- Bimetallic Ru/Ni supported catalysts for the gas phase hydrogenation of acetonitrile
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A family of bimetallic Ni-Ru catalysts supported on a mesoporous SBA-15 silica was prepared by conventional impregnation method, with constant metal molar loadings, but varying Ni/(Ni + Ru) atomic ratios. The corresponding Ni and Ru monometallic catalysts were also prepared for comparison. These catalysts were characterized by XRD, N2 adsorption-desorption at -196 °C, TEM, XPS, H2-TPR, chemisorption of H2 at r.t., H2-TPD and NH3-TPD techniques. Finally, they were also tested in the hydrogenation of acetonitrile reaction, in the gas phase and at atmospheric pressure. Acetonitrile conversion values depended on the Ni/(Ni + Ru) composition of the bimetallic catalysts. Ru-rich bimetallic catalysts exhibited acetonitrile conversion values higher than that of pure Ni one; thus, although selectivity patterns remained almost unchanged, primary amine yields were increased. These higher conversion values resulted as a consequence of enhanced specific activity of Ni0 atoms, attributable to a strong interaction between both metals, Ni and Ru, likely because NiRu alloy nanoparticles were formed.
- Braos-García,García-Sancho,Infantes-Molina,Rodríguez-Castellón,Jiménez-López
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- Electron spin resonance of spin-trapped radicals of amines and polyamines. Hydroxyl radical reactions in aqueous solutions and γ-radiolysis in the solid state
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The reactions of hydroxyl radicals with methylamine, dimethylamine, trimethylamine, diethylamine, sec-butylamine, ethylenediamine, 1,3-diaminopropane, putrescine, cadaverine, 1,7-diaminoheptane, ornithine, spermidine, spermine, agmatine, and arcaine in aqueous solutions have been investigated by spin-trapping and esr.Hydroxyl radicals were generated by the uv photolysis of H2O2 and 2-methyl-2-nitrosopropane (MNP) was used as the spin-trap.The effects of ionizing radiation on the same polyamines in the polycrystalline state were also investigated.The free radicals produced by γ-radiolysis of these solids at room temperature in the absence of air were identified by dissolution in aqueous solutions of MNP.The predominant reaction of .OH with amines and polyamines below pH 7 was the abstraction of hydrogen atoms from the carbon that is not adjacent to the protonated amino group.For agmatine and arcaine which contain guanidinium groups abstraction occured from from the α-CH.Dimethylamine was oxidized to the dimethylnitroxyl radical by H2O2 in the dark. γ-Radiolysis of polyamines in the polycrystalline state generated radicals due to H-abstraction from either the α-CH or from a carbon atom in the middle of the alkyl chain.The deamination radical was obtained from ornithine.
- Mossoba, Magdi M.,Rosenthal, Ionel,Riesz, Peter
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- Transformations of dialkyl(4-hydroxy-2-butynyl)-(3-phenylallyl)ammonium bromides in an KOH aqueous solution or in the presence of powdered KOH
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Under the action of a twofold excess of KOH and heating in aqueous solution, and also under the conditions of the Stevens rearrangement (with KOH powder and a small amount of methanol) dialkyl-(4-hydroxy-2-butynyl)(3- phenylallyl)ammonium bromides form dialkyl[4-(1-phenylallyl)-2,5-dihydro-2- furyl]amines. Rearrangement-cleavage reaction also occurs under the same conditions.
- Chukhadjian,Gabrielyan,Chukhadjian,Shahkhatuni,Panosyan
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- Photooxidation pathway of sulforhodamine-B. Dependence on the adsorption mode on TiO2 exposed to visible light radiation
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The temporal course of the photooxidation of sulforhodamine-B (SRB) in aqueous media illuminated by visible wavelengths in the presence of TiO2 has been examined to determine the nature of the intermediate species produced and to explore the operative reaction pathway(s). Two pathways are described to account for the differences in the final photooxidation products whose nature depends on the different modes of adsorption of the dye on the metal-oxide mediator. In the SRB/TiO2 system, when SRB is adsorbed on the positively charged TiO2 particle surface through a sulfonate group cleavage of the SRB chromophore structure predominates and N-de-ethylation occurs only to a slight extent with the major photooxidation products being diethylamine and carbon dioxide. In the presence of the anionic dodecylbenzenesulfonate surfactant DBS, when SRB is near the negatively charged DBS/TiO2 interface through the positive diethylamine group N-de-ethylation occurs preferentially before destruction of the structure with the major products being acetaldehyde and carbon dioxide. The temporal course of the photooxidation of sulforhodamine-B (SRB) in aqueous media illuminated by visible wavelengths in the presence of TiO2 has been examined to determine the nature of the intermediate species produced and to explore the operative reaction pathway(s). Two pathways are described to account for the differences in the final photooxidation products whose nature depends on the different modes of adsorption of the dye on the metaloxide mediator. In the SRB/TiO2 system, when SRB is adsorbed on the positively charged TiO2 particle surface through a sulfonate group cleavage of the SRB chromophore structure predominates and N-de-ethylation occurs only to a slight extent with the major photooxidation products being diethylamine and carbon dioxide. In the presence of the anionic dodecylbenzenesulfonate surfactant DBS, when SRB is near the negatively charged DBS/TiO2 interface through the positive diethylamine group N-de-ethylation occurs preferentially before destruction of the structure with the major products being acetaldehyde and carbon dioxide.
- Liu,Li,Zhao,Hidaka,Serpone
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- Zeolite catalysts for the selective synthesis of mono- and diethylamines
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The kinetics and mechanism of ethylamine synthesis from ammonia and ethanol over several large pore acid catalysts are described. Mordenite produced higher monoethylamine yields than the zeolites beta, Y, mazzite, and amorphous silica-alumina. The reaction proceeds via the initial formation of ethylammonium ions, and alkylamines desorb with the assistance of ammonia and equilibrate with other ethylammonium ions before leaving the catalyst pores. The high yields of ethylamines with mordenite are related to the high acid strength of the catalyst stabilizing (alkyl)ammonium ions and so blocking the dehydration of ethanol. By choosing high ammonia partial pressures, reaction temperatures below 573 K (minimizing ethene elimination from ethylammonium ions), and subtle modifications of the parent mordenite material (EDTA leaching, silylation of the external surface) ethene selectivity was further decreased. These measures allowed us to prepare a catalyst on the basis of mordenite with a Si/Al ratio of 5 that showed 99% selectivity to ethyl amines at 60% conversion and that was stable for long times on stream.
- Veefkind, Victor A.,Lercher, Johannes A.
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- New composite catalysts for the synthesis of acetonitrile from ethanol and ammonia, prepared using calcium aluminates (Talyum)
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Experiments on direct synthesis of acetonitrile from ethanol, ammonia, and hydrogen at 513–573 K in the presence of new Cu-, Cu–Zn–(Zr)-, and Cu–Mg-containing composite catalysts prepared using calcium aluminates (Talyum, technical-grade calcium aluminate) were performed The following results were reached: ethanol conversion 96.0–99.0%, selectivity with respect to acetonitrile 99.0%, and acetonitrile output exceeding the reported level by a factor of 1.2–1.4. The new technology can be implemented in industry.
- Belov,Markov,Sova,Golosman,Nechugovskii
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- A cluster growth route to quantum-confined CdS nanowires
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Quantum-confined CdS nanowires with diameters around 4 nm and lengths ranging from 150 to 250 nm were grown for the first time from cadmium bis(diethyldithiocarbamate) [Cd(DDTC)2]2 by removal of the four thione groups with ethylenediamine (en) at 117°C for 2 min.
- Yan, Ping,Xie, Yi,Qian, Yitai,Liu, Xianming
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- Reactions of group 4 amide guanidinates with dioxygen or water. Studies of the formation of oxo products
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Reactions of the zirconium amide guanidinates (R2N) 2M[iPrNC(NR2)NiPr]2 (R = Me, M = Zr, 1; M = Hf, 2; R = Et, M = Zr, 3) with O2 or H 2O give products that are consistent with the oxo dimers {M(μ-O)[iPrNC(NR2)NiPr]2} 2 (R = Me, M = Zr, 4; M = Hf, 5; R = Et, M = Zr, 6) and polymers {M(μ-O)[iPrNC(NR2)NiPr]2} n (R = Me, M = Zr, 7; M = Hf, 8; R = Et, M = Zr, 9). Mass spectrometric (MS) analyses of the reactions of water in air with 1 and 2 show formation of the Zr monomer Zr(=O)[iPrNC(NMe2)N iPr]2 (10), oxo dimers 4 and 5, and dihydroxyl complexes M(OH)2[iPrNC(NMe2)NiPr]2 (M = Zr, 11; Hf, 12). Similar MS analyses of the reaction of diethylamide guanidinate 3 with water in air show the formation of Zr(=O)[ iPrNC(NEt2)NiPr]2 (13), Zr(OH) 2[iPrNC(NEt2)NiPr]2 (14), 6, and {(Et2N)Zr[iPrNC(NEt2)N iPr]2}+ (15). Kinetic studies of the reaction between 1 and a continuous flow of 1.0 atm of O2 at 80-105 C indicate that it follows pseudo-first-order kinetics with ΔH? = 8.7(1.1) kcal/mol, ΔS? = -54(3) eu, ΔG ?358 K = 28(2) kcal/mol, and a half-life of 213(1) min at 85 C.
