- Merger of Johnson-Claisen rearrangement and alkoxycarbonylation for atom efficient diester synthesis
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The orthoester Johnson-Claisen rearrangement of allyl alcohol with triethyl orthoacetate for the synthesis of ethyl 4-pentenoate has been optimized, in order to allow for a selective and efficient subsequent alkoxycarbonylation using formates in an atom efficient manner. Diethyl adipate was successfully yielded in up to 89% applying very low orthoester excess, formic acid and mild reaction conditions in an innovative, one-pot procedure.
- Seidensticker, Thomas,M?ller, David,Vorholt, Andreas J.
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- A short high yielding synthesis of the potent anti-VZV carbocyclic nucleoside analogue carba-BVDU
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A short high yielding synthesis of the potent anti-varicella-zoster virus (VZV) carbocyclic nucleoside analogue carba-BVDU 1 starting from aminodiol 2 is described. Reaction of 2 with acyl carbamate 3 and subsequent ring closure under acidic conditions afforded 5-ethyl-2'-deoxy-4'a-carbauridine 5. In situ acetylation of 5 afforded 3',5'-di-O-acetyl-5-ethyl-2'-deoxy-4'a-carbauridine 6 in 78% overall yield from 2. Radical bromination of 6 with either bromine or NBS and subsequent treatment with triethylamine gave an efficient conversion to 3',5'-di-O-acetyl-5-(E)-(2-bromovinyl)-2'-deoxy-4'a- carbauridine 7. Deacetylation of 7 afforded 1 in an overall 45-53% yield from 2.
- Wyatt,Anslow,Coomber,Cousins,Evans,Gilbert,Humber,Paternoster,Sollis,Tapolczay,Weingarten
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- Formic acid directly assisted solid-state synthesis of metallic catalysts without further reduction: As-prepared Cu/ZnO catalysts for low-temperature methanol synthesis
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Metallic catalysts (Cu/ZnO) and pure metals (Co, Ni, and Ag) without any impurities are directly prepared by a novel formic acid-assisted solid-state method without further reduction. During the decomposition of metal-formic acid precursors at 523 K under argon, H2 and CO are liberated and act in situ as reducing agents to obtain pure metals and metallic catalysts (C argon). X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive spectroscopy, and temperature-programmed reduction analysis reveal that the as-prepared catalyst Cargon without further reduction is converted into metallic Cu0 and ZnO species. TPR analysis results, Fourier transform infrared analysis, and the thermal decomposition behavior in air illustrate that no amorphous carbon or carbonic residues are left in Cargon when formic acid is used as the chelating agent and reductant, because formic acid is the simplest organic acid. The as-prepared Cu/ZnO catalyst is tested for low-temperature methanol synthesis at 443 K from syngas containing CO2 and using ethanol as a solvent and catalyst; it exhibits much higher activity and methanol selectivity than catalysts prepared by conventional solid-state methods.
- Shi, Lei,Shen, Wenzhong,Yang, Guohui,Fan, Xiaojing,Jin, Yuzhou,Zeng, Chunyang,Matsuda, Kenji,Tsubaki, Noritatsu
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- Etherification of biomass-derived furanyl alcohols with aliphatic alcohols over silica-supported nickel phosphide catalysts: Effect of surplus P species on the acidity
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The acidity of nickel phosphide (Ni2P) catalysts plays a crucial role in producing a desired hydrodeoxygenation molecule from biomass-derived substrates; yet, it has never been explored in acid-catalyzed reactions. Herein, we demonstrated the activity of silica-supported Ni2P catalyst prepared with the nominal P/Ni ratio of 2 (Ni2P/SiO2-2P) in the etherification of furanyl alcohols (particularly, 5-(hydroxymethyl)furfural) with aliphatic alcohols including ethanol. By comparing the characteristics of Ni/SiO2, PxOy/SiO2, and Ni2P/SiO2-xP (x = 0.5 and 1), Ni2P/SiO2-2P was revealed to contain the Br?nsted and Lewis acid sites of which both contributed to the etherification reaction. Notably, the Br?nsted acidity was associated with the surplus P species added to produce the Ni2P phase. Consequently, supported Ni2P catalysts can work in acid-catalyzed reactions if an adequate ratio of Br?nsted to Lewis acid sites is provided by the amount of the surplus P species determined by adjusting the P/Ni ratio.
- Kim, Jinsung,Shin, Mi,Suh, Young-Woong
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- The products of the reaction of the hydroxyl radical with 2-ethoxyethyl acetate
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The gas-phase reaction products of the OH radical with 2-ethoxyethyl acetate (EEA, CH3C(O)OCH2CH2OCH2CH3) have been investigated. 1,2-Ethanediol acetate formate (EAF, CH3C(O)OCH2CH2OC(O)H)and ethyl formate (EF, HC(O)OCH2CH3) were identified as the two main products. A third product, ethylene glycol diacetate (EGD, CH3C(O)OCH2CH2OC(O)CH3), was also observed. EAF, EF, and EGD formation yields were determined to be 0.37 ±0.03 and 0.328 ± 0.018 and 0.040 ± 0.005. respectively. Proposed reaction mechanisms are discussed and compared with these data. 1996 John Wiley & Sons, inc.
- Wells,Wiseman, Floyd L.,Williams, Dale C.,Baxley, J. Steven,Smith
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- Ru catalyzed hydrogenation of CO2 to formate under basic and acidic conditions
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The hydrogenation of CO2 to MeOH is pertinent to advance future energy schemes. Towards this end, phosophine-ligated Ru catalysts have been shown to achieve this transformation under either acidic or basic conditions. In this manuscript, we screen catalytic conditions for a novel tris(phosphine) ligand with Ru to see if it can facilitate the conversion of CO2 to MeOH under both acidic and basic conditions. With both sets of conditions, we observe hydrogenation of CO2 to formate. This work shows that the same catalytic system can function under both reaction types but is limited to formate production.
- Cannon, Austin T.,Saouma, Caroline T.
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- The hydroxyl radical reaction rate constant and products of ethyl 3-ethoxypropionate
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The relative rate technique has been used to measure the hydroxyl radical (OH) reaction rate constant of ethyl 3-ethoxypropionate (EEP, CH3CH2-O-CH2CH2C(O)O-CH 2CH3). EEP reacts with OH with a bimolecular rate constant of (22.9 ± 7.4) × 10-12 cm3 molecule-1 s-1 at 297 ± 3 K and l atmosphere total pressure. In order to more clearly define EEP's atmospheric reaction mechanism, an investigation into the OH + EEP reaction products was also conducted. The OH + EEP reaction products and yields observed were: ethyl glyoxate (EG, 25 ± 1% HC(=O)C(=O)-O-CH2CH3), ethyl (2-formyl) acetate (EFA, 4.8 ± 0.2%, HC(=O)-CH2-C(=O)-O-CH2CH3), ethyl (3-formyloxy) propionate (EFP, 30 ± 1%, HC(=O)-O-CH2CH2-C(=O)-O-CH2CH3), ethyl formate (EF, 37 ± 1%, HC(=O)O-CH2CH3), and acetaldehyde (4.9 ± 0.2%, HC(=O)CH3). Neither the EEP's OH rate constant nor the OH/EEP reaction products have been previously reported. The products' formation pathways are discussed in light of current understanding of oxygenated hydrocarbon atmospheric chemistry.
- Steven Baxley,Henley, Michael V.,Wells
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- Synthesis, characterization, and catalytic application of a cationic metal-organic framework: Ag2(4,4′-bipy)2(O 3SCH2CH2so3)
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We report a silver-based cationic metal-organic framework with two mixed organic linkers directing the structure. The structure consists of ID Ag(4,4′-bipy) cationic chains arranged into closepacked layers. Weakly bound alkanedisulfonate anions charge-balance the layers, where only one oxygen of each sulfonate makes a long contact with the Ag. The unsaturated linear Ag centers likely allow the Lewis acidity displayed by the material for ketone protection as well as esterification. The material showed no reduction in yield after three catalytic runs with average 95% conversion yield for ketal formation and 57% for esterification without further water removal. In addition to hydrothermal conditions, the structure can be synthesized by reflux or room temperature, with almost identical catalytic ability. Other properties of this compound including chemical and thermal stability are also described.
