- Selective defunctionalization of citric acid to tricarballylic acid as a precursor for the production of high-value plasticizers
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Strong concerns about the toxicity and endocrine disrupting properties of widespread phthalate plasticizers stimulate the demand for safe and preferably biobased alternatives. Citric acid forms in this respect an excellent and abundant platform chemical for the production of valuable plasticizers. Here, we report a new and direct synthesis route for propane-1,2,3-tricarboxylic acid (PTA) from citric acid via a sequential one pot dehydration-hydrogenation process. This saturated triacid can serve as a basis for the production of tricarballylate esters via esterification, which have been shown to possess excellent plasticizing properties in vinyl resins. In the presence of a solid acid H-Beta zeolite and Pd/C hydrogenation catalyst, yields up to 85% of PTA were obtained under mild reaction conditions and in water as a green solvent. Partial dealumination of the H-Beta zeolite by citric acid could be counteracted by reincorporating aluminium into the framework of the recycled H-Beta zeolite through realumination, regenerating a significant fraction of the initial activity of the catalytic system. The success of the realumination procedure was verified via MAS NMR spectroscopy.
- De Vos, Dirk E.,Krajnc, Andra?,Mali, Gregor,Stuyck, Wouter,Verduyckt, Jasper
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- Electrocatalytic upgrading of itaconic acid to methylsuccinic acid using fermentation broth as a substrate solution
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Biomass presents a promising renewable feedstock allowing access to valuable platform chemicals. In particular, biotechnological processes enable a highly selective product formation but are carried out in aqueous electrolyte-containing solutions. Consequently, the separation of usually polar products poses severe challenges on product separation associated with a high energy demand of product purification. A direct further catalytic transformation within fermentation broth reduces the number of unit operations and the need for an energy intensive separation. We herein study the potential of a chemo- and electrochemical reduction of itaconic acid (IA) to methylsuccinic acid (MS) using acidic media or crude fermentation broth as a case study. Despite an efficient chemo-catalytic hydrogenation of neat IA over Ru/C or RANEY nickel, the presence of various salts as well as glucose prohibits a direct chemo-catalytic valorisation in fermentation broth. In contrast, the electrochemical hydrogenation enabled very benign conditions. The selection of the electrode material proved to be decisive and had, together with the voltage, a strong influence on the conversion and faradaic efficiency of electrolysis facilitating 99% faradaic efficiency. The conversion of IA only slightly declined for an IA fermentation broth instead of neat IA in a diluted sulfuric acid environment reaching 60 versus 64%. Moreover, a full conversion and yield could also be achieved by simple optimizations of the reaction period and the substrate concentration. The electrocatalytic valorisation of a crude biotechnological product stream reduces not only energy demand and unit operations but presents a promising approach to introduce renewable electrical energy in biomass utilization.
- Holzh?user, F. Joschka,Artz, Jens,Palkovits, Stefan,Kreyenschulte, Dirk,Büchs, Jochen,Palkovits, Regina
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- Stabilising Ni catalysts for the dehydration-decarboxylation-hydrogenation of citric acid to methylsuccinic acid
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A new reaction sequence of dehydration-decarboxylation-hydrogenation to transform citric acid into methylsuccinic acid has recently been developed using Pd as a noble metal catalyst in water. In this work Ni catalysts were investigated as low cost, non-noble metal alternatives. Several home-made and commercial catalysts were screened for this reaction. Citric acid was very reactive and full conversions were readily obtained in all cases. However, the selectivity to methylsuccinic acid was initially low, since typical Ni catalysts were not stable and therefore not able to hydrogenate the formed CC double bonds. Due to the lower hydrogenation activity of Ni compared to Pd, new side products appeared. Particularly, hydration of the CC double bonds made the reaction network more complex in this case. Fortunately, the formation of all hydration products-even the rather stable lactone, β-carboxy-γ-butyrolactone-was eventually shown to be completely reversible. Three routes were then studied to stabilise Ni catalysts and to enable the Ni catalyzed conversion of citric acid to methylsuccinic acid; partial neutralisation of the acid reactant, adding Fe to Ni/ZrO2 or to the reaction mixture and coating Ni particles with carbon, all proved to stabilise Ni and all resulted in high to very high methylsuccinic acid yields. Furthermore, the role of Fe was unravelled by performing reference reactions with different Fe compounds and by in depth characterisation of the NiFe/ZrO2 catalyst. Finally, the reaction conditions were optimised using the carbon-coated Ni nanoparticles and kinetic profiles were recorded to confirm the extended reaction network.
- Verduyckt, Jasper,Geers, Anton,Claes, Birgit,Eyley, Samuel,Van Goethem, Cédric,Stassen, Ivo,Smolders, Simon,Ameloot, Rob,Vankelecom, Ivo,Thielemans, Wim,De Vos, Dirk E.
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- Monitoring of itaconic acid hydrogenation in a trickle bed reactor using fiber-optic coupled near-infrared spectroscopy
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Near-infrared (NIR) spectroscopy has been applied to determine the conversion of itaconic acid in the effluent stream of a trickle bed reactor. Hydrogenation of itaconic to methyl succinic acid was carried out, with the trickle bed operating in recycle mode. For the first time, NIR spectra of itaconic and methyl succinic acids in aqueous solution, and aqueous mixtures withdrawn from the reactor over a range of reaction times, have been recorded using a fiberoptic sampling probe. The infrared spectra displayed a clear isolated absorption band at a wavenumber of 6186 cm-1 (wavelength 1.617 μm) resulting from the =C-H bonds of itaconic acid, which was found to decrease in intensity with increasing reaction time. The feature could be more clearly observed from plots of the first derivatives of the spectra. A partial least-squares (PLS) model was developed from the spectra of 13 reference samples and was used successfully to calculate the concentration of the two acids in the reactor effluent solution. Itaconic acid conversions of 23-29% were calculated after 360 min of reaction time. The potential of FT-NIR with fiber-optic sampling for remote monitoring of three-phase catalytic reactors and validation of catalytic reactor models is highlighted in the paper.
- Wood, Joseph,Turner, Paul H.
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- Ligandgesteuerte Ringkontraktion von Nickela-Fuenf- in Vierringkomplexe-neuartige Startsysteme fuer die praeparative Chemie
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Nickela-compounds with a five-membered ring, 4, are formed on Ni0 from CO2 and alkenes in the presence of the heterodifunctional ligand (cyclo-C6H11)2PCH2-CH2-2-pyridyl (2).A ring contraction occurs on addition of a promotor, such as BeCl2 or on heating.The greater reactivity of the nickela-complex with a four-membered ring, 6, can be used in the former reactions with CO2, CO or CH2=CH2.Such a sequence of reactions can be employed for the catalytic reaction of ethene with acrylic anilide on a (C6H11)3P/Ni0 system.
