erythritol; 1,2- 1,4- and 2,3-butandiol; 1,2-propandiol; glycerol) have been investigated at low molecular hydrogen pressure (5 bar) by using Pd/Fe3O4, as heterogeneous catalyst and water as the reaction medium. Catalytic experiments show that the carbon chain of polyols is initially shortened through dehydrogenation/decarbonylation and dehydrogenation/retro-aldol mechanisms followed by a series of cascade reactions that include dehydrogenation/decarbonylation and dehydration/hydrogenation processes. At 240 °C, sorbitol is fully converted into lower alcohols with ethanol being the main reaction product in liquid phase.
- Gumina, Bianca,Mauriello, Francesco,Pietropaolo, Rosario,Galvagno, Signorino,Espro, Claudia
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p. 152 - 160
(2018/02/17)
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- Late-stage deuteration of 13C-enriched substrates for: T 1 prolongation in hyperpolarized 13C MRI
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A robust and selective late-stage deuteration methodology was applied to 13C-enriched amino and alpha hydroxy acids to increase spin-lattice relaxation constant T1 for hyperpolarized 13C magnetic resonance imaging. For the five substrates with 13C-labeling on the C1-position ([1-13C]alanine, [1-13C]serine, [1-13C]lactate, [1-13C]glycine, and [1-13C]valine), significant increase of their T1 was observed at 3 T with deuterium labeling (+26%, 22%, +16%, +25% and +29%, respectively). Remarkably, in the case of [2-13C]alanine, [2-13C]serine and [2-13C]lactate, deuterium labeling led to a greater than four fold increase in T1. [1-13C,2-2H]alanine, produced using this method, was applied to in vitro enzyme assays with alanine aminotransferase, demonstrating a kinetic isotope effect.
- Taglang, Céline,Korenchan, David E.,Von Morze, Cornelius,Yu, Justin,Najac, Chloé,Wang, Sinan,Blecha, Joseph E.,Subramaniam, Sukumar,Bok, Robert,Vanbrocklin, Henry F.,Vigneron, Daniel B.,Ronen, Sabrina M.,Sriram, Renuka,Kurhanewicz, John,Wilson, David M.,Flavell, Robert R.
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supporting information
p. 5233 - 5236
(2018/05/28)
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- PROCESS FOR THE PREPARATION OF GLYCOLS
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The invention provides a process for the preparation of ethylene glycol and 1, 2-propylene glycol from starting material comprising one or more saccharide, wherein the process comprises the steps of: i) providing the starting material and hydrogen to a first reactor and reacting said starting material and hydrogen therein in the presence of a solvent and a first catalyst system comprising a retro-aldol catalyst composition and a hydrogenation catalyst composition; ii) continuously removing a first reactor product stream from the first reactor, said first reactor product stream comprising ethylene glycol, 1, 2-propylene glycol and in the range of from 2 to 40 wt% of sugar alcohols; iii) contacting said first reactor product stream in a second reactor in the presence of hydrogen with a second catalyst system comprising at least a hydrogenation catalyst composition; and iv) converting a portion of the sugar alcohols in the second reactor into ethylene glycol and/or 1, 2-propylene glycol to provide a second reactor product stream comprising ethylene glycol, 1, 2-propylene glycol and in the range of from 10 to 80% of the amount of sugar alcohols present in the first reactor product stream.
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Page/Page column 13; 14
(2018/06/30)
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- Production of ethylene glycol from direct catalytic conversion of cellulose over a binary catalyst of metal-loaded modified SBA-15 and phosphotungstic acid
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This study presents the utilization of a binary catalyst composed of metal-loaded modified SBA-15 (M/SBA-15) and phosphotungstic acid (H3PW12O40) for ethylene glycol (EG) production from direct catalytic conversion of cell
- Yu, Shitao,Cao, Xincheng,Liu, Shiwei,Li, Lu,Wu, Qiong
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p. 24857 - 24865
(2018/07/29)
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- A Kinetic Investigation of Triacetin Methanolysis and Assessment of the Stability of a Sulfated Zirconium Oxide Catalyst
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In this work, the activity and stability of a sulfated zirconium catalyst in transesterification reactions of triacetin, a model molecule, were investigated. This catalyst has Lewis and Br?nsted acid sites and has shown to be highly active in reactions converting triacetin into methyl esters. This catalyst was synthesized using the impregnation method, and systematically characterized using the techniques of x-rays diffraction (XRD), scanning electron microscopy, Fourier transform-infrared spectroscopy (FT-IR), Brunauer, Emmett, and Teller, and thermal gravimetry analysis (TGA). Kinetic studies were carried out to determine the activation energy as well as the reaction order. The effects of the main reaction parameters, such as temperature, the molar ratio, and the catalyst content, were evaluated. The reuse and possible leaching of the catalyst were also investigated. The highest efficiency (ca. 99% of methyl esters) was achieved in the sulfated zirconium oxide-catalyzed transesterification reaction.
- Temóteo, Rafael L.,da Silva, Marcio J.,de ávila Rodrigues, Fabio,da Silva, Wagner F.,de Jesus Silva, Deusanilde,Oliveira, Cesar M.
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p. 865 - 874
(2018/07/31)
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- Efficient Catalytic Greenhouse Gas-Free Hydrogen and Aldehyde Formation from Alcohols
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Catalytic preparation of hydrogen and aldehyde(s) from alcohols, including bioalcohols, without production of carbon monoxide or carbon dioxide.