- Fei, Honghan,Paw U, Latisha,Rogow, David L.,Bresler, Marc R.,Abdollahian, Yashar A.,Oliver, Scott R. J.
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- The Reaction of Alkoxides with Dicobalt Octacarbonyl: Trapping of the Co(I) Intermediate in the Disproportionation ( Base Reaction ) with a Hard Lewis Base
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Dicobalt octacarbonyl reacts with alcoholates (RO(-)) yielding alkoxycarbonylcobalt tetracarbonyls, ROC(O)Co(CO)4. - (Keywords: Alkoxides, reaction with dicobalt octacarbonyl; Alkoxycarbonylcobalt tetracarbonyls; Hydrocarbalkoxylation intermediates)
- Tasi, Miklos,Sisak, Attila,Ungvary, Ferenc,Palyi, Gyula
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- Hydrolysis of Imidazole-Containing Amide Acetals
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N-(Dialkoxymethyl)imidazoles (amide acetals 1a-c) are shown to hydrolyze by a common mechanism between pH 1 and pH 11 that involves preequilibrium protonation of the imidazole distal N, followed by rate-llimiting C - N cleavage.The Broensted plot of the log C - N cleavage rate vs. pKa of the parent imidazole has a slope of -1.0 and suggest a transition sate in which (+) is nearly completely transferred to the departing dialkoxymethyl group.Throughout the pH range studied, C - N cleavage is the dominant process.The bicyclic amide acetal 2 formed from 4(5)-(hydroxyethyl)imidazole and triethyl orthoformate behaves similarly to the acyclic cases at pHs > 5 except that the observed rate of C - N cleavage for the former is depressed by (1 - 2) x 102-fold.This apparent reduction of C - N cleavage rate is analyzed in terms of reversibility of the ring opening.Such reversal is demonstrated by the ability of good nucleophiles such as N3- or H2NOH to trap the open ion, preventing reversal and hence increasing the apparent rate of loss of 2.From pH 0 to pH 5, an additional sigmoidal event in the pH/log kobsd profile for 2 is observed, which is analyzed as a protonation of the imidazole of the open ion.Such a protonation prevents the reversible reclosure and concomitantly increases the kobsd.Bicyclic 2 can be taken as a model for the tetrahedral intermediate formed during intramolecular alcoholysis of an N-acylimidazole or intramolecular attack of an imidazole on an ester.
- Brown, R. S.,Ulan, J. G.
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- Enhanced Hydrogenation of Carbon Dioxide to Methanol by a Ruthenium Complex with a Charged Outer-Coordination Sphere
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We report the hydrogenation of CO2 to MeOH by a Ru(triphos) catalyst containing a cationic tetraalkylammonium moiety in the outer coordination sphere. This catalyst affords higher TON and TOF values for MeOH than isostructural catalysts with neutral phosphine ligands. Kinetic data from operando NMR spectroscopy studies indicate the improvement in MeOH production arises from a 12-fold enhancement in the rate of hydrogenation of the transient formaldehyde intermediate. These results provide insight into the catalyst characteristics that promote MeOH formation.
- Erickson, Jeremy D.,Linehan, John C.,Preston, Andrew Z.,Wiedner, Eric S.
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- Photocatalitic Decomposition of 2-Ethoxyethanol on Titanium Dioxide
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The reaction mechanism of the photocatalytic oxidation of 2-etoxyethanol (Ethyl Cellosolve, EtOCH2CH2OH) on TiO2 powder was investigated by gas chromatography-mass spectrometry (GC-Ms) infrared (IR) spectroscopy, and electron spin resonance (ESR) with spin trapping technique.Irradiation of TiO2 powder with UV light in the presence of EtOCH2CH2OH under air led to the formation of ethyl formate, ethanol, acetaldehyde and carbon dioxide.The main product, ethyl formate was different from the product trough the reaction pathway proposed before for primary alcohols.It was also different from the product of electrolysis on Pt.Reaction mechanism is proposed based on Ir and ESR studies.
- Yamagata, Sadamu,Baba, Ryo,Fujishima, Akira
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- Transfer Hydrogenation of Carbon Dioxide to Methanol Using a Molecular Ruthenium-Phosphine Catalyst
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Transfer hydrogenation using molecular catalysts has become a powerful tool in synthetic chemistry and a wide range of unsaturated substrates can be reduced with this protocol. Whereas reactions using iso-propanol as hydrogen donor are already well established, recent examples demonstrate the possibility to use linear alcohols from renewable resources. Herein, the first effective transfer hydrogenation of the challenging substrate carbon dioxide (CO2) directly to methanol is described, applying a molecular ruthenium catalyst and linear alcohols as the hydrogen source. In neat ethanol, TONs up to 121 are achieved under moderate pressures of CO2. Moreover, systematic investigations enable to propose initial acceptorless dehydrogenation of the alcohol, followed by the reduction of CO2 to methanol via ethyl formate, as mechanistic basis.
- Westhues, Niklas,Klankermayer, Jürgen
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- Kinetics of the Three Components Condensation of Triethoxymethane, Aniline and CH2-Acidic Compounds Forming Arylaminomethylene Compounds
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Condensation of triethoxymethane and aniline with dimedone gives 2-anilinomethylene dimedone as the main product.An 1H-NMR-spectroscopic investigation of the kinetics in chloroform-d1 and methanol-d4 shows different rate determining steps in these solvents.There are two predominant rate determining steps in a complicated multistep reaction sequence.The initial one involves condensation of aniline with triethoxymethane to form diphenyl formamidine via ethyl phenyl formimidate.The second step involves reaction of the intermediate diphenyl formamidine with dimedone.The rates are strongly dependent upon the nature of the solvent and the concentration of catalytic acid.In methanol the reaction of dimedone with the intermediate diphenyl formamidine is rate determining.For preparative purposes the isolation of the intermediate diphenyl formamidine and the subsequent use of less polar solvents offer an advantage, because the second step is found to be accelerated. - Keywords: Enaminones; Formimidate; Formamidine
- Uray, Georg,Wolfbeis, Otto S.
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- PROMOTION BY PHOSPHORUS COMPOUNDS OF RUTHENIUM-CATALYZED METHYL FORMATE HOMOLOGATION
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Trivalent phosphorus compounds are promoters for methyl formate homologation to ethanol and ethyl formate catalyzed by ruthenium compounds in the presence of iodide at 220 deg C and 27 MPa of synthesis gas.Under these conditions the phosphines are quaternized, but decomposition of phosphonium salts occurs during the reaction.Promotion is also observed for methyltriphenylphosphonium bromide and triphenylphosphine sulfide, but benzyltrimethylammonium bromide, triphenylarsine, and triphenylantimony are not effective.The major ruthenium species present is Ru(CO)3I3 but with triphenylantimony a trimethylantimony complex, Ru(CO)2(Sb(CH3)3)2I2, can be isolated in high yield.
- Keister, Jerome B.,Gentile, Robert
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- The effect of oxygen pressure on the tropospheric oxidation of diethyl ether, H-atom elimination from the 1-ethoxyethoxy radical
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The simulated tropospheric oxidation of diethyl ether gave yields of the products ethyl formate, acetaldehyde and ethyl acetate in broad agreement with previous studies. However the effect of variation of oxygen pressure on the relative yields of ethyl acetate and ethyl formate disagrees with the prediction of the mechanism previously proposed. It is suggested that ethyl acetate is produced by the reaction C2H5OCH(O)CH3 → CH3COOC2H5 + H as well as by the reaction of the 1-ethoxyethoxy radical with oxygen.