- Sharma, Bhavna,Callaway, Tabitha M.,Lamb, Adam C.,Steren, Carlos A.,Chen, Shu-Jian,Xue, Zi-Ling
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- Microcalorimetric adsorption and infrared spectroscopic studies of KNi/MgAlO catalysts for the hydrogenation of acetonitrile
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Ni/MgAlO and K2CO3Ni/MgAlO catalysts for the hydrogenation of acetonitrile to primary amine were studied. Microcalorimetric measurements and infrared spectroscopy were used to study the adsorption of CO, H2, acetonitrile,
- Zhao, Jie,Chen, Hui,Tian, Xiaocong,Zang, Han,Fu, Yuchuan,Shen, Jianyi
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- Photocatalytic degradation of dye sulforhodamine B: A comparative study of photocatalysis with photosensitization
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The direct photocatalytic degradation of dye pollutant sulforhodamine B (SRB) in aqueous TiO2 dispersions has been examined and compared to the photosensitization process. The mineralization extent of SRB degradation, the formation of intermediates and final products were monitored to assess the degradation pathways caused by direct photocatalysis. In the initial stage of the direct photocatalysis, SRB is mainly oxidized by a positive hole upon band-gap excitation of TiO2 by UV light (330 nm 420 nm). Diethylamine, N,N-diethylacetamide, N-ethylformamide, N,N-diethylformamide, formic acid and acetic acid were identified as intermediate species; SO42-, NH4+, CO2 and H2O are final mineralized products produced in the direct photocatalytic process.
- Liu, Guangming,Zhao, Jincai
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- Effect of surface composition on the catalytic performance of molybdenum phosphide catalysts in the hydrogenation of acetonitrile
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A series of molybdenum phosphide catalysts with initial Mo/P ratios varying in a narrow range of 0.90-1.10 was prepared by temperature-programmed reaction; characterized by X-ray diffraction, BET, elemental analysis, X-ray photoelectron spectroscopy, and CO chemisorption measurements; and tested for the hydrogenation of acetonitrile at different pressures (0.1-1.0 MPa) and temperatures (473-513 K). The catalysts exhibited attractive catalytic activity, especially at a H2 pressure above 0.2 MPa. The surface composition of the MoP catalysts could be fine-tuned by the initial Mo/P ratio, which consequently led to different surface properties (e.g., CO uptakes) and catalytic behaviors. Catalysts with high initial Mo amount gave high selectivity to the primary amine, ethylamine, whereas those with high initial P amount created more condensed amines, diethylamine and triethylamine.
- Yang, Pengfei,Jiang, Zongxuan,Ying, Pinliang,Li, Can
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- Electrochemical detection of nitric oxide and peroxynitrite anion in microchannels at highly sensitive platinum-black coated electrodes. application to ROS and RNS mixtures prior to biological investigations
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The electrochemical detection of nitric oxide (NO) and peroxynitrite anion (ONOO-) was investigated at Pt-black electrodes in microchannels. Owing to the high reactivity of these species under conditions close to physiological media, kinetic parameters were determined before evaluating the detection performances from synthetic solutions. Highly sensitive and stable Pt-black electrodes allowed detection limits down to 30 nM (NO) and 40 nM (ONOO-) to be reached with very high sensitivities. As NO and ONOO-are two relevant biological molecules involved in oxidative stress their simultaneous detections with other major molecules like hydrogen peroxide and nitrite were also performed and validated experimentally at pH 8.4. These results demonstrated that relative ROS/RNS contents in synthetic mixtures can be easily assessed at selected detection potentials. Beyond the interest of using small volumes in microfluidic channels, optimization of detection requires precise conditions easy to implement. These were delineated to lead in microdevices to high-performances detection of oxidative stress metabolites either from analytes or from the production of a few living cells like macrophages.
- Li, Yun,Sella, Catherine,Lema?tre, Frédéric,Guille-Collignon, Manon,Thouin, Laurent,Amatore, Christian
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- Palladium-catalyzed azathiolation of carbon monoxide
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A novel palladium-catalyzed azathiolation of carbon monoxide using sulfenamide (RSNR'2) (1) is described to provide thiocarbamate 2 in good yields. The mechanistic proposal includes the following: (1) insertion of CO into Pd-S bond of Pd(SR)2(PPh3)(n) 4 to provide Pd[C(O)SR](SR)(PPh3)(n) 5 and (2) σ-bond metathesis between S-N and Pd-C(O) bonds to afford 2 with the regeneration of 4.
- Kuniyasu, Hitoshi,Hiraike, Hiroshi,Morita, Masaki,Tanaka, Aoi,Sugoh, Kunihiko,Kurosawa, Hideo
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- Ditiocarb: Decomposition in aqueous solution and effect of the volatile product on its pharmacological use
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The kinetic profile for the decomposition of ditiocarb sodium salt in aqueous solution was achieved with UV-visible absorption spectrometry. The kinetic profile indicates that the decomposition reaction is hydrogen ion- catalyzed over the entire 4-10 pH range and enables the determination of the value of the acid-base equilibrium constant (K(a) = 4.0 · 10-4 at 5 °C). Decomposition of ditiocarb produces volatile carbon disulfide, exclusive of hydrogen sulfide, as shown with electrochemical methods. This feature is of interest from a toxicological point of view.
- Martens,Langevin-Bermond,Fleury
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- Efficient degradation of organic pollutants by using dioxygen activated by resin-exchanged iron(II) bipyridine under visible irradiation
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Excellent response to visible light is shown by the [FeII(bpy)3]-amberlite photocatalyst, which can effectively activate molecular oxygen in such a way as to put us one giant step nearer to our goal - the development of the ultimate green technology for decontamination [Eq. (1)].
- Ma, Wanhong,Li, Jing,Tao, Xia,He, Ju,Xu, Yiming,Yu, Jimmy C.,Zhao, Jincai
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- Mechanistic studies on the reaction between R2N-NONOates and aquacobalamin: evidence for direct transfer of a nitroxyl group from R 2N-NONOates to cobalt(III) centers
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Tales of the unexpected: Transfer of a nitroxyl group from R2N-NONOates to aquacobalamin to form nitroxylcobaiamin does not proceed via H+-catalyzed R2NNONOate decomposition, but instead occurs via a probable NONOate-cobalamin intermediate (see scheme; r.
- Hassanin, Hanaa A.,Hannibal, Luciana,Jacobsen, Donald W.,El-Shahat, Mohamed F.,Hamza, Mohamed S. A.,Brasch, Nicola E.
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- Reactions of zirconium amide amidinates with dioxygen. Observation of an unusual peroxo intermediate in the formation of oxo compounds
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Reaction of d0 Zr(NMe2)2[MeC(N iPr)2]2 (1) with O2 at -30°C gives three Zr containing products: a peroxo trimer {(μ-η2: η2-O2)Zr[MeC(NiPr)2] 2}3 (2), an oxo dimer {(μ-O)Zr[MeC(N iPr)2]2}2 (3), and an oxo polymer {(μ-O)Zr[MeC(NiPr)2]2}n (4). 2 is a rarely observed peroxo complex from the reaction of a d0 complex with O2. This journal is the Partner Organisations 2014.
- Lamb, Adam C.,Lu, Zheng,Xue, Zi-Ling
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- Direct Amination of Ethylene by Zeolite Catalysis
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Formation of ethylamine by addition of ammonia to ethylene is catalysed by acidic zeolites such as H-Y, H-mordenite, and H-erionite.
- Deeba, Michel,Ford, Michael E.,Johnson, Thomas A.
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- Reduction of (chloro)-μ-nitrido-bis[(tetra-tert-butyl-phthalocyaninato)iron(IV)] with organic N-bases
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The interaction of (chloro)-μ-nitrido-bis[(tetra-Tert-butyl-phthalocyaninato)iron(IV)] Cl(FePc)2N with organic N-bases L as electron-donors (L diethylamine, imidazole, 1-methylimidazole, 2-methylimidazole) with the formation of one-electron reduced species (L)PcFeIII-N?FeIVPc(L) was investigated in benzene at 298 K by UV-visible spectroscopy. The reaction was established to be stepwise process including fast reversible axial binding of two substrate molecules onto iron cations followed by slow one-electron metal-centered reduction. The results of IR, ESI-MS and EPR study support the formation of final product with Fe?3-N?Fe?4 unit and two substrate molecules in the first coordination sphere. The reaction kinetics was studied, the pre-equilibrium constants Keq and rate constants κ were obtained. The Keq and κ values were found to be linearly correlated with basicity of substrates pκa. The possibility of the transition Fe4?→Fe3??is promoted by electron-donor properties of substrate combined with the presence of both electron-rich macrocycle and φ-backdonation Fe →NPc.
- Zaitseva, Svetlana V.,Zdanovich, Sergei A.,Tyulyaeva, Elena Y.,Grishina, Ekaterina S.,Koifman, Oskar I.
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- Selective hydrogenation of acetonitrile to ethylamine using palladium-based alloy catalysts
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The gas phase hydrogenation of acetonitrile was studied with various Pd-based catalysts using several supports, i.e., ZrO2, CeO2, MgO, SiO2, Al2O3, ZnO, Ga2O3, and In2O3. Pd/ZnO and Pd/Ga2O3 catalysts showed smaller conversions, but selective to the formation of MEA and DEA. For all the catalysts studied, MEA selectivity at 170°C was higher than that at 120°C. In the case of Pd/ZrO2, the total conversion at 120°C was slightly higher than that at 170°C. For the simple supported Pd catalysts after hydrogenation reactions, only metallic Pd could be observed with the catalysts except for the three samples, i.e., Pd/ZnO, Pd/Ga2O3, and Pd/In2O3. For the Pd/ZnO catalyst that is most selective to the formation of MEA, the total conversion and the selectivity of DEA and triethylamine decreased while the selectivity of MEA increased with increasing reduction temperature. The modified Pd catalysts showed larger total activities compared with the corresponding simple supported Pd catalysts reduced at 500°C. Zn addition on the total conversion and product selectivity showed that the conversion was significantly decreased when the quantity of Zn added was Zn/Pd ≥ 0.3:1 The higher selectively to MEA formation was achieved at Zn/Pd > 1. thus, the formation of such a Pd alloy was responsible for the enhancement of the MEA selectivity and the decrease of the total activity.
- Arai,Iwasa,Yoshikawa
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- A reaction of tin tetra(N,N-diethylcarbamate) with phenylacetylene as a new route to tetra(phenylethynyl)tin
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A reaction of tin tetra(N,N-diethylcarbamate) with phenylacetylene afforded tetra-(phenylethynyl)tin in 77% yield. The reaction can be promoted by Lewis acids.
- Levashov,Andreev,Buryi,Konshin
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- Characteristics of Si-Y mixed oxide supported nickel catalysts for the reductive amination of ethanol to ethylamines
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Si-Y mixed oxide synthesis was achieved via Si dissolution from a Pyrex reactor during the synthesis of yttrium hydroxide by the precipitation method at pH 10 and an aging temperature of 100 ℃. The Ni/SY mixed oxide catalysts with 5–25 wt% Ni contents were synthesized using an incipient wetness impregnation method. The characterization of the calcined Ni/SY oxide catalysts was performed using N2-sorption, X-ray diffraction, H2-temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), and ethanol-TPD. The reaction parameters such as reaction temperature and the partial pressures of ethanol, NH3, and H2 were varied in the reductive amination reaction, and the catalytic activities for the production of monoethylamine, diethylamine, triethylamine, and acetonitrile as main products were compared. The 10 wt% Ni/SY oxide catalyst containing 11 wt% Si showed the maximum activity, and the presence and absence of H2 and NH3 had a great effect on the conversion and selectivities. The stability after 110 h on stream was observed to be 2.5% less than the initial activity. The cause of this deactivation is the formation of nickel carbonitride, as confirmed by XPS and temperature programmed oxidation (TPO) measurements. On the basis of a detailed proposed reaction mechanism, reaction rates were determined, and the kinetic parameters were estimated by fitting the experimental data obtained under a variety of conditions. Our kinetic model showed that the temperature and the partial pressures of ethanol and hydrogen significantly influenced the conversion, whereas the partial pressure of ammonia had little influence because the imine partial pressure rapidly reached saturation.
- Jeong, Ye-Seul,Woo, Yesol,Park, Myung-June,Shin, Chae-Ho
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- Coordinating ability of rhodium(III) porphyrins toward organic bases
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Reactions of hydroxo(2,3,7,8,12,13,17,18-octaethylporphyrinato)rhodium(III) and acetylacetato-(5,10,15,20-tetraphenylporphyrinato)rhodium(III) with nitrogen-containing substrates were studied by spectrophotometry. The stability constants and compositions of the resulting molecular complexes were determined, and the effects of the macrocycle nature and substrate basicity on the stability constants were estimated. The structures of the isolated rhodium porphyrin molecules and their complexes with organic bases were optimized by the PM3 quantum chemical method. The degree of macrocycle deformation was found to change in the course of metal-substrate coordination. A correlation between the metal-substrate bond energy and equilibrium constant was revealed.
- Zaitseva,Zdanovich,Bryukhanova,Koifman
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- Tungsten nitrido complexes as precursors for low temperature chemical vapor deposition of WNxCy films as diffusion barriers for Cu metallization
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Tungsten nitrido complexes of the form WN(NR2)3 [R = combinations of Me, Et, iPr, nPr] have been synthesized as precursors for the chemical vapor deposition of WNxCy, a material of interest for diffusion barriers in Cu-metallized integrated circuits. These precursors bear a fully nitrogen coordinated ligand environment and a nitrido moiety (Wi - N) designed to minimize the temperature required for film deposition. Mass spectrometry and solid state thermolysis of the precursors generated common fragments by loss of free dialkylamines from monomeric and dimeric tungsten species. DFT calculations on WN(NMe 2)3 indicated the lowest gas phase energy pathway for loss of HNMe2 to be β-H transfer following formation of a nitrido bridged dimer. Amorphous films of WNxCy were grown from WN(NMe2)3 as a single source precursor at temperatures ranging from 125 to 650 C using aerosol-assisted chemical vapor deposition (AACVD) with pyridine as the solvent. Films with stoichiometry approaching W2NC were grown between 150 and 450 C, and films grown at 150 C were highly smooth, with a RMS roughness of 0.5 nm. In diffusion barrier tests, 30 nm of film withstood Cu penetration when annealed at 500 C for 30 min.
- McClain, K. Randall,O'Donohue, Christopher,Koley, Arijit,Bonsu, Richard O.,Abboud, Khalil A.,Revelli, Joseph C.,Anderson, Timothy J.,McElwee-White, Lisa
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- STOICHIOMETRY OF THE SHORT-RANGE SOLVATION OF DIETHYLAMINE IN PROTON TRANSFER REACTIONS WITH 2,4-DINITROPHENOL AND SOLVATION BY ETHERS
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Equilibrium constants were determined at 25 deg C for the formation of the proton transfer complex between 2,4-dinitrophenol and diethylamine in mixed solvents of benzene and small amounts of the following electron-donating solvents: nitrobenzene, n-propyl ether, 1,2-dimethoxyethane, tetrahydropyran, and 1,3-dioxalane.These solvents form hydrogen bonds with the amine proton of diethylamine, resulting in an increased effective basicity for the amine.In every case the stoichiometry of the interaction is found to be diethylamine:solvent = 1:2, inferring the existence ofa bifurcated hydrogen bond in solution.Dioxane had previously been shown to be a dramatically effective short-range solvent.Of the several ethers that were studied to determine what structural aspect of dioxane is responsible for its solvation powers, only 1,3-dioxalane, another cyclic diether, shows similar properties.
- Abduljaber, Mohamad,Scott, Ronald M.
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- Efficient coupling reactions of allylamines with soft nucleophiles using nickel-based catalysts
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Substitution reactions of N,N-diethylallylamine 1 with soft nucleophiles such as active methylene compounds 2a-c and piperidine 5 proceed much more rapidly in the presence of Ni(dppb)2 [dppb = 1,4-bis(diphenylphosphino)butane] as catalyst than with comparable palladium systems.
- Bricout, Herve,Carpentier, Jean-Francois,Mortreux, Andre
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- Quantitation of the P2Y1 receptor with a high affinity radiolabeled antagonist
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2-Chloro-N6-methyl-(N)-methanocarba-2′-deoxyadenosine-3 ′,5′-bisphosphate (MRS2279) was developed previously as a selective high-affinity, non-nucleotide P2Y1 receptor (P2Y1-R) antagonist (J Med Chem 43:829-842, 2002; Br J Pharmacol 135:2004-2010, 2002). We have taken advantage of the N6-methyl substitution in the adenine base to incorporate [3H]methylamine into the synthesis of [3H]MRS2279 to high (89 Ci/mmol) specific radioactivity and have used this molecule as a radioligand for the P2Y1-R. [3H]MRS2279 bound to membranes from Sf9 insect cells expressing recombinant human P2Y1-R but not to membranes from wild-type Sf9 cells or Sf9 cells expressing high levels of recombinant P2Y2 or P2Y12 receptors. Equilibrium binding of [3H]MRS2279 to P2Y1-R expressed in Sf9 membranes was with a high affinity (Kd = 8 nM) essentially identical to the apparent affinity of MRS2279 determined previously in studies of P2Y1-R-promoted inositol phosphate accumulation or platelet aggregation. A kinetically derived Kd calculated from independent determinations of the rate constants of association (7.15 × 107 M-1 min-1) and dissociation (0.72 min-1) of [3H]MRS2279 also was in good agreement with the Kd derived from equilibrium binding studies. Competition binding assays with [3H]MRS2279 and P2Y1-R expressing Sf9 cell membranes revealed Ki values for the P2Y1-R antagonists MRS2279 (Ki = 13 nM), N6-methyl-2′-deoxyadenosine-3′,5′-bisphosphate (MRS2179; Ki = 84 nM), adenosine-3′,5′-bisphosphate (Ki = 900 nM), and pyridoxal phosphate-6-azophenyl-2′,4′-disulfonic acid (Ki = 6 μM) that were in good agreement with antagonist activities of these molecules previously determined at the P2Y1-R in intact tissues. Moreover, [3H]MRS2279 also bound with high affinity (Kd = 4-8 nM) to Chinese hamster ovary (CHO) or 1321N1 human astrocytoma cells stably expressing the human P2Y1-R, but specific binding was not observed in wild-type CHO or 1321N1 cells. [3H]MRS2279 bound with high affinity (Kd = 16 nM) to a binding site on out-dated human platelets (5-35 receptors/platelet) and rat brain membranes (210 fmol/mg protein) that fit the expected drug selectivity of a P2Y1-R. Taken together, these results indicate that [3H]MRS2279 is the first broadly applicable antagonist radioligand for a P2Y receptor.
- Waldo, Gary L.,Corbitt, James,Boyer, Jose L.,Ravi, Gnana,Kim, Hak Sung,Ji, Xiao-Duo,Lacy, James,Jacobson, Kenneth A.,Kendall Harden
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- Chemistry of the diazeniumdiolates. 2. Kinetics and mechanism of dissociation to nitric oxide in aqueous solution
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Diazeniumdiolate ions of structure R2N[N(O)NO]- (1) are of pharmacological interest because they spontaneously generate the natural bioregulatory species, nitric oxide (NO), when dissolved in aqueous media. Here we report the kinetic
- Davies,Wink,Saavedra,Keefer
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- Photocatalysis of Oligo(p-phenylenes). Photoreductive Production of Hydrogen and Ethanol in Aqueous Triethylamine
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Oligo(p-phenylenes) (OPP-n), p-terphenyl (OPP-3) to p-sexiphenyl (OPP-6), catalyze water-reductive H2 formation and reduction of concomitantly formed acetaldehyde to ethanol upon irradiation of heterogeneous suspensions in aqueous organic solution in the presence of triethylamine (TEA) and RuCl3.Colloidal Ru0 is photoformed in situ to work as an electron relay.The activity of OPP-n increases with the number of phenylene units except for the cases of OPP-3 and of the alkylated derivatives, where the net photocatalytic activities are higher, mainly due to the effective homogeneous catalysis, since their solubilities in the solvents employed are significantly larger.The homogeneous catalysis of OPP-3 leads not only to H2 evolution but also to effective formation of ethanol in the absence of colloidal Ru0, being accompanied by photo-Birch reduction of OPP-3.Dynamics studies of OPP-3 reveal that photocatalysis should be initiated by formation of the excited singlet state of OPP-3 (1OPP-3*, which is reductively quenched by TEA at a rate controlled by diffusion to produce the OPP-3 radical anion (OPP-3.-) and the TEA radical cation (TEA.+).From laser flash photolysis and pulse radiolysis experiments, it is concluded that electron transfer from OPP-3.- leads to effective reduction of water to H2 catalyzed by Ru0 colloid.Furthermore, it is confirmed that OPP-3.- gives electrons directly to acetaldehyde without any electron relays like colloidal metals, resulting in the formation of ethanol.During photocatalysis, OPP-3 itself undergoes photo-Birch reduction to some extent.
- Matsuoka, Shinjiro,Fujii, Hiroyuki,Yamada, Taisuke,Pac, Chyongjin,Ishida, Akito,et al.
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- Photocatalysis of Oligo(p-phenylene) Leading to Reductive Formation of Hydrogen and Ethanol from Triethylamine in Aqueous Organic Solvent
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Oligo(p-phenylene)s, i.e., p-terphenyl to p-sexiphenyl, catalyze photoreductive formation of H2 and ethanol in photolysis of aqueous solution of triethylamine under > 290-nm irradiation in the presence of RuCl3. p-Terphenyl shows unusually effective photocatalysis for the formation of ethanol in aqueous tetrahydrofuran even without RuCl3.
- Matsuoka, Shinjiro,Fujii, Hiroyuki,Pac, Chyongjin,Yanagida, Shozo
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- Is water a suitable solvent for the catalytic amination of alcohols?
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The catalytic conversion of biomass and biogenic platform chemicals typically requires the use of solvents. Water is present already in the raw materials and in most cases a suitable solvent for the typically highly polar substrates. Hence, the development of novel catalytic routes for further processing would profit from the optimization of the reaction conditions in the aqueous phase mainly for energetic reasons by avoiding the initial water separation. Herein, we report the amination of biogenic alcohols in aqueous solutions using solid Ru-based catalysts and ammonia as a reactant. The influence of different support materials and bimetallic catalysts is investigated for the amination of isomannide as a biogenic diol. Most importantly, the transferability of the reaction conditions to various other primary and secondary alcohols is successfully proved. Hence, water appears to be a suitable solvent for the sustainable production of biogenic amines and offers great potential for further process development.
- Niemeier, Johannes,Engel, Rebecca V.,Rose, Marcus
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Read Online
- New aspects for heterogeneous cobalt-catalyzed hydroamination of ethanol
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Gas-phase hydroamination of ethanol and ammonia over supported cobalt on silica catalysts was investigated at 103 kPa. Besides the desired products, mono-, di- and triethylamine, acetonitrile, diethylimine, and hydrocarbons (methane, ethene, ethane, propane, and propene) were identified as byproducts. The formation of hydrocarbons was found to depend on the cobalt loading of the catalyst and on the pretreatment of the catalyst. Guaranteeing a sufficient reduction of the cobalt catalyst allows a reduction in the selectivity of hydrocarbons from 25 to 10 mol% at a constant conversion of 90%. In addition, rapid deactivation of the catalyst was observed in the absence of hydrogen. The deactivation was ascribed to the interaction of ammonia with the catalyst and is largely reversible. Carbonaceous species are present on the spent catalyst, as shown by temperature-programmed reduction. These species are thought to be responsible for a slow deactivation in the presence of hydrogen.
- Rausch,van Steen,Roessner
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Read Online
- Gas-phase elimination kinetics of ethyl, isopropyl and tert-butyl N,N-diethylcarbamates. Application of Taft-Topsom correlation for substituents other than carbon at the acid side of organic ethyl esters
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The elimination kinetics of ethyl, isopropyl and tert-butyl N,N-diethylcarbamates were investigated in a static reaction vessel over the temperature range 220-400°C and pressure range 17-160 Torr. These reactions are homogeneous, unimolecular and follow a first-order rate law. The temperature dependance of the rate coefficients is given by the following equations: for ethyl N,N-diethylcarbamate, log k1 (s-1) = (11.47 ± 0.25) - (178.4 ± 3.1) kJ mol-1 (2.303 RT)-1, for isopropyl N,N-diethylcarbamate, log k1 (s-1) = (12.83 ± 0.70) - (179.8 ± 7.9) kJ mol-1 (2.303 RT)-1; and for tert-butyl N,N-diethylcarbamate, log k1 (s-1) = (12.87 ± 0.62) - (158.6 ± 6.2) kJ mol-1 (2.303 RT)-1. The branching of the alkyl groups at the alcohol side of the ester exerts a significant effect on the rates in the order tert-butyl > isopropyl > ethyl. In addition, the presence of different substituents other than carbon at the acid side of organic ethyl esters gives the best correlation when using the Taft-Topsom equation: log k/kH = -(0.68 ± 0.12)σs + (2.57 ± 0.12)σF - (1.18 ± 0.27)σR (r = 0.984 ± 0.119 at 400°C). According to this relationship, the field (inductive) effect of the substituent has the greatest influence on rate enhancement, while the polarizability (steric) and resonance factors, although small in effect, favour the elimination process. Copyright
- Herize, Armando,Dominguez, Rosa M.,Rotinov, Alexandra,Nunez, Oswaldo,Chuchani, Gabriel
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- Water Oxidation Reaction Mediated by an Octanuclear Iron-Oxo Cluster
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A one-pot synthetic procedure yields the octanuclear FeIII complex [Fe8(μ4-O)4(μ-4-tBu-pz)12Cl4] (2). The molecular structure of 2 resembles the building units of iron-containing minerals like magnetite, ferrihydrite and maghemite. Based on mechanistic investigation we propose that in presence of Et3N, iron(III) pyrazolates are reduced to iron(II) pyrazolates, which then activate dioxygen to form 2. Complex 2 exhibits unique spectroscopic and electrochemical properties relative to those of the previously reported Fe8 clusters based on pyrazolate ligands. Furthermore, 2 can oxidize water to hydrogen peroxide, thereby mimicking the water splitting process taking place at the surface of magnetite. Compound 2 therefore acts as both structural and functional models of iron-containing minerals.
- Deutscher, Jennifer,Corona, Teresa,Warm, Katrin,Engelmann, Xenia,Sobottka, Sebastian,Braun-Cula, Beatrice,Sarkar, Biprajit,Ray, Kallol
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- Coordination properties of μ-carbidodimeric iron(IV) 2,3,7,8,12,13,17,18-octapropyltetraazaporphyrinate and 5,10,15,20-tetraphenylporphyrinate in reactions with nitrogen-containing bases
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The equilibria of μ-carbidodimeric iron(IV) 2,3,7,8,12,13,17,18-octapropyltetraazaporphyrinate and 5,10,15,20-tetraphenylporphyrinate in reactions with nitrogen-containing bases in an inert solvent were studied spectrophotometrically. The equilibrium constants of the studied processes and the compositions of molecular complexes were determined. The effect of the electronic and conformation factors of a macrocycle and the nature of the base on the equilibrium constant was pointed out. A comparative analysis of the substrate specificity of the studied compounds was performed.
- Zaitseva,Zdanovich,Kudrik,Koifman
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- ZINC SULFIDE-CATALYZED PHOTOCHEMICAL CONVERSION OF PRIMARY AMINES TO SECONDARY AMINES
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Nonmetallized ZnS catalizes efficiently the photochemical conversion of primary amines to secondary amines with liberation of ammonia under irradiation of the UV light of λ>290 nm.The conversion is interpreted as due to the two-hole-oxidation of primary amines to Schiff bases and their two-electron-reduction to secondary amines by the photogenerated electrons in ZnS.
- Yanagida, Shozo,Kizumoto, Hirotoshi,Ishimaru, Yoshiteru,Pac, Chyongjin,Sakurai, Hiroshi
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Read Online
- A Lewis Base Nucleofugality Parameter, NFB, and Its Application in an Analysis of MIDA-Boronate Hydrolysis Kinetics
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The kinetics of quinuclidine displacement of BH3 from a wide range of Lewis base borane adducts have been measured. Parameterization of these rates has enabled the development of a nucleofugality scale (NFB), shown to quantify and predict the leaving group ability of a range of other Lewis bases. Additivity observed across a number of series R′3-nRnX (X = P, N; R′ = aryl, alkyl) has allowed the formulation of related substituent parameters (nfPB, nfAB), providing a means of calculating NFB values for a range of Lewis bases that extends far beyond those experimentally derived. The utility of the nucleofugality parameter is explored by the correlation of the substituent parameter nfPB with the hydrolyses rates of a series of alkyl and aryl MIDA boronates under neutral conditions. This has allowed the identification of MIDA boronates with heteroatoms proximal to the reacting center, showing unusual kinetic lability or stability to hydrolysis.
- García-Domínguez, Andrés,Gonzalez, Jorge A.,Leach, Andrew G.,Lloyd-Jones, Guy C.,Nichol, Gary S.,Taylor, Nicholas P.
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supporting information
(2022/01/04)
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- Selective Synthesis of Symmetrical Secondary Amines from Nitriles with a Pt?CuFe/Fe3O4 Catalyst and Ammonia Borane as Hydrogen Donor
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Hydrogenation of nitriles is an efficient and environmentally friendly route to synthesize symmetrical secondary amines, but it usually produces a mixture of amines, imines, and hydrogenolysis by-products. Herein we report a magnetic quaternary-component Pt?CuFe/Fe3O4 nanocatalyst system for the selective synthesis of symmetrical secondary amines with ammonia borane as hydrogen donor. The catalyst with a low Pt loading (0.456 wt%) is the source of the activity, and the d-band electron transfer from Cu to Fe enhances the selectivity. This synergistic effect results in the transformation of benzonitrile to dibenzylamine with excellent conversion (up to 99 %) and nearly quantitative selectivity (up to 96 %) under mild reaction conditions, nevertheless, the reaction TOF is as high as up to 1409.9 h?1. A variety of nitriles are suitable for the synthesis of symmetrical secondary amines. More importantly, unwanted hydrogenolysis byproducts, especially toluene, is not detected at all. In addition, the catalyst is magnetically recoverable, and it can be reused up to five times.
- Ai, Yongjian,Guo, Rongxiu,He, GuangQi,Hu, Ze-nan,Liang, Qionglin,Liu, Lei,Niu, Dun,Sun, Hong-bin,Tian, Haimeng,Zhang, Xinyue
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p. 1783 - 1788
(2020/09/02)
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- Discovery and characterization of an acridine radical photoreductant
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Photoinduced electron transfer (PET) is a phenomenon whereby the absorption of light by a chemical species provides an energetic driving force for an electron-transfer reaction1–4. This mechanism is relevant in many areas of chemistry, including the study of natural and artificial photosynthesis, photovoltaics and photosensitive materials. In recent years, research in the area of photoredox catalysis has enabled the use of PET for the catalytic generation of both neutral and charged organic free-radical species. These technologies have enabled previously inaccessible chemical transformations and have been widely used in both academic and industrial settings. Such reactions are often catalysed by visible-light-absorbing organic molecules or transition-metal complexes of ruthenium, iridium, chromium or copper5,6. Although various closed-shell organic molecules have been shown to behave as competent electron-transfer catalysts in photoredox reactions, there are only limited reports of PET reactions involving neutral organic radicals as excited-state donors or acceptors. This is unsurprising because the lifetimes of doublet excited states of neutral organic radicals are typically several orders of magnitude shorter than the singlet lifetimes of known transition-metal photoredox catalysts7–11. Here we document the discovery, characterization and reactivity of a neutral acridine radical with a maximum excited-state oxidation potential of ?3.36 volts versus a saturated calomel electrode, which is similarly reducing to elemental lithium, making this radical one of the most potent chemical reductants reported12. Spectroscopic, computational and chemical studies indicate that the formation of a twisted intramolecular charge-transfer species enables the population of higher-energy doublet excited states, leading to the observed potent photoreducing behaviour. We demonstrate that this catalytically generated PET catalyst facilitates several chemical reactions that typically require alkali metal reductants and can be used in other organic transformations that require dissolving metal reductants.
- MacKenzie, Ian A.,Wang, Leifeng,Onuska, Nicholas P. R.,Williams, Olivia F.,Begam, Khadiza,Moran, Andrew M.,Dunietz, Barry D.,Nicewicz, David A.
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- Reductive Electrochemical Activation of Molecular Oxygen Catalyzed by an Iron-Tungstate Oxide Capsule: Reactivity Studies Consistent with Compound i Type Oxidants
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The reductive activation of molecular oxygen catalyzed by iron-based enzymes toward its use as an oxygen donor is paradigmatic for oxygen transfer reactions in nature. Mechanistic studies on these enzymes and related biomimetic coordination compounds designed to form reactive intermediates, almost invariably using various "shunt" pathways, have shown that high-valent Fe(V)=O and the formally isoelectronic Fe(IV) =O porphyrin cation radical intermediates are often thought to be the active species in alkane and arene hydroxylation and alkene epoxidation reactions. Although this four decade long research effort has yielded a massive amount of spectroscopic data, reactivity studies, and a detailed, but still incomplete, mechanistic understanding, the actual reductive activation of molecular oxygen coupled with efficient catalytic transformations has rarely been experimentally studied. Recently, we found that a completely inorganic iron-tungsten oxide capsule with a keplerate structure, noted as {Fe30W72}, is an effective electrocatalyst for the cathodic activation of molecular oxygen in water leading to the oxidation of light alkanes and alkenes. The present report deals with extensive reactivity studies of these {Fe30W72} electrocatalytic reactions showing (1) arene hydroxylation including kinetic isotope effects and migration of the ipso substituent to the adjacent carbon atom ("NIH shift"); (2) a high kinetic isotope effect for alkyl C - H bond activation; (3) dealkylation of alkylamines and alkylsulfides; (4) desaturation reactions; (5) retention of stereochemistry in cis-alkene epoxidation; and (6) unusual regioselectivity in the oxidation of cyclic and acyclic ketones, alcohols, and carboxylic acids where reactivity is not correlated to the bond disassociation energy; the regioselectivity obtained is attributable to polar effects and/or entropic contributions. Collectively these results also support the conclusion that the active intermediate species formed in the catalytic cycle is consistent with a compound I type oxidant. The activity of {Fe30W72} in cathodic aerobic oxidation reactions shows it to be an inorganic functional analogue of iron-based monooxygenases.