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Paragraph 0057; 0058
(2017/11/07)
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- Metal nanoparticles supported on WO3 nanosheets for highly selective hydrogenolysis of cellulose to ethylene glycol
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Although the conversion of cellulose to polyols is currently well-developed, the production of the considerably valuable ethylene glycol (EG) is still challenging. Reactions have long relied on the design of suitable catalysts to obtain a high selectivity and yield of EG. Herein, using well-shaped rectangular tungsten trioxide nanosheets as the substrate, we investigated the catalytic performances of various metal supported catalysts for the convertion of cellulose to EG. Results show that Ru/WO3 is more favorable for EG production, with the highest EG yield of 76.3% over the 1% Ru/WO3 nanosheet catalyst. Our characterizations and activity tests suggest that the embedding of Ru nanoparticles onto the WO3 nanosheets produces more W5+ active sites under the same reduction conditions (NaBH4 or H2), which act as Lewis base sites to promote the glucose retro-aldol condensation reaction. Moreover, the Ru/WO3 catalyst holds a portion of Ru in the form of amorphous RuOxδ+ phases, which could further increase the H+ released into an aqueous solution for cellulose hydrogenolysis. A possible catalytic mechanism for this hydrogenolysis process is accordingly proposed.
- Li, Naixu,Zheng, Yu,Wei, Lingfei,Teng, Hongcheng,Zhou, Jiancheng
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p. 682 - 691
(2017/02/26)
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- Influence of the Surface Chemistry of Multiwalled Carbon Nanotubes on the Selective Conversion of Cellulose into Sorbitol
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Carbon nanotubes (CNT) were submitted to liquid-phase chemical treatments using HNO3 and subsequently to gas-phase thermal treatments to incorporate different sets of oxygenated groups on the surface. The modified CNT were used as supports for 0.4 wt % Ru in the direct conversion of ball-milled cellulose to sorbitol and high conversions were reached after 3 h at 205 °C. Ru supported on the original CNT, although less active, was the most selective catalyst for the one-pot process (70 % sorbitol selectivity after 2 h). Unlike the one-pot process, the support acidity greatly promoted the rate of cellulose hydrolysis (35 % increase after 2 h) and the glucose selectivity (12 % increase after 2 h). The rate of glucose hydrogenation was almost not affected by the support modification. However, the catalyst acidity improved the sorbitol selectivity from glucose. The support acidity was a central factor for the one-pot conversion of cellulose, as well as for the individual hydrolysis and hydrogenation steps, and the original CNT supported Ru catalyst was the most efficient and selective catalyst for the direct conversion of cellulose to sorbitol.
- Ribeiro, Lucília S.,Delgado, Juan J.,de Melo órf?o, José J.,Ribeiro Pereira, M. Fernando
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p. 888 - 896
(2017/03/13)
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- Influence of the functional groups of multiwalled carbon nanotubes on performance of Ru catalysts in sorbitol hydrogenolysis to glycols
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Different functional groups (i.e. [sbnd]NH2, [sbnd]COOH, [sbnd]OH and nitrogen-doping) modified CNTs (denoted as AMCN, CMCN, HMCN and NMCN, respectively) supported ruthenium catalysts (Ru/AMCN, Ru/CMCN, Ru/HMCN and Ru/NMCN) were prepared by incipient wetness impregnation method. They were fully characterized by XRD, TG, Raman, XPS, TPD and TEM to elucidate the relationship between the physical property and their catalytic performance. TEM results shown that Ru particles were well dispersed on the surface for all the samples with the size of 1.48–1.99 nm. The effects of functional groups of carbon nanotubes (CNTs), nitrogen doping and base additive types on activity and selectivity of ethylene glycol (EG) and propylene glycol (1,2-PD) were investigated. In addition, the activity and final products distribution were much influenced by the properties of functional groups on CNTs and the type of metal cation of the base promoters, which probably participated in the reaction for accelerating a retro-aldol reaction for C[sbnd]C cleavage. Among the catalysts, Ru supported on AMCN exhibited the best catalytic activities and glycols selectivities than on MCN, CMCN, HMCN and NMCN.
- Guo, Xingcui,Dong, Huihuan,Li, Bin,Dong, Linlin,Mu, Xindong,Chen, Xiufang
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- Anodization of bismuth doped TiO2 nanotubes composite for photocatalytic degradation of phenol in visible light
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Bismuth doped TiO2 photocatalyst was synthesized in a one-step electrochemical anodization method. Bismuth nitrate Bi(NO3)3 was used as a bismuth source. The obtained samples were characterized by FE-SEM, XRD, EDX and XPS. The optimum synthesis conditions for bismuth doping were 1.0 M bismuth nitrate in an ethylene glycol electrolyte with anodization at 40 V for 2 h. Compared with undoped TiO2 nanotubes, bismuth doped TiO2 photocatalyst showed a higher photocatalytic activity by a factor of 4.0 for phenol degradation under visible light irradiation. The optimum phenol degradation using a photoelectrocatalytic method was observed at a 0.5 V external bias, and this degradation rate was 5.2 times faster than that observed for undoped TiO2 nanotubes. The doped bismuth TiO2 nanotubes are favorable for the separation of photo-induced electrons and holes, reducing the recombination of charges, and promoting the formation of hydroxyl radicals and superoxides that degrade phenol.
- Ali, Imran,Kim, Seu-Run,Kim, Sung-Pil,Kim, Jong-Oh
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