- Cheema,Holbrook,Oldershaw,Starkey,Walker
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- Hydroxyl Radical Induced Oxidation of Diethyl Ether in Oxygenated Aqueous Solution. A Product and Pulse Radiolysis Study
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The reaction of peroxyl radicals derived from diethyl ether were investigated by product analyses and pulse-radiolytic techniques.The products and their G values in the γ radiolysis of diethyl ether (1E-3 M) in N2O/O2-saturated aqeous solutions at 0.43 W kg-1 are acetaldehyde , ethanol , ethyl acetate , ethyl formate , formaldehyde , hydrogen peroxide , 1-ethoxyethyl hydroperoxide , and 2-ethoxyacetaldehyde .Except for the latter, all products have the 1-ethoxyethylperoxy radical (I) as a precursor.It is formed as the major radical by OH abstraction of the α-H atom (96percent) followed by O2 addition.Besides other bimolecular decay processes of I which are also discussed, there is an important route leading to 1-ethoxyethyloxyl radicals and O2: 2I -> 2CH3CH(O*)OEt + O2.The oxyl radical rearrangment in aqueous solutions to the 1-ethoxy-1-hydroxyethyl radical: CH3CH(O*)OEt -> CH3C*(OH)OEt.The latter adds oxygen to give the corresponding peroxyl radical, which eliminates HO2* in a fast spontaneous reaction to give ethyl acetate: CH3C*(OH)OEt + O2 - HO2* -> CH3COOEt.Evidence for the formation of HO2* (O2-* in neutral and basic solutions) according to the above reaction sequence was provided by pulse-spectrometric and pulse-conductometric measurements. 1-Ethoxyethyl hydroperoxide is thought to result from the reduction of I by O2-*.At much lower dose rates (0.0048 W kg-1) an intramolecular H abstraction competes with the bimolecular decay of I.This process leads to a different product distribution and to formation of acidic products.
- Schuchmann, Man Nien,Sonntag, Clemens von
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- The atmospheric oxidation of diethyl ether: Chemistry of the C 2H5-O-CH(O?)CH3 radical between 218 and 335 K
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The products of the Cl atom initiated oxidation of diethyl ether (DEE) were investigated at atmospheric pressure over a range of temperatures (218-335 K) and O2 partial pressures (50-700 Torr), both in the presence and absence of NOx. The major products observed at 298 K and below were ethyl formate and ethyl acetate, which accounted for ≈60-80% of the reacted diethyl ether. In general, the yield of ethyl formate increased with increasing temperature, with decreasing O2 partial pressure, and upon addition of NO to the reaction mixtures. The product yield data show that thermal decomposition reaction (3), CH3CH2-O-CH(O ?)CH3 → CH3CH2-O-CH=O + CH3, and reaction (6) with O2, CH3CH 2-O-CH(O?)CH3 + O2 → CH3CH2-O-C(=O)CH3 + HO2 are competing fates of the CH3CH2-O-CH(O?) CH3 radical, with a best estimate of k3/k6 ≈ 6.9 × 1024 exp(-3130/T). Thermal decomposition via C-H or C-O bond cleavage are at most minor contributors to the CH3CH 2-O-CH(O?)CH3 chemistry. The data also show that the CH3CH2-O-CH(O?)CH 3 radical is subject to a chemical activation effect. When produced from the exothermic reaction of the CH3CH2-O-CH(OO ?)CH3 radical with NO, prompt decomposition via both CH3- and probably H-elimination occur, with yields of about 40% and ≤15%, respectively. Finally, at temperatures slightly above ambient, evidence for a change in mechanism in the absence of NOx, possibly due to chemistry involving the peroxy radical CH3CH2-O-CH(OO ?)CH3, is presented. the Owner Societies.
- Orlando, John J.
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- Homogeneous, unimolecular gas-phase elimination kinetics of ethyl esters of glyoxylic, 2-oxo-propanoic, and 3-methyl-2-oxo-butanoic acids
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The rates of elimination of several ethyl esters of 2-oxo-carboxylic acid were determined in a seasoned static reaction vessel over the temperature range 350-430°C and pressure range 33-240 Torr. The reactions, in the presence of a free-radical inhibitor, are homogeneous, unimolecular, and follow a first-order rate law. The overall and partial rate coefficients are expressed by the Arrhenius equation. Ethyl glyoxalate log k1(CO2)(s-1) = (13.43±0.25)-(213.1±3.3) kJ mol-1 (2.303 RT) -1, r = 0.9996 log k2(CO) (s-1) = (14.06±0.54) - (232.9±7.0) kJ mol-1 (2.303 RT) -1, r = 0.9986 log kt(overall) (s-1) = (13.72±0.25) - (216.1±3.3) kJ mol-1 (2.303 RT) -1, r = 0.9997 Ethyl 2-oxo-propionate log k1 (s -1) = (13.03±0.15) - (205.1±2.0) kJ mol-1 (2.303 RT)-1, r = 0.9998 Ethyl 3-methyl-2-oxo-butyrate log k 1 (s-1) = (12.58±0.31)-(198.4±4.1) kJ mol-1 (2.303 RT)-1, r = 0.9994 The mechanisms of these elimination reactions are described in terms of concerted cyclic transition state structures.
- Reyes, Andreina,Dominguez, Rosa M.,Tosta, Maria,Herize, Armando,Chuchani, Gabriel
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- Low-Temperature Hydrogenation of Carbon Dioxide to Methanol with a Homogeneous Cobalt Catalyst
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Herein we describe the first homogeneous non-noble metal catalyst for the hydrogenation of CO2to methanol. The catalyst is formed in situ from [Co(acac)3], Triphos, and HNTf2and enables the reaction to be performed at 100 °C without a decrease in activity. Kinetic studies suggest an inner-sphere mechanism, and in situ NMR and MS experiments reveal the formation of the active catalyst through slow removal of the acetylacetonate ligands.
- Schneidewind, Jacob,Adam, Rosa,Baumann, Wolfgang,Jackstell, Ralf,Beller, Matthias
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- Experimental Data on Chemical Equilibrium in the System with Ethyl Formate Synthesis Reaction at 298.15 K
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Chemical equilibrium (CE) in the quaternary reacting system formic acid-ethanol-ethyl formate-water was experimentally studied at 298.15 K and atmospheric pressure. The CE compositions were determined by gas chromatography analysis. The obtained data gave an opportunity to present the disposition of the surface of CE in a composition tetrahedron. The constants of CE ("concentration" and thermodynamic) were determined on the base of experimental data and UNIFAC model.
- Samarov, Artemiy,Trofimova, Maya,Toikka, Maria,Toikka, Alexander
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- OH radical initiated photooxidation of 2-ethoxyethanol under laboratory conditions related to the troposphere: Product studies and proposed mechanism
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The products formed by the hydroxyl radical-initiated oxidation of 2- ethoxyethanol (CH3CH2OCH2CH2OH) have been investigated by irradiating synthetic air mixtures containing the substrate, methyl nitrite, and nitric oxide at ppm levels in a Teflon bag reactor at room temperature. The decay of reactants and the formation of products were monitored by gas chromatography and mass spectrometry. The major products ethyl formate [HC(O)OCH2CH3], ethylene glycol monaformate [HC(O)OCH2CH2OH], ethylene glycol monaacetate [CH3C(O)OCH2CH2OH], and ethoxyacetaldehyde [CH3CH2OCH2C(O)H] give a quantitative mass balance with the decay of the substrate molecule. The yields of these products were 34 ± 10%, 36 ± 7%, 7.8 ± 2.4%, and 24 ± 13%, respectively, in terms of percent of 2-ethoxyethanol removed by the OH radical. The product distribution is explained by a mechanism involving initial OH attack at the three CH2 groups in 2-ethoxyethanol followed by the subsequent reactions of the resulting alkyl and alkoxy radicals. The decomposition reactions of the alkoxy radicals from 2-ethoxyethanol, which can take place either by C-C or C-O bond breaking, involve preferential C-C cleavage rather than C-O cleavage. Rate coefficients at room temperature for the reactions of OH radicals with ethoxyacetaldehyde and 2-methyl-1,3- dioxolane (CH3CHOCH2CH2O, a minor product) have been determined to be 16.6 x 10-12 and 9.4 x 10-12 cm3 molecule-1 s-1, respectively.
