- The thermodynamic properties of 1,2,3,4- and 5,6,7,8-tetrahydroquinolines
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Measurements leading to the calculation of the ideal-gas thermodynamic properties for 1,2,3,4- and 5,6,7,8-tetrahydroquinoline are reported.Thermochemical and thermophysical properties were determined by adiabatic heat-capacity calorimetry, comparative ebulliometry, inclined-piston-gauge manometry, and combustion calorimetry.Results were used to calculate standard entropies, enthalpies, and Gibbs energies of formation for the ideal-gas state at selected temperatures to 500 K.The results of the thermodynamic-property measurements were used to determine equilibrium constants, and hence, equilibrium mol alities, for the quinoline/hydrogen/tetrahydroquinoline reaction network at temperatures of interest in the processing of fossil-fuel feedstocks with a high nitrogen content.The results show that under typical processing conditions (650 K and 7.0 MPa hydrogen pressure) there is thermodynamic equilibrium between quinoline and 1,2,3,4-tetrahydroquinoline.That equilibrium conditions exist between quinoline and 5,6,7,8-tetrahydroquinoline in processing is more equivocal; however, there is strong evidence for such an equilibrium.
- Steele, W. V.,Chirico, R. D.,Hossenlopp, I. A.,Nguyen, A.,Smith, N. K.,Gammon, B. E.
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- Reactions of 5-, 6-, 7-, 8-hydroxyquinolines and 5-hydroxyisoquinoline with benzene and cyclohexane in superacids
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Isomeric 5-, 6-, 7-hydroxyquinolines (11-13) and 5-hydroxyisoquinoline (14) gave N,C-diprotonated dications in CF3SO3H-SbF5 superacid medium. Compounds 11, 13, 14, and 8-hydroxyquinoline (5) underwent selective ionic hydro
- Koltunov, Konstantin Yu.,Prakash, G. K. Surya,Rasul, Golam,Olah, George A.
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- Superelectrophilic activation of 8-hydroxyquinoline in acid media and its reactions with weak nucleophiles
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According to the 1H and 13C NMR data, 5-azonia-4-hydroxynaphthalen-1-onium cation, generated by protonation of 8-hydroxyquinoline in the system CF3SO3H-SbF5, reacts with cyclohexane to give diprotonated 5,6,7,8-tetrahydroquinolin-8-one. Further reaction of the latter with cyclohexane yields 5,6,7,8-tetrahydroquinolinium ion. The reaction of 8-hydroxyquinoline with benzene in the presence of aluminum bromide or chloride gives 6-phenyl-5,6,7,8-tetrahydroquinolin-8-one and product of its intramolecular cyclization, 11-hydroxy-6,11-dihydro-6,11-methano-5H-benzo[5,6]cyclohepta[1,2-b]pyridine. The effect of the protonated nitrogen atom on the electrophilicity of dications is discussed.
- Koltunov,Repinskaya
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- Selective hydrogenation of N-heterocyclic compounds using Ru nanocatalysts in ionic liquids
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N-Heterocyclic compounds have been tested in the selective hydrogenation catalysed by small 1-3 nm sized Ru nanoparticles (NPs) embedded in various imidazolium based ionic liquids (ILs). Particularly a diol-functionalised IL shows the best performance in the hydrogenation of quinoline to 1,2,3,4-tetrahydroquinoline (1THQ) with up to 99% selectivity.
- Konnerth, Hannelore,Prechtl, Martin H. G.
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- Compounds with Bridgehead Nitrogen. Part 49. The Synthesis and Stereochemistry of Perhydropyridobenzoxazepines and of r-3a,t-11a,c-14a,t-14b,t-22a,t-22b-Perhydrodiquinodioxadiazacyclotetradecine
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Ring closure of the diastereoisomeric 2-decahydroquinolin-8-ylethanols with formaldehyde gave r-4a,c-7a,t-11a-, r-4a,t-7a,t-11a, and r-4a,c-7a,c-11a-perhydropyridobenzoxazepines, but instead of the fourth isomer a dimer, r-3a,t-11a,c-14a,t-14b,t-22a,t-22b-perhydrodiquinodioxadiazacyclotetradecine, was obtained.Comparison of 13C n.m.r. shifts of the conformationally locked isomers with those of perhydropyridooxazepine showed different average perhydro-1,3-oxazepine ring conformations in the various structures so that an estimate of the position of conformational equilibrium (CDCl3 solution) of the bicyclic compound from this data could not be made.The 13C n.m.r. spectrum of perhydropyridooxazepine in CDCl3-CFCl3, however, showed a ratio of ca. 5:1 trans-fused:O-inside-cis-fused conformers at -80 oC.
- Crabb, Trevor A.,Jupp, Philip A.
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- Asymmetric synthesis of myrioxazines A and B, novel alkaloids of Myrioneuron nutans
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Two new epimeric tricyclic alkaloids, myrioxazines A and B were isolated from the leaves of Myrioneuron nutans and their structures elucidated by spectral analysis (mass spectrometry and 2D NMR). Absolute configurations were determined by total asymmetric synthesis.
- Pham, Van Cuong,Jossang, Akino,Chiaroni, Angèle,Sévenet, Thierry,Bodo, Bernard
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- Convenient procedure for the α-methylation of simple pyridines
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A convenient and straightforward laboratory procedure is presented for a highly selective mono-α-methylation of pyridines without reactive functional groups. The methylating agent is probably carbon monoxide/dihydrogen generated in situ from a high-boiling alcohol on a metal surface. The reaction is catalyzed by a Raney nickel catalyst at ambient pressure, which renders the protocol practicable in standard organic laboratories. The intrinsically high reaction temperature and long reaction times restrict the application to pyridine derivatives with less reactive substituents. The outcome of the reaction can be rationalized by the assumption of a simple heterogeneous mechanism. Copyright Taylor & Francis Group, LLC.
- Broering, Martin,Kleeberg, Christian
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- ALKALOIDS OF Nitraria komarovii SYNTHESIS OF NITRARINE AND ISONITRARINE
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The natural alkaloids nitrarine and isonitrarine with the new heterocyclic system 14,21-ethano-16-azayohimban have been synthesized.
- Tulyganov, T. S.,Ibragimov, A. A.
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- Superacidic activation of quinoline and isoquinoline; their reactions with cyclohexane and benzene
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(Chemical Equation Presented) Quinoline (1) and isoquinoline (2), upon activation by strong acids, lead to intermediate N,C-diprotonated dications, which are involved in reactions with weak nucleophiles. Thus, 1 and 2 undergo selective ionic hydrogenation with cyclohexane in CF3SO 3H-SbF5, HBr-AlBr3-CH2Br 2, or HCl-AlCl3-CH2Cl2 acid systems to give their 5,6,7,8-tetrahydro derivