- Spectroscopy of Hydrothermal Reactions, Part 26: Kinetics of Decarboxylation of Aliphatic Amino Acids and Comparison with the Rates of Racemization
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The kinetics of decarboxylation of six α-amino acids (glycine, alanine, aminobutyric acid, valine, leucine, and isoleucine) and β-aminobutyric acid were studied in aqueous solution at 310-330 deg C and 275 bar over the pH25 range 1.5-8.5 by using an in situ FT-IR spectroscopy flow reactor. Based on the rate of formation of CO2, the first-order or pseudo-first-order rate constants were obtained along with the Arrhenius parameters. The decarboxylation rates of amino acids follow the order Gly > Leu ca. Ile ca. Val > Ala > α-Aib > β-Aib. Differences in the concentration between 0.05 and 0.5 m had only a minor effect on the decarboxylation rate. The effect of the position of the amino group on the decarboxylation rate was investigated for α-, β-, and γ-aminobutyric acid and the order was found to be α > β >> γ. Although the pH dependence is complex, the decarboxylation rates of α-amino acids qualitatively have the inverse trend of the racemization rates.
- Li, Jun,Brill, Thomas B.
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- Merging constitutional and motional covalent dynamics in reversible imine formation and exchange processes
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The formation and exchange processes of imines of salicylaldehyde, pyridine-2-carboxaldehyde, and benzaldehyde have been studied, showing that the former has features of particular interest for dynamic covalent chemistry, displaying high efficiency and fast rates. The monoimines formed with aliphatic α,ω-diamines display an internal exchange process of self-transimination type, inducing a local motion of either "stepping-in- place" or "single-step" type by bond interchange, whose rate decreases rapidly with the distance of the terminal amino groups. Control of the speed of the process over a wide range may be achieved by substituents, solvent composition, and temperature. These monoimines also undergo intermolecular exchange, thus merging motional and constitutional covalent behavior within the same molecule. With polyamines, the monoimines formed execute internal motions that have been characterized by extensive one-dimensional, two-dimensional, and EXSY proton NMR studies. In particular, with linear polyamines, nondirectional displacement occurs by shifting of the aldehyde residue along the polyamine chain serving as molecular track. Imines thus behave as simple prototypes of systems displaying relative motions of molecular moieties, a subject of high current interest in the investigation of synthetic and biological molecular motors. The motional processes described are of dynamic covalent nature and take place without change in molecular constitution. They thus represent a category of dynamic covalent motions, resulting from reversible covalent bond formation and dissociation. They extend dynamic covalent chemistry into the area of molecular motions. A major further step will be to achieve control of directionality. The results reported here for imines open wide perspectives, together with other chemical groups, for the implementation of such features in multifunctional molecules toward the design of molecular devices presenting a complex combination of motional and constitutional dynamic behaviors.
- Kovaricek, Petr,Lehn, Jean-Marie
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- N,N-Bis(trimethylsilyl)methoxymethylamine as a Convenient Synthetic Equivalent for +CH2NH2: Primary Aminomethylation of Organometallic Compounds
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The introduction of the primary aminomethyl unit at carbon through N,N-bis(trimethylsilyl)aminomethylation of Grignard and organolithium compounds can be achieved in good yield using N,N-bis(trimethylsilyl)methoxymethylamine (1).
- Morimoto, Toshiaki,Takahashi, Toshio,Sekiya, Minoru
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- Water-soluble platinum and palladium nanoparticles modified with thiolated β-cyclodextrin
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Pt and Pd nanoparticles can be modified with surface-attached cyclodextrin receptors leading to water-soluble materials that exhibit catalytic activity for the hydrogenation of allylamine.
- Alvarez, Julio,Liu, Jian,Roman, Esteban,Kaifer, Angel E.
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- Rice husk-SiO2supported bimetallic Fe-Ni nanoparticles: as a new, powerful magnetic nanocomposite for the aqueous reduction of nitro compounds to amines
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This paper reports a novel green procedure for immobilization of bimetallic Fe/Ni on amorphous silica nanoparticles extracted from rice husk (RH-SiO2). The heterogeneous nanocomposite (Fe/Ni?RH-SiO2) was identified using SEM, EDX, TEM, BET, H2-TPR, TGA, XRD, VSM, ICP-OES, and FT-IR analyses. The Fe/Ni?RH-SiO2nanocomposite was applied as a powerful catalyst for the reduction of structurally diverse nitro compounds with sodium borohydride (NaBH4) in green conditions. This procedure suggests some benefits such as green chemistry-based properties, short reaction times, non-explosive materials, easy to handle, fast separation and simple work-up method. The catalyst was separated by an external magnet from the reaction mixture and was reused for 9 successive cycles with no detectable changes of its catalytic efficiency.
- Ghadermazi, Mohammad,Moradi, Setareh,Mozafari, Roya
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- Reduced reactivity of amines against nucleophilic substitution via reversible reaction with carbon dioxide
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The reversible reaction of carbon dioxide (CO2) with primary amines to form alkyl-ammonium carbamates is demonstrated in this work to reduce amine reactivity against nucleophilic substitution reactions with benzophenone and phenyl isocyanate. The reversible formation of carbamates has been recently exploited for a number of unique applications including the formation of reversible ionic liquids and surfactants. For these applications, reduced reactivity of the carbamate is imperative, particularly for applications in reactions and separations. In this work, carbamate formation resulted in a 67% reduction in yield for urea synthesis and 55% reduction for imine synthesis. Furthermore, the amine reactivity can be recovered upon reversal of the carbamate reaction, demonstrating reversibility. The strong nucleophilic properties of amines often require protection/de-protection schemes during bi-functional coupling reactions. This typically requires three separate reaction steps to achieve a single transformation, which is the motivation behind Green Chemistry Principle #8: Reduce Derivatives. Based upon the reduced reactivity, there is potential to employ the reversible carbamate reaction as an alternative method for amine protection in the presence of competing reactions. For the context of this work, CO2 is envisioned as a green protecting agent to suppress formation of n-phenyl benzophenoneimine and various n-phenyl-n-alky ureas.
- Mohammed, Fiaz S.,Kitchens, Christopher L.
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- Supramolecular solid-gas complexes: A thermodynamic approach
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(Table Presented) Phasing up to complex problems: A thermodynamic approach based on solution data has been proposed for the determination of the stability of gas complexes and elucidation of the selectivity of gas binding. Stability constants, reaction enthalpies, and entropies for the complexation of gaseous guests (n-alkylamines) by solid macrocyclic hosts (β-cyclodextrin, cucurbit[6]uril) were calculated by using the Born-Haber type cycle (see picture).