- Hoberg, Heinz,Ballesteros, Alfredo,Sigan, Andrei,Jegat, Corine,Baerhausen, Dieter,Milchereit, Armin
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- Stereochemistry of bertyadionol and related compounds
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Two new diterpenes related to bertyadionol have been isolated and their structure determined. Degradation of bertyadionol to 2R-methylsuccinic acid provided the configuration at C-2 for this compound. The absolute stereochemistry of bertyadionol and its c
- Ghisalberti,Jefferies,Toia,Worth
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- Mechanistic aspects of hydrogen addition during enantioselective rhodium-catalysed reduction of C=C double bonds with formic acid/triethylamine or molecular hydrogen
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Deuterium labelling experiments reveal a remarkably different hydrogen addition mode during homogeneously catalysed C=C bond reduction of itaconic acid derivatives 1a-d using molecular hydrogen (hydrogenation) or formic acid/triethylamine (transfer hydrogenation). The expected vicinal addition of two hydrogen atoms across the double bond prevails for all substrates in conventional hydrogenation, whereas the deuterium pattern depends largely on the nature of the carboxyl group in the β (or allylic) position during transfer hydrogenation. Vicinal addition is observed only in case of itaconic acid 1a and α-methylitaconate 1c, while 1,3-addition is preferred with dimethylitaconate 1b and β-methylitaconate 1d. Significant amounts of polydeuterated products are formed also during hydrogenation and transfer hydrogenation. Monitoring the deuterium pattern as a function of time reveals that deuterium scrambling is responsible for polydeuteration, but not for the change of the addition mode. The use of monodeuterated formic acid isotopomers shows that the incorporation from the hydridic formyl position occurs preferentially at the terminal end of the double bond (C-3) whereas the protic hydrogen is directed either in the higher substituted olefinic (C-2) or the methylene (C-1) position. Control experiments using mesaconic (2) and citraconic (3) acids demonstrate that double bond migration in 1a-d is negligible under the reaction conditions. These results are best rationalised on the basis of a common mechanism for hydrogenation and transfer hydrogenation that involves (i) the generation of Rh-H intermediates, (ii) reversible hydride transfer to coordinated substrate to form two isomeric σ-alkyl intermediates, and (iii) irreversible product liberation through protolytic Rh-C cleavage. The key intermediates are similar if not identical for hydrogenation and transfer hydrogenation. The change of the hydrogen transfer pattern can be explained on the basis of the relative rates of the individual steps within the catalytic cycle as compared to the rate of isomerisation of the σ-alkyl intermediates. The Royal Society of Chemistry 2002.
- Lange, Susanne,Leitner, Walter
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- Efficient conversion of bio-renewable citric acid to high-value carboxylic acids on stable solid catalysts
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Citric acid is an important biomass-derived platform chemical for the synthesis of high-value organic acids, such as itaconic acid (ICA), 2-methylsuccinic acid (MSA) and tricarballylic acid (TCA). However, these reactions frequently encounter low efficiency and severe leaching of catalysts imposed by the acidity of citric acid under hydrothermal conditions, limiting their practical applications. Here, we report that highly acid- and etching-resistant monoclinic zirconium dioxide (m-ZrO2) exhibited high catalytic efficiency in the conversion of citric acid to ICA via sequential dehydration and decarboxylation steps, providing a high yield of 70.3% at 180 °C on m-ZrO2 (calcined at 300 °C). The correlation between the activity of the m-ZrO2 catalysts and their acid-basicity demonstrates that the synergistic effect of acidic and basic sites facilitates the rate-determining dehydration step for the citric acid conversion to ICA. On the bifunctional catalysts, Pt and Pd nanoparticles supported on P25 and anatase TiO2, citric acid can be selectively converted to MSA and TCA, respectively, with yields as high as 83.1% and 64.9%. The hydrogenation activity of the bifunctional catalysts was found to be crucial for regulating the relative rates of the decarboxylation and hydrogenation steps involved in the selective conversion of citric acid to MSA and TCA. These catalysts showed excellent stability and recyclability in acidic aqueous solutions. This study provides a rationale for tuning catalytic functions required for the green production of important carboxylic acids from citric acid and other biomass-derived feedstocks. This journal is
- Li, Zhaowei,Liu, Haichao,Wen, Xin
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p. 1650 - 1658
(2022/03/07)
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- CATALYST AND METHOD OF HYDROGENATING UNSATURATED COMPOUND WITH MULTI-CARBOXYLIC ACID GROUPS
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A method of hydrogenating unsaturated compound with multi-carboxylic acid groups is provided, which includes introducing hydrogen to an unsaturated compound with multi-carboxylic acid groups in the presence of a catalyst to hydrogenate the alkene or alkyne group of the unsaturated compound with multi-carboxylic acid groups without hydrogenating the carboxylic acid groups of the unsaturated compound with multi-carboxylic acid groups. The catalyst includes a support, and palladium and metal oxide loaded on the support.
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Paragraph 0024-0040; 0042
(2021/06/26)
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- Catalytic Aerobic Oxidation of Lignocellulose-Derived Levulinic Acid in Aqueous Solution: A Novel Route to Synthesize Dicarboxylic Acids for Bio-Based Polymers
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The world is facing grand and ever-increasing pressures on energy and environmental issues. Using carbon-neutral biomass to prepare monomers such as dicarboxylic acids for degradable polymers is of great significance and an urgent but challenging task. Herein, we report a catalytic route for the synthesis of 2-hydroxy-2-methylsuccinic acid, an excellent monomer: e.g., it is able to remarkably enhance the comprehensive properties of polybutylene succinate as shown herein. By catalytic aerobic oxidation of levulinic acid, a bulk platform chemical derived from lignocellulose, the target product was obtained with a very high selectivity of up to ca. 95%. The mild reaction conditions below 100 °C in water and the low-cost reusable heterogeneous catalyst further make the process highly attractive for applications. This process was also found to be effective for the conversion of homologues of levulinic acid to dicarboxylic acids. We studied the C-C bond rearrangement and the roles of catalysts in the reaction that are highly likely involved in a superoxide anion radical mechanism. This study may provide inspiration for the synthesis of bio-based dicarboxylic acids via alternative routes.
- Che, Li,Jiang, Min,Jiang, Yu,Pang, Jifeng,Song, Lei,Wang, Rui,Zhang, Tao,Zhao, Yu,Zheng, Mingyuan,Zhou, Guangyuan,Zhou, Mo
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p. 11588 - 11596
(2021/09/22)
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- 1,3,2-Diazaphospholenes Catalyze the Conjugate Reduction of Substituted Acrylic Acids
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The potent nucleophilicity and remarkably low basicity of 1,3,2-diazaphospholenes (DAPs) is exploited in a catalytic, metal-free 1,4-reduction of free α,β-unsaturated carboxylic acids. Notably, the reduction occurs without a prior deprotonation of the carboxylic acid moiety and hence does not consume an additional hydride equivalent. This highlights the excellent nucleophilic character and low basicity of DAP-hydrides. Functional groups such as Cbz group or alkyl halides which can be problematic with classical transition-metal catalysts are well tolerated in the DAP-catalyzed process. Moreover, the transformation is characterized by a low catalyst loading, mild reaction conditions at ambient temperature as well as fast reaction times and high yields. The proof-of-principle for a catalytic enantioselective version is described.
