- Transesterification of glyceryl tributyrate with methanol using strontium borate as the solid base catalyst
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Four kinds of strontium borates were prepared and characterized by XRD, SEM, EDS, TG-DTA and Hammett titration method, and their catalytic activities were examined in the transesterification of glyceryl tributyrate with methanol for the first time. The separate effects of the molar ratio of methanol to oil, the reaction time, and reusability were investigated. In addition, the catalytic activities of Sr(OH)2 and SrCO3 were also examined for the comparison. The results showed that the basicity and catalytic activity of these catalysts were decreased as the following order: Sr(OH) 2 > SrB2O44H2O >SrB6O 105H2O >SrB2O4 >SrB 6O10 >SrCO3, and the reusability decreases as the following order: anhydrous strontium borates (SrB2O 4, SrB6O10) >hydrated strontium borates (SrB2O44H2O, SrB6O 105H2O) >Sr(OH) 2. The results indicate that the SrB2O44H2O with regular morphology, which was obtained at low temperature by a simple preparation method, might be as one kind of good potential alkaline earth salts catalyst for transesterification. Moreover, the possible reaction mechanism is proposed and analyzed. Science China Press and Springer-Verlag Berlin Heidelberg 2013.
- Huang, Hong Sheng,Liu, Zhi Hong
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- Transesterification of ethyl butyrate with methanol over 1-butyl-3-methylimidazolium exchanged mordenite
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Transesterification of ethyl butyrate with methanol on the organic cation-exchanged mordenite ([bmim]M20) was studied in order to examine the reactivity of the methoxide ions that were generated on [bmim]M20 by the dissociation of methanol. Since transesterification occurred by addition of NaCl, the methoxide ions on [bmim]M20 were demonstrated to be utilizable in the reaction. The activity improved with a concentration of NaCl below 3 mmol L -1, whereas it was constant at concentrations above 3 mmol L -1. The adsorption of ethyl butyrate on the partially ion-exchanged [bmim]M20 samples was observed by FT-IR spectroscopy. It was found that it was difficult for ethyl butyrate to enter the micropores of [bmim]M20. From these results, a reaction mechanism was proposed in which the methoxide ions generated in the micropores of [bmim]M20 reacted with ethyl butyrate after they diffused outside of the micropores.
- Yoda, Eisuke
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- The exceptional activity of a phosphazenium hydroxide catalyst incorporated onto silica in the transesterification of tributyrin with methanol
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A phosphazenium hydroxide catalyst incorporated onto silica showed exceptional activity in the transesterification of tributyrin with methanol and could be used repeatedly without suffering any appreciable deactivation. The Royal Society of Chemistry 2009
- Kim, Mi-Young,Seo, Gon,Kwon, O Zoon,Chang, Duk Rye
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- Transesterification of Tributyrin and Dehydration of Fructose over a Carbon-Based Solid Acid Prepared by Carbonization and Sulfonation of Glucose
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A series of carbon-based sulfonated solid acid (CS) catalysts can be prepared through a facile method of direct simultaneous carbonization and sulfonation of d-glucose with concentrated sulfuric acid without a hydrothermal process. Temperature is a key factor in obtaining CS catalysts with higher amounts of -SO3H acid sites. The transesterification of tributyrin with methanol and the dehydration of fructose to 5-hydroxymenthylfurfural (5-HMF) are investigated over the CS catalysts. The CS-150 catalyst, which is the CS catalyst prepared at 150C, shows much higher catalytic activity to give a tributyrin conversion of 99.4 %. The yield of methyl butyrate is 97.2 % and a remarkably high yield of 5-HMF (93 %) can be obtained efficiently; these yields result from the high acid density of -SO3H. Good linearity is displayed between the total acid density and yield of methyl butyrate/5-HMF. The CS-150 catalyst has high stability and good recyclability for the dehydration of fructose.
- Wang, Chuanxu,Yuan, Fulong,Liu, Lijing,Niu, Xiaoyu,Zhu, Yujun
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- Characterization of LipN (Rv2970c) of Mycobacterium Tuberculosis H37Rv and its Probable Role in Xenobiotic Degradation
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LipN (Rv2970c) belongs to the Lip family of M. tuberculosis H37Rv and is homologous to the human Hormone Sensitive Lipase. The enzyme demonstrated preference for short carbon chain substrates with optimal activity at 45C/pH 8.0 and stability between pH 6.0-9.0. The specific activity of the enzyme was 217 U/mg protein with pNP-butyrate as substrate. It hydrolyzed tributyrin to di- and monobutyrin. The active-site residues of the enzyme were confirmed to be Ser216, Asp316, and His346. Tetrahydrolipstatin, RHC-80267 and N-bromosuccinimide inhibited LipN enzyme activity completely. Interestingly, Trp145, a non active-site residue, demonstrated functional role to retain enzyme activity. The enzyme was localized in cytosolic fraction of M. tuberculosis H37Rv. The enzyme was able to synthesize ester of butyric acid, methyl butyrate, in presence of methanol. LipN was able to hydrolyze 4-hydroxyphenylacetate to hydroquinone. The gene was not expressed in in-vitro growth conditions while the expression of rv2970c gene was observed post 6h of macrophage infection by M. tuberculosis H37Ra. Under individual in-vitro stress conditions, the gene was expressed during acidic stress condition only. These findings suggested that LipN is a cytosolic, acid inducible carboxylesterase with no positional specificity in demonstrating activity with short carbon chain substrates. It requires Trp145, a non active site residue, for it's enzyme activity. J. Cell. Biochem.
- Jadeja, Dipendrasinh,Dogra, Nandita,Arya, Stuti,Singh, Gurpreet,Singh, Gurdyal,Kaur, Jagdeep
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- Application of the Water-gas Shift Reaction. I. Hydrogenation and Hydroformylation Reactions of Olefins with Carbon Monoxide and Water Catalyzed by Rhodium Phosphine Complexes
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The hydrogenation of methyl crotonate with CO and H2O is efficiently catalyzed by RhH2(O2COH)2 or 2/P(i-Pr)3/n-BuLi (C7H8=norbornadiene).Both catalyst precursors are shown to form the same active species; trans-Rh(OH)(CO)2.The catalytic activity of the system (2/phosphine/n-BuLi) increases with increase of the basicity of the phosphine ligands (phosphine=P(i-Pr)3 > P(n-Bu)3 > PPh(i-Pr)2 > PPh2(i-Pr) > PPh3).This reaction is also applicable to the hydrogenation of the C=C bond of electron-withdrawing olefins and the C=O bondof ketones and aldehydes.Interestingly, the catalysis for the C=C bond, to which less electron-withdrawing groups are attached, gives dominantly aldehydes due to hydroformylation.The mechanism is also discussed.
- Okano, Tamon,Kobayashi, Teruyuki,Konishi, Hisatoshi,Kiji, Jitsuo
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- Enhanced base-catalyzed activity and structural stability of nitrogen-doped carbon modified MgO-MgFe2O4 magnetic composites as catalysts for transesterification of tributyrin
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In this work, nitrogen-doped carbon modified MgO-MgFe2O4 (CN-MgFeO) magnetic composites were synthesized by a facile thermal decomposition of Mg-Fe layered double hydroxide (MgFe-LDH) and cyanamide mixture precursors. A series of comprehensive characterization studies including powder X-ray diffraction, transmission electron microscopy, Fourier transform infrared of CO2 adsorption, CO2-temperature programmed desorption, and X-ray photoelectron spectroscopy indicated that the introduction of cyanamide could finely tune the surface basicity of the resulting CN-MgFeO composites, especially surface strong Lewis basicity. Compared with CN-free MgFeO, the as-fabricated CN-MgFeO catalysts showed higher activity in the liquid-phase transesterification of tributyrin with methanol. Particularly, the CN-MgFeO composite prepared at a cyanamide/Mg molar ratio of 1.5 in the synthesis mixture gave a highest methylbutyrate yield of 80% after a reaction for 20 min. The high catalytic performance was attributable to the presence of a large amount of strong Lewis basic sites originating from highly dispersed basic MgO-MgFe2O4 mixed metal oxides and CN component in the composite. What is more, such a cost-effective CN-MgFeO catalyst had the advantages of intrinsic magnetic properties and an excellent structural stability. We expect that they may have potential practical applications in the field of industrial production of biodiesels.