- Bugnola, Marco,Shen, Kaiji,Haviv, Eynat,Neumann, Ronny
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p. 4227 - 4237
(2020/05/05)
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- Selective Synthesis of Secondary and Tertiary Amines by Reductive N-Alkylation of Nitriles and N-Alkylation of Amines and Ammonium Formate Catalyzed by Ruthenium Complex
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A new ruthenium catalytic system for the syntheses of secondary and tertiary amines via reductive N-alkylation of nitriles and N-alkylation of primary amines is proposed. Isomeric complexes 8 catalyze transfer hydrogenation and N-alkylation of nitriles in ethanol to give secondary amines. Unsymmetrical secondary amines can be produced by N-alkylation of primary amines with alcohols via the borrowing hydrogen methodology. Aliphatic amines were obtained with excellent yields, while only moderate conversions were observed for anilines. Based on kinetic and mechanistic studies, it is suggested that the rate determining step is the hydrogenation of intermediate imine to amine. Finally, ammonium formate was applied as the amination reagent for alcohols in the presence of ruthenium catalyst 8. Secondary amines were obtained from primary alcohols within 24 hours at 100 °C, and tertiary amines can be produced after prolonged heating. Secondary alcohols can only be converted to secondary amines with moderate yield. Based on mechanistic studies, the process is suggested to proceed through an ammonium alkoxy carbonate intermediate, where carbonate acts as an efficient leaving group.
- Alshakova, Iryna D.,Nikonov, Georgii I.
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p. 5370 - 5378
(2019/06/14)
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- Method of preparation of ethylamine or acetonitrile by reductive amination of ethanol
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The present invention relates to a catalyst for manufacturing ethylamine and a method for manufacturing the same. More specifically, the present invention relates to: a nickel-supported catalyst for manufacturing ethylamine or acetonitrile which has impregnated nickel on a supporter as a catalyst capable of efficiently manufacturing ethylamine or acetonitrile at a normal pressure or lower by reacting ethanol with ammonia, a method for manufacturing the same, and a method for manufacturing ethylamine using the same.COPYRIGHT KIPO 2019
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Paragraph 0095-0099; 0107; 0144
(2019/06/22)
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- Sodium Triethylborohydride-Catalyzed Controlled Reduction of Unactivated Amides to Secondary or Tertiary Amines
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The first transition-metal-free catalytic protocol for controlled reduction of amide functions using cheap and bench-stable hydrosilanes as reducing agents has been established. By altering the hydrosilane and solvent, the new method enables the selective cleavage of unactivated C-O bonds in amides and allows the C-N bonds to selectively break via the deacylated cleavage. Overall, this novel process may offer a versatile alternative to current methodologies employing stoichiometric metal systems for the controlled reduction of carboxamides.
- Yao, Wubing,He, Lili,Han, Deman,Zhong, Aiguo
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p. 14627 - 14635
(2019/12/02)
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- Sodium Triethylborohydride-Catalyzed Controlled Reduction of Unactivated Amides to Secondary or Tertiary Amines
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The first transition-metal-free catalytic protocol for controlled reduction of amide functions using cheap and bench-stable hydrosilanes as reducing agents has been established. By altering the hydrosilane and solvent, the new method enables the selective cleavage of unactivated C-O bonds in amides and allows the C-N bonds to selectively break via the deacylated cleavage. Overall, this novel process may offer a versatile alternative to current methodologies employing stoichiometric metal systems for the controlled reduction of carboxamides.
- Yao, Wubing,He, Lili,Han, Deman,Zhong, Aiguo
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- Alkyl coupling in tertiary amines as analog of Guerbet condensation reaction
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We report here that C-C coupling in tertiary amines for the synthesis of long chain and hindered amines might be efficiently performed over Pt and Pd catalysts. The mechanism study confirms similarity with the Guerbet reaction through dehydrogenation of the alkyl group and subsequent attack of the α-carbon atom by an alkyl group of another molecule. Finally, secondary amines and tertiary amines with longer alkyl chains are formed.
- Zhou, Yage,Wu, Dan,Hernández, Willinton Yesid,Ma, Changru,Su, Huangyang,Ordomsky, Vitaly
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p. 9845 - 9849
(2019/04/01)
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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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supporting information
p. 5326 - 5335
(2019/10/11)
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- Method for treating florfenicol fluorination process product
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The invention discloses a method for treating a florfenicol fluorination process product. The method comprises a reduction reaction and an elimination reaction. A reducing agent is adopted for the molecular structure of N,N-diethyl-2,3,3,3-tetrafluoropropionamide to carry out a direct reduction reaction, a special catalyst anhydrous zinc chloride or anhydrous aluminum chloride is added to obtain an unexpected effect, and the direct reduction is adopted to obtain diethylamine and 2,3,3,3-tetrafluoropropanol. The process product treatment method effectively recovers four fluorine atoms, and alsocan directly obtain diethylamine, so wastes are changed into valuables, and the economic values are greatly increased.
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Paragraph 0023; 0024; 0027; 0028; 0031; 0032; 0035; 0036
(2019/10/01)
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- The role of proton shuttling mechanisms in solvent-free and catalyst-free acetalization reactions of imines
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Proton transfer is central to the understanding of chemical processes. More so in addition reactions of the type NuH + E → Nu-EH taking place under solvent-free and catalyst-free conditions. Herein we show that the addition of alcohols or amines (the NuH component) to imine derivatives (the E component), in 1:1 ratio, under solvent-free and catalyst-free conditions, are efficient methods to access N,O and N,N-acetal derivatives. In addition, computational studies reveal that they are catalyzed reactions involving two or even three NuH molecules operating in a cooperative manner as H-bonded NuH?(NuH)n?NuH associates (many body effects) in the transition state through a concerted proton shuttling mechanism (addition of alcohols) or stepwise proton shuttling mechanism (addition of amines), thereby facilitating the key proton transfer step.
- Lillo, Victor J.,Mansilla, Javier,Saá, José M.
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supporting information
p. 4527 - 4536
(2018/06/29)
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- Lewis Acid-Catalyzed Reductive Amination of Aldehydes and Ketones with N,N-Dimethylformamide as Dimethylamino Source, Reductant and Solvent
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A practical zinc acetate dihydrate-catalyzed reductive amination of various carbonyl compounds with N,N-dimethylformamide (DMF) as dimethylamino (Me2N) source, reductant and solvent has been developed. This reaction shows broad substrate scope,
- Yang, Luo,Lin, Jie,Kang, Lei,Zhou, Wang,Ma, Da-You
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supporting information
p. 485 - 490
(2018/01/15)
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- An Additive-Free, Base-Catalyzed Protodesilylation of Organosilanes
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We report an additive-free, base-catalyzed C-, N-, O-, and S-Si bond cleavage of various organosilanes in mild conditions. The novel catalyst system exhibits high efficiency and good functional group compatibility, providing the corresponding products in good to excellent yields with low catalyst loadings. Overall, this transition-metal-free process may offer a convenient and general alternative to current employing excess bases, strong acids, or metal-catalyzed systems for the protodesilylation of organosilanes.
- Yao, Wubing,Li, Rongrong,Jiang, Huajiang,Han, Deman
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p. 2250 - 2255
(2018/02/23)
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- Photolysis of Tertiary Amines in the Presence of CO2: The Paths to Formic Acid, α-Amino Acids, and 1,2-Diamines
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The photolysis of triethylamine (1a) in the presence of carbon dioxide leads to the hydrogenation of CO2, the α-C-C coupling of 1a, and the CO2 insertion into the α-C-H σ-bond of amine 1a. This reaction is proposed to proceed through the radical ion pair [R3N?+·CO2?-] generated by the photoionization of amine 1a and the electron capture by CO2. The presence of lithium tetrafluoroborate in the reaction medium promotes the efficient and stereoselective α-C-C coupling of 1a by enhancing the production of α-dialkylamino radicals and the isomerization of N,N,N′,N′-tetraethylbutane-2,3-diamine (4a).
- Berton, Mateo,Mello, Rossella,Acerete, Rafael,González Núnez, María Elena
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- Heterogeneously catalyzed selective hydrogenation of amides to alcohols and amines
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We report the heterogeneously catalyzed hydrogenation of amides to form alcohols and amines. This C-N bond cleavage reaction is catalyzed by silver on γ-alumina, proceeds smoothly in high yields and 100% selectivity, and is effective for both benzamides and aliphatic amides. This is in contrast to amide hydrogenation catalyzed by heterogeneous catalysts, which generally proceeds via C-O bond cleavage. Recycling experiments show that the catalyst Ag/γ-Al2O3 can be easily recovered and regenerated without decrease in catalytic activity.