- Grechin, Alexander G.,Buschmann, Hans-Juergen,Schollmeyer, Eckhard
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- Insight into the mechanism of hydrogenation of amino acids to amino alcohols catalyzed by a heterogeneous MoOx-modified Rh catalyst
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Hydrogenation of amino acids to amino alcohols is a promising utilization of natural amino acids. We found that MoOx-modified Rh/SiO2 (Rh-MoOx/SiO2) is an efficient heterogeneous catalyst for the reaction at low temperature (323 K) and the addition of a small amount of MoOx drastically increases the activity and selectivity. Here, we report the catalytic potential of Rh-MoOx/SiO2 and the results of kinetic and spectroscopic studies to elucidate the reaction mechanism of Rh-MoOx/SiO2 catalyzed hydrogenation of amino acids to amino alcohols. Rh-MoOx/SiO2 is superior to previously reported catalysts in terms of activity and substrate scope. This reaction proceeds by direct formation of an aldehyde intermediate from the carboxylic acid moiety, which is different from the reported reaction mechanism. This mechanism can be attributed to the reactive hydride species and substrate adsorption caused by MoOx modification of Rh metal, which results in high activity, selectivity, and enantioselectivity.
- Tamura, Masazumi,Tamura, Riku,Takeda, Yasuyuki,Nakagawa, Yoshinao,Tomishige, Keiichi
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- Catalytic Reductions and Tandem Reactions of Nitro Compounds Using in Situ Prepared Nickel Boride Catalyst in Nanocellulose Solution
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A mild and efficient method for the in situ reduction of a wide range of nitroarenes and aliphatic nitrocompounds to amines in excellent yields using nickel chloride/sodium borohydride in a solution of TEMPO-oxidized nanocellulose in water (0.01 wt %) is described. The nanocellulose has a stabilizing effect on the catalyst, which increases the turnover number and enables low loading of nickel catalyst (0.1-0.25 mol % NiCl2). In addition, two tandem protocols were developed in which the in situ formed amines were either Boc-protected to carbamates or further reacted with an epoxide to yield β-amino alcohols in excellent yields.
- Prathap, Kaniraj Jeya,Wu, Qiong,Olsson, Richard T.,Dinér, Peter
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- Amination of alcohols with ammonia in water over Rhin catalyst
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Amination of various C3 alcohols such as 1,2-propanediol with ammonia was catalyzed by RhIn/C in water while Rh/C was totally inactive. Activated carbon FAC-10 was the best support in terms of activity and resistance to metal leaching. In the amination of 1,2-propanediol, RhIn/C produced amino alcohols in 68% total selectivity and 38% conversion. XRD and TEM measurements showed that RhIn alloy particle with size of 34 nm was formed on the carbon support.
- Takanashi, Tsukasa,Nakagawa, Yoshinao,Tomishige, Keiichi
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- Sustainable hydrogenation of aliphatic acyclic primary amides to primary amines with recyclable heterogeneous ruthenium-tungsten catalysts
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The hydrogenation of amides is a straightforward method to produce (possibly bio-based) amines. However current amide hydrogenation catalysts have only been validated in a rather limited range of toxic solvents and the hydrogenation of aliphatic (acyclic) primary amides has rarely been investigated. Here, we report the use of a new and relatively cheap ruthenium-tungsten bimetallic catalyst in the green and benign solvent cyclopentyl methyl ether (CPME). Besides the effect of the Lewis acid promotor, NH3 partial pressure is identified as the key parameter leading to high primary amine yields. In our model reaction with hexanamide, yields of up to 83% hexylamine could be achieved. Beside the NH3 partial pressure, we investigated the effect of the catalyst support, PGM-Lewis acid ratio, H2 pressure, temperature, solvent tolerance and product stability. Finally, the catalyst was characterized and proven to be very stable and highly suitable for the hydrogenation of a broad range of amides.
- Coeck, Robin,Berden, Sarah,De Vos, Dirk E.
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- CoFe2O4?SiO2-NH2-CoII NPs: An effective magnetically recoverable catalyst for Biginelli reaction
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Biginelli reaction entails acid-catalyzed one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones (DHPMs) with simply-accessible initial substances, specifically, aldehyde, urea, and active methylene compound. DHPMs have stimulated a resurgence of attention in the previous two decades because of their broad-ranging pharmacological actions and the existence of varied all-natural products. Currently, green methods to asymmetric Biginelli reaction have been researched for anti-inflammatory DHPMs. In materials chemistry, DHPMs are increasingly decision applications in the creation of materials like polymers, adhesives, fabric dyes, etc. In light of the simplicity by which the Biginelli reaction is conducted, numerous interesting prospects expect its exploitation in variety fields. CoFe2O4?SiO2-NH2-CoII is herein turned out to be an effective catalyst at a three-component Biginelli reaction. The yield of the corresponding DHPMs was rather large (20 cases; average 92 percent). Finally, we herein suggest a procedure that shows lots of advantages and benefits such as the whole lack of solvents, mild reaction conditions, comparatively short reaction times. Also, CoFe2O4?SiO2-NH2-CoII NPs catalyst has been readily recovered from the reaction combination and reused, without the decrease of catalytic action.
- Allahresani, Ali,Hemmat, Kaveh,Nasseri, Mohammad Ali,Sangani, Mehri Mohammadpour
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- Chemosensor for the optical detection of aliphatic amines and diamines
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Two new chemosensor dyes with either one or two trifluoroacetophenone recognition moieties have been investigated in terms of reversibly interacting with amines and diamines. The Royal Society of Chemistry.
- Reinert, Susanne,Mohr, Gerhard J.
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- Comparison of the Activity and Lifetime of Raney Nickel and Nickel Boride in the Hydrogenation of Various Functional Groups
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Nickel borides (Ni2B) are prepared by the reduction of a nickel salt with sodium borohydride.These materials have been shown to be active hydrogenation catalysts.The activity and lifetime of a P-1.50 nickel boride catalyst, which is prepared in a 50percent water/ethanol solvent, are reported for the hydrogenation of unsaturated carbon and nitrogen bonds and for aldehydes.The data are compared to those obtained for similar reductions which employ Raney nickel as the catalyst.The nickel boride is more active and productive than Raney nickel in the hydrogenation of hexene,cyclohexene, and acrylonitrile.The properties of the two catalysts are similar for the reduction of cinnamaldehyde, 2-ethylhexanal, and benzaldehyde.The data for the reduction of nitrobenzene, adiponitrile, and propionitrile indicate that the nickel boride is more susceptible to nitrogen poisoning than Raney nickel.
- Schreifels, John A.,Maybury, P. Calvin,Swartz, William E.
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- Palladium/Graphitic Carbon Nitride (g-C3N4) Stabilized Emulsion Microreactor as a Store for Hydrogen from Ammonia Borane for Use in Alkene Hydrogenation
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Direct hydrogenation of C=C double bonds is a basic transformation in organic chemistry which is vanishing from simple practice because of the need for pressurized hydrogen. Ammonia borane (AB) has emerged as a hydrogen source through its safety and high hydrogen content. However, in conventional systems the hydrogen liberated from the high-cost AB cannot be fully utilized. Herein, we develop a novel Pd/g-C3N4 stabilized Pickering emulsion microreactor, in which alkenes are hydrogenated in the oil phase with hydrogen originating from AB in the water phase, catalysed by the Pd nanoparticles at the interfaces. This approach is advantageous for more economical hydrogen utilization over conventional systems. The emulsion microreactor can be applied to a range of alkene substrates, with the conversion rates achieving >95 % by a simple modification.