- Zhang, Yanhua,Zhang, Ming,Yang, Lan,Fan, Guoli,Li, Feng
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- Synthesis of methyl butyrate using heterogeneous catalyst: Kinetic studies
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This paper illustrates a kinetic investigation of esterification reaction involving butyric acid and methanol over amberlyst-15 catalyst. The catalytic reactions were performed in an isothermal well stirred batch reactor using excess of alcohol to prevent the reverse reaction. The experimental parameters studied were reaction temperature, molar ratios of reactants, catalyst loading, stirring speed, initial water present and quantity of molecular sieves added. The optimum reaction conditions for the ester synthesis were found at temperature 343 K, alcohol to acid ratio 3, stirrer speed 300 rpm, catalyst loading of 6.5 % (w/w basis) and molecular sieves 8.5 %. Addition of water to reactor contents has negative effect as expected. Conversion increased with temperature and catalyst loading whereas it decreased as the molar ratio of alcohol to acid increased beyond 3. Molecular sieves added adsorb water formed in the reaction hence favoring reaction in forward direction. Kinetic data was tested for pseudo-homogeneous model, Langmuir-Hinshelwood model and Eley-Rideal model. Studies show that dual site LHHW with reactants and products adsorbing on catalyst surface is most suited for the experimental data. Graphical Abstract: [Figure not available: see fulltext.]
- Dange, P. N.,Sharma, A.,Rathod, V. K.
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- Transesterification of triglycerides using nitrogen-functionalized carbon nanotubes
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Nitrogen-functionalized carbon nanotubes were synthesized by grafting amino groups to the surface of the nanotubes. The nanotubes exhibited promising results in the base-catalyzed liquid phase transesterification of glyceryl tributyrate with methanol, which is a model reaction for the production of biodiesel. The concentration of the active sites and the reaction parameters, such as temperature and glyceryl tributyrate to methanol ratio, were shown to significantly affect catalytic performance. The grafting technique employed allowed for design and control of the active sites. As a consequence, it was possible to design a nitrogen-functionalized carbon nanotube catalyst with a few strong, basic groups. This might be of interest for carbohydrate conversion reactions where strong basic sites are required but the pH of the solution should remain mild to avoid the degradation of the reactants and/or products.
- Villa, Alberto,Tessonnier, Jean-Philippe,Majoulet, Olivier,Su, Dang Sheng,Schl?gl, Robert
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- Synthesis of β-Silyl-α-amino Acid Derivatives by Cu-Catalyzed Regio- and Enantioselective Silylamination of α,β-Unsaturated Esters
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A copper-catalyzed silylamination of α,β-unsaturated esters with silylboranes and hydroxylamines has been developed to afford the corresponding β-silyl-α-amino acid derivatives, which are of great interest in medicinal and pharmaceutical chemistry. Additionally, by using a suitable chiral bisphosphine ligand, the asymmetric induction is possible, delivering the optically active β-silyl-α-amino acids with synthetically acceptable diastereomeric ratios (55:45-82:18 dr) and high enantiomeric ratios (81:19-99:1 er).
- Kobayashi, Toshimichi,Nishino, Soshi,Miura, Masahiro,Hirano, Koji
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supporting information
p. 1418 - 1422
(2022/02/14)
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- METHOD FOR PRODUCING BIO ALCOHOL FROM INTERMEDIATE PRODUCTS OF ANAEROBIC DIGESTION TANK
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The present invention relates to a method for producing a bio-alcohol by reacting a mixture of volatile fatty acid with methanol in 2 through 11 in a reactor in the presence of a 280 °C-membered alkaline earth metal catalyst or 400 °C transition metal catalyst formed based on a support.
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Paragraph 0038-0041
(2021/05/25)
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- MATERIALS COMPRISING CARBON-EMBEDDED IRON NANOPARTICLES, PROCESSES FOR THEIR MANUFACTURE, AND USE AS HETEROGENEOUS CATALYSTS
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201900257 Ausland 18 Abstract The present invention relates to catalytically active material, comprising grains of non-graphitizing carbon with iron nanoparticles dispersed therein, wherein dp, the average diameter of iron nanoparticles in the non-graphitizing carbon grains, is in the range of 1 nm to 20 nm, D, the average distance between iron nanoparticles in the non-graphitizing carbon grains, is in the range 5 of 2 nm to 150 nm, and ω, the combined total mass fraction of metal in the non-graphitizing carbon grains, is in the range of 30 wt% to 70 wt% of the total mass of the non-graphitizing carbon grains, and wherein dp, D and ω conform to the following relation: 4.5 dp / ω > D ≥ 0.25 dp / ω. The present invention, further, relates to a process for the manufacture of material according to the invention, as well as its use as a catalyst. 10
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Page/Page column 14
(2021/03/13)
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- MATERIALS COMPRISING CARBON-EMBEDDED COBALT NANOPARTICLES, PROCESSES FOR THEIR MANUFACTURE, AND USE AS HETEROGENEOUS CATALYSTS
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The present invention relates to catalytically active material, comprising grains of non-graphitizing carbon with cobalt nanoparticles dispersed therein, wherein dP, the average diameter of cobalt nanoparticles in the non-graphitizing carbon grains, is in the range of 1 nm to 20 nm, D, the average distance between cobalt nanoparticles in the non-graphitizing carbon grains, is in the range of 2 nm to 150 nm, and ω, the combined total mass fraction of metal in the non-graphitizing carbon grains, is in the range of 30 wt% to 70 wt% of the total mass of the non-graphitizing carbon grains, and wherein dP, D and ω conform to the following relation: 4.5 dP / ω > D ≥ 0.25 dP / ω. The present invention, further, relates to a process for the manufacture of material according to the invention, as well as its use as a catalyst.
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Page/Page column 17
(2021/03/13)
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- Highly efficient and selectivity-controllable aerobic oxidative cleavage of C-C bond over heterogeneous Fe-based catalysts
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A base-free selectivity-controllable aerobic oxidative cleavage of C-C bond with heterogeneous Fe-based catalysts (FexOy-N@C3N4) is developed. In the presence of oxygen, 1,2-diols are selectively transformed to the corresponding aldehyde, while the methyl esters are orientedly produced from 1,2-diones in methanol medium.
- Guo, Pengfei,Liao, Shengyun,Wang, Shun,Shi, Jing,Tong, Xinli
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p. 399 - 403
(2021/02/27)
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- Discovery and Design of Family VIII Carboxylesterases as Highly Efficient Acyltransferases
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Promiscuous acyltransferase activity is the ability of certain hydrolases to preferentially catalyze acyl transfer over hydrolysis, even in bulk water. However, poor enantioselectivity, low transfer efficiency, significant product hydrolysis, and limited substrate scope represent considerable drawbacks for their application. By activity-based screening of several hydrolases, we identified the family VIII carboxylesterase, EstCE1, as an unprecedentedly efficient acyltransferase. EstCE1 catalyzes the irreversible amidation and carbamoylation of amines in water, which enabled the synthesis of the drug moclobemide from methyl 4-chlorobenzoate and 4-(2-aminoethyl)morpholine (ca. 20 % conversion). We solved the crystal structure of EstCE1 and detailed structure–function analysis revealed a three-amino acid motif important for promiscuous acyltransferase activity. Introducing this motif into an esterase without acetyltransferase activity transformed a “hydrolase” into an “acyltransferase”.