- Stemmler, Konrad,Mengon, Wolfgang,Kerr, J. Alistair
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- Introduction of a carboxyl group through an acetal as a new route to carboxylic acid derivatives of sugars
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A new class of carboxylic acid derivatives of sugars is described. Acetalation of mono- and disaccharides with a functionalized vinylic ether or a diethoxybutanoate afforded mono- and diacetals bearing an ester group. Their saponification led to the corresponding carboxylic acid acetals in which the length of the acetal side chain can be modulated. Copyright (C) 1999 Elsevier Science Ltd.
- Carbonnel, Sylvie,Fayet, Catherine,Gelas, Jacques
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- OH and O3-initiated oxidation of ethyl vinyl ether
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The reaction rate constants of OH and O3 with ethyl vinyl ether (EVE, C2H5OCH=CH2) have been measured in the temperature range 230-372 K and 298 K, respectively. The temperature dependent rate constant for the r
- Thiault,Thevenet,Mellouki,Le Bras
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- Photooxidation Reactions of Ethyl 2-Methylpropionate (E2MP) and Ethyl 2,2-Dimethylpropionate (E22DMP) Initiated by OH Radicals: An Experimental and Computational Study
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The relative rate (RR) technique was used for the measurement of OH-initiated photooxidation reactions of ethyl 2-methylpropionate (E2MP) and ethyl 2,2-dimethylpropionate (E22DMP) in the temperature range of 268-363 K at 760 Torr. In addition to this, the
- Kaipara, Revathy,Rajakumar, B.
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- Kinetics and mechanisms for the reactions of ozone with unsaturated oxygenated compounds
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Rate coefficients for the reaction of ozone with a series of unsaturated oxygenated compounds are determined in air at atmospheric pressure and (298±3) K. Rate data are obtained using both relative and absolute rate techniques, and the measured rate coefficients are found to be in good agreement. The results show that the reactivity of the compounds with respect to addition of ozone to the double bond is a function of the nature of the oxygenated substituent. Product distribution studies on the reactions provide information on the decomposition pathways for the primary ozonides, and on the effect of the oxygenated group on the relative importance of the degradation pathways. The results are discussed in terms of their importance in the atmospheric oxidation of unsaturated oxygenated compounds.
- Al Mulla, Ismael,Viera, Lisa,Morris, Rebecca,Sidebottom, Howard,Treacy, Jack,Mellouki, Abdelwahid
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- Kinetic and product studies of the reactions of selected glycol ethers with OH radicals
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Glycol ethers are widely used as solvents and are hence liable to be released into the atmosphere where they may contribute to the formation of photochemical air pollution in urban and regional areas. The dominant reaction of glycol ethers in the atmosphere has been previously shown to be with OH radicals. Using a relative rate method, rate constants have been measured at 296 ± 2 K for the gasphase reactions of the OH radical with 1-butoxy-2propanol [CH3CH2CH2CH2OCH2CH (OH)CH3], diethylene glycol ethyl ether [CH3CH2OCH2 CH2OCH2CH2OH], and diethylene glycol n-butyl ether [CH3CH2CH2CH2OCH2 CH2OCH2CH2OH] of (in units of 10-11 cm3 molecule-1 s-1) 3.76 ± 0.54, 5.72 ± 0.85, and 7.44 ± 0.94, respectively, where the error limits include the estimated overall uncertainties in the rate constants for the reference compounds. Products of the OH radical-initiated reactions of these glycol ethers have been investigated using gas chromatography with flame ionization detection (GC-FID), combined gas chromatography-mass spectrometry(GC-MS), in situ Fourier transform infrared (FT-IR) spectroscopy, and in situ atmospheric pressure ionization tandem mass spectrometry (API-MS). The products identified and quantified account for 102 ± 11% of the reaction products from 1-butoxy-2-propanol, 87 ± 9% of those from diethylene glycol ethyl ether, and 83 ± 12% of those from diethylene glycol n-butyl ether. An empirical estimation method for calculating reaction rates of alkoxy radicals under atmospheric conditions appears to fairly well predict the products formed and their yields. Detailed reaction schemes after the initial OH radical reactions are formulated for each of these glycol ethers, with the majority of the reactions involving H-atom abstraction from the CH2 groups adjacent to the ether linkage.
- Aschmann,Martin,Tuazon,Arey,Atkinson
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- Pleuromutilin derivative with 1, 3, 4-oxadiazole side chain and preparation and application thereof
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The invention belongs to the field of medicinal chemistry, and particularly relates to a pleuromutilin derivative with a 1, 3, 4-oxadiazole side chain and preparation and application thereof The pleuromutilin derivative with the 1, 3, 4-oxadiazole side chain is a compound shown in a formula 2 or a pharmaceutically acceptable salt thereof, and a solvent compound, an enantiomer, a diastereoisomer and a tautomer of the compound shown in the formula 2 or the pharmaceutically acceptable salt thereof or a mixture of the solvent compound, the enantiomer, the diastereoisomer and the tautomer in any proportion, including a racemic mixture. The pleuromutilin derivative has good antibacterial activity, is especially suitable for being used as a novel antibacterial agent for systemic system infection of animals or human beings, and has good water solubility.
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Paragraph 0055-0056; 0070; 0090; 0092
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- Design, synthesis, in vitro and in vivo evaluation against MRSA and molecular docking studies of novel pleuromutilin derivatives bearing 1, 3, 4-oxadiazole linker
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A class of pleuromutilin derivatives containing 1, 3, 4-oxadiazole were designed and synthesized as potential antibacterial agents against Methicillin-resistant staphylococcus aureus (MRSA). The ultrasound-assisted reaction was proposed as a green chemistry method to synthesize 1, 3, 4-oxadiazole derivatives (intermediates 85–110). Among these pleuromutilin derivatives, compound 133 was found to be the strongest antibacterial derivative against MRSA (MIC = 0.125 μg/mL). Furthermore, the result of the time-kill curves displayed that compound 133 could inhibit the growth of MRSA in vitro quickly (- 4.36 log10 CFU/mL reduction). Then, compound 133 (- 1.82 log10 CFU/mL) displayed superior in vivo antibacterial efficacy than tiamulin (- 0.82 log10 CFU/mL) in reducing MRSA load in mice thigh model. Besides, compound 133 exhibited low cytotoxicity to RAW 264.7 cells. Molecular docking studies revealed that compound 133 was successfully localized in the binding pocket of 50S ribosomal subunit (ΔGb = -10.50 kcal/mol). The results indicated that these pleuromutilin derivatives containing 1, 3, 4-oxadiazole might be further developed into novel antibiotics against MRSA.
- Liu, Jie,Zhang, Guang-Yu,Zhang, Zhe,Li, Bo,Chai, Fei,Wang, Qi,Zhou, Zi-Dan,Xu, Ling-Ling,Wang, Shou-Kai,Jin, Zhen,Tang, You-Zhi
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- Operando systems chemistry reaction catalysis (OSCR-Cat) for visible light driven CO2conversion
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A systems chemistry approach is taken for compartmentalization of a continuous reaction medium (water and CO2) with induced creation of micro-heterogeneity in the medium by using a SOM (soft-oxometalate) catalyst. The first step involves compartmentalization of an assembled catalyst-photosensitizer duo catalysing the reduction of CO2into formic acid in two reaction spaces: the interior of the compartment and the exterior of the compartment. The exterior compartment obeys typical surface activity driven nanocatalysis principles where the perturbation of the catalyst surface area inversely varies with product yield. The second step of disassembly to disrupt the SOM-catalyst, induced by addition of a base, releases the interior reaction product with total disappearance of the catalyst system. The assembly-disassembly cascade demonstrates the application of systems chemistry principles in perturbation, compartmentalization, catalysis and release of products with well-defined externally controlled stimuli such as concentration, light, and pH. The OSCR-catalyst reported here is an attempt to emulate Golgi bodies in the context of cellular chemistry on a functional level.