- Reed, John H.,Cramer, Nicolai
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p. 4262 - 4266
(2020/07/13)
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- Sustainable electroorganic synthesis of lignin-derived dicarboxylic acids
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The oxidative ring opening of lignin-derived alkylated cyclohexanols to bio-based alkylated dicarboxylic acids is successfully performed by an electrocatalytic conversion. To establish this transformation as a green method, we developed a simple protocol for the anodic oxidation at nickel oxide-hydroxide (NiOOH) foam anodes in caustic soda in both a batch and flow electrolysis approach.
- Rauen, Anna Lisa,Waldvogel, Siegfried R.,Weinelt, Frank
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supporting information
p. 5956 - 5960
(2020/10/18)
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- Regioselective Hydrogenation of Itaconic Acid to Γ-Isovalerolactone by Transition-Metal Nanoparticle Catalysts
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Current methods for hydrogenation of bio-derived itaconic acid (IA) lead to a mixture of isomeric lactone products. Transition-metal nanoparticles (TM-NPs), in situ-generated through thermolysis of TM(0) (Ru, Fe, W, Cr) carbonyls, in particular Ru-NPs, were found to catalyze regioselective hydrogenation of IA by syngas (2 H2/CO) into γ-isovalerolactone (GiVL) in approximately 70 % isolated yield. Key sustainability features of this new route include: a one-pot direct transformation of bio-renewable IA into value-added GiVL selectively, use of inexpensive and renewable syngas in aqueous solution, and development of a supported recyclable NP catalyst system, Al2O3-Ru-NPs.
- Gowda, Ravikumar R.,Chen, Eugene Y.-X.
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p. 973 - 977
(2019/02/06)
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- METHOD FOR THE PRODUCTION OF METHYLSUCCINIC ACID AND THE ANHYDRIDE THEREOF FROM CITRIC ACID
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A process for the preparation of methylsuccinic acid in any form, including its salts, its mono- and diester derivatives and the anhydride thereof, which comprises reacting citric acid or a derivative thereof in decarboxylation conditions, said process comprising (i) reacting citric acid or mono- and diester derivatives thereof in a non- aqueous solvent, specifically excluding alcohols, on a metallic catalyst at a temperature between 50 to 400°C and under a partial hydrogen pressure from 0.1 to 50 bar or (ii) reacting citric acid or any salt thereof or mono-, di- and triester derivatives thereof on a metallic catalyst in solvents comprising at least 5% water, at a temperature of from 50 to 400°C under a hydrogen partial pressure from 0.1 to 400 bar
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Page/Page column 13-17
(2018/04/21)
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- Highly selective one-step dehydration, decarboxylation and hydrogenation of citric acid to methylsuccinic acid
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The one-step dehydration, decarboxylation and hydrogenation of the bio-based and widely available citric acid is presented. This reaction sequence yields methylsuccinic acid with yields of up to 89%. Optimal balances between the reaction rates of the different steps were found by varying the hydrogenation catalyst and the reaction parameters (H2 pressure, pH, temperature, time and catalyst-to-substrate ratio).
- Verduyckt, Jasper,De Vos, Dirk E.
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p. 2616 - 2620
(2017/04/06)
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- Method for preparing pyrovinic acid through catalysis of itaconic acid for hydrogenation by ruthenium carbon catalyst after carbon thermal reduction
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The invention discloses a method for preparing pyrovinic acid through catalysis of itaconic acid for hydrogenation by a ruthenium carbon catalyst after carbon thermal reduction. The pyrovinic acid is an important organic synthesis intermediate, has chirality, and has wide application on medicine synthesis aspect. Under water phase mild reaction condition, the ruthenium carbon catalyst prepared by the carbon thermal reduction performs catalytic hydrogenation on itaconic acid to prepare the pyrovinic acid, conversion rate and selectivity can reach 99%, and a catalyst enables multitime recycling.
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Paragraph 0022-0033
(2017/08/29)
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- Method for aqueous-phase catalytic synthesis of methyl succinic acid
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The invention discloses a method for aqueous-phase catalytic synthesis of methyl succinic acid. The methyl succinic acid is an important organic synthesis intermediate and is wide in application. According to the method disclosed by the invention, a Ru-based catalyst is adopted to make itaconic acid have a catalytic hydrogenation reaction to prepare the methyl succinic acid under an aqueous-phase neutral and moderate reaction condition, the conversion rate and the selectivity can both be as high as 99%, and the catalyst can be used repeatedly.
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Paragraph 0022; 0023; 0024; 0025; 0026
(2017/08/28)
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- Palladium Complexes with Bulky Diphosphine Ligands as Highly Selective Catalysts for the Synthesis of (Bio-) Adipic Acid from Pentenoic Acid Mixtures.
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A series of sterically bulky diphosphines have been prepared, including P2 = trans-1,2-bis[(di-tert-butylphosphino)methyl]cyclohexane (4), (2-methylenepropane-1,3-diyl)bis(di-tert-butylphosphine) (5), bis[(di-tert-butylphosphino)methyl]dimethylsilane (6), and cis- and trans-11,12-bis[(di-tert-butylphosphino)methyl]-9,10-dihydro-9,10-ethanoanthracene (10 and 11). The corresponding palladium complexes of these ligands, P2Pd(CF3CO2)2, have been synthesized and characterized. The solid-state structures of [Pd(4)(CF3CO2)2], [Pd(5)(CF3CO2)2], [Pd(6)(CF3CO2)2], and [Pd(11)(CF3CO2)2] were obtained by single-crystal X-ray diffraction and confirm the bidentate binding mode of the ligand and a square-planar coordination geometry with a minor distortion from the ideal. The diphosphines in combination with Pd(OAc)2 have been applied in the hydroxycarbonylation of a mixture of pentenoic acid isomers to produce adipic acid with high selectivity (in several cases >95%). The (regio)selectivity of the hydroxycarbonylation reaction is highly dependent on the P2 diphosphine ligand structure, particularly the steric bulk of the substituents on the diphosphine donor and the P-Pd-P bite angle in the complexes, with respectively tertiary alkyl phosphine substituents (tert-butyl, adamantyl) and a C4 backbone P-Pd-P bite angle >100° being the common features of highly adipic acid selective systems. It is suggested that the regioselectivity of hydroxycarbonylation becomes largely driven by the chelation of the carboxylic acid functionality of pentenoic acid substrates, when smaller size P substituents and/or when P2 ligands with smaller bite angles (100°) are applied.
- Low, Choon Heng,Nobbs, James D.,Van Meurs, Martin,Stubbs, Ludger P.,Drent, Eite,Aitipamula, Srinivasulu,Pung, Michelle H. L.
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p. 4281 - 4292
(2015/09/22)
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- Aqueous-phase hydrogenation of biomass-derived itaconic acid to methyl-γ-butyrolactone over Pd/C catalysts: Effect of pretreatments of active carbon
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The effect of active carbon pretreatment on the catalytic performance of Pd/C catalysts in the hydrogenation of itaconic acid was studied. The catalysts were prepared by deposition-precipitation and characterized by XRD, BET, NH3-TPD, TEM and F
- Li, Sha,Wang, Xicheng,Liu, Xiaoran,Xu, Guoqiang,Han, Sheng,Mu, Xindong
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- Metal-free transfer hydrogenation of olefins via dehydrocoupling catalysis
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A major advance in main-group chemistry in recent years has been the emergence of the reactivity of main-group species that mimics that of transition metal complexes. In this report, the Lewis acidic phosphonium salt [(C 6F5)3PF][B(C6F5) 4] 1 is shown to catalyze the dehydrocoupling of silanes with amines, thiols, phenols, and carboxylic acids to form the Si-E bond (E = N, S, O) with the liberation of H2 (21 examples). This catalysis, when performed in the presence of a series of olefins, yields the concurrent formation of the products of dehydrocoupling and transfer hydrogenation of the olefin (30 examples). This reactivity provides a strategy for metal-free catalysis of olefin hydrogenations. The mechanisms for both catalytic reactions are proposed and supported by experiment and density functional theory calculations.
- Pérez, Manuel,Caputo, Christopher B.,Dobrovetsky, Roman,Stephan, Douglas W.
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p. 10917 - 10921
(2014/08/18)
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- A biocompatible alkene hydrogenation merges organic synthesis with microbial metabolism
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Organic chemists and metabolic engineers use orthogonal technologies to construct essential small molecules such as pharmaceuticals and commodity chemicals. While chemists have leveraged the unique capabilities of biological catalysts for small-molecule production, metabolic engineers have not likewise integrated reactions from organic synthesis with the metabolism of living organisms. Reported herein is a method for alkene hydrogenation which utilizes a palladium catalyst and hydrogen gas generated directly by a living microorganism. This biocompatible transformation, which requires both catalyst and microbe, and can be used on a preparative scale, represents a new strategy for chemical synthesis that combines organic chemistry and metabolic engineering. Reduction to practice: A hydrogenation reaction has been developed that employs hydrogen generated in situ by a microorganism and a biocompatible palladium catalyst to reduce alkenes on a synthetically useful scale. This type of transformation, which directly combines tools from organic chemistry with the metabolism of a living organism for small-molecule production, represents a new strategy for chemical synthesis.
- Sirasani, Gopal,Tong, Liuchuan,Balskus, Emily P.
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supporting information
p. 7785 - 7788
(2014/08/05)
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- Highly efficient D2 generation by dehydrogenation of formic acid in D2O through H+/D+ exchange on an iridium catalyst: Application to the synthesis of deuterated compounds by transfer deuterogenation
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Deuterated compounds have received increasing attention in both academia and industrial fields. However, preparations of these compounds are limited for both economic and practical reasons. Herein, convenient generation of deuterium gas (D2) and the preparation of deuterated compounds on a laboratory scale are demonstrated by using a half-sandwich iridium complex with 4,4'-dihydroxy-2,2'-bipyridine. The "umpolung" (i.e., reversal of polarity) of a hydrogen atom of water was achieved in consecutive reactions, that is, a cationic H+/D+ exchange reaction and anionic hydride or deuteride transfer, under mild conditions. Selective D2 evolution (purity up to 89%) was achieved by using HCO2H as an electron source and D2O as a deuterium source; a rhodium analogue provided HD gas (98%) under similar conditions. Furthermore, pressurized D 2 (98%) without CO gas was generated by using DCO2D in D2O in a glass autoclave. Transfer deuterogenation of ketones gave α-deuterated alcohols with almost quantitative yields and high deuterium content by using HCO2H in D2O. Mechanistic studies show that the H+/D+ exchange reaction in the iridium hydride complex was much faster than β-elimination and hydride (deuteride) transfer. Cheap D2 gas! Convenient generation of deuterium gas (D2) and preparation of deuterated compounds on a laboratory scale are demonstrated using a half-sandwich iridium complex with 4,4'-dihydroxy-2,2'- bipyridine (see scheme). The "umpolung" of a hydrogen atom of water was achieved in consecutive reactions (cationic H+/D+ exchange reaction and anionic hydride (deuteride) transfer) under mild conditions. Copyright
- Wang, Wan-Hui,Hull, Jonathan F.,Muckerman, James T.,Fujita, Etsuko,Hirose, Takuji,Himeda, Yuichiro
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supporting information; scheme or table
p. 9397 - 9404
(2012/10/08)
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- MIXTURES OF ITACONIC ACID OR ITACONIC ACID DERIVATIVES AND PRIMARY AMINES FOR PRODUCING 1,3- AND 1,4-ALKYL METHYL PYRROLIDONES
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The present invention relates to a mixture comprising itaconic acid or an itaconic acid derivative and a primary amine of the formula (I) [in-line-formulae]R—NH2??(I)[/in-line-formulae] where the molar ratio of primary amine to itaconic acid or the itaconic acid derivative is in the range from 0.5:1 to 20:1, wherein the mixture comprises 50 mole percent or less of 4-carboxypyrrolidones of the formula (II), derivatives of the 4-carboxypyrrolidones of the formula (II) and 4-carbamidopyrrolidones of the formula (III) based on the itaconic acid used or the itaconic acid derivative used and in which R is a linear or branched saturated aliphatic radical having 1 to 24 carbon atoms or a saturated cycloaliphatic radical having 3 to 24 carbon atoms. The invention further provides for the use of the inventive mixtures for preparing 1,3-alkylmethylpyrrolidones and/or 1,4-alkylmethylpyrrolidones, and also a process for preparing 1,3-alkylmethylpyrrolidones and/or 1,4-alkylmethylpyrrolidones. In addition, the present invention relates to mixtures comprising 1,3-alkylmethylpyrrolidones and/or 1,4-alkylmethylpyrrolidones and 1,3-alkylmethylpyrrolidines, where the proportion of 1,3-alkylmethylpyrrolidines is in the range from 10 to 10 000 ppm, and to mixtures comprising 1,3-alkylmethylpyrrolidone and 1,4-alkylmethylpyrrolidone, wherein the molar ratio of 1,3-alkylmethylpyrrolidone to 1,4-alkylmethylpyrrolidone is in the range from 1:1 to 10:1.