- Müller, Henrik,Godehard, Simon P.,Palm, Gottfried J.,Berndt, Leona,Badenhorst, Christoffel P. S.,Becker, Ann-Kristin,Lammers, Michael,Bornscheuer, Uwe T.
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supporting information
p. 2013 - 2017
(2020/11/30)
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- Process for the production of esters
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A process for making methyl esters in high yields. The process comprises contacting aliphatic or aromatic aldehydes and methanol with a homogeneous dimeric ruthenium catalyst, to catalyze the dehydrogenative coupling between aliphatic or aromatic aldehydes and methanol. The reaction is highly selective (99.9%) toward the formation of methyl esters over homoesters and alcohols and operates at temperatures of less than 100° C. for 2-8 hours.
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Page/Page column 8
(2020/03/18)
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- Soluble asphaltene oxide: A homogeneous carbocatalyst that promotes synthetic transformations
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Carbocatalysts, materials which are predominantly composed of carbon and catalyze the synthesis of organic or inorganic compounds, are promising alternatives to metal-based analogues. Even though current carbocatalysts have been successfully employed in a broad range of synthetic transformations, they suffer from a number of drawbacks in part due to their heterogeneous nature. For example, the insolubility of prototypical carbocatalysts, such as graphene oxide (GO), may restrict access to catalytically-active sites in a manner that limits performance and/or challenges optimization. Herein we describe the preparation and utilization of soluble asphaltene oxide (sAO), which is a novel material that is composed of oxidized polycyclic aromatic hydrocarbons and is soluble in a wide range of organic solvents as well as in aqueous media. sAO promotes an array of synthetically useful transformations, including esterifications, cyclizations, multicomponent reactions, and cationic polymerizations. In many cases, sAO was found to exhibit higher catalytic activities than its heterogeneous analogues and was repeatedly and conveniently recycled, features that were attributed to its ability to form homogeneous phases.
- Bielawski, Christopher W.,Jung, Hyosic
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p. 15598 - 15603
(2020/05/05)
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- Efficient C-H Amination Catalysis Using Nickel-Dipyrrin Complexes
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A dipyrrin-supported nickel catalyst (AdFL)Ni(py) (AdFL: 1,9-di(1-adamantyl)-5-perfluorophenyldipyrrin; py: pyridine) displays productive intramolecular C-H bond amination to afford N-heterocyclic products using aliphatic azide substrates. The catalytic amination conditions are mild, requiring 0.1-2 mol% catalyst loading and operational at room temperature. The scope of C-H bond substrates was explored and benzylic, tertiary, secondary, and primary C-H bonds are successfully aminated. The amination chemoselectivity was examined using substrates featuring multiple activatable C-H bonds. Uniformly, the catalyst showcases high chemoselectivity favoring C-H bonds with lower bond dissociation energy as well as a wide range of functional group tolerance (e.g., ethers, halides, thioetheres, esters, etc.). Sequential cyclization of substrates with ester groups could be achieved, providing facile preparation of an indolizidine framework commonly found in a variety of alkaloids. The amination cyclization reaction mechanism was examined employing nuclear magnetic resonance (NMR) spectroscopy to determine the reaction kinetic profile. A large, primary intermolecular kinetic isotope effect (KIE = 31.9 ± 1.0) suggests H-atom abstraction (HAA) is the rate-determining step, indicative of H-atom tunneling being operative. The reaction rate has first order dependence in the catalyst and zeroth order in substrate, consistent with the resting state of the catalyst as the corresponding nickel iminyl radical. The presence of the nickel iminyl was determined by multinuclear NMR spectroscopy observed during catalysis. The activation parameters (ΔH? = 13.4 ± 0.5 kcal/mol; ΔS?= -24.3 ± 1.7 cal/mol·K) were measured using Eyring analysis, implying a highly ordered transition state during the HAA step. The proposed mechanism of rapid iminyl formation, rate-determining HAA, and subsequent radical recombination was corroborated by intramolecular isotope labeling experiments and theoretical calculations.
- Betley, Theodore A.,Clarke, Ryan M.,Dong, Yuyang,Porter, Gerard J.
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supporting information
p. 10996 - 11005
(2020/07/08)
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- Iron-catalysed 1,2-aryl migration of tertiary azides
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1,2-Aryl migration of α,α-diaryl tertiary azides was achieved by using the catalytic system of FeCl2/N-heterocyclic carbene (NHC) SIPr·HCl. The reaction generated aniline products in good yields after one-pot reduction of the migration-resultant imines.
- Wei, Kaijie,Yang, Tonghao,Chen, Qing,Liang, Siyu,Yu, Wei
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supporting information
p. 11685 - 11688
(2020/10/19)
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- Method for preparing organic carboxylic ester through combined catalysis of aryl bidentate phosphine ligand
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The invention discloses a method for preparing organic carboxylic ester by combined catalysis of an aryl bidentate phosphine ligand. The method comprises the following steps: under the action of a palladium compound/aryl bidentate phosphine ligand/acidic additive combined catalyst, carrying out a hydrogen esterification reaction on terminal olefin, carbon monoxide and alcohol so as to generate theorganic carboxylic ester with one more carbon than olefin. According to the invention, by adoption of the palladium compound/aryl bidentate phosphine ligand/acidic additive combined catalyst, good catalytic activity and selectivity for the hydrogen esterification reaction of the olefin are achieved, and olefin carbonylation to synthesize organic carboxylic ester can be efficiently catalyzed. Thearyl bidentate phosphine ligand has a rigid skeleton structure of a rigid ligand and the flexibility of a flexible ligand, so the aryl bidentate phosphine ligand has proper flexibility due to the characteristic that the aryl bidentate phosphine ligand is soft and rigid, and a most favorable coordination mode and a stable active structure in space are favorably formed. In addition, the aryl bidentate phosphine ligand has the advantages of high stability, simple and convenient synthesis method and the like; and a novel industrial technology is provided for production of organic carboxylate compounds.
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Paragraph 0041-0042
(2020/05/29)
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- Method for preparing carboxylic ester by alcohol direct oxidation esterification method
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The invention discloses a method for preparing a carboxylic ester by an alcohol direct oxidation esterification method. The method comprises the following steps: taking an aromatic alcohol compound ora saturated linear aliphatic alcohol as a reaction substrate, taking an Au-Co composite particle carrier as a catalyst, adding a low catalytic amount of alkali, reacting for 0.5-15 h in a methanol solvent at the temperature of 25-150 DEG C in air or oxygen or a mixed atmosphere of the air or the oxygen, and performing aftertreatment to obtain a target product carboxylic ester. According to the preparation method disclosed by the invention, the process steps are reduced, conditions are mild, catalyst consumption is less, atom economy is high, the method is simple to operate, the application range of the substrate is wide, and industrial practicability is achieved.
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Paragraph 0068; 0069
(2019/06/30)
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- Selective hydrogenation of α,β-unsaturated carbonyl compounds on silica-supported copper nanoparticles
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Silica-supported copper nanoparticles prepared via surface organometallic chemistry are highly efficient for the selective hydrogenation of various α,β-unsaturated carbonyl compounds yielding the corresponding saturated esters, ketones, and aldehydes in the absence of additives. High conversions and selectivities (>99%) are obtained for most substrates upon hydrogenation at 100-150 °C and under 25 bar of H2.