- Han, Chenhui,Meng, Peng,Waclawik, Eric R.,Zhang, Chao,Li, Xin-Hao,Yang, Hengquan,Antonietti, Markus,Xu, Jingsan
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- Postcolumn Photolysis of Pesticides for Fluorometric Determination by High-Performance Liquid Chromatography
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A high-performance liquid chromatography postcolumn reaction detector that employs UV photolysis with an optional reaction by using o-phthalaldehyde-2-mercaptoethanol (OPA-MERC) followed by fluorescence detection was found to be useful for several classes of pesticides.In the presence of the OPA-MERC reagent, most carbamates, carbamoyl oximes, carbamothioic acids, and substituted ureas gave a sensitive response while the response of dithiocarbamates, phenylamides, and phenylcarbamates varied.The response of most of the pesticides tested was significantly affected bythe solvent used.Method detection limits for aldicarb sulfoxide, aldicarb, propoxur, thiram, and neburon in groundwater were 2.5, 2.3, 3.3, 3.8, and 2.0 νg/L, respectively.In the absence of OPA-MERC reagent, several of the substituted aromatic compounds also gave strong fluorescence after photolysis.This detector is applicable to a broad range of nitrogenous pesticides.
- Miles, Carl J.,Moye, H. Anson
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- Kinetic study of the reaction between iodide and N-chloramines
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We carried out a kinetic study of the reaction between iodide ion and various primary N-chloramines and found it to be first-order in the latter.Experiments also showed the rate constant for the reaction to be directly proportional to the iodide and hydrogen ion concentrations.The influence of the concentration reveals the presence of general acid catalysis processes.
- Antelo, J. M.,Arce, F.,Campos, J.,Parajo, M.
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- Mechanism of β-lactam ring opening in cephalosporins
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The mechanism of the aminolysis of cephalosporins is a stepwise process. A tetrahedral intermediate is formed by the reversible addition of the amine to the beta -lactam carbonyl carbon. Expulsion of the attacking amine from the tetrahedral intermediate occurs faster than fission of the beta -lactam C-N bond. The reaction proceeds by trapping the intermediate with base. Expulsion of a leaving group at C-3 prime in cephalosporins is not concerted with nucleophilic attack of the amine on the beta -lactam carbonyl carbon and makes little difference to the rate of beta -lactam C-N bond fission.
- Page,Proctor
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- Development and Application of Efficient Ag-based Hydrogenation Catalysts Prepared from Rice Husk Waste
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The development of strategies for the sustainable management and valorization of agricultural waste is of outmost importance. With this in mind, we report the use of rice husk (RH) as feedstock for the preparation of heterogeneous catalysts for hydrogenation reactions. The catalysts were prepared by impregnating the milled RH with a silver nitrate solution followed by carbothermal reduction. The composition and morphology of the prepared catalysts were fully assessed by IR, AAS, ICP-MS, XPS, XRD and STEM techniques. This novel bio-genic silver-based catalysts showed excellent activity and remarkable selectivity in the hydrogenation of nitro groups in both aromatic and aliphatic substrates, even in the presence of reactive functionalities like halogens, carbonyls, borate esters or nitriles. Recycling experiments showed that the catalysts can be easily recovered and reused multiple times without significant drop in performance and without requiring re-activation.
- Unglaube, Felix,Kreyenschulte, Carsten Robert,Mejía, Esteban
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p. 2583 - 2591
(2021/04/09)
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- Highly selective synthesis of primary amines from amide over Ru-Nb2O5 catalysts
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Amines are an important class of compounds in natural products and medicines. The universal availability of amides provides a potential way for the synthesis of amines. Herein, Ru/Nb2O5 catalyst is demonstrated to be highly efficient and stable for the selective hydrogenation of propionamide to propylamine (as a model reaction), with up to 91.4% yield of propylamine under relatively mild conditions. Results from XPS analyses, CO chemisorption, TEM images and DRIFTS spectra revealed that the unique properties of Nb2O5 can effectively activate the C=O group of amides, and the smaller Ru particles on Nb2O5 could further promote the activation, leading to superior catalytic performance of Ru/Nb2O5 for amide hydrogenation. Meanwhile, reducing the surface acidity of Nb2O5 can greatly inhibit the side reactions to by-products, and further enhance the selectivity to amine. Moreover, this catalytic system is also applicable for the hydrogenation of a variety of amides and provides high potential for the industrial production of primary amines from amides.
- Guo, Wanjun,Guo, Yong,Jia, Hongyan,Liu, Xiaohui,Pan, Hu,Wang, Yangang,Wang, Yanqin,Xia, Qineng
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supporting information
(2021/12/22)
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- Indirect reduction of CO2and recycling of polymers by manganese-catalyzed transfer hydrogenation of amides, carbamates, urea derivatives, and polyurethanes
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The reduction of polar bonds, in particular carbonyl groups, is of fundamental importance in organic chemistry and biology. Herein, we report a manganese pincer complex as a versatile catalyst for the transfer hydrogenation of amides, carbamates, urea derivatives, and even polyurethanes leading to the corresponding alcohols, amines, and methanol as products. Since these compound classes can be prepared using CO2as a C1 building block the reported reaction represents an approach to the indirect reduction of CO2. Notably, these are the first examples on the reduction of carbamates and urea derivatives as well as on the C-N bond cleavage in amides by transfer hydrogenation. The general applicability of this methodology is highlighted by the successful reduction of 12 urea derivatives, 26 carbamates and 11 amides. The corresponding amines, alcohols and methanol were obtained in good to excellent yields up to 97%. Furthermore, polyurethanes were successfully converted which represents a viable strategy towards a circular economy. Based on control experiments and the observed intermediates a feasible mechanism is proposed.
- Liu, Xin,Werner, Thomas
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p. 10590 - 10597
(2021/08/20)
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- Half-sandwiched ruthenium complex containing carborane schiff base ligand and preparation and application thereof
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The invention relates to a half-sandwiched ruthenium complex containing a carborane schiff base ligand and a preparation and an application thereof. The preparation method specifically comprises the following steps; i) dissolving o-carborane formaldehyde and aromatic amine in an organic solvent, carrying out reaction at 60-100 DEG C for 8-12h, cooling to room temperature after the reaction; ii) adding n-butyllithium, carrying out reaction at room temperature for 1.5-2.5h; ii) adding phellandrene ruthenium chloride dimer, carrying out reaction at room temperature for 3-6h, and obtaining the half-sandwiched ruthenium complex through separation. The half-sandwiched ruthenium complex is applied to catalyze transfer hydrogenation reaction of nitrile compounds. Compared with the prior art, the complex of the present invention is not sensitive to air and water, has stable properties, and shows high-efficiency catalytic activity in catalyzing the transfer hydrogenation reaction of nitrile compounds. The preparation method of the complex is simple and green, high in yield, mild in reaction conditions and good in universality.