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Page/Page column 12-13
(2011/10/19)
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- Water-tolerant Ru-Starbon materials for the hydrogenation of organic acids in aqueous ethanol
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Highly active and stable ruthenium-supported nanoparticles show excellent activities and selectivities to target products in the aqueous hydrogenation of organic acids including succinic, fumaric, itaconic, levulinic and pyruvic acids. The materials were also highly reusable and comparably more active than related supported Ru materials.
- Luque, Rafael,Clark, James H.
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experimental part
p. 928 - 931
(2010/11/04)
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- Suzuki-Miyaura, Mizoroki-Heck carbon-carbon coupling and hydrogenation reactions catalysed by PdII and RhI complexes containing cyclodiphosphazane cis-{tBuNP(OC6H4OMe-o)} 2
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The catalytic activity of the palladium complex cis-[PdCl 2{(tBuNP(OC6H4OMe-o)) 2-κP}2] (2) containing cis-{tBuNP(OC 6H4OMe-o)}2 (1) in Suzuki-Miyaura and Mizoroki-Heck carbon-carbon cross coupling reactions is described. The compound 2 also displays very high activity in Mizoroki-Heck coupling reactions. The rhodium(I) complex [RhCl(COD){(tBuNP(OC6H 4OMe-o))2-κP}] (3) acts as an excellent catalyst for the hydrogenation of several terminal olefins. Indian Academy of Sciences.
- Mohanty, Sasmita,Balakrishna, Maravanji S.
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experimental part
p. 137 - 142
(2010/11/17)
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- Nicotinamide-independent asymmetric bioreduction of C{double bond, long}C-bonds via disproportionation of enones catalyzed by enoate reductases
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The asymmetric bioreduction of activated C{double bond, long}C-bonds catalyzed by a single flavoprotein was achieved via direct hydrogen transfer from a sacrificial 2-enone or 1,4-dione as hydrogen donor without requirement of a nicotinamide cofactor. Due to its simplicity, this system has clear advantages over conventional FAD-recycling systems.
- Stueckler, Clemens,Reiter, Tamara C.,Baudendistel, Nina,Faber, Kurt
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experimental part
p. 663 - 667
(2010/09/18)
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- DIPEPTIDYL PEPTIDASE-IV INHIBITING COMPOUNDS, METHODS OF PREPARING THE SAME, AND PHARMACEUTICAL COMPOSITIONS CONTAINING THE SAME AS ACTIVE AGENT
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Disclosed herein are novel compounds of Formula (1) as defined in the specification having excellent inhibitory activity against dipeptidyl peptidase-IV (DPP-IV), methods of preparing the same and pharmaceutical compositions comprising the same as an active agent.
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Page/Page column 88-89
(2009/07/25)
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- Asymmetric bioreduction of activated C=C bonds using Zymomonas mobilis NCR enoate reductase and old yellow enzymes OYE 1-3 from yeasts
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The asymmetric bioreduction of C=C-bonds bearing an electron-withdrawing group, such as an aldehyde, ketone, imide, nitro, carboxylic acid, or ester moiety by a novel enoate reductase from Zymomonas mobilis and Old Yellow Enzymes OYE 1-3 from yeasts furnished the corresponding saturated products in up to >99%ee. Depending on the substrate type, stereocontrol was achieved by variation of the substrate structure, by switching the (E/Z) geometry of the alkene or by choice of the appropriate enzyme. This substrate- or enzyme-based stereocontrol allowed access to the opposite enantiomeric products. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Hall, Melanie,Stueckler, Clemens,Hauer, Bernhard,Stuermer, Rainer,Friedrich, Thomas,Breuer, Michael,Kroutil, Wolfgang,Faber, Kurt
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supporting information; experimental part
p. 1511 - 1516
(2009/04/11)
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- Hydrogen-free homogeneous catalytic reduction of olefins in aqueous solutions
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(Chemical Equation Presented) Herein we report a study involving the homogeneous catalytic reduction of unsaturated substrates in aqueous solutions or water-organic solvent mixtures. The reduction of olefins has been carried out in the presence of catalytic amounts of [Fe(CN)5NH3] 3- and excess of NH2OH, which under mild reaction conditions can be used to reduce carbon-carbon unsaturations without affecting carbonyl functionalities and aromatic rings. To explore the scope of the catalytic reduction, a wide variety of representative unsaturated substrates have been examined. The steric effects of the substituents on the carbon-carbon multiple bond as well as the regioselectivity and stereoselectivity of the catalyst have been studied. The deuterium kinetic isotope effect on the catalytic reduction of double bonds in olefins has been analyzed, and no significant kinetic isotope effect was found. Among the great advantages of this novel procedure for catalytic reduction are that hydrogen and high pressures are not needed, the catalyst is inexpensive and easily prepared, and water as well as water-organic solvent mixtures can be used as reaction media.
- Gaviglio, Carina,Doctorovich, Fabio
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p. 5379 - 5384
(2008/12/20)
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- Impact of incorporating substituents onto the P-o-anisyl groups of DiPAMP ligand on the rhodium(I)-catalyzed asymmetric hydrogenation of olefins
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The introduction of 1,2-bis[(o-anisyl)-(phenyl)phosphino]ethane (DiPAMP) as a P-stereogenic ligand for rhodium(I)-catalyzed hydrogenation by Knowles et al. came after their evaluation of several diphosphines. However, no in-depth study was carried out on incorporating various substituents on its P-o-anisyl groups. In this work, we have prepared a large series of enantiopure and closely related DiPAMP analogues possessing various substituents (MeO, TMS, t-Bu, Ph, fused benzene ring) on the o-anisyl rings. The new ligands were evaluated in rhodium-catalyzed hydrogenation of several model substrates: methyl α-acetamidoacrylate, methyl (Z)-α-acetamidocinnamate, methyl (Z)-β-acetamidocrotonate, dimethyl itaconate, and atropic acid. They displayed enhanced activities and increased enantioselectivities, particularly the P-(2,3,4,5-tetra-MeO-C6H)-substituted ligand (4MeBigFUS). Interestingly enough, 88% ee was obtained in the hydrogenation of atropic acid using the Rh-(4MeBigFUS) catalyst under mild conditions (10 bar H2, room temperature) versus 7% ee using Rh-DiPAMP. Conversely, the ligand possessing P-(2,6-di-MeO-C6H3) groups proved to slow down considerably the hydrogenation. X-Ray structures of their corresponding Rh complexes are presented and discussed.
- Zupancic, Borut,Mohar, Barbara,Stephan, Michel
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supporting information; experimental part
p. 2024 - 2032
(2009/09/07)
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- Asymmetric bioreduction of activated alkenes using cloned 12-oxophytodienoate reductase isoenzymes OPR-1 and OPR-3 from Lycopersicon esculentum (tomato): A striking change of stereoselectivity
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(Chemical Equation Presented) Tomato source: 12-Oxophytodienoate reductase isoenzymes OPR1 and OPR3 from tomato possess a broad substrate spectrum for the asymmetric bioreduction of α,β-unsaturated enals, enones, dicarboxylic acids, and N-substituted male-imides (see scheme). Stereocomplementary behavior of both isoenzymes was observed in the reduction of a nitroalkene that led to the formation of opposite stereoisomers in high enantiomeric excess.