- Das, Kousik,De, Ratnadip,Roy, Soumyajit,Verpoort, Francis
-
p. 13355 - 13365
(2021/06/16)
-
- Method for preparing formate by using nitromethane process byproduct formic acid
-
The invention belongs to the technical field of organic synthesis, and particularly relates to a method for preparing formate by using a nitromethane process byproduct formic acid. The method comprises the following steps: adding alcohol into a nitromethane hydrolysis reaction solution to carry out esterification reaction, distilling and rectifying to obtain the formate, wherein the nitromethane hydrolysis reaction liquid contains formic acid and hydrochloric acid. The method solves the problems that in the prior art, formic acid is not easy to remove, and the added value of the byproduct calcium formate is low, and the byproduct formic acid can be fully recycled by adopting the esterification reaction of the low-carbon alcohol and the byproduct formic acid; the used low-carbon alcohol is ethanol or methanol, and the esterification product is low in boiling point and easy to separate; and the produced methyl formate and ethyl formate are high in added value and wide in application.
- -
-
Paragraph 0039-0046
(2021/07/08)
-
- Alcohol-Activated Vanadium-Containing Polyoxometalate Complexes in Homogeneous Glucose Oxidation Identified with 51V-NMR and EPR Spectroscopy
-
Alcoholic solvents, especially methanol, show an activating affect for heteropolyacids in homogenously catalysed glucose transformation reactions. In detail, they manipulate the polyoxometalate-based catalyst in a way that thermodynamically favoured total oxidation to CO2 can be completely supressed. This allows a nearly 100 % carbon efficiency in the transformation reaction of glucose to methyl formate in methanolic solution at mild reaction conditions of 90 °C and 20 bar oxygen pressure. By using powerful spectroscopic tools like 51V-NMR and continuous wave EPR we could unambiguously prove that the vanadate-methanol-complex[VO(OMe)3]n is responsible for the selectivity shift in methanolic solution compared to the aqueous reference system.
- Wesinger, Stefanie,Mendt, Matthias,Albert, Jakob
-
p. 3662 - 3670
(2021/06/18)
-
- Zeolite 4A supported CdS/g-C3N4 type-II heterojunction: A novel visible-light-active ternary nanocomposite for potential photocatalytic degradation of cefoperazone
-
The CdS/g-C3N4 heterojunction photocatalyst supported on 4A zeolite was successfully synthesized using a simple chemical precipitation method. The physicochemical characteristics of the as-prepared ternary composite were assessed using X-Ray diffraction (XRD), field emission- scanning electron microscopy (FE-SEM), energy dispersive X-Ray (EDX), transmission electron microscopy (TEM), N2 adsorption–desorption, differential reflectance spectroscopy (UV–Vis-DRS), and photoluminescence (PL) techniques. The results confirmed the successful synthesis of the CdS/g-C3N4/4AZ nanocomposite and introduction of the CdS and g-C3N4 on the substrate of 4A zeolite. Cefoperazone (CFP) antibiotic was tested as the model pollutant to assess the photocatalytic performance of the synthesized nanocomposite under visible light irradiation. The response surface methodology (RSM) and artificial neural network (ANN) showed desirable reasonability for the prediction of the CFP degradation efficiency. More than 93% of CFP with a concentration of 17 mg L-1 degraded in the presence of the 0.4 g L-1 of the catalyst at pH of 9 after 80 min treatment time (RSM-based optimization results). The pH of the solution, irradiation time, catalyst dosage, and the initial concentration of the CFP affected degradation efficiency with a percentage impact of 37, 29, 19, and 15 %, respectively (ANN-based modeling results). The addition of 1 mM of isopropanol, benzoquinone, and sodium oxalate reduced the CFP degradation efficiency from 93.23% to 85.18, 41.16, and 32.47%, respectively, proving the decisive role of the °O2– and h+ in the photodegradation process. The kinetic studies indicated the following of the process from the Langmuir-Hinshelwood's pseudo-first-order model (kapp = 3.71 × 10-2 min?1). The structure of the identified by-products using GC-MS analysis confirmed that CFP mainly decomposed through the cleavage of C-S, C-N, and N-N bonds. Moreover, the formation of the aliphatic compounds and carboxylic acids as by-products confirmed nearly complete mineralization of the CFP to non-toxic products.
- AttariKhasraghi, Naime,Behnajady, Mohammad A.,Mehrizad, Ali,Modirshahla, Nasser,Zare, Karim
-
-
- A Bioinspired Multicomponent Catalytic System for Converting Carbon Dioxide into Methanol Autocatalytically
-
Nature utilizes multicomponent catalyst systems to convert simple, abundant starting materials into complex molecules that are essential for life. In contrast, synthetic chemical transformations rarely adopt this strategy because it is difficult to replicate the sophisticated supramolecular assemblies used by biology for active-site separation and substrate trafficking. Here, we describe a method for multicomponent catalyst separation that involves encapsulating transition-metal complexes in nanoporous materials called metal-organic frameworks. The multicomponent catalyst system was highly active for converting hydrogen and carbon dioxide to methanol, and it could be formulated to be readily recyclable. Moreover, we uncovered an autocatalytic feature that was possible only when we utilized the multicomponent catalyst strategy. These results open avenues for obtaining fuel from abundant and renewable resources. Methanol is a promising renewable fuel that can be adapted to the current liquid fuel infrastructure. It can be produced from hydrogen and carbon dioxide, mitigating greenhouse gas emissions and storing hydrogen in the process. However, the industrial production of methanol through this hydrogenation reaction currently requires elevated temperatures and pressures and can produce significant amounts of unwanted byproducts. Here, we employ a bioinspired tandem catalytic system to efficiently hydrogenate carbon dioxide to methanol selectively at low temperatures. We achieved superior performance by eliminating catalyst incompatibility through encapsulating at least one of the catalysts involved in the tandem process in nanoporous materials called metal-organic frameworks. In the long term, this method could be applied to other tandem catalytic processes, allowing more efficient access to alternative fuels, commodity chemicals, and valuable pharmaceutical products. Tsung and co-workers describe a three-component tandem catalytic process for the hydrogenation of carbon dioxide to methanol. The bioinspired process is enabled by encapsulation of at least one of the two ruthenium-based catalysts required in the metal-organic framework (MOF) UiO-66. The reaction was found to have an autocatalytic feature that enables the reaction to be carried out without superstoichiometric additives. Encapsulating both ruthenium-based catalysts in the MOF allowed the catalyst to be recycled.
- Rayder, Thomas M.,Adillon, Enric H.,Byers, Jeffery A.,Tsung, Chia-Kuang
-
supporting information
p. 1742 - 1754
(2020/05/25)
-
- PRECURSOR COMPOUNDS OF ESTER COMPOUNDS
-
The present disclosure relates to compounds of the formula (I) which are precursor compounds of esters, whereby upon hydrolysis of the precursor compound, an ester compound is released. This ester precursor approach can be useful for applications where controlled release of, for example, ethyl formate, is beneficial.
- -
-
Paragraph 00127-00128
(2020/12/30)
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- Sustainable Co-Synthesis of Glycolic Acid, Formamides and Formates from 1,3-Dihydroxyacetone by a Cu/Al2O3 Catalyst with a Single Active Sites
-
Glycolic acid (GA), as important building block of biodegradable polymers, has been synthesized for the first time in excellent yields at room temperature by selective oxidation of 1,3-dihyroxyacetone (DHA) using a cheap supported Cu/Al2O3 catalyst with single active CuII species. By combining EPR spin-trapping and operando ATR-IR experiments, different mechanisms for the co-synthesis of GA, formates, and formamides have been derived, in which .OH radicals formed from H2O2 by a Fenton-like reaction play a key role.