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Paragraph 0067-0071
(2020/12/09)
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- Catalyst for producing 3-aminopropanol by hydrogenating 3-hydroxypropionitrile and preparation method thereof
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The invention discloses a catalyst for producing 3-aminopropanol by hydrogenating 3-hydroxypropionitrile. The catalyst is characterized in that the catalyst comprises an active component and a carrier, wherein the active component comprises active metal elements; the active metal elements comprise M and Re; M is selected from at least one of Ni, Co and Cu; M accounts for 5.0-50.0% of the weight ofthe catalyst; Re accounts for 0.1-15.0% of the weight of the catalyst; and the carrier is selected from at least one of inorganic porous materials. The catalyst has high catalytic activity and selectivity.
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Paragraph 0114; 0115; 0116-0118; 0126
(2020/06/09)
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- ZnFe-LDH/GO nanocomposite coated on the glass support as a highly efficient catalyst for visible light photodegradation of an emerging pollutant
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This study reports the fabrication of ZnFe-layered double hydroxides with sulfate-intercalated anion (ZnFe-SO4-LDH) modified with graphene oxide (GO) by chemical co-precipitation method. They were then coated on the glass substrates (denoted as ZnFe-LDH/GO/GS). The XRD, SEM, EDX, X-ray Dot-mapping, FTIR, AFM, UV–Vis DRS, and PL analyses were used for the characterization of the as-synthesized sample. The photocatalytic implementation of the as-prepared photocatalyst was scrutinized for the degradation of phenazopyridine hydrochloride (PhP) from the solution under visible light irradiation. The prepared photocatalyst showed photocatalytic performance of elimination PhP, the degraded rate of pollutant could reach 60.01% in 150 min of photocatalysis process under the optimum conditions: initial PhP concentration of 15 mg/L, pH of 8 (natural pH), and 3 photocatalysts plates. The addition of 1 mmol/L of potassium persulfate (k2S2O8) caused the degradation efficiency of 93.95% within the 150 min of photocatalytic process. Trapping experiments indicated the influence order of O2 ?· > [rad]OH > h+ for the ROSs present in decomposition. The transformation of five intermediates of PhP produced in the photocatalytic degradation process was identified by the GC–MS technique. 60% COD removal efficiency was achieved after 300 min of photocatalytic reaction confirming mineralization of the PhP solution. Finally, a reusability test of ZnFe-LDH/GO/GS photocatalyst in the PhP degradation revealed that almost 12% drop occurred after five successive cycles.
- Motlagh, Parisa Yekan,Khataee, Alireza,Hassani, Aydin,Sadeghi Rad, Tannaz
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- Cobalt nanoparticles anchoring on nitrogen doped carbon with excellent performances for transfer hydrogenation of nitrocompounds to primary amines and N-substituted formamides with formic acid
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Cobalt nanoparticles anchoring on nitrogen doped carbon derived from pyrolysis of a cobalt complex and chitosan were developed for reduction of nitrocompounds with neat formic acid to their corresponding amines or N-substituted formamides by switch of solvents. Characterization results revealed that most of the nitrogen atoms are present as graphitic N and pyridinic N as anchoring sites, and the cobalt nanoparticles are wrapped by nitrogen doped carbon layers, endowing the catalyst with excellent activity and superior reusability.
- Zhang, Yuecheng,Cao, Pengwei,Zhang, Hong-Yu,Yin, Guohui,Zhao, Jiquan
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- Biomolecule-derived supported cobalt nanoparticles for hydrogenation of industrial olefins, natural oils and more in water
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Catalytic hydrogenation of olefins using noble metal catalysts or pyrophoric RANEY nickel is of high importance in the chemical industry. From the point of view of green and sustainable chemistry, design and development of Earth-abundant, less toxic, and more environmentally friendly catalysts are highly desirable. Herein, we report the convenient preparation of active cobalt catalysts and their application in hydrogenations of a wide range of terminal and internal carbon-carbon double bonds in water under mild conditions. Catalysts are prepared on multi-gram scale by pyrolysis of cobalt acetate and uracil, guanine, adenine or l-tryptophan. The most active material Co-Ura/C-600 showed good productivity in industrially relevant hydrogenation of diisobutene to isooctane and in natural oil hardening.
- Pews-Davtyan, Anahit,Scharnagl, Florian Korbinian,Hertrich, Maximilian Franz,Kreyenschulte, Carsten,Bartling, Stephan,Lund, Henrik,Jackstell, Ralf,Beller, Matthias
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supporting information
p. 5104 - 5112
(2019/09/30)
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- Highly Stable COF-Supported Co/Co(OH)2 Nanoparticles Heterogeneous Catalyst for Reduction of Nitrile/Nitro Compounds under Mild Conditions
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Ordered nanoporosity in covalent organic framework (COF) offers excellent opportunity for property development. Loading nanoparticles (nPs) onto them is one approach to introducing tailor-made properties into a COF. Here, a COF–Co/Co(OH)2 composite containing about 16 wt% of 2 nPs is prepared on a N-rich COF support that catalyzes the release of theoretical equivalence of H2 from readily available, safe, and cheap NaBH4. Furthermore, the released H2 is utilized for the hydrogenation of nitrile and nitro compounds to amines under ambient conditions in a facile one-pot reaction. The COF “by choice” is built from “methoxy” functionalized dialdehydes which is crucial in enabling the complete retention of the COF structure under the conditions of the catalysis, where the regular Schiff bonds would have hydrolyzed. The N-rich binding pockets in the COF ensure strong nP–COF interactions, which provides stability and enables catalyst recycling. Modeling studies reveal the crucial role played by the COF in exposing the active facets and thereby in controlling the activation of the reducing agent. Additionally, via density functional theory, we provide a rational explanation for how these COFs can stabilize nanoparticles which grow beyond the limiting pore size of the COF and yet result in a truly stable heterogeneous catalyst – a ubiquitous observation. The study underscores the versatility of COF as a heterogeneous support for developing cheap and highly active nonnoble metal catalysts.
- Mullangi, Dinesh,Chakraborty, Debanjan,Pradeep, Anu,Koshti, Vijay,Vinod, Chathakudath P.,Panja, Soumendranath,Nair, Sunil,Vaidhyanathan, Ramanathan
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- Application of Silicon-Initiated Water Splitting for the Reduction of Organic Substrates
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The use of water as a donor for hydrogen suitable for the reduction of several important classes of organic compounds is described. It is found that the reductive water splitting can be promoted by several metalloids among which silicon shows the best efficiency. The developed methodologies were applied for the reduction of nitro compounds, N-oxides, sulfoxides, alkenes, alkynes, hydrodehalogenation as well as for the gram-scale synthesis of several substrates of industrial importance.