- Mendes-Burak, Jorge,Ghaffari, Behnaz,Copéret, Christophe
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supporting information
p. 179 - 181
(2019/01/04)
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- Photolysis of Tp′Rh(CNneopentyl)(PhNCNneopentyl) in the presence of ketones and esters: Kinetic and thermodynamic selectivity for activation of different aliphatic C-H bonds
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The active fragment [Tp′Rh(CNneopentyl)], generated from the precursor Tp′Rh(CNneopentyl)(PhNCNneopentyl), underwent oxidative addition of substituted ketones and esters resulting in Tp′Rh(CNneopentyl)(R)(H) complexes (Tp′ = tris-(3,5-dimethylpyrazolyl)borate). These C-H activated complexes underwent reductive elimination at varying temperatures (24-70 °C) in C6D6 or C6D12. Using previously established kinetic techniques, the relative Rh-C bond strengths were calculated. Analysis of the relative Rh-C bond strengths vs. C-H bond strengths shows a linear correlation with slope RM-C/C-H = 1.22 (12). In general, α-substituents increase the relative Rh-C bond strengths compared to the C-H bond that is broken.
- Jones, William D.,Parsons, Astrid M.
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supporting information
p. 10945 - 10952
(2019/08/01)
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- Elaborate Tuning in Ligand Makes a Big Difference in Catalytic Performance: Bulky Nickel Catalysts for (Co)polymerization of Ethylene with Promising Vinyl Polar Monomers
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To reveal effect of electronic or steric modification of phosphino-phenolate nickel complex for preparing optimized catalysts, we take elaborated studies on structure-performance relationship by finely modifying substituents on ortho-phenoxy position or phosphorus moiety of this catalyst. It reveals that these newly synthesized complexes are thermally robust, and exhibits very high activity (up to 107 g molNi?1 h?1) in ethylene polymerization even at 120 °C. Associated with stoichiometric experiments, experimental results prove that nickel complexes bearing electron-withdrawing substituents on ortho-phenoxy position or electron-donating substituents on phosphorus atom show higher activity than contrastive catalysts toward ethylene polymerization and ethylene–methyl acrylate (MA) copolymerization. Among these catalysts, 3 g bearing a strong electron-withdrawing substituent on ortho-phenoxy position exhibits the highest activity, and produces copolymers with the highest molecular weight and analogous MA incorporation. Various challenging polar vinyl monomers, like polyethylene glycol monomethyl ether acrylate, can be efficiently copolymerized with ethylene.
- Zhang, Yanping,Mu, Hongliang,Wang, Xuling,Pan, Li,Li, Yuesheng
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p. 2329 - 2340
(2019/04/25)
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- Method for synthesizing propionate through ester-ester exchange path
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The invention provides a method for synthesizing propionate through an ester-ester exchange path and relates to a method for synthesizing the propionate. According to the method, reaction raw materials include, but are not limited to ethyl formate, propyl formate, butyl formate, ethyl acetate, propyl acetate, butyl acetate and the like; the method for synthesizing the propionate through an ester exchange one-step method is adopted. A catalyst comprises alkaline materials including ionic liquid, soluble strong base, solid base and the like respectively; the catalyst has the advantages of high catalysis efficiency and no pollution. By taking methyl propionate and ethyl acetate reaction as an example, KOH is used as the catalyst, the mol ratio of the raw materials is 1 to 1, the reaction temperature is 60 DEG C and the reaction time is 5 min; the conversion ratios of the methyl propionate and the ethyl acetate can reach 70 percent or more; products comprise ethyl propionate and the methylacetate. The whole reaction path has the characteristics of short synthetic route, simple technological flow and high yield and the catalyst is stable, does not become inactive and can be repeatedlyutilized.
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Paragraph 0030-0031
(2019/04/04)
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- Effect of the Presence of Surfactants and Immobilization Conditions on Catalysts’ Properties of Rhizomucor miehei Lipase onto Chitosan
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Lipase from Rhizomucor miehei (RML) was immobilized onto chitosan support in the presence of some surfactants added at low levels using two different strategies. In the first approach, the enzyme was immobilized in the presence of surfactants on chitosan supports previously functionalized with glutaraldehyde. In the second one, after prior enzyme adsorption on chitosan beads in the presence of surfactants, the complex chitosan beads-enzyme was then cross-linked with glutaraldehyde. The effects of surfactant concentrations on the activities of free and immobilized RML were evaluated. Hexadecyltrimethylammonium bromide (CTAB) promoted an inhibition of enzyme activity while the nonionic surfactant Triton X-100 caused a slight increase in the catalytic activity of the free enzyme and the derivatives produced in both methods of immobilization. The best derivatives were achieved when the lipase was firstly adsorbed on chitosan beads at 4?°C for 1?h, 220?rpm followed by cross-link the complex chitosan beads-enzyme with glutaraldehyde 0.6% v.v?1 at pH 7. The derivatives obtained under these conditions showed high catalytic activity and excellent thermal stability at 60° and 37?°C. The best derivative was also evaluated in the synthesis of two flavor esters namely methyl and ethyl butyrate. At non-optimized conditions, the maximum conversion yield for methyl butyrate was 89%, and for ethyl butyrate, the esterification yield was 92%. The results for both esterifications were similar to those obtained when the commercial enzyme Lipozyme and free enzyme were used in the same reaction conditions and higher than the one achieved in the absence of the selected surfactant.
- de Oliveira, Ulisses M. F.,Lima de Matos, Leonardo J. B.,de Souza, Maria Cristiane M.,Pinheiro, Bruna B.,dos Santos, José C. S.,Gon?alves, Luciana R. B.
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p. 1263 - 1285
(2017/10/17)
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- A methodical selection process for the development of ketones and esters as bio-based replacements for traditional hydrocarbon solvents
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A "top down" approach to the development of sustainable, greener, low-polarity solvents is presented. Methyl butyrate, ethyl isobutyrate, methyl pivalate and pinacolone were identified as potential target solvents from trends in Hansen solubility parameters and known physical properties. Solubility, flammability and physical properties were determined which showed their potential to replace traditional, hazardous, volatile, non-polar solvents such as toluene. Each new candidate then demonstrated their suitability to replace these traditional solvents in solubility tests, despite being esters and ketones, each candidate demonstrated their similarity to traditional volatile non-polar solvents in terms of their solubility properties by their ability to dissolve natural rubber, a particularly low-polarity solute. This was reinforced by their performance in a model Menschutkin reaction and a radical-initiated polymerisation for the production of pressure-sensitive adhesives, where their performance was found to be similar to that of toluene. Importantly, a preliminary toxicity test (Ames test) suggested non-mutagenicity in all candidates. Each of the four candidates can be synthesised via a catalytic route from potentially renewable resources, thus enhancing their green credentials.
- Byrne, Fergal P.,Forier, Bart,Bossaert, Greet,Hoebers, Charly,Farmer, Thomas J.,Hunt, Andrew J.
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supporting information
p. 4003 - 4011
(2018/09/11)
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- STABILIZATION OF ACTIVE METAL CATALYSTS AT METAL-ORGANIC FRAMEWORK NODES FOR HIGHLY EFFICIENT ORGANIC TRANSFORMATIONS
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Metal-organic framework (MOFs) compositions based on post?synthetic metalation of secondary building unit (SBU) terminal or bridging OH or OH2 groups with metal precursors or other post-synthetic manipulations are described. The MOFs provide a versatile family of recyclable and reusable single-site solid catalysts for catalyzing a variety of asymmetric organic transformations, including the regioselective boryiation and siiylation of benzyiic C—H bonds, the hydrogenation of aikenes, imines, carbonyls, nitroarenes, and heterocycles, hydroboration, hydrophosphination, and cyclization reactions. The solid catalysts can also be integrated into a flow reactor or a supercritical fluid reactor.
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Paragraph 0338
(2019/01/07)
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- Fluorescent microplate assay method for high-throughput detection of lipase transesterification activity
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This study describes a sensitive and fluorescent microplate assay method to detect lipase transesterification activity. Lipase-catalyzed transesterification between butyryl 4-methyl umbelliferone (Bu-4-Mu) and methanol in tert-butanol was selected as the model reaction. The release of 4-methylumbelliferone (4-Mu) in the reaction was determined by detecting the fluorescence intensity at λex 330 nm and λem 390 nm. Several lipases were used to investigate the accuracy and efficiency of the proposed method. Apparent Michaelis constant (Km) was calculated for transesterification between Bu-4-Mu and methanol by the lipases. The main advantages of the assay method include high sensitivity, inexpensive reagents, and simple detection process.