- Hall, Melanie,Stueckler, Clemens,Kroutil, Wolfgang,Macheroux, Peter,Faber, Kurt
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p. 3934 - 3937
(2008/03/11)
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- Stereocomplementary bioreduction of α,β-unsaturated dicarboxylic acids and dimethyl esters using enoate reductases: Enzyme- And substrate-based stereocontrol
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Asymmetric bioreduction of α,β-unsaturated dicarboxylic acids, such as 2-methylmaleic/fumaric and 2-methylenesuccinic acid, as well as the corresponding dimethyl esters, using three cloned enoate reductases furnished 2-methylsuccinic acid or dimethyl 2-methylsuccinate, respectively. Opposite stereoisomeric products were obtained in up to >99% ee either by choice of the enzyme or by using E/Z-configurated substrates. Cofactor-recycling systems (NADH/FDH/formate, NADH/GDH/glucose or NADPH/G6PDH/glucose-6-phosphate) only worked in presence of a divalent metal ion, such as Ca2+, Mg 2+, or Zn2+.
- Stueckler, Clemens,Hall, Melanie,Ehammer, Heidemarie,Pointner, Eva,Kroutil, Wolfgang,Macheroux, Peter,Faber, Kurt
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p. 5409 - 5411
(2008/09/18)
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- Inverted supercritical carbon dioxide/aqueous biphasic media for rhodium-catalyzed hydrogenation reactions
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An inverted supercritical carbon dioxide (scCO2)/aqueous biphasic system has been used as reaction media for Rh-catalysed hydrogenation of polar substrates. Chiral and achiral CO2-philic catalysts were efficiently immobilised in scCO2 as the stationary phase, while the polar substrates and products were contained in water as the mobile phase. Notably, product separation and catalyst recycling were conducted without depressurisation of the autoclave, The catalyst phase was reused several times with high conversion and product recovery of more than 85%. Loss of rhodium and phosphorus by leaching were found to be below the detection limit after the first two cycles in the majority of repetitive experiments. The reaction conditions were optimised with a minimum of experiments by using a simplex algorithm in a sequential optimisation. Total turnover numbers (TTNs) of up to 1600, turnover frequencies (TOFs) of up to 340 h-1 and ee's up to 99% were obtained in repetitive batch operations. The scope of the devised catalytic system has been investigated and a semicontinuous reaction setup has been implemented. The chiral ligand (R,S)-3-H2F6-BINAPHOS allowed highly enantioselective hydrogenation of itaconic acid and methyl-2-acetamidoacrylate combined with a considerable catalyst stability in these reaction media.
- Burgemeister, Katja,Francio, Giancarlo,Gego, Volker H.,Greiner, Lasse,Hugl, Herbert,Leitner, Walter
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p. 2798 - 2804
(2008/02/04)
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- Expanding the scope of atropisomeric monodentate P-donor ligands in asymmetric catalysis: Hydrogen-transfer reduction of α,β-unsaturated acid derivatives by rhodium/Ph-binepine catalysts
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A range of α,β-unsaturated acids and esters have been selectively reduced to the corresponding saturated acid derivatives by hydrogen transfer. As the reducing agent, formic acid was used in the presence of Rh 1 complexes formed with the powerful chiral ligand Ph-binepine (1), an axially chiral binaphthalene-type monodentate P-donor ligand. Very high stereoselectivities (up to 97% ee) were obtained in the case of itaconic acid (2a).
- Alberico, Elisabetta,Nieddu, Ilenia,Taras, Rossana,Gladiali, Serafino
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p. 1716 - 1729
(2007/10/03)
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- Cationic iridium complexes with chiral dithioether ligands: Synthesis, characterisation and reactivity under hydrogenation conditions
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A series of cationic IrI complexes containing chiral dithioether ligands have been prepared in order to study the influence of the sulfur substituents and the metallacycle size on the acetamidoacrylate hydrogenation reaction. In the case of complexes 6, 7 and 10, a mixture of diastereomers is observed in solution due to the sulfur inversion processes. In contrast, this fluxional behaviour is efficiently controlled by using bicyclic ligands which inhibit the S-inversion in complexes 8 and 9. The solid-state structure of complex 10b shows only one diastereomer with the sulfur substituents in a relative anti disposition and in an overall configuration of SCS CSSSS at the coordinated dithioether ligand. Iridium com plexes containing seven- and six-membered metallacycles (6b-d, 7b,c, 10a,b) react with the substrate through S-ligand substitution, and the rate of this substitution is related to the position of the fluorine atom on the aromatic ring. On the contrary, complexes containing a bismetallacycle (8 and 9) are not displaced by the substrate. The catalytic hydrogenation activity of complexes 8 and 9 is analysed in terms of the high stability of the corresponding dihydride complexes (13 and 14). In both cases, only two of the four possible diastereomeric dihydride species are formed in solution. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).
- Flores-Santos, Leticia,Martin, Erika,Aghmiz, Ali,Dieguez, Montserrat,Claver, Carmen,Masdeu-Bulto, Anna M.,Munoz-Hernandez, Miguel Angel
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p. 2315 - 2323
(2007/10/03)
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- Enantioselective hydrogenation of polar substrates in inverted supercritical CO2/aqueous biphasic media
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An inverted supercritical CO2/aqueous biphasic catalytic system allows highly enandoselective hydrogenation of polar water-soluble substrates and efficient recycling of the CO2-philic catalysts. The Royal Society of Chemistry 2005.
- Burgemeister, Katja,Francio, Giancarlo,Hugl, Herbert,Leitner, Walter
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p. 6026 - 6028
(2008/01/27)
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- Chemoselective Reduction of α,βUnsaturated Aldehydes, Ketones, Carboxylic Acids, and Esters with Nickel Boride in Methanol-Water
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A facile procedure for the conjugate reduction of α,β -unsaturated aldehydes, ketones, carboxylic acids, and esters is reported with nickel boride generated in situ from NiCl2·6H 2O/NaBH4 in methanol-water at ambient temperature.
- Khurana, Jitender Mohan,Sharma, Purnima
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p. 549 - 552
(2007/10/03)
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- Synthesis of new monodentate spiro phosphoramidite ligand and its application in Rh-catalyzed asymmetric hydrogenation reactions
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(Chemical Equation Presented) A new spirocyclic diol, 9,9′- spirobixanthene-1,1′-diol, was synthesized in two steps from readily available starting material m-phenoxyanisole. Resolution of the racemic diol was achieved by cocrystallization with N-benzylcinchondimium chloride and N-benzylquininium chloride in acetonitrile. The corresponding spiro monodentate phosphoramidite ligand has been prepared for Rh-catalyzed asymmetric hydrogenation of α-dehydroamino acid derivatives and itaconic acid with excellent enantioselectivities (up to >99% ee).