- Gevorgyan, Ashot,Mkrtchyan, Satenik,Grigoryan, Tatevik,Iaroshenko, Viktor O.
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p. 375 - 382
(2018/06/04)
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- Benzhydrylamine: An effective aminating agent for the synthesis of primary amines
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Aldehydes, ketones, alkyl toluene-p-sulfonates and halides are converted into the corresponding primary amines with benzhydrylamine as a valuable ammonia synthon in moderate to excellent yields.
- Sun, Quan-Wei,Xing, Jun-De,Qin, Yu-Hong,Yin, Xu-Wen,Zhou, Yi
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p. 181 - 183
(2018/05/26)
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- O -Phthalaldehyde catalyzed hydrolysis of organophosphinic amides and other P(O)-NH containing compounds
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Over 50 years ago, Jencks and Gilchrist showed that formaldehyde catalyses the hydrolysis of phosphoramidate through electrophilic activation, induced by covalent attachment to its nitrogen atom. Given our interest in the use of aldehydes as catalysts, this work was revisited to identify a superior catalyst, o-phthalaldehyde, which facilitates hydrolyses of various organophosphorus compounds bearing P(O)-NH subunits under mild conditions. Interestingly, chemoselective hydrolysis of the P(O)-N bonds could be accomplished in the presence of P(O)-OR bonds.
- Li, Bin-Jie,Simard, Ryan D.,Beauchemin, André M.
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supporting information
p. 8667 - 8670
(2017/08/10)
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- Manganese-Catalyzed Direct Deoxygenation of Primary Alcohols
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Deoxygenation of alcohols is an important tool in the repertoire of defunctionalization methods in modern synthetic chemistry. We report the base-metal-catalyzed direct deoxygenation of benzylic and aliphatic primary alcohols via oxidative dehydrogenation/Wolff-Kishner reduction. The reaction is catalyzed by a well-defined PNP pincer complex of Earth-abundant manganese, evolving H2, N2, and water as the only byproducts.
- Bauer, Jonathan O.,Chakraborty, Subrata,Milstein, David
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p. 4462 - 4466
(2017/07/24)
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- Efficient Reduction of C–N Multiple Bonds Catalyzed by Magnetically Retrievable Magnetite Nanoparticles with Sodium Borohydride
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Abstract: A simple, rapid and efficient methodology has been developed for the reductive transformation of the compounds bearing C–N multiple bonds such as oximes and nitriles to the corresponding amines by sodium borohydride catalyzed by highly active solid Fe3O4 nanoparticles. The catalyst was easily recovered using external magnet and reused five times without losing its catalytic activity. Graphical Abstract: A simple, rapid, efficient and reusable heterogeneous catalytic system has been developed for the reductive transformation of oximes and nitriles into corresponding amines by sodium borohydride in presence of Fe3O4 nanoparticles.[Figure not available: see fulltext.]
- Kumari, Pratibha,Gautam, Renu,Yadav, Harshit,Kushwaha, Vikas,Mishra, Avinash,Gupta, Shilpi,Arora, Veena
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p. 2149 - 2156
(2016/10/18)
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- Integrated Heterogeneous Metal/Enzymatic Multiple Relay Catalysis for Eco-Friendly and Asymmetric Synthesis
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Organic synthesis is in general performed using stepwise transformations where isolation and purification of key intermediates is often required prior to further reactions. Herein we disclose the concept of integrated heterogeneous metal/enzymatic multiple relay catalysis for eco-friendly and asymmetric synthesis of valuable molecules (e.g., amines and amides) in one-pot using a combination of heterogeneous metal and enzyme catalysts. Here reagents, catalysts, and different conditions can be introduced throughout the one-pot procedure involving multistep catalytic tandem operations. Several novel cocatalytic relay sequences (reductive amination/amidation, aerobic oxidation/reductive amination/amidation, reductive amination/kinetic resolution and reductive amination/dynamic kinetic resolution) were developed. They were next applied to the direct synthesis of various biologically and optically active amines or amides in one-pot from simple aldehydes, ketones, or alcohols, respectively.
- Palo-Nieto, Carlos,Afewerki, Samson,Anderson, Mattias,Tai, Cheuk-Wai,Berglund, Per,Córdova, Armando
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p. 3932 - 3940
(2016/07/06)
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- SYNTHESIS OF AMIDES AND AMINES FROM ALDEHYDES OR KETONES BY HETEROGENEOUS METAL CATALYSIS
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This invention concerns the first mild and efficient synthesis of primary amines and amides from aldehydes or ketones using a heterogeneous metal catalystand amine donor. The initial heterogeneous metal- catalyzed reaction between the carbonyl and the amine donor components is followed up with the addition of a suitable acylating agent component in one-pot. Hence, the present invention provides a novel catalytic one-pot three-component synthesis of amides. Moreover, the integration of enzyme catalysis allows for eco-friendly one-pot co-catalytic synthesis ofamides from aldehyde and ketone substrates, respectively. The process can be applied to the co-catalytic one-pot three-component synthesis of capsaicin and its analogues from vanillin or vanillyl alcohol. It can also be applied for asymmetric synthesis. In the present invention, a novel co-catalytic reductive amination/dynamic kinetic resolution (dkr) relay sequence for the asymmetric synthesis of optically active amides from ketones is disclosed. Moreover, implementation of a catalytic reductive amination/kinetic resolution (kr) relay sequence produces the corresponding optically active amide product and optical active primary amine product with the opposite stereochemistry from the starting ketones.
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Page/Page column 17
(2016/07/05)
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- One-pot reductive amination of carbonyl compounds with ammonia via ‘hydrogen borrowing’ using hydrido- and bis-ammine P,O(Me)-ruthenacycles
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The novel cationic [RuH{PPh2(2-OMeC6H4)}2]BPh4and neutral trans-[Ru(NH3)2{PPh2(2-OC6H4)}2] complexes were isolated from phosphine substitution reactions with [RuH(1,5-cod)(NH2NMe2)3]BPh4and [RuCl(1,5-cod)(NH3)2(NH2NMe2)]BPh4respectively. Ligand induced bisdemethylation of the pendent ether moieties of the phosphines occurred to give rise to the bis-phosphanylphenoxy moieties. Both complexes catalyzed the one-pot reductive amination of carbonyl compounds where excellent selectivity of aryl aldehydes over aryl ketones as precursors to the alcoholic species existed. Through substrate screening and1H NMR studies, both steric and electronic effects of the substrates were found to influence the hydrogenation/amination mechanistic pathway, as well as direct the alcohol:amine selectivity.