- Zheng, Jianyong,Wei, Wei,Lan, Xing,Zhang, Yinjun,Wang, Zhao
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- A biocatalytic method for the chemoselective aerobic oxidation of aldehydes to carboxylic acids
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Herein, we present a study on the oxidation of aldehydes to carboxylic acids using three recombinant aldehyde dehydrogenases (ALDHs). The ALDHs were used in purified form with a nicotinamide oxidase (NOx), which recycles the catalytic NAD+ at the expense of dioxygen (air at atmospheric pressure). The reaction was studied also with lyophilised whole cell as well as resting cell biocatalysts for more convenient practical application. The optimised biocatalytic oxidation runs in phosphate buffer at pH 8.5 and at 40 °C. From a set of sixty-one aliphatic, aryl-Aliphatic, benzylic, hetero-Aromatic and bicyclic aldehydes, fifty were converted with elevated yield (up to >99%). The exceptions were a few ortho-substituted benzaldehydes, bicyclic heteroaromatic aldehydes and 2-phenylpropanal. In all cases, the expected carboxylic acid was shown to be the only product (>99% chemoselectivity). Other oxidisable functionalities within the same molecule (e.g. hydroxyl, alkene, and heteroaromatic nitrogen or sulphur atoms) remained untouched. The reaction was scaled for the oxidation of 5-(hydroxymethyl)furfural (2 g), a bio-based starting material, to afford 5-(hydroxymethyl)furoic acid in 61% isolated yield. The new biocatalytic method avoids the use of toxic or unsafe oxidants, strong acids or bases, or undesired solvents. It shows applicability across a wide range of substrates, and retains perfect chemoselectivity. Alternative oxidisable groups were not converted, and other classical side-reactions (e.g. halogenation of unsaturated functionalities, Dakin-Type oxidation) did not occur. In comparison to other established enzymatic methods such as the use of oxidases (where the concomitant oxidation of alcohols and aldehydes is common), ALDHs offer greatly improved selectivity.
- Knaus, Tanja,Tseliou, Vasilis,Humphreys, Luke D.,Scrutton, Nigel S.,Mutti, Francesco G.
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supporting information
p. 3931 - 3943
(2018/09/11)
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- Hydrogenation of Ketones and Esters Catalyzed by Pd/C?SiO2
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Hydrogenation of unsaturated ketones and esters with molecular hydrogen on the 5%Pd/C?SiO2 heterogeneous catalyst has been studied. The reaction direction and yield are determined by the starting compounds structure. Hydrogenation of unsaturated ketones containing phenyl group at the double carbon–carbon atom is accompanied by the reduction of the ketone group into the alcohol one. Hydrogenation of unsaturated esters is accompanied by transesterification.
- Akchurin,Baibulatov,Dokichev
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p. 195 - 198
(2018/03/26)
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- Methylation of Aliphatic and Aromatic Carboxylic Acids with Dimethyl Carbonate under the Influence of Manganese and Iron Carbonyls
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The synthesis of methyl esters has been carried out via the reaction of aliphatic and aromatic carboxylic acids with dimethyl carbonate in the presence of manganese and iron carbonyls. The optimal ratio of catalyst and reagents and other conditions for the synthesis of methyl esters of carboxylic acids with high yield have been found.
- Khusnutdinov,Shchadneva,Mayakova, Yu. Yu.
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- Amberlyst-15 catalysed oxidative esterification of aldehydes using a H2O2 trapped oxidant as a terminal oxidant
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A simple and efficient method has been developed for the selective oxidative esterification of aldehydes using commercially available Amberlyst-15 as a catalyst. H2O2 released from a clathrate structured 4Na2SO4·2H2O2·NaCl oxidant serves as an efficient source of terminal oxidants. Various aromatic, heteroaromatic, and aliphatic aldehydes undergo selective esterification to give good to excellent yield. The heterogeneous catalyst, Amberlyst-15, exhibits high reactivity and can be recycled over several runs. The 4Na2SO4·2H2O2·NaCl oxidant was found to be superior to commonly used oxidizing agents providing an anhydrous, easy to handle and stable form of H2O2
- Gayakwad, Eknath M.,Patil, Vilas V.,Shankarling, Ganapati S.
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p. 2695 - 2701
(2017/04/03)
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- Efficient Palladium-Catalyzed Alkoxycarbonylation of Bulk Industrial Olefins Using Ferrocenyl Phosphine Ligands
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The development of ligands plays a key role and provides important innovations in homogeneous catalysis. In this context, we report a novel class of ferrocenyl phosphines for the alkoxycarbonylation of industrially important alkenes. A basic feature of our ligands is the combination of sterically hindered and amphoteric moieties on the P atoms, which leads to improved activity and productivity for alkoxycarbonylation reactions compared to the current industrial state-of-the-art ligand 1,2-bis((di-tert-butylphosphino)methyl)benzene). Advantageously, palladium catalysts with these novel ligands also enable such transformations without additional acid under milder reaction conditions. The practicability of the optimized ligand was demonstrated by preparation on >10 g scale and its use in palladium-catalyzed carbonylations on kilogram scale.
- Dong, Kaiwu,Sang, Rui,Fang, Xianjie,Franke, Robert,Spannenberg, Anke,Neumann, Helfried,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 5267 - 5271
(2017/04/27)
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- Zinc Complexes with Cyanoxime: Structural, Spectroscopic, and Catalysis Studies in the Pivaloylcyanoxime-Zn System
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Reaction of 2-hydroxyimino-4,4-dimethyl-3-oxo-pentanenitrile (common abbreviation HPiCO, pivaloyl-cyanoxime) with zinc sulfate in an aqueous solution results in the formation of the two new complexes: [Zn(PiCO){H(PiCO)2}(H2O)] (I) and tetranuclear Zn complex [Zn4(μ3-OH)2(PiCO)6 (H2O)4] (II). Both complexes were characterized by elemental analysis, IR- and UV-visible spectra, DSC/TGA studies, and X-ray analysis. In complex II, the PiCO- cyanoxime anion adopts three bidentate binding modes: O-monodentate, chelating (κ2), and bridging (2) coordinations. Also, the ligand represents the mixture of two diasteromers (cis-anti and cis-syn) that form five- and six-membered chelate rings with Zn atoms and cocrystallize in one unit cell at population of 0.57-0.43. There are two crystallographically different Zn-centers in the ASU, and two μ3-bridging hydroxo-groups arrange via inversion center the formation of an elegant tetranuclear complex. Each Zn atom has a molecule of coordinated water and is in the distorted octahedral environment. Because of the structural flexibility and multidentate propensity of the pivaloyl-cyanoxime, complex II may act as a structural model of naturally occurring Zn-containing enzymes. Indeed, compound I exhibits an efficient catalytic performance for transesterification reaction of various esters in ethanol under mild reaction conditions. Therefore, obtained results allow assignment of observed activity as green catalysis.
- Opalade, Adedamola A.,Karmakar, Anirban,Rúbio,Pombeiro, Armando J. L.,Gerasimchuk, Nikolay
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p. 13962 - 13974
(2017/11/24)
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- Rethinking the Claisen–Tishchenko Reaction
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Pincer-type complexes [OsH2(CO){PyCH2NHCH2CH2NHPtBu2}] and [OsH2(CO){HN(CH2CH2PiPr2)2}] catalyze the disproportionation reaction of aldehydes via an outer-sphere bifunctional mechanism achieving turnover frequencies up to 14 000 h?1. The N?H group of the catalysts is a key player in this process, elucidated with the help of DFT calculations.