- Dai, Xingchao,Adomeit, Sven,Rabeah, Jabor,Kreyenschulte, Carsten,Brückner, Angelika,Wang, Hongli,Shi, Feng
-
supporting information
p. 5251 - 5255
(2019/03/07)
-
- Method for preparing formate-type compound
-
The invention discloses a method for preparing a formate-type compound. The method comprises the following steps of: adopting an alcohol-type compound and 1,3-dihydroxyacetone as reaction raw materials, and under the existence of a composite catalyst and an oxidant, reacting for 2-48 hours in a reaction medium in a reactor at a reaction temperature of 25-100 DEG C so as to obtain the formate-typecompound. The method disclosed by the invention is simple, and is mild in reaction condition, and by the method, a target product can be obtained by low cost and high yield; the used catalyst has highcatalytic activity, and is easily separated from a reaction system to be repeatedly used; the whole process is environment-friendly, and the reaction raw material (1,3-dihydroxyacetone) is easily converted from a side product (glycerol) of biodiesel, so that the utilization of the glycerol is promoted.
- -
-
Paragraph 0039; 0047; 0048
(2018/07/30)
-
- Preparation method of methylallyl alcohol
-
The invention discloses a preparation method of methylallyl alcohol. The method is characterized in that the methylallyl alcohol and a carboxylate compound are obtained by adopting methylallyl chloride and carboxylate as raw materials and alcohol as a solvent. The solvent creatively adopts the alcohol, not an alkali or other solvents, so reaction conditions are mild, and the irritation to the rawmaterials is low; and more importantly, the carboxylate also can be obtained, the content of ether and salt products is low, the yield of the target product is high, so the method in the invention hasadvantages over traditional technologies characterized by adoption of the alkali as a hydrolysis agent, a two-step reaction and high byproduct content.
- -
-
Paragraph 0019
(2018/06/04)
-
- Atmospheric Chemistry of CH3CH2OCH3: Kinetics and Mechanism of Reactions with Cl Atoms and OH Radicals
-
The atmospheric chemistry of methyl ethyl ether, CH3CH2OCH3, was examined using FT-IR/relative-rate methods. Hydroxyl radical and chlorine atom rate coefficients of k(CH3CH2OCH3+OH) = (7.53 ± 2.86) × 10?12 cm3 molecule?1 s?1 and k(CH3CH2OCH3+Cl) = (2.35 ± 0.43) × 10?10 cm3 molecule?1 s?1 were determined (297 ± 2 K). The Cl rate coefficient determined here is 30% lower than the previous literature value. The atmospheric lifetime for CH3CH2OCH3 is approximately 2 days. The chlorine atom–initiated oxidation of CH3CH2OCH3 gives CH3C(O)H (9 ± 2%), CH3CH2OC(O)H (29 ± 7%), CH3OC(O)H (19 ± 7%), and CH3C(O)OCH3 (17 ± 7%). The IR absorption cross section for CH3CH2OCH3 is (7.97 ± 0.40) × 10?17 cm molecule?1 (1000–3100 cm?1). CH3CH2OCH3 has a negligible impact on the radiative forcing of climate.
- Sulbaek Andersen, Mads P.,Svendsen, Sissel Bj?rn,?sterstr?m, Freja From,Nielsen, Ole John
-
-
- Tailor-made Molecular Cobalt Catalyst System for the Selective Transformation of Carbon Dioxide to Dialkoxymethane Ethers
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Herein a non-precious transition-metal catalyst system for the selective synthesis of dialkoxymethane ethers from carbon dioxide and molecular hydrogen is presented. The development of a tailored catalyst system based on cobalt salts in combination with selected Triphos ligands and acidic co-catalysts enabled a synthetic pathway, avoiding the oxidation of methanol to attain the formaldehyde level of the central CH2 unit. This unprecedented productivity based on the molecular cobalt catalyst is the first example of a non-precious transition-metal system for this transformation utilizing renewable carbon dioxide sources.
- Schieweck, Benjamin G.,Klankermayer, Jürgen
-
supporting information
p. 10854 - 10857
(2017/08/30)
-
- CYCLIC ORTHO ESTER FUEL ADDITIVE
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The invention relates to liquid hydrocarbons containing cyclic ortho esters as dehydrating dehydrating icing inhibitors and to methods of using the compounds. The liquid hydrocarbons include fuels such aviation fuels, lubricants, hydraulic fluids and hydrocarbon solvents.
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-
Paragraph 0094
(2016/04/20)
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- Ruthenium-Catalyzed Synthesis of Dialkoxymethane Ethers Utilizing Carbon Dioxide and Molecular Hydrogen
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The synthesis of dimethoxymethane (DMM) by a multistep reaction of methanol with carbon dioxide and molecular hydrogen is reported. Using the molecular catalyst [Ru(triphos)(tmm)] in combination with the Lewis acid Al(OTf)3resulted in a versatile catalytic system for the synthesis of various dialkoxymethane ethers. This new catalytic reaction provides the first synthetic example for the selective conversion of carbon dioxide and hydrogen into a formaldehyde oxidation level, thus opening access to new molecular structures using this important C1source.
- Thenert, Katharina,Beydoun, Kassem,Wiesenthal, Jan,Leitner, Walter,Klankermayer, Jürgen
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supporting information
p. 12266 - 12269
(2016/10/13)
-
- Low-temperature CO2 hydrogenation to liquid products via a heterogeneous cascade catalytic system
-
Research described in this paper targeted a cascade system for the hydrogenation of CO2 to methanol via formic acid and/or formate intermediates, a reaction sequence that has been accomplished previously using homogeneous catalysts. On the basis of results for the hydrogenation of CO2, formic acid, and ethyl formate over a series of Cu- and Mo2C-based catalysts, we selected a Cu chromite catalyst for CO2 hydrogenation to the formate and a Cu/Mo2C catalyst to convert the formate to methanol. These catalysts worked cooperatively in the presence of ethanol, yielding a methanol turnover frequency of 4.7 × 10-4 s-1 at 135 °C, 10 bar of CO2, and 30 bar of H2 in 1,4-dioxane. The performance for this Cu chromite:Cu/Mo2C cascade system surpassed the additive production of the individual catalysts by 60%. The results also allowed an investigation of the reaction pathways. The hydrogenation of CO2 to formic acid appeared to be the rate-limiting step for most of the catalysts. This is not surprising given the thermodynamics for this reaction. Finally, the hydrogenation of CO2 to dimethyl ether was also demonstrated using a system consisting of the Cu/Mo2C catalyst to produce methanol from CO2 and HZSM-5 to produce dimethyl ether from methanol. The systems described in this paper are, to our knowledge, the first demonstrating cascade CO2 hydrogenation via heterogeneous catalysts.
- Chen, Yuan,Choi, Saemin,Thompson, Levi T.
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p. 1717 - 1725
(2015/03/14)
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- Oxygen-Controlled Catalysis by Vitamin B12-TiO2: Formation of Esters and Amides from Trichlorinated Organic Compounds by Photoirradiation
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An oxygen switch in catalysis of the cobalamin derivative (B12)-TiO2 hybrid catalyst for the dechlorination of trichlorinated organic compounds has been developed. The covalently bound B12 on the TiO2 surface transformed trichlorinated organic compounds into an ester and amide by UV light irradiation under mild conditions (in air at room temperature), while dichlorostilbenes (E and Z forms) were formed in nitrogen from benzotrichloride. A benzoyl chloride was formed as an intermediate of the ester and amide, which was detected by GC-MS. The substrate scope of the synthetic strategy is demonstrated with a range of various trichlorinated organic compounds. A photo-duet reaction utilizing the hole and conduction band electron of TiO2 in B12-TiO2 for the amide formation was also developed.