- Malan, Frederick P.,Noh, Ji-Hyang,Naganagowda, Gadada,Singleton, Eric,Meijboom, Reinout
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p. 139 - 145
(2016/11/18)
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- Selective Cobalt-Catalyzed Reduction of Terminal Alkenes and Alkynes Using (EtO)2Si(Me)H as a Stoichiometric Reductant
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While attempting to effect Co-catalyzed hydrosilylation of β-vinyl trimethylsilyl enol ethers, we discovered that, depending on the silane, solvent, and the method of generation of the reduced cobalt catalyst, a highly efficient and selective reduction or hydrosilylation of an alkene can be achieved. This paper deals with this reduction reaction, which has not been reported before in spite of the huge research activity in this area. The reaction, which uses the air-stable [2,6-bis(aryliminoyl)pyridine)]CoCl2 activated by 2 equiv of NaEt3BH as the catalyst (0.001-0.05 equiv) and (EtO)2SiMeH as the hydrogen source, is best run at ambient temperature in toluene and is highly selective for the reduction of simple unsubstituted 1-alkenes and the terminal double bonds in 1,3- and 1,4-dienes, β-vinyl ketones, and silyloxy dienes. The reaction is tolerant of various functional groups such as bromide, alcohol, amine, carbonyl, di- or trisubstituted double bonds, and water. Highly selective reduction of a terminal alkyne to either an alkene or alkane can be accomplished by using stoichiometric amounts of the silane. Preliminary mechanistic studies indicate that the reaction is stoichiometric in the silane and both hydrogens in the product come from the silane.
- Raya, Balaram,Biswas, Souvagya,Rajanbabu
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p. 6318 - 6323
(2016/09/09)
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- Metal Nanoparticles Catalyzed Selective Carbon-Carbon Bond Activation in the Liquid Phase
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Understanding the C-C bond activation mechanism is essential for developing the selective production of hydrocarbons in the petroleum industry and for selective polymer decomposition. In this work, ring-opening reactions of cyclopropane derivatives under hydrogen catalyzed by metal nanoparticles (NPs) in the liquid phase were studied. 40-atom rhodium (Rh) NPs, encapsulated by dendrimer molecules and supported in mesoporous silica, catalyzed the ring opening of cyclopropylbenzene at room temperature under hydrogen in benzene, and the turnover frequency (TOF) was higher than other metals or the Rh homogeneous catalyst counterparts. Comparison of reactants with various substitution groups showed that electron donation on the three-membered ring boosted the TOF of ring opening. The linear products formed with 100% selectivity for ring opening of all reactants catalyzed by the Rh NP. Surface Rh(0) acted as the active site in the NP. The capping agent played an important role in the ring-opening reaction kinetics. Larger particle size tended to show higher TOF and smaller reaction activation energy for Rh NPs encapsulated in either dendrimer or poly(vinylpyrrolidone). The generation/size of dendrimer and surface group also affected the reaction rate and activation energy.
- Ye, Rong,Yuan, Bing,Zhao, Jie,Ralston, Walter T.,Wu, Chung-Yeh,Unel Barin, Ebru,Toste, F. Dean,Somorjai, Gabor A.
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p. 8533 - 8537
(2016/07/26)
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- Silica supported palladium phosphine as a robust and recyclable catalyst for semi-hydrogenation of alkynes using syngas
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This work reports a chemo-selective semi-hydrogenation of alkynes to alkenes using silica supported palladium phosphine catalyst with syngas (CO/H2). This developed methodology is an alternative to classical Lindlar catalyst for chemo-selective semi-hydrogenation of alkynes to alkenes. Various alkynes were smoothly convert to alkenes in 60-97% conversion with 85-98% selectivity. The prepared catalyst was well characterized by Field Emmission Gun Scanning Electron Microscopy (FEG-SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS), Inductively Coupled Plasma- Atomic Emmission Spectroscopy (ICP-AES) analysis techniques. In addition, catalyst was effectively recycled up to four consecutive run without significant loss in its catalytic activity and selectivity.
- Jagtap, Samadhan A.,Sasaki, Takehiko,Bhanage, Bhalchandra M.
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- Cross-Linked "poisonous" Polymer: Thermochemically Stable Catalyst Support for Tuning Chemoselectivity
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Designed catalyst poisons can be deliberately added in various reactions for tuning chemoselectivity. In general, the poisons are "transient" selectivity modifiers that are readily leached out during reactions and thus should be continuously fed to maintain the selectivity. In this work, we supported Pd catalysts on a thermochemically stable cross-linked polymer containing diphenyl sulfide linkages, which can simultaneously act as a catalyst support and a "permanent" selectivity modifier. The entire surfaces of the Pd clusters were ligated (or poisoned) by sulfide groups of the polymer support. The sulfide groups capping the Pd surface behaved like a "molecular gate" that enabled exceptionally discriminative adsorption of alkynes over alkenes. H2/D2 isotope exchange revealed that the capped Pd surface alone is inactive for H2 (or D2) dissociation, but in the presence of coflowing acetylene (alkyne), it becomes active for H2 dissociation as well as acetylene hydrogenation. The results indicated that acetylene adsorbs on the Pd surface and enables cooperative adsorption of H2. In contrast, ethylene (alkene) did not facilitate H2-D2 exchange, and hydrogenation of ethylene was not observed. The results indicated that alkynes can induce decapping of the sulfide groups from the Pd surface, while alkenes with weaker adsorption strength cannot. The discriminative adsorption of alkynes over alkenes led to highly chemoselective hydrogenation of various alkynes to alkenes with minimal overhydrogenation and the conversion of side functional groups. The catalytic functions can be retained over a long reaction period due to the high thermochemical stability of the polymer.
- Yun, Seongho,Lee, Songhyun,Yook, Sunwoo,Patel, Hasmukh A.,Yavuz, Cafer T.,Choi, Minkee
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p. 2435 - 2442
(2016/04/26)
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- Characterization of a novel amine transaminase from Halomonas elongata
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Chiral amines are indispensable building blocks in the production of biologically active compounds. They are fundamental for the pharmaceutical industry, both as active molecules themselves and as chiral auxiliaries in asymmetric synthesis; however, the available synthetic strategies often present disadvantages. ω-Transaminases (ω-TAs) appear as an attractive alternative by driving the stereoselective amination of prochiral ketones. HEWT is a novel amine transaminase from the moderate halophilic bacterium, Halomonas elongata DSM 2581, which is highly (S)-selective, being able to fully convert (S)-1-phenylethylamine to acetophenone and showing no activity with the corresponding (R)-1-phenylethylamine. HEWT has a broad substrate scope, active with a range of amino donors and acceptors, and naturally accepts isopropylamine (IPA) as amino donor in asymmetric synthesis providing a 41% conversion of pyruvate in 24 h at 37°C starting with 1:1 molar ratio between the reagents. HEWT also accepts ortho-xylylenediamine as amino donor in for amine synthesis, in particular, with benzaldehyde yielding high conversions between 90 and 95%. The enzyme is also tolerant to the presence of cosolvents up to 20% making it a promising candidate for industrial applications.