- Xie, Yinjun,Hu, Peng,Bendikov, Tatyana,Milstein, David
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p. 2784 - 2788
(2018/06/18)
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- Intramolecular alkene hydroamination and degradation of amidines: Divergent behavior of rare earth metal amidinate intermediates
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Direct N-H addition of amidines to alkenes is a highly valuable but challenging transformation that remains elusive. Now, the intramolecular hydroamidination of N-alkenylamidines is achieved by using a rare earth catalyst, which provides an efficient and atom-economical approach for substituted imidazolines and tetrahydropyrimidines. Moreover, a mild and efficient method for the catalytic degradation of amidines to give amines and nitriles is also developed. Additionally, amidine reconstruction followed by an intramolecular alkene hydroamidination strategy for the synthesis of substituted imidazolines and tetrahydropyrimidines from secondary enamines and inactive amidines has also been established, which may circumvent the need for some unavailable starting materials. The mechanistic studies prove that these reactions proceed via a key lanthanide amidinate intermediate that can undergo substrate- and amine-controlled chemodivergent transformations: intramolecular alkene insertion, nitrile extrusion, amidinate reconstruction, or a combination of the reactions. The results presented here not only demonstrate the synthetic potential and versatility of alkene hydroamidination with substrates, but also provide a good insight into the factors that promote or deter the hydroamidination of alkenes.
- Zhang, Dexing,Liu, Ruiting,Zhou, Xigeng
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p. 5573 - 5581
(2018/11/20)
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- Method for generating nitrile and amine by means of rare-earth catalytic amidines compound degradation
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The invention belongs to the technical field of chemical engineering, and particularly discloses a method for generating nitrile and amine by means of rare-earth catalytic amidines compound degradation. The method includes directly degrading amidines compounds in rare-earth catalytic systems to generate the corresponding nitrile and the corresponding amine. The method has the advantages that the method is wide in application range and easy and convenient to operate; the nitrile can be generated by the aid of the method under mild conditions in a high-yield manner, and the method is high in reaction selectivity.
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Paragraph 0024
(2018/10/19)
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- Preparation method of the formamide
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The invention relates to a preparation method of methanamide. The method uses formamide or its derivative and amine (primary or secondary amine) as reactants, which are subjected to amidomethylation in the presence of a catalyst to prepare methanamide. The method is characterized in that solid acidic metal oxide or precious metal loaded acidic metal oxide is used as the catalyst and the reaction is carried out efficiently under mild conditions. The reaction process is as follows: mixing formamide with certain concentration or its derivatives with primary or secondary amine and a certain amount of catalyst, placing the mixture into pressure vessel without adding or additionally adding other solvent, sealing, stirring at a temperature no less than 60 DEG C, and reacting for no less than 0.5 h to obtain the reaction product methanamide. The method has the advantages of simple preparation of the catalyst, easy separation process of the catalyst and product, repeated usage of the catalyst, high controllability of the reaction process, and yield of the product formamide reaching more than 95%.
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Paragraph 0035; 0036; 0052
(2017/07/01)
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- Phototriggered Dehydration Condensation Using an Aminocyclopropenone
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A phototriggered dehydration condensation using an aminocyclopropenone has been developed. The UV irradiation of an aminocyclopropenone generated a highly reactive ynamine in situ and the dehydration condensation of a carboxylic acid and an amine coexisting in the reaction solution smoothly proceeded to afford an amide. This reaction is completely controllable by the ON/OFF states of a UV lamp.
- Mishiro, Kenji,Yushima, Yuki,Kunishima, Munetaka
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supporting information
p. 4912 - 4915
(2017/09/23)
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- A second class of liquid phase in the production of asymmetrical cyclobutylamines tert-
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The present invention relates to a process for preparing unsymmetrical secondary tert-butylamines which, in addition to the tert-butyl radical, also contain an alkyl, cycloalkyl or benzyl radical. They are prepared by reacting corresponding aldehydes with tert-butylamine and hydrogen in the presence of hydrogenation catalysts (reductive amination) in the liquid phase.
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Paragraph 0057
(2017/03/23)
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- Quantitative Reactivity Scales for Dynamic Covalent and Systems Chemistry
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Dynamic covalent chemistry (DCC) has become a powerful tool for the creation of molecular assemblies and complex systems in chemistry and materials science. Herein we developed for the first time quantitative reactivity scales capable of correlation and prediction of the equilibrium of dynamic covalent reactions (DCRs). The reference reactions are based upon universal DCRs between imines, one of the most utilized structural motifs in DCC, and a series of O-, N-, and S- mononucleophiles. Aromatic imines derived from pyridine-2-carboxyaldehyde exhibit capability for controlling the equilibrium through distinct substituent effects. Electron-donating groups (EDGs) stabilize the imine through quinoidal resonance, while electron-withdrawing groups (EWGs) stabilize the adduct by enhancing intramolecular hydrogen bonding, resulting in curvature in Hammett analysis. Notably, unique nonlinearity induced by both EDGs and EWGs emerged in Hammett plot when cyclic secondary amines were used. This is the first time such a behavior is observed in a thermodynamically controlled system, to the best of our knowledge. Unified quantitative reactivity scales were proposed for DCC and defined by the correlation log K = SN (RN + RE). Nucleophilicity parameters (RN and SN) and electrophilicity parameters (RE) were then developed from DCRs discovered. Furthermore, the predictive power of those parameters was verified by successful correlation of other DCRs, validating our reactivity scales as a general and useful tool for the evaluation and modeling of DCRs. The reactivity parameters proposed here should be complementary to well-established kinetics based parameters and find applications in many aspects, such as DCR discovery, bioconjugation, and catalysis.
- Zhou, Yuntao,Li, Lijie,Ye, Hebo,Zhang, Ling,You, Lei
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supporting information
p. 381 - 389
(2016/01/26)
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- Preparation of all N-coordinated zirconium amide amidinates and studies of their reactions with dioxygen and water
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Zr(NR2)2[MeC(NiPr)2]2 (R = Me, 1; Et, 2) have been prepared through aminolysis and their reactions with O2 and water have been studied. Two major products from the reactions are the oxo dimer {(μ-O)Zr[MeC(NiPr)2]2}2 (3) and its insoluble polymer {(μ-O)Zr[MeC(NiPr)2]2}n (4). Over time the dimer 3 polymerizes to 4. Zr peroxo trimer {(μ-η2:η2-O2)Zr[MeC(NiPr)2]2}3 (5) was also observed from the reaction of 1 with O2 and its crystal structure is reported. DFT calculations show that the reaction of 1 with O2 follows a radical process, yielding the peroxo trimer 5. Mass spectrometric studies of the reactions of water in air with 1 and 2 show the formation of the oxo monomer (O=)Zr[MeC(NiPr)2]2 (6), oxo dimer {(μ-O)Zr[MeC(NiPr)2]2}2 (3), and the dihydroxy monomer (HO)2Zr[MeC(NiPr)2]2 (7). In addition, the cations {Zr(NR2)[MeC(NiPr)2]2}+ (R = Me, Et) were observed. 2 revealed an interesting dynamic NMR behavior. Variableerature (VT) NMR spectroscopy has been used to study the Bailar twist process in 2, giving activation parameters ΔH? = 10.9(1.1) kcal mol-1, ΔS? = -11(4) eu and ΔG?303 K = 14(2) kcal mol-1.
- Lamb, Adam C.,Wang, Zheng,Cook, Tabitha M.,Sharma, Bhavna,Chen, Shu-Jian,Lu, Zheng,Steren, Carlos A.,Lin, Zhenyang,Xue, Zi-Ling
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- Degradation of the active species in the catalytic system Pd(OAc)2/NEt3
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The degradation under ambient humidity and room temperature of Pd(OAc)2(NEt3), which is an efficient catalyst for the aerobic oxidation of alcohols, to diethylamine and acetaldehyde derivatives is disclosed. Evolved diethylamine reacted with Pd(OAc)2 to give Pd(OAc)2(HNEt2), which is in dynamic equilibrium with Pd(OAc)2(HNEt2)2. The evolved acetaldehyde generated during degradation process was trapped with a nucleophile to form 2-methyl-3-tosyl-1,2,3,4-tetrahydroquinazoline. NMR spectroscopy and single crystal X-ray diffraction studies have been used to characterize the reaction products of the reaction system.
- Sanmartín-Matalobos, Jesús,González-Bello, Concepcion,Briones-Miguéns, Lucía,Fondo, Matilde,García-Deibe, Ana M.
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p. 103088 - 103094
(2016/11/13)
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- Iron-catalyzed Cα-H oxidation of tertiary, aliphatic amines to amides under mild conditions
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De novo syntheses of amides often generate stoichiometric amounts of waste. Thus, recent progress in the field has focused on precious metal catalyzed, oxidative protocols to generate such functionalities. However, simple tertiary alkyl amines cannot be used as starting materials in these protocols. The research described herein enables the oxidative synthesis of amides from simple, noncyclic tertiary alkyl amines under synthetically useful, mild conditions through a biologically inspired approach: Fe-catalyzed Cα-H functionalization. Mechanistic investigations provide insight into reaction intermediates and allow the development of a mild Cα-H cyanation method using the same catalyst system. The protocol was further applied to oxidize the drug Lidocaine, demonstrating the potential utility of the developed chemistry for metabolite synthesis. Let′s iron it out! The title reaction enables the oxidative synthesis of amides directly from tertiary, noncyclic alkyl amines under synthetically useful, mild conditions through a biologically inspired approach employing oxidative iron catalysis. Mechanistic studies suggest that hemiaminals are likely intermediates in this reaction and that the catalytic system can be employed for other Cα-H oxidations of amines.