- Wu, Shulin,Zhang, Weicheng,Zhang, Zhaoguo,Zhang, Xumu
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p. 3565 - 3567
(2007/10/03)
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- Asymmetric catalysis based on chiral phospholanes and hydroxyl phospholanes
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Chiral phosphine ligands derived from chiral natural products including D-mannitol and tartaric acid. The ligands contain one or more 5-membered phospholane rings with multiple chiral centers, and provide high stereoselectivity in asymmetric reactions.
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Page column 22
(2010/02/06)
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- Superoxide ion induced oxidation of γ-lactones to γ-ketocarboxylic acids
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γ-Ketocarboxylic acids have been achieved in reasonably good yield from their corresponding lactones under the significantly mild reaction conditions of in situ generated tetraethylammonium superoxide.
- Singh,Verma,Singh
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p. 4471 - 4475
(2007/10/03)
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- Ozonolysis of 1-methylcyclohexanol
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The kinetic features and composition of products of 1-methylcyclohexanol ozonolysis were studied.
- Syroezhko,Begak
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p. 962 - 966
(2007/10/03)
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- Synthesis, structure, and catalytic activity of some new chiral 2-menthylindenyl and 2-menthyl-4,7-dimethylindenyl rhodium complexes
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Optically active rhodium complexes containing the chiral, menthyl-substituted indenyl ligands (-)-2-menthyl-4,7-dimethylindene and (-)-2-menthylindene are described. Metathesis reactions of the chiral lithium salts of these indenyl systems with the appropriate starting materials yielded the complexes (-)-(2-menthyl-4,7-dimethylindenyl)Rh(CO)2 (2), (-)-(2-menthyl-4,7-dimethylindenyl)Rh(dppe) (3), (+)-(2-menthylindenyl)Rh(dppe) (5), (-)-(2-menthylindenyl)Rh(PMe3)2 (6), and (-)-(2-menthylindenyl)Rh(nbd) (8). All compounds obtained were diastereomerically pure. The structures of 2, 3, and 6 were determined by single crystal X-ray diffractometry. Complexes 3 as well as (-)-bis(η2-ethylene)(η5-2-menthyl-4, 7-dimethylindenyl)rhodium(I) (9), (-)-(cycloocta-1,5- diene)(η5-1-menthyl-4,7-dimethylindenyl)rhodium(I) (10), (-)-(cycloocta-1,5-diene)(η5- 2-menthyl-4,7-dimethylindenyl)rhodium(I) (11), and (-)-(cycloocta-1,5-diene)(η5-2- menthylindenyl)rhodium(I) (12) were found to be active as double bond hydrogenation catalysts. Two of them proved to induce asymmetry up to 18% ee. These complexes also promote the hydroformylation of olefins yielding both linear and branched aldehydes in varying ratios but hardly transfer chirality.
- Schumann, Herbert,Stenzel, Oleg,Dechert, Sebastian,Girgsdies, Frank,Blum, Jochanan,Gelman, Dmitri,Halterman, Ronald L.
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p. 211 - 219
(2007/10/03)
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- 'Diopium', a chiral phosphoniophosphine derived from Kagan's diop. Rhodium complexes and reducing catalytic properties
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Cationic chiral monophosphines are devised as a novel type of ligands for catalytic transformations of polar substrates with polar reagents. A phosphonio-phosphine derived from (R,R)-diop ('methyldiopium') proved to act as a chiral version of Baird's ω-phosphonio-phosphine ligands ('phophos') in Rh(I) complexes in both 1:1 and 2:1 P:Rh stoichiometry. Their versatile structure in CDCl3 solution has been studied by NMR spectroscopy in the presence of various anions (Cl-, I-, BF4-, PF6-). The in situ 2.5:1 methyldiopium-Rh catalytic system slowly hydrogenated (Z)-α-acetamidocinnamic acid in 63% conversion and 5% ee. This system was, however, specifically active in a novel hydrogen transfer procedure by a 1:1 HCOOH:NEt3 mixture under mild conditions (40 C, in the absence of DMSO), for which the corresponding diop-Rh system was not active. Itaconic acid was thus quantitatively reduced to racemic methylsuccinic acid. (Z)-α-acetamidocinnamic acid was reduced in up to 85% conversion to N-acetylphenylalanine in various solvents. Though still moderate, the ee's depend on the solvent: 10% in (R) product in THF, 14% in (S) product in acetonitrile.
- Viau, Lydie,Chauvin, Remi
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p. 180 - 186
(2007/10/03)
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- Asymmetric catalysis based on chiral phospholanes and hydroxyl phospholanes
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Chiral phosphine ligands derived from chiral natural products including D-mannitol and tartaric acid. The ligands contain one or more 5-membered phospholane rings with multiple chiral centers, and provide high stereoselectivity in asymmetric reactions.
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Page column 22
(2010/01/30)
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- Methods for solid-phase synthesis of hydroxylamine compounds and derivatives, and combinatorial libraries thereof
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A novel method for generating hydroxylamine, hydroxamic acid, hydroxyurea, and hydroxylsulfonamide compounds is disclosed. The method involves the nucleophilic attack of an alkoxyamine on a suitable solid phase support. Techniques of combinatorial chemistry can then be applied to the immobilized alkoxyamine to generate a diverse set of compounds. Cleavage of the compounds from the support yields a library of hydroxylamine or hydroxylamine derivative compounds, which can be screened for biological activity (e.g., inhibition of metalloproteinases).
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- Cooperative attractive interactions in asymmetric hydrogenations with dihydroxydiphosphine Rh(I) catalysts - A competition study
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Studies for controlling rate and enantioselectivity of the asymmetric hydrogenation with Rh-diphosphine catalysts by cooperative attractive interactions within the framework of catalyst-substrate complexes are represented. In strong contrast to a Rh(I)[threo-1,4-bis(diphenylphosphino)butane-2,3-diol] catalyst an extremely fast reaction took place applying the complex of the analogue erythro ligand. This is likely due to a strong intramolecular hydrogen bond between the vicinal HO groups impeding the hemilabile coordination of one of the hydroxy groups on the metal center during the hydrogenation. When a substrate with strong hydrogen bond acceptor properties such as (E)-methyl 3-dimethoxyphosphorylbut-2-enoate was hydrogenated even the threo catalyst exhibited a fast reaction. The product was obtained in 83% ee. In contrast, when in the ligand both HO groups were replaced by MeO groups only poor conversion and 24% ee were achieved. While with the complex bearing HO groups in methanolic solution the corresponding diastereomeric catalyst substrate complexes were dominant, analogue MeO groups bearing catalyst substrate complexes could not be detected by NMR. For the latter, only the Rh(I)-solvent complex was found revealing the high importance of the additional functional groups on this equilibrium.