- Cerioli, Lorenzo,Planchestainer, Matteo,Cassidy, Jennifer,Tessaro, Davide,Paradisi, Francesca
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p. 141 - 150
(2015/09/01)
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- Method for manufacturing ammonia-N
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PROBLEM TO BE SOLVED: To provide a method for producing an N-alkyl hydroxylamine, which produces a pure N-alkyl hydroxylamine in a high yield under a mild condition by a simple method, does not require a strict time management and is advantageous for industrial-scale production. SOLUTION: The method for producing an N-alkyl hydroxylamine includes bringing an N-alkyl nitro compound into contact with a hydrogen source in the presence of a solid catalyst supporting palladium on silica and in the absence of a significant quantity of a fourth reaction component. The method for producing an N-alkyl hydroxylamine includes bringing (A) an N-alkyl nitro compound into contact only with (B) a hydrogen source and (C) a solid catalyst supporting palladium on silica, or bringing (A) an N-alkyl nitro compound into contact only with (B) a hydrogen source, (C) a solid catalyst supporting palladium on silica and (D) a solvent that does not deactivate catalytic activity and has a pKa of ≥12. COPYRIGHT: (C)2012,JPOandINPIT
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Paragraph 0075; 0095
(2018/12/01)
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- Lamellar Ni/Al-SBA-15 fibers: Preparation, characterization, and applications as highly efficient catalysts for amine and imine syntheses
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A novel Ni/Al-SBA-15 fiber catalyst with a lamellar structure was prepared by the urea precipitation method and successfully utilized in the environmental-friendly reduction of nitro functionality. The applications of the catalyst in highly efficient one-pot amine and imine syntheses were developed; the physicochemical properties of the samples were evaluated with ICP-OES, N2 adsorption, XRD, HRTEM, and EDX. This new catalyst highlights potent catalytic activities and a simple recycling process as an important environmentally-friendly feature.
- Ren, Ren,Ma, Jiantai
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p. 74802 - 74810
(2015/09/21)
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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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- Unique Chemoselective Hydrogenation using a Palladium Catalyst Immobilized on Ceramic
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A heterogeneous palladium catalyst supported on a ceramic (5 % Pd/ceramic) was developed. The catalyst exhibited a specific chemoselectivity for hydrogenation that has never been achieved by other palladium-catalyzed methods. Either aliphatic or aromatic N-Cbz groups could be deprotected to the corresponding free-amines, while the hydrogenolysis of benzyl esters and ethers did not proceed. Furthermore, aryl chlorides and epoxides were tolerant under the Pd/ceramic-catalyzed hydrogenation conditions. 5 % Pd/ceramic could be reused without any loss of catalyst activity, as no palladium leaching was detected in the reaction media.
- Monguchi, Yasunari,Marumoto, Takahisa,Ichikawa, Tomohiro,Miyake, Yutaka,Nagae, Yoshiyuki,Yoshida, Michiyuki,Oumi, Yasunori,Sawama, Yoshinari,Sajiki, Hironao
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p. 2155 - 2160
(2015/11/24)
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- Tandem dehydrogenation of ammonia borane and hydrogenation of nitro/nitrile compounds catalyzed by graphene-supported NiPd alloy nanoparticles
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We report a facile synthesis of monodisperse NiPd alloy nanoparticles (NPs) and their assembly on graphene (G) to catalyze the tandem dehydrogenation of ammonia borane (AB) and hydrogenation of R-NO2 and/or R-CN to R-NH2 in aqueous methanol solutions at room temperature. The 3.4 nm NiPd alloy NPs were prepared by coreduction of nickel(II) acetate and palladium(II) acetlyacetonate by borane-tert-butylamine in oleylamine and deposition on G via a solution phase self-assembly process. G-NiPd showed composition-dependent catalysis on the tandem reaction with G-Ni 30Pd70 being the most active. A variety of R-NO 2 and/or R-CN derivatives were reduced selectively into R-NH 2 via G-Ni30Pd70 catalyzed tandem reaction in 5-30 min reaction time with the conversion yields reaching up to 100%. Our study demonstrates a new approach to G-NiPd-catalyzed dehydrogenation of AB and hydrogenation of R-NO2 and R-CN. The G-NiPd NP catalyst is efficient and reusable, and the reaction can be performed in an environment-friendly process with short reaction times and high yields.
- Goeksu, Haydar,Ho, Sally Fae,Metin, Oender,Korkmaz, Katip,Mendoza Garcia, Adriana,Gueltekin, Mehmet Serdar,Sun, Shouheng
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p. 1777 - 1782
(2014/06/24)
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- Ruthenium/imidazolylphosphine catalysis: Hydrogenation of aliphatic and aromatic nitriles to form amines
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A convenient and efficient catalyst system for the hydrogenation of aliphatic nitriles towards the corresponding primary amines in high to excellent yields is presented. In addition, aromatic nitriles are reduced smoothly, too. The use of low catalyst loadings and molecular hydrogen make this protocol an attractive methodology. It's not complicated: A general and easy homogeneous catalyst system based on [Ru(cod)(methylallyl)2] and a cyclohexyl-substituted imidazolylphosphine ligand for selective hydrogenation of aliphatic nitriles is presented. In addition, by using an isopropyl-substituted imidazolylphosphine ligand, selected aromatic nitriles were reduced with excellent yields towards the primary amine. Furthermore, two new crystal structures give an insight of possible pre-catalysts.
- Werkmeister, Svenja,Junge, Kathrin,Wendt, Bianca,Spannenberg, Anke,Jiao, Haijun,Bornschein, Christoph,Beller, Matthias
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supporting information
p. 4227 - 4231
(2014/05/06)
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- Polymethylhydrosiloxane derived palladium nanoparticles for chemo- and regioselective hydrogenation of aliphatic and aromatic nitro compounds in water
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Chemo- and regioselective hydrogenation of a wide range of aliphatic, unsaturated, aromatic and heteroaromatic nitro compounds into their corresponding amines has been achieved with highly efficient polysiloxane-stabilised "Pd" nanoparticles on NAP-magnesium oxide supports using an environmentally friendly hydrogenating agent, polymethylhydrosiloxane [PMHS] in water. Highly stable and active Pd nanoparticles were prepared by the reduction of NAP-Mg-PdCl4 with PMHS, which serves as a reducing agent as well as a capping agent. The well-dispersed palladium nanoparticles on NAP-MgO catalysts also exhibit excellent regioselectivity in the hydrogenation of dinitrobenzenes to the corresponding nitroanilines. The catalyst has high durability against sintering during the hydrogenation reaction and can be reused with no loss in its activity. This journal is the Partner Organisations 2014.
- Damodara, Dandu,Arundhathi, Racha,Ramesh Babu, T. Venkata,Legan, Margaret K.,Kumpaty, Hephzibah J.,Likhar, Pravin R.
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p. 22567 - 22574
(2014/06/23)
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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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- RUTHENIUM-BASED COMPLEX CATALYSTS
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The present invention provides novel Ruthenium-based transition metal complex catalysts comprising specific ligands, their preparation and their use in hydrogenation processes. Such complex catalysts are inexpensive, thermally robust, and olefin selective.