- Morris, Stacey A.,Gusev, Dmitry G.
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supporting information
p. 6228 - 6231
(2017/05/19)
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- Methylation of mono- and dicarboxylic acids with dimethyl carbonate catalyzed with binder-free zeolite NaY
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Synthesis of methyl mono- and dicarboxylates was developed consisting in treating the corresponding acids with dimethyl carbonate in the presence of a heterogenic catalyst, crystalline aluminosilicate whose mechanically strong granules to 90–95% were built of crystal aggregates of zeolite Y with modulus of about 5.0 in the Na-form. Optimum catalyst and reagents ratio and the reaction conditions were found for the preparation in high yields of methyl esters of mono- and dicarboxylic acids.
- Khusnutdinov,Shchadneva,Mayakova, Yu. Yu.,Konovalova, Yu. S.,Khazipova,Kutepov
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p. 163 - 168
(2017/04/24)
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- Highly efficient metal salt catalyst for the esterification of biomass derived levulinic acid under microwave irradiation
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The esterification of levulinic acid (LA) to alkyl levulinates has been investigated in the presence of various metal salt catalysts under microwave irradiation. The reaction obtained 99.4% yield of methyl levulinate (ML) in the presence of Al2(SO4)3 catalyst in methanol solution under microwave conditions. The optimized reaction conditions were 110 °C and 10 minutes with a 20 mol% catalyst loading. Alcohols with longer carbon chains showed lower reactivities in the microwave electromagnetic field due to their poorer abilities to absorb and transmit microwave energy. Moreover, microwave irradiation provided a significantly higher reaction rate compared to conventional oil bath heating. LA aqueous solution was also converted to ML with high yields. The Al2(SO4)3 catalyst was successfully applied to the esterification of other biomass derived organic acids to their corresponding esters in high yields. Finally, the catalyst was recycled 5 times without much decrease in activity.
- Huang, Yao-Bing,Yang, Tao,Cai, Bo,Chang, Xin,Pan, Hui
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p. 2106 - 2111
(2016/01/20)
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- By using low-temperature co- melt solvent a method of catalytic ester (by machine translation)
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The invention discloses a method of utilizing low-temperature co- melt solvent catalytic ester method, will be 0.05-0.5 mole of sharemelt solvent of low-temperature co-preprocessing, 1-5 mole of share alcohol and 1-10 mole of share of acid in the reaction vessel, stirring and heating, 25-200 ° C reaction under 2-96h, then the reaction fluid settlement , liquid, organic is accepted after passing an examination the level , get the esterification reaction products of the; reaction after the treatment and recovery of low-temperature co- melt solvent the preprocessing, can be reused. This invention utilizes the easy preparation of low-temperature co- melt solvent the preprocessing of catalytic esterification reaction, the reaction front is homogeneous, can be formed after the reaction of the two-phase reaction in the process of direct dehydration, without adding other dehydrating agent, has the advantages of simple operation, the reaction efficiency is high, corrosion of small equipment, less side reactions, the product quality is good, no pollution to the environment, and the like, it has broad application prospects. (by machine translation)
- -
-
Paragraph 0044; 0045
(2017/01/17)
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- Preparation, characterization, and catalytic testing of different Me–chitosan complexes for triglycerides transesterification
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A number of homogeneous and heterogenized chitosan complexes with different metals (Zn, Co, Ca, Ni, Sn, Pb) were synthesized and tested as catalysts in the reaction of transesterification of tributyrin simulating the process of biodiesel production from renewable natural feedstock (triglycerides, vegetable oils). It is found that chitosan complexes are effective catalysts for transformation of tributyrin into the corresponding esters. The comparative analysis of Me–chitosan (homogeneous), Me–chitosan (heterogeneous) and Me–chitosan/SiO2 catalysts testify that the efficiency of three-component egg-shell systems is close to that of homogeneous catalysts.
- Finashina,Kramareva,Kucherov,Tkachenko,Kustov
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p. 4907 - 4920
(2016/07/06)
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- Single-Site Cobalt Catalysts at New Zr8(μ2-O)8(μ2-OH)4 Metal-Organic Framework Nodes for Highly Active Hydrogenation of Alkenes, Imines, Carbonyls, and Heterocycles
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We report here the synthesis of robust and porous metal-organic frameworks (MOFs), M-MTBC (M = Zr or Hf), constructed from the tetrahedral linker methane-tetrakis(p-biphenylcarboxylate) (MTBC) and two types of secondary building units (SBUs): cubic M8(μ2-O)8(μ2-OH)4 and octahedral M6(μ3-O)4(μ3-OH)4. While the M6-SBU is isostructural with the 12-connected octahedral SBUs of UiO-type MOFs, the M8-SBU is composed of eight MIV ions in a cubic fashion linked by eight μ2-oxo and four μ2-OH groups. The metalation of Zr-MTBC SBUs with CoCl2, followed by treatment with NaBEt3H, afforded highly active and reusable solid Zr-MTBC-CoH catalysts for the hydrogenation of alkenes, imines, carbonyls, and heterocycles. Zr-MTBC-CoH was impressively tolerant of a range of functional groups and displayed high activity in the hydrogenation of tri- and tetra-substituted alkenes with TON > 8000 for the hydrogenation of 2,3-dimethyl-2-butene. Our structural and spectroscopic studies show that site isolation of and open environments around the cobalt-hydride catalytic species at Zr8-SBUs are responsible for high catalytic activity in the hydrogenation of a wide range of challenging substrates. MOFs thus provide a novel platform for discovering and studying new single-site base-metal solid catalysts with enormous potential for sustainable chemical synthesis.
- Ji, Pengfei,Manna, Kuntal,Lin, Zekai,Urban, Ania,Greene, Francis X.,Lan, Guangxu,Lin, Wenbin
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supporting information
p. 12234 - 12242
(2016/09/28)
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- (Ferrocenylpyrazolyl)palladium(II) complexes: Syntheses, characterization and rearrangement in solution
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Reactions of L1-L6 (3-ferrocenylpyrazolyle (L1), 3-ferrocenyl-5-methylpyrazolyle (L2) 3-ferrocenylpyrazolyl-methylenepyridine (L3) and 3-ferrocenyl-5-methylpyrazolylmethylene-pyridine (L4), 3-ferrocenylpyrazolylethylamine (L5) and 3-ferrocenyl-5-methylpyrazolylethyl-amine (L6)) with [PdCl(Me) (cod)] formed the mononuclear complexes [PdCl(Me) (κ1-L1)2] (1), [PdCl(Me) (κ1-L2)2] (2), [PdCl(Me) (κ2-L3)] (3), [PdCl(Me) (κ2-L4)] (4), [PdCl(Me) (κ2-L5)] (5) and [PdCl(Me) (κ2-L6)] (6). Reactions of 1-6 with the halide abstractor, Na[BAr4], (Ar = 3,5-(CF3)2C6H3), led to the formation of the salts, [PdMe(NCMe) (κ1-L1)2][BAr4] (7), [PdMe(NCMe) (κ1-L2)2][BAr4] (8), [PdMe(NCMe) (κ2-L3)][BAr4] (9), [PdMe(NCMe) (κ2-L4)][BAr4] (10), [PdMe(NCMe) (κ2-L5)][BAr4] (11), [PdMe(NCMe) (κ2-L6)][BAr4] (12) respectively. However, when 3 or 4 was reacted with of Na[BAr4] and a slight excess of methyl acrylate, the products were surprisingly the bis(ligand)palladium complexes [Pd(κ2-L3)2][BAr4]2 (13) and [Pd(κ2-L4)2][BAr4]2 (14) instead of the expected acylpalladium chelate complexes ([(κ2-L)Pd{(CH2)2C(O)OMe}][BAr4]). Complexes 1-6, activated with Na[BAr4], and pre-activated complexes 7-12 at 10 bar of ethylene and 30 bar of carbon monoxide produced polyketones, albeit with low activity (ca. 1.00 g.mmol-1Pd.h-1); with the active catalysts rearranging to mainly bis(pyrazolyl)palladium complexes similar to 13 and 14.