- Shimakoshi, Hisashi,Hisaeda, Yoshio
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p. 15439 - 15443
(2016/01/26)
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- PROCESS FOR PREPARING FORMAMIDES AND FORMIC ESTERS
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A process for preparing carboxylic acid derivatives of the formula H—(C═O)—R, R is OR1 or NR2R3, R1 is optionally substituted C1-C15-alkyl, C5-C10-cycloalkyl, C5-C10-heterocyclyl, C5-C10-aryl or C5-C10-heteroaryl, substituents are C1-C15-alkyl, C1-C6-alkoxy, C5-C10-cycloalkyl or C5-C10-aryl; R2 and R3 are independently hydrogen or optionally substituted C1-C15-alkyl, C5-C10 cycloalkyl, C5-C10-heterocyclyl, C5-C10-aryl or C5-C10-heteroaryl, substituents are selected from the group consisting of C1-C15-alkyl, C5-C10-cycloalkyl and C5-C10-aryl or R2 and R3 together with the nitrogen atom form a five- or six-membered ring which optionally comprises one or more heteroatoms selected from O, S and N and bearing the substituent R4, R4 is hydrogen or C1-C6-alkyl; by reacting a reaction mixture comprising carbon dioxide, hydrogen and an alcohol of the formula R1—OH or an amine of the formula NHR2R3 in the presence of a catalyst comprising gold at a pressure from 0.2 to 30 MPa and a temperature from 20 to 200° C. in a hydrogenation reactor.
- -
-
Paragraph 0135; 1036
(2013/05/08)
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- Reversible carbon-carbon bond formation between carbonyl compounds and a ruthenium pincer complex
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This communication describes the reversible reaction of a ruthenium pincer complex with a variety of carbonyl compounds. Both NMR spectroscopic and X-ray crystallographic characterization of isomeric carbonyl adducts are reported, and the equilibrium constants for carbonyl binding have been determined.
- Huff, Chelsea A.,Kampf, Jeff W.,Sanford, Melanie S.
-
supporting information
p. 7147 - 7149
(2013/08/23)
-
- Nickel-catalyzed hydrosilylation of CO2 in the Presence of Et3B for the synthesis of formic acid and related formates
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The reaction of CO2 with Et3SiH catalyzed by the nickel complex [(dippe)Ni(μ-H)]2 (1) afforded the reduction products Et3SiOCH2OSiEt3 (12%), Et 3SiOCH3 (3%), and CO, which were characterized by standard spectroscopic methods. Part of the generated CO was found as the complex [(dippe)Ni(CO)]2 (2), which was characterized by single-crystal X-ray diffraction. When the same reaction was carried out in the presence of a Lewis acid, such as Et3B, the hydrosilylation of CO2 efficiently proceeded to give the silyl formate (Et3SiOC(O)H) in high yields (85-89%), at 80 C for 1 h. Further reactivity of the silyl formate to yield formic acid, formamides, and alkyl formates was also investigated.
- Gonzalez-Sebastian, Lucero,Flores-Alamo, Marcos,Garcia, Juventino J.
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p. 7186 - 7194
(2014/01/06)
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- Activation reactions of 1,1-dialkoxoalkanes and unsaturated O-donors by titanium tetrafluoride
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The reactivity of TiF4 with a variety of non cyclic 1,1-dialkoxoalkanes [CH2(OR)2, R = Me, Et, Me 2C(OMe)2, MeCH(OEt)2, ClCH2CH(OEt) 2, CH(OMe)3, PhCCCH(OEt)2], 1,3-dioxolane, N2CHCO2Et and 1,2-epoxybutane has been investigated. Activation, including fragmentation and/or rearrangement of the organic moiety, has been observed at room temperature in some cases; it generally occurs unselectively via C-O bond fission and the formation of new C-O, C-H and C-C bonds. Small differences in the structure of the organic substrate may determine significant differences in the reactivity with TiF4.
- Marchetti, Fabio,Pampaloni, Guido,Biancalana, Lorenzo
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experimental part
p. 135 - 139
(2012/05/20)
-
- Etherification and reductive etherification of 5-(hydroxymethyl)furfural: 5-(alkoxymethyl)furfurals and 2,5-bis(alkoxymethyl)furans as potential bio-diesel candidates
-
A low energy intensive process for the production of diesel fuel has been delineated from both 5-(hydroxymethyl)furfural (HMF) and its sugar precursor d-(-)-fructose. Alcoholic solutions of the above produced a mixture of potential bio-diesel candidates namely, 5-(alkoxymethyl)furfural, 5-(alkoxymethyl) furfural dialkylacetal, and alkyl levulinate, in the presence of solid acid catalysts. Sulfonic acid functionalized resins, Amberlyst-15 and Dowex DR2030 showed exceptional reactivity and selectivity for these reactions. Production of another potential diesel candidate 2,5-bis(alkoxymethyl)furan has been optimized through both sequential reduction/etherification and one-pot reductive etherification processes. During the metal catalyzed hydrogenation of HMF, platinum showed an exclusive selectivity for the reduction of the carbonyl functionality of HMF. Both Pt and Pt/Sn supported on Al2O3 catalysts have been optimized for the production of 2,5-bis(alkoxymethyl)furan from HMF. The reaction mechanisms of etherification and reductive etherification have been discussed in detail on the basis of intermediates observed during these processes. The Royal Society of Chemistry.
- Balakrishnan, Madhesan,Sacia, Eric R.,Bell, Alexis T.
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p. 1626 - 1634
(2013/02/22)
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- Catalytic hydrosilylation of carbonyls via Re(CO)5Cl photolysis
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The hydrosilylation reaction between silanes and various carbonyl substrates such as aldehyde, ketone, ester, and carbonate has been catalyzed by Re(CO)5Cl UV photolysis. Kinetic studies have shown that the reaction is favored for the least sterically hindered silanes with aldehydes followed by aliphatic ketones. The IR spectrum of the rhenium carbonyl dimer HRe 2(CO)9(SiR3) has been recorded in the reaction mixture. This complex is believed to be the resting state of the active catalyst Re(CO)4SiR3, which could be released upon photactivation. A catalytic mechanism involving this species has been proposed and shown to be thermodynamically feasible using computational studies. In addition, the relative hydrosilylation rates among the various carbonyl substrates can be explained using the same mechanism.
- Toh, Chun Keong,Sum, Yin Ngai,Fong, Wai Kit,Ang, Siau Gek,Fan, Wai Yip
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experimental part
p. 3880 - 3887
(2012/07/02)
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- METHOD FOR PREPARING DIFLUOROACETIC ACID
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A method for preparing difluoroacetic acid is described. The method can include: reacting a difluoroacetic acid ester with an aliphatic carboxylic acid which, after transesterification, results in the formation of difluoroacetic acid and the corresponding carboxylic acid ester, the carboxylic acid being selected such that the ester of the carboxylic acid has a lower boiling point than that of difluoroacetic acid; and removing the ester of the carboxylic acid by distillation as the ester forms, thus enabling the difluoroacetic acid to be recovered.
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Page/Page column 3-4
(2012/05/21)
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- PURIFICATION OF CARBOXYLIC ESTERS BY EXTRACTIVE DISTILLATION
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In a process for purifying carboxylic esters such as ethyl formate, a carboxylic ester to be purified is distilled in the presence of an extractant, preferably by (a) allowing vapor of the carboxylic ester to be purified to ascend in a distillation column; (b) conveying the extractant in countercurrent to the vapor in an extractive distillation column; (c) taking off pure carboxylic ester above the extractive distillation zone. The extractant is, for example, selected from among diols, polyols, open-chain or cyclic amides.
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Page/Page column 5
(2011/10/31)
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- Competition between reaction and intramolecular energy redistribution in solution: Observation and nature of nonstatistical dynamics in the ozonolysis of vinyl ethers
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Experimental product ratios in ozonolyses of alkyl vinyl ethers in solution do not fit with expectations based on statistical rate theories. The selectivity among cleavage pathways increases with the size of the alkyl group but to an extent that is far less than RRKM theory would predict. Trajectory studies account for the observed selectivities and support a mechanism involving a competition between cleavage of the primary ozonide and intramolecular vibrational energy redistribution. A statistical model is presented that assumes that RRKM theory holds for a molecular subset of the primary ozonides, allowing the rates of energy loss from the ozonides to be estimated from the observed product ratios.
- Quijano, Larisa Mae M.,Singleton, Daniel A.