- Holz, Jens,Kadyrov, Renat,Borns, Susanne,Heller, Detlef,B?rner, Armin
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- Chiral rhodium(I)-(polyether-phosphite) complexes for the enantioselective hydroformylation of styrene: Homogeneous and thermoregulated phase-transfer catalysis
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Chiral polyether-phosphite ligands derived from (S)-binaphtol were prepared and combined with [Rh(cod)2]BF4 complex. These systems showed high activity, chemo- and regioselectivity, for the catalytic enantioselective hydroformylation of styrene in thermoregulated phase-transfer conditions. ee Values of up to 25% were obtained and recycling was possible, without loss of enantioselectivity. Catalytic activity of the organic and aqueous phases was studied.
- Breuzard, Jérémy A.J.,Tommasino, M. Lorraine,Bonnet, Michel C.,Lemaire, Marc
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- The effect of metal ions on the reaction of hydrogen peroxide with Kraft lignin model compounds
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Peroxide bleaching is significantly affected by transition and alkaline earth metals. Isolating the effects of different transition and alkaline earth metals on the reactions of peroxide with different representative lignin structures allows the separation of the positive from the negative contributions of these metal ions. In this work, five monomeric or dimeric phenolic lignin model compounds were treated with alkaline hydrogen peroxide in the absence or presence of Mn2+, Cu2+, Fe3+, and Mg2+. We followed the disappearance of the starting material and the progress of demethylation, radical coupling and oxalic acid formation were followed. Transition metals increased the reactivities of all the lignin model compounds with hydrogen peroxide in the order Mn2+ > Cu2+ > Fe3+, which is the same as the order of activity toward peroxide decomposition while Mg2+ stabilized the system. Demethylation, radical coupling, and oxalic acid formation were all increased by the presence of transition metals in the system and decreased by the addition of Mg2+. The acceleration of the total degree of reaction and of the demethoxylation reactions improves peroxide bleaching, but the increase in the radical coupling reactions can affect the further bleachability of pulp while the increase in the formation of oxalic acid could lead to a greater probability of scaling.
- Sun, Yujun,Fenster, Michael,Yu, Annie,Berry, Richard M.,Argyropoulos, Dimitris S.
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p. 667 - 675
(2007/10/03)
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- Synthesis of chiral organophosphorous ligands based on transformations of methyl 3,4-O-isopropylidene-L-threonate
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Chiral organophosphorous compounds which are or interest as ligands for metallocomplex catalysts for enantioselective transformations were synthesized from methyl 3,4-O-isopropylidene-L-threonate.
- Tolstikov,Amosov,Tolstikova,Khlebnikova,Zakharova
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p. 381 - 383
(2007/10/03)
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- Synthesis and reactivity of cationic iridium(I) complexes of cycloocta-1,5-diene and chiral dithioether ligands. Application as catalyst precursors in asymmetric hydrogenation
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New chiral dithioether compounds (-)-2,2-dimethyl-4,5-bis(isopropylsulfanylmethyl)-1,3-dioxolane (-)-diospr and (+)-2,2-dimethyl-4,5-bis(phenylsulfanylmethyl)-1,3-dioxolane (+)-diosph were prepared from diethyl (+)-L-tartrate. An alternative synthetic method for preparing the previously described bis(methylsulfanylmethyl) dithioether (-)-diosme was devised. By co-ordinating of the dithioethers to different (cycloocta-1,5-diene)iridium(I) compounds chiral cationic complexes [Ir(cod){(-)-diosme}]BF4 1, [Ir(cod){(-)-diospr}]BF4·CH2Cl2 2 and [Ir(cod){(+)-diosph}]BF4 3 were synthesized and then studied by 1H, 13C NMR and FAB mass spectrometry. The complexes reacted with CO to give the corresponding binuclear tetracarbonyls [Ir2(μ-L)2(CO)4][BF]2 4-6. The dithioether ligands were replaced by PPh3 in 1-3 providing [Ir(cod)(PPh3)2]BF4. The addition of H2 to complexes 1 and 2 at -70°C gave cis-dihydridoiridium(III) complexes [IrH2(cod){(-)-L}]BF4 7 and 8 which are in equilibrium in solution with the parent complexes, depending on the temperature. Two possible diastereomers were distinguished for 8 at low temperatures. Complexes 1-3 were active precursors in the asymmetric hydrogenation of different prochiral dehydroamino acid derivatives and itaconic acid, at room temperature under an atmospheric pressure of H2, and the highest enantiomeric excess obtained was 47%.
- Dieguez, Montserrat,Orejon, Aranzazu,Masdeu-Bulto, Anna M.,Echarri, Raouf,Castillon, Sergio,Claver, Carmen,Ruiz, Aurora
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p. 4611 - 4618
(2007/10/03)
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- Aqueous organometallic chemistry: The mechanism of catalytic hydrogenations with chlorotris(1,3,5-triaza-7-phosphaadamantane) rhodium(I)
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The water-soluble phosphine complex of Rh(I), RhCl(PTA)3 (1) was shown to be an active catalyst for the hydrogenation of various olefinic and oxo-acids, as well as of allyl alcohol and 4-sulfostyrene in aqueous solution under mild conditions. Detailed kinetic investigations were carried out with crotonic acid and allyl alcohol as substrates. The rate of hydrogenation of both compounds showed a sharp maximum as a function of pH at 4.7. Hydrogenation of itaconic, crotonic and α-acetamidocinnamic acid in D2O led to 45-100% deuteration of the products with 25-100% stereoselectivity towards the α-carbon atom. These results, together with those of pH-static hydrogenation of complex 1, suggest that water strongly assists the dehydrochlorination of 1 to yield the catalytically active monohydrido species HRh(PTA)3 (2). Nevertheless, depending on the substrate and the pH of the solution the dihydridic pathway may remain partially operative.
- Joo, Ferenc,Nadasdi, Levente,Benyei, Attila Cs.,Darensbourg, Donald J.
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- Synthesis and spectroscopic characterisation of 13C-labelled ubiquinone-0 and ubiquinone-10
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(1-13C)-, (2-13C)-, (3-13C)-, (3-13CH3)-, (4-13C)-, and (13CH3O)2-ubiquinone-10 and the corresponding (1-13C)-, (6-13C)-, (5-13C)-, (5-13CH3)-, (4-13C)-, and (13CH3O)2-ubiquinone-0 have been synthesised from simple labelled starting materials via a single reaction scheme.The ubiquinones have been characterised using mass spectrometry, 1H NMR and 13C NMR.The spectroscopic results indicate that, within experimental error, the syntheses have been accomplished without scrambling or dilution of label.All labelled ubiquinones have been synthesised on a decigram scale.
- Liemt, W. B. S. van,Steggerda, W. F.,Esmeijer, R.,Lugtenburg, J.
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p. 153 - 162
(2007/10/02)
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