- Obuah, Collins,Darkwa, James
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- An efficient one-pot oxidative esterification of aldehydes to carboxylic esters using B(C6F5)3-TBHP
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A simple and efficient protocol for oxidative esterification of diverse aldehydes with alcohols was accomplished with tert-butyl hydroperoxide and 1 mol % of tris(pentafluorophenyl)borane [B(C6F5)3] to generate the corresponding esters in good to excellent yields. The present protocol represents compatibility with wide range of functional groups as well as exceptional tolerance toward acid labile protecting groups such as TBDPS, TBDMS, acetonide, and Boc.
- Guggilapu, Sravanthi Devi,Prajapti, Santosh Kumar,Babu, Bathini Nagendra
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supporting information
p. 889 - 892
(2015/02/05)
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- One pot oxidative esterification of aldehyde over recyclable cesium salt of nickel substituted phosphotungstate
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First time, one-pot oxidative esterification of aldehydes with methanol and hydrogen peroxide as a green oxidant was carried out over Keggin-type cesium salt of nickel substituted phosphotungstate. This protocol affords a novel and efficient approach for achieving high conversion (87%), selectivity for ester (80%) with high turnover numbers (TONs). The catalyst proved to be a bi-functional one, showing synergic effect of lacunary phosphotungstate and nickel by combining their acidic and redox properties. Mechanistic study carried out by UV-Visible spectrophotometer shows that tungsten and nickel both take part in the reaction. The scope of various aldehyde substrates were also evaluated and it was found that the reactions are facile, easy to work up and provide a mild oxidative alternative for organic chemists.
- Singh, Sukriti,Patel, Anjali,Prakashan, Pravya
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p. 131 - 140
(2015/08/24)
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- Highly efficient and chemoselective hydrogenation of α,β-unsaturated carbonyls over Pd/N-doped hierarchically porous carbon
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Palladium nanoparticles supported on N-doped hierarchically porous carbon, Pd/CNx, has been developed as a highly efficient, reusable and environmentally benign heterogeneous catalyst for the selective hydrogenation of various α,β-unsaturated carbonyls to their corresponding saturated carbonyls under mild conditions (303 K, 1 bar H2). Complete conversion of a series of α,β-unsaturated carbonyls was achieved with excellent selectivity (>99%) within 4 h. Moreover, the catalyst can be easily recovered by centrifugation and withstands recycling up to 8 times without apparent loss of activity and selectivity. The considerable catalytic performance is attributed to the hierarchically porous network and incorporation of nitrogen atoms. This catalytic system opens up an efficient, selective, recyclable and sustainable method for selective hydrogenation.
- Wei, Zhongzhe,Gong, Yutong,Xiong, Tianyi,Zhang, Pengfei,Li, Haoran,Wang, Yong
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p. 397 - 404
(2015/02/02)
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- Gold nanoparticles supported on metal oxides as catalysts for the direct oxidative esterification of alcohols under mild conditions
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Gold nanoparticles supported on metal oxides were used to catalyze the direct oxidative esterification of alcohols; esters were obtained using molecular oxygen as an oxidant under ambient temperature and pressure. Higher activities for the reaction between the benzyl alcohol and methanol were obtained over Au/CeO2 and Au/ZrO2 than Au/TiO2 (anatase), Au/HT (hydrotalcite) and Au/Al2O3. These catalysts were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic absorption spectroscopy (AAS) and X-ray photoelectron spectroscopy (XPS). The distribution of gold nanoparticles was uniform; no change of chemical states occurred for supports and gold nanoparticles after the catalysts were reused 10 times. The oxidative esterification of various alcohols over these catalysts could also occur under optimized reaction conditions. The substituted benzyl alcohols and cinnamyl alcohols were more active than heterocyclic alcohols and aliphatic alcohols because their α-H could be eliminated more easily during the induction of adsorbed dioxygen. Self-oxidative esterification was available for benzyl alcohol in inert solvents with low polarity indexes. A reaction mechanism was proposed for the synthesis of esters from alcohols with molecular oxygen.
- Wei, Huili,Li, Jingyi,Yu, Jing,Zheng, Jianwei,Su, Haiquan,Wang, Xiaojing
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- Primary alkanols: oxidative homocondensation in water and cross-condensation in methanol
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Water was used as a reaction medium and a reagent in oxidation of primary alkanols to dimeric esters and alkanoic acids using either molecular bromine or a hydrogen peroxide—hydrobromic acid mixture as the oxidants. The similar reaction in methanol produced methyl alkanoates.
- Nikishin,Sokova,Terent′ev,Kapustina
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p. 2845 - 2850
(2016/09/28)
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- Four new pentasaccharide resin glycosides from Ipomoea cairica with strong α-glucosidase inhibitory activity
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Six pentasaccharide resin glycosides from Ipomoea cairica, including four new acylated pentasaccharide resin glycosides, namely cairicoside I-IV (1-4) and the two known compounds cairicoside A (5) and cairicoside C (6), were isolated from the aerial parts of Ipomoea cairica. Their structures were established by a combination of spectroscopic, including two dimensional (2D) NMR and chemical methods. The core of the six compounds was simonic acid A, and they were esterfied the same sites, just differing in the substituent groups. The lactonization site of the aglycone was bonded to the second saccharide moiety at C-2 in 1-4, and at C-3 in 5-6. Compounds 1 and 5, 4 and 6 were two pairs of isomers. The absolute configuration of the aglycone in 1-6 which was (11S)-hydroxyhexadecanoic acid (jalapinolic acid) was established by Mosher's method. Compounds 1-4 have been evaluated for inhibitory activity against α-glucosidase, which all showed inhibitory activities.
- Pan, Jie-Tao,Yu, Bang-Wei,Yin, Yong-Qin,Li, Jie-Hong,Wang, Li,Guo, Li-Bing,Shen, Zhi-Bin
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p. 6601 - 6610
(2015/05/13)
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- Antitrypanosomal acetylene fatty acid derivatives from the seeds of Porcelia macrocarpa (Annonaceae)
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Chagas' disease is caused by a parasitic protozoan and affects the poorest population in the world, causing high mortality and morbidity. As a result of the toxicity and long duration of current treatments, the discovery of novel and more efficacious drugs is crucial. In this work, the hexane extract from seeds of Porcelia macrocarpa R.E. Fries (Annonaceae) displayed in vitro antitrypanosomal activity against trypomastigote forms of T. cruzi by the colorimetric MTT assay (IC50 of 65.44 μg/mL). Using chromatographic fractionation over SiO2, this extract afforded a fraction composed by one active compound (IC50 of 10.70 μg/mL), which was chemically characterized as 12,14-octadecadiynoic acid (macrocarpic acid). Additionally, two new inactive acetylene compounds (α,α′-dimacro-carpoyl-β-oleylglycerol and α-macrocarpoyl-α′-oleylglycerol) were also isolated from the hexane extract. The complete characterization of the isolated compounds was performed by analysis of NMR and MS data as well as preparation of derivatives.
- Santos, Luciana de á.,Cavalheiro, Alberto J.,Tempone, Andre G.,Correa, Daniela S.,Alexandre, Tatiana R.,Quintiliano, Natalia F.,Rodrigues-Oliveira, AndréF,Oliveira-Silva, Diogo,Martins, Roberto Carlos C.,Lago, Jo?o Henrique G.