- Legacy, Christopher J.,Wang, Anqi,O'Day, Brian J.,Emmert, Marion H.
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supporting information
p. 14907 - 14910
(2016/02/05)
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- 4-Hydroxyphenacyl Ammonium Salts: A Photoremovable Protecting Group for Amines in Aqueous Solutions
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Irradiation of N-protected p-hydroxyphenacyl (pHP) ammonium caged derivatives at 313 nm releases primary and secondary amines or ammonia in nearly quantitative yields via the photo-Favorskii reaction when conducted in acidic or neutral aqueous buffered media. The reaction efficiencies are strongly dependent on the pH with the most efficient and highest yields obtained when the pH of the media maintains the ammonium and p-hydroxyl groups as their conjugate acids. For example, the overall quantum yields of simple secondary amines release are 0.5 at acidic pH from 3.9 to 6.6 dropping to 0.1 at neutral pH 7.0 and 0.01 at pH 8.4. Speciation studies provide an acid-base profile that helps define the scope and limitations of the reaction. When the pKa of the ammonium group is lower than that of the phenolic hydroxyl group, as is the case for the α-amino-protected amino acids, the more acidic ammonium ion deprotonates as the media pH is changed from acidic toward neutral or basic, thus diminishing the leaving group ability of the amino group. This, in turn, lowers the propensity for the photo-Favorskii rearrangement reaction to occur and opens the reaction pathway to alternative competing photoreduction process.
- Bownik, Iwona,?ebej, Peter,Literák, Jaromír,Heger, Dominik,?imek, Zdeněk,Givens, Richard S.,Klán, Petr
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p. 9713 - 9721
(2015/10/12)
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- ANTI-NOTCH3 ANTIBODIES AND ANTIBODY-DRUG CONJUGATES
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The present invention provides for anti-Notch3 antibodies, anti-Notch3 antibody-drug conjugates and methods for preparing and using the same.
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Page/Page column
(2014/05/20)
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- PREPARING METHOD OF SOLID CARBAMIC ACID DERIVATIVES
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The present disclosure relates to a preparation method for powder of a carbamic acid derivative, which includes reacting a liquid amine derivative with carbon dioxide at a temperature in a range of from about ?30° C. to about 500° C. at a pressure in a range of from about 0.3 MPa to about 100 MPa. In addition, the present disclosure relates to a reduction method for powder of a carbamic acid derivative to a liquid amine derivative and carbon dioxide, which includes dissolving powder of the carbamic acid derivative prepared in a solvent; refluxing the carbamic acid derivative at a temperature in a range of from about 30° C. to about 100° C.; and evaporating the solvent. The preparation method for a carbamic acid derivative powder according to the present disclosure enables easy conversion into pure powder of solid carbamic acid derivative without by-products and can remarkably reduce time and energy required for solidification by reacting carbon dioxides and amines with carbon dioxides in high pressure conditions without the use of a solvent. In addition, the prepared solid compounds can be used as a liquid amine substitute or used in a carbamic acid derivative form as necessary.
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Paragraph 0083-0084
(2014/03/24)
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- Decomposition of amino diazeniumdiolates (NONOates): Molecular mechanisms
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Although diazeniumdiolates (X[N(O)NO]-) are extensively used in biochemical, physiological, and pharmacological studies due to their ability to release NOand/or its congeneric nitroxyl, the mechanisms of these processes remain obscure. In this
- Shaikh, Nizamuddin,Valiev, Marat,Lymar, Sergei V.
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- Aerobic oxidative N-dealkylation of tertiary amines in aqueous solution catalyzed by rhodium porphyrins
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Aerobic oxidative N-dealkylation of a variety of aliphatic tertiary amines and anilines catalyzed by rhodium(iii) tetra (p-sulfonatophenyl) porphyrin ((TSPP)RhIII) is achieved in aqueous solution using dioxygen as the sole oxidant.
- Ling, Zhen,Yun, Lin,Liu, Lianghui,Wu, Bing,Fu, Xuefeng
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supporting information
p. 4214 - 4216
(2013/05/22)
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- CYTOTOXIC PEPTIDES AND ANTIBODY DRUG CONJUGATES THEREOF
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The present invention is directed to cytotoxic pentapeptides, to antibody drug conjugates thereof, and to methods for using the same to treat cancer.
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Page/Page column
(2013/06/04)
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- Dissociation or cyclization: Options for a triad of radicals released from oxime carbamates
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A set of oxime carbamates having N-alkyl and N,N-dialkyl substituents were prepared via carbonyldiimidazole intermediates. It was shown by EPR spectroscopy that they underwent clean homolysis of their N-O bonds upon UV photolysis. During photolysis of acetophenone O-allylcarbamoyl oxime, the corresponding oxazolidin-2-onylmethyl radical was detected by EPR spectroscopy, providing the first evidence that N-monosubstituted carbamoyloxyl radicals can hold their structural integrity. N,N-Disubstituted carbamoyloxyl radicals dissociated rapidly at the lowest accessible temperatures. Above room temperature, both types of oxime carbamate acted as selective new precursors for aminyl and iminyl radicals. Rate parameters were measured for 5-exo cyclization of N-benzyl-N-pent-4-enylaminyl radicals; the rate constant was smaller than for C-centered and O-centered analogues. Oxime carbamates derived from the volatile diethylamine afforded aryliminyl radicals that proved convenient for phenanthridine preparations.
- McBurney, Roy T.,Walton, John C.
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supporting information
p. 7349 - 7354
(2013/06/27)
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- [1-Hydroxy-1-(2-hydroxyphenyl)ethyl]phosphonates and -phosphinates: Convenient synthesis through intramolecular Abramov reaction and protective activity against influenza A
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A combination of intramolecularization and tandem reaction methodologies has been applied to the synthesis of diethylammonium[1-hydroxy-1-(2- hydroxyphenyl)ethyl]phosphonates and -phosphinates, which were found to be unavailable through a standard intermolecular hydrophosphonylation/hydrolysis sequence. A mild hydrolysis of amidophosphites and -phosphonites, bearing 2-acetylphenoxy-fragment and a hydrolytically labile diethylamino-group at the same trivalent phosphorus atom, directly afforded the title compounds. The overall process probably consists of three steps: (i) selective hydrolysis of the P(III)-N bond to generate the hydrophosphoryl-type intermediates; (ii) formation of the strained 2-substituted 3-hydroxy-2-oxo-2,3-dihydro-1,2- benzoxaphospholes through intramolecular Abramov reaction; (iii) hydrolysis of the endocyclic P(IV)-O bond in the 1,2-benzoxaphospholes to give the acyclic products. Being only modestly active in vitro, at high dosage non-toxic water-soluble title α,γ-dihydroxyphosphonates and -phosphinates exhibited beneficial, but short-lasting effect against experimental influenza A infection (H3N2) in mice.
- Korshin, Edward E.,Pozdeev, Oskar K.
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p. 11109 - 11115
(2014/01/06)
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- Studies in the effect of light on trimethoprim, furosemide and metoclopramide
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Photolysis of trimethoprim, furosemide and metoclopramide under 60 W and 200 W tungsten lamp and 125 W and 250 W mercury vapour lamp in different conditions like different pH (acidic, neutral, alkaline) and different phases (solid and liquid) gave different products. Structures of these products have been established by spectral and elemental analysis.
- Jetti, Srinivasa Rao,Dubey, Manoj,Jain, Shubha
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- The synthesis of N-ethyl-n-butylamine by amines disproportionation
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A synthesis of N-ethyl-n-butylamine with simple separation method in a fixed-bed reactor using CuO-NiO-PtO/γ-Al2O3 as the catalyst was proposed and investigated. The present catalytic system gave high activity and good selectivity, and the reaction conditions such as temperature and liquid hourly space velocity were optimized. Since no water was generated, the protocol proved to be easy to separate, and N-ethyl-n-butylamine was collected at 110 °C by distillation. The yield and the purity were 60.7 and 99.5 %, respectively.
- Xu, Lu-Feng,Huang, Jia-Min,Qian, Chao,Chen, Xin-Zhi,Feng, Lie,Chen, Yun-Bin,He, Chao-Hong
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p. 2697 - 2704
(2013/07/26)
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- Reductive cleavage of amides to alcohols and amines catalyzed by well-defined bimetallic molybdenum complexes
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Triple bonds do it! The molybdenum-catalyzed Ci-N bond cleavage of organic amides with hydrosilanes to produce alcohols and amines has been investigated. This work complements previously established protocols that lead to the cleavage of the Ci-O bond. Modified triply bonded dimolybdenum(III) alkoxides have been found to be crucial for tuning the selectivity to Ci-N bond cleavage (see figure). Copyright
- Krackl, Sebastian,Someya, Chika I.,Enthaler, Stephan
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supporting information
p. 15267 - 15271
(2013/01/15)
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