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supporting information; experimental part
p. 13824 - 13827
(2011/10/12)
-
- Room-temperature selective aliphatic carbon-carbon bond activation and functionalization of ethers by rhodium(II) porphyrin
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Selective aliphatic carbon(α)-carbon(β) bond activation of ethers by (5,10,15,20-tetramesitylporphyrinato)rhodium(II) (Rh(tmp) (1)) was achieved at room temperature to yield corresponding rhodium porphyrin alkyls and the functionalized esters. Rh(tmp)OH was the proposed intermediate responsible for cleaving the C(α)-C(β) bond. The reaction is general for both straight- and branch-chain ethers.
- Lee, Siu Yin,Lai, Tsz Ho,Choi, Kwong Shing,Chan, Kin Shing
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scheme or table
p. 3691 - 3693
(2011/09/20)
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- Levulinic esters from the acid-catalysed reactions of sugars and alcohols as part of a bio-refinery
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Polymeric humin formation greatly diminishes levulinic acid yields in acid treatment of C6 sugars in aqueous medium. Protecting reactive functional groups of sugars and reaction intermediates via acetalisation and etherification in methanol medium effectively suppresses humin formation and remarkably enhances the production of levulinic esters.
- Hu, Xun,Li, Chun-Zhu
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supporting information; body text
p. 1676 - 1679
(2011/09/12)
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- A well-defined iron catalyst for the reduction of bicarbonates and carbon dioxide to formates, alkyl formates, and formamides
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A will of iron: An active well-defined iron complex (see structure; gray C, white H, yellow B, green F, brown Fe, pink P) catalyzes the title reaction (see scheme). The iron-catalyzed reduction of readily available bicarbonates to formates has also been demonstrated for the first time. This reaction could be an important step in the use of CO2 for hydrogen storage. Copyright
- Federsel, Christopher,Boddien, Albert,Jackstell, Ralf,Jennerjahn, Reiko,Dyson, Paul J.,Scopelliti, Rosario,Laurenczy, Gabor,Beller, Matthias
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experimental part
p. 9777 - 9780
(2011/03/16)
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- Hypervalent λ3-bromane strategy for Baeyer-Villiger oxidation: Selective transformation of primary aliphatic and aromatic aldehydes to formates, which is missing in the classical Baeyer-Villiger oxidation
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A conceptually distinct, modern strategy for Baeyer-Villiger oxidation (BVO) was developed. Our novel method involves initial hydration of water to carbonyl compounds, followed by ligand exchange of hypervalent aryl-λ3-bromane on bromane(III) with the resulting hydrate, yielding a new type of activated Criegee intermediate. The intermediate undergoes BV rearrangement and produces an ester via facile reductive elimination of an aryl-λ3-bromanyl group, because of the hypernucleofugality. The novel strategy makes it possible to induce selectively the BV rearrangement of straight chain primary aliphatic as well as aromatic aldehydes, which is missing in the classical BVO: for instance, octanal and benzaldehyde afforded rearranged formate esters with high selectivity (>95%) under our conditions, while the attempted classical BVO produced only carboxylic acids. This firmly establishes the powerful nature of new methodology for BVO.
- Ochiai, Masahito,Yoshimura, Akira,Miyamoto, Kazunori,Hayashi, Satoko,Nakanishi, Waro
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supporting information; experimental part
p. 9236 - 9239
(2010/11/02)
-
- Methods for Treating Dependence
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Provided are methods of treating patients suffering from or susceptible to at least one symptom of abuse of, dependence on, or withdrawal from at least one substance with Compound A. Also provided are methods of treating at least one phase of substance dependence on at least one substance in patients and certain methods of treating at least one phase of cocaine dependence in patients.
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- Low energy light-triggered oxidative cleavage of olefins
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A series of substituted olefins were tested for their reactivity with singlet oxygen as a singlet oxygen-mediated cleavable linker. Low intensity light of 200 mW/cm2 was irradiated to the solution of an olefin and 5,10,15-triphenyl-20-(4-hydroxyphenyl)-21H,23H-porphyrin under atmospheric condition. Among the tested olefins, 1,2-cis-diphenoxyethylene reacted fast with singlet oxygen, >80% within 15 min yielding a stoichiometric conversion to aldehyde product without any side reactions.
- Murthy, Rajesh S.,Bio, Moses,You, Youngjae
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scheme or table
p. 1041 - 1044
(2009/05/27)
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- Promotional effect of potassium salt in low-temperature formate and methanol synthesis from CO/CO2/H2 on copper catalyst
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Alkyl formates can be formed from CO2-containing syngas with C1-C4 alkyl alcohol solvents in the presence of potassium carbonate, which changed to potassium formate as catalyst. The formates can be in situ hydrogenolysized further to produce methanol effectively over manganese oxide or magnesia-supported copper catalysts. These homogeneous and heterogeneous catalysts constitute a novel system for methanol synthesis from CO/CO2/H2 even at 443 K. Copyright
- Zhao, Tian-Sheng,Yoneyama, Yoshiharu,Fujimoto, Kaoru,Yamane, Nodyuki,Fujimoto, Kenichiro,Tsubaki, Noritatsu
-
p. 734 - 735
(2008/02/09)
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- METHOD FOR THE PRODUCTION OF ACETAMIDE ACETALS
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The invention relates to a method for production of acetamide acetals of formula (I), where R1 and R2 independently = C1-C6 alkyl, phenyl or benzyl, or together form a C2-C6 alkylene and R3 and R4 independently = H, C1-C6 alkyl or benzyl, or together form a C3-C6 alkylene, whereby a glyoxylate ester diacetal of formula (II), in which R1 and R2 are as above and R5 = C1-C4 alkyl, is reacted with DMF or an amine of formula (III) NHR4R5, where R4 and R5 are as above, in the presence of 0.005 to 3 Mol %, based on the amine of formula (III), of an alcoholate of formula (IV) XOC1-C4, where X = Na, K or Li, at a reaction temperature of 0 to 100 °C to give the corresponding compound of formula (I).
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- Ruthenium-catalyzed hydrogenation of carbon dioxide to formic acid in alcohols
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Catalytic hydrogenation of CO2 to formic acid with the (solvento)metal hydride complex, TpRu(PPh3)(CH3CN)H [Tp = hydrotris(pyrazolyl)borate], in various alcohols was studied. High-pressure NMR monitoring of the catalytic reaction in non-acidic methanol shows that the observable intermediate is a formate complex resulting from CO2 insertion into the Ru-H bond and is stabilized by the hydrogen-bonding interaction between the formato ligand and a methanol molecule. However, in the case of the acidic alcohol, CF3CH2OH, the observable intermediates are [TpRu(PPh3)(CH3CN)2] +CF3CH2O- and the alkyl carbonate complex, TpRu(PPh3)(η2O2COCH 2CF3), which are formed by the reaction of CO2 with the alkoxide species, TpRu(PPh3)(CH3CN)(OCH 2CF3), generated by a very facile reaction between TpRu(PPh3)(CH3CN)H and CF3CH2OH. We propose that the productive catalytic cycles of the reactions conducted in a variety of alcohols are similar to the one we formulated for the catalytic hydrogenation of CO2 in hydrous THF. The formic acid is produced by the transfer of a hydride and a proton from the transient alcohol hydride intermediate, TpRu(PPh3)(ROH)H, to an approaching CO2 molecule. The activity of TpRu(PPh3)(CH3CN)H is higher in CF3CH2OH than in methanol and other non-acidic alcohols and it is probably due to the enhanced electrophilicity of the carbon atom of CO2, which results from the strong interaction between the proton of the highly acidic alcohol in TpRu(PPh3)(CF3CH 2OH)H and an oxygen atom of CO2. The electrophilic carbon atom of CO2 could in turn abstract the hydride from Ru-H in a more facile manner. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Ng, Siu Man,Yin, Chuanqi,Yeung, Chi Hung,Chan, Tak Chung,Lau, Chak Po
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p. 1788 - 1793
(2007/10/03)
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