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p. 8168 - 8180
(2015/05/20)
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- Methyl ester synthesis catalyzed by nanoporous gold: from 10-9 Torr to 1 atm
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The oxidative coupling reaction of aldehydes with methanol occurs in the vapor phase over a support-free nanoporous gold (npAu) catalyst over a wide pressure range - from 10-9 Torr to 1 atm. The dependence of the aldehyde-to-ester reaction rate on the oxygen, methanol and aldehyde partial pressures suggests that the rate-limiting step for coupling is the reaction of the aldehyde with surface sites saturated with adsorbed methoxy. Stable catalyst activity is achieved for aldehyde-methanol coupling in flowing reactant mixtures at 70 °C. While the conditioned npAu catalyst exhibits high selectivity for methanol-aldehyde coupling, its activity for the self-coupling reaction of methanol to methyl formate is reduced by the exposure to the alcohol-aldehyde mixture in a manner that is consistent with the buildup of spectator species. The activity for methanol self-coupling can be regenerated by extended exposure to flowing methanol, CO and O2 at 70 °C. Overall, the observed catalytic esterification is consistent with model studies of both the npAu catalyst and single crystal gold in ultrahigh vacuum.
- Wang, Lu-Cun,Stowers, Kara J.,Zugic, Branko,Biener, Monika M.,Biener, Juergen,Friend, Cynthia M.,Madix, Robert J.
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p. 1299 - 1306
(2015/02/19)
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- Acid-catalyzed oxidation of levulinate derivatives to succinates under mild conditions
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Levulinate derivatives are an attractive platform for the production of renewable chemicals. Here we report on the oxidation of methyl levulinate into dimethyl succinate with peroxides under mild conditions using Br?nsted and Lewis acid catalysts. Selectivities to succinate and acetate derivatives of approximately 60 and 40 %, respectively, were obtained with strong Br?nsted acids in methanol. Although the molecular structure (i.e., carbon-chain length and branching around the C=O group) and the oxidant type affect the product distribution, solvent choice has the strongest impact on changing the location of oxygen insertion into the carbon backbone. Specifically, switching the solvent from methanol to heptane resulted in a decrease in the succinate/acetate ratio from 1.6 to 0.3. In contrast to Br?nsted acids, we demonstrate that the nature of the metal cation is responsible for changing the reaction selectivity of water-tolerant Lewis acidic triflate salts.
- Wang, Yuran,Vogelgsang, Ferdinand,Román-Leshkov, Yuriy
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p. 916 - 920
(2015/03/18)
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- 1,2,3-Triazolylidene ruthenium(ii)-cyclometalated complexes and olefin selective hydrogenation catalysis
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Silver(i) 1,2,3-triazol-5-ylidenes [(RCH2C2N2(NMe)Ph)2Ag][AgCl2] (R = Ph 3a, C6H2iPr33b, C6H2Me33c) and [(PhCH2C2N2(NMe)R)2Ag][AgCl2] (R = C6H4Me 3d, C6H4CF33e) were synthesized and subsequently treated with RuHCl(PPh3)3 and RuHCl(H2)(PCy3)2. The reaction of 3a with RuHCl(PPh3)3 gave RuHCl(PPh3)2(PhCH2C2N2(NMe)Ph) (4a1) as the minor product and the cyclometalated complex RuCl(PPh3)2(PhCH2C2N2(NMe)C6H4) (4a2) as the major product. However, similar reaction with 3b selectively formed the cyclometalated complex RuCl(PPh3)2((C6H2iPr3)CH2C2N2(NMe)C6H4) (4b2). Similarly the silver(i) triazolylidenes 3a and 3b were reacted with RuHCl(H2)(PCy3)2; gave RuHCl(PCy3)2(PhCH2C2N2(NMe)Ph) (5a1), RuCl(PCy3)2(PhCH2C2N2(NMe)C6H4) (5a2) and RuCl(PCy3)2((C6H2iPr3)CH2C2N2(NMe)C6H4) (5b2), respectively. Species 3c, 3d and 3e resulted in the cyclometalated complexes (5c2, 5d2 and 5e2) as the major products as well as the ruthenium-hydride complexes (5c1, 5d1 and 5e1) as the minor products. The cyclometalated species are derived from the ruthenium-hydride complexes via C(sp2)-H activation. These Ru-complexes were shown to act as hydrogenation catalyst precursors for olefinic substrates including those containing a variety of functional groups. This journal is
- Bagh, Bidraha,McKinty, Adam M.,Lough, Alan J.,Stephan, Douglas W.
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p. 2712 - 2723
(2015/02/19)
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- Oxidative esterification of aldehydes to esters over anchored phosphotungstates
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12-Tungstophosphoric acid and lacunary phosphotungstate anchored to MCM-41 and ZrO2 were synthesized, characterized and used as bifunctional catalyst for oxidative esterification of benzaldehyde with methanol. The different aldehyde substrates study show excellent selectivity for esters, indicating the scope of the catalysts. A tentative reaction mechanism for oxidative esterification of aldehyde is also proposed. Graphical Abstract: [Figure not available: see fulltext.]
- Singh, Sukriti,Patel, Anjali
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p. 1557 - 1567,11
(2014/10/15)
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- PIFA-mediated esterification reaction of alkynes with alcohols via oxidative cleavage of carbon triple bonds
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A metal-free esterification of alkynes via C≡C triple bond cleavage has been developed. In the presence of phenyliodine bis(trifluoroacetate), a diverse range of alkyne and alcohol substrates undergoes triple bond cleavage to produce carboxylic ester motifs in moderate to good yields. The transformation is proposed to proceed via hydroxyethanones and ethanediones as intermediates on the basis of mechanistic studies and exhibits a broad substrate scope and good functional group tolerance.
- Jiang, Qing,Zhao, An,Xu, Bin,Jia, Jing,Liu, Xin,Guo, Cancheng
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p. 2709 - 2715
(2014/04/17)
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- Half sandwich ruthenium(ii) hydrides: Hydrogenation of terminal, internal, cyclic and functionalized olefins
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Bis(1,2,3-triazolylidene) silver(i) complex 1a was reacted with [RuCl2(p-cymene)]2 to give the ruthenium complex [PhCH2N2(NMe)C2(C6H4CF3)]RuCl2(p-cymene) (2a) as major product in addition to the minor C(sp2)-H activated product [PhCH2N2(NMe)C2(C6H3CF3)]RuCl(p-cymene) (2a′). Similar ruthenium complexes 2b, 2c, 2d and 2e with general formula RuCl2(p-cymene)(NHC) (NHC = MesCH2N2(NMe)C2Ph 2b, PhCH2N2(NMe)C2Ph 2c, TripCH2N2(NMe)C2Ph 2d, IMes 2e) were also synthesized. Subsequent reaction of Me3SiOSO2CF3 with 2a and 2b resulted in cationic ruthenium species [(PhCH2N2(NMe)C2(C6H4CF3))RuCl(p-cymene)][OSO2CF3] (3a) and [(MesCH2N2(NMe)C2Ph)RuCl(p-cymene)][OSO2CF3] (3b), respectively. Complexes 3a and 3b dissolved in CD3CN to give [(PhCH2N2(NMe)C2(C6H4CF3))RuCl(CD3CN)(p-cymene)][OSO2CF3] (4a) and [(MesCH2N2(NMe)C2Ph)RuCl(CD3CN)(p-cymene)][OSO2CF3] (4b), respectively. Cationic ruthenium species 4a and 4b failed to show catalytic activity towards hydrogenation of olefins. Ruthenium(ii) complexes 2b-e with the general formula RuCl2(p-cymene)(NHC) were reacted with Et3SiH to generate a series of ruthenium(ii) hydrides 5b-e. These compounds 5b-e are effective catalysts for the hydrogenation of terminal, internal and cyclic and functionalized olefins.
- Bagh, Bidraha,Stephan, Douglas W.
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p. 15638 - 15645
(2015/01/08)
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