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Page/Page column 54; 64
(2013/03/26)
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- Hydroxylamine as an oxygen nucleophile: Substitution of sulfonamide by a hydroxyl group in benzothiazole-2-sulfonamides
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Benzothiazole-2-sulfonamides react with an excess of hydroxylamine in aqueous solutions to form 2-hydroxybenzothiazole, sulfur dioxide, and the corresponding amine. Mechanistic studies that employ a combination of structure-reactivity relationships, oxygen labeling experiments, and (in)direct detection of intermediates and products reveal that the reaction proceeds via oxygen attack, and that oxygen incorporated in the 2-hydroxybenzothiazole product derives from hydroxylamine. The reaction, which is performed under mild conditions, can be used as a deprotection method for cleavage of benzothiazole-2-sulfonyl-protected amino acids.
- Kamps, Jos J. A. G.,Belle, Roman,Mecinovi?, Jasmin
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p. 1103 - 1108
(2013/03/28)
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- Catalytic hydrogenation of amides to amines under mild conditions
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Under (not so much) pressure: A general method for the hydrogenation of tertiary and secondary amides to amines with excellent selectivity using a bimetallic Pd-Re catalyst has been developed. The reaction proceeds under low pressure and comparatively low temperature. This method provides organic chemists with a simple and reliable tool for the synthesis of amines. Copyright
- Stein, Mario,Breit, Bernhard
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supporting information
p. 2231 - 2234
(2013/03/28)
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- Enhanced reduction of C-N multiple bonds using sodium borohydride and an amorphous nickel catalyst
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Amorphous nickel powder (Ni0) was utilised as a catalyst under mild, aqueous, basic conditions for enhancing the sodium borohydride-mediated reduction of C-N multiple bonds such as oximes, imines, hydrazones and nitriles to produce the corresponding amines in good to excellent yields.
- Liu, Shouxin,Yang, Yihua,Zhen, Xiaoli,Li, Junzhang,He, Huimin,Feng, Juan,Whiting, Andrew
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experimental part
p. 663 - 670
(2012/01/15)
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- Hydrogen transfer reduction of nitriles in DBU based ionic liquids
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Raney nickel catalyzed transfer hydrogenation of nitrile was proposed, with formats as hydrogen donor. Three ionic liquids, including [DBUH +][C2H5COO-], [DBUH +][C3H7COO-], and [DBUH +][C4H9COO-], were prepared as reaction medium, and [DBUH+][C4H9COO -] showed the best performance. Various nitriles were reduced with potassium formate as hydrogen donor, and considerable to excellent yields of amines were given. The ionic liquid can be used for 6 times at least, and the reaction process is clean. ARKAT-USA, Inc.
- Chen, Xinzhi,Zhou, Shaodong,Qian, Chao
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experimental part
p. 128 - 136
(2012/09/11)
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- Application of alkoxide in catalytic transfer hydrogenation of unsaturated nitrogen compounds
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Alcoholate was utilized in catalytic transfer hydrogenation of unsaturated nitrogen compounds. In the reduction of nitro compounds, oximes and imines, alkoxide was used as the promoter, with alcohol as the hydrogen source, while in the reduction of nitriles, alkoxide was used as the hydrogen source. Springer Science+Business Media B.V. 2012.
- Chen, Xinzhi,Zhou, Shaodong,Chen, Yuehan,Dong, Zehan,Gao, Yeyu,Qian, Chao,He, Chaohong
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p. 2255 - 2269
(2013/02/23)
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- ω-Transaminase-catalyzed kinetic resolution of chiral amines using l-threonine as an amino acceptor precursor
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Kinetic resolution of chiral amines using l-threonine as a cosubstrate was demonstrated by a biocatalytic strategy in which (S)-selective ω-transaminase (ω-TA) was coupled with threonine deaminase (TD), eliminating the need to use an expensive keto acid as an amino acceptor. The coupled enzyme reaction enabled simultaneous production of enantiopure (R)-amine and l-homoalanine which are pharmaceutically important building blocks. To extend the versatility of this strategy to production of both enantiomers of chiral amines, (R)-selective ω-TA coupled with TD was employed to produce (S)-amine.
- Malik, M. Shaheer,Park, Eul-Soo,Shin, Jong-Shik
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body text
p. 2137 - 2140
(2012/09/25)
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- PROCESS FOR PREPARING TRI-N-PROPYLAMINE (TPA)
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Process for preparing tri-n-propylamine (TPA), wherein di-n-propylamine (DPA) is reacted in the presence of hydrogen and a copper-comprising heterogeneous catalyst. An integrated process for preparing TPA, which comprises the following operations: I) reaction of n-propanol with ammonia in a reactor in the presence of an amination catalyst and optionally hydrogen to form a mixture of mono-n-propylamine, DPA and TPA,II) separation of unreacted ammonia, unreacted n-propanol and possibly hydrogen from the reaction product mixture and recirculation of at least the ammonia and propanol to the reactor in I) and also separation of the n-propylamine mixture by distillation and isolation of the TPA,III) reaction of the DPA obtained in the separation by distillation in II) in a reactor in the presence of hydrogen and a copper-comprising heterogeneous catalyst to form TPA andIV) feeding of the reactor output from III) to operation II).
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Page/Page column 5
(2012/01/14)
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- A cis-bis-mixed-carbene ruthenium hydride complex: An olefin-selective hydrogenation catalyst
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The N-heterocyclic carbene C3H2N2(CH 2CH2OMe)2 (1; IOMe) reacts with RuHCl(PPh 3)3 to give RuClH(IOMe)(PPh3)2 (2), which reacts further with SIMes to give the cis-bis-mixed-carbene complex RuClH(IOMe)(SIMes)(PPh3) (3). This species has been shown to be a highly effective hydrogenation catalyst that tolerates the presence of a wide range of functional and donor groups.
- Lund, Clinton L.,Sgro, Michael J.,Cariou, Renan,Stephan, Douglas W.
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scheme or table
p. 802 - 805
(2012/04/17)
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- ANTIPROLIFERATIVE COMPOUNDS, CONJUGATES THEREOF, METHODS THEREFOR, AND USES THEREOF
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Antiproliferative compounds having a structure represented by formula (II), where n, R1, R2, R3, R4, and R5 are as defined herein, can be used to treat tumors, optionally when conjugated to a ligand such as an antibody.
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- Unprecedented catalytic hydrogenation of urea derivatives to amines and methanol
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Indirect CO2 hydrogenation: Hydrogenation of urea derivatives to the corresponding amines and methanol is reported (see picture). The reaction is catalyzed by a bipyridine-based tridentate PNN Ru(II) pincer complex and proceeds under mild, neutral conditions using 13.6 atm of H2. A mild approach is offered for the indirect hydrogenation of CO2 to methanol as urea derivatives are available from CO2. Copyright
- Balaraman, Ekambaram,Ben-David, Yehoshoa,Milstein, David
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supporting information; experimental part
p. 11702 - 11705
(2012/01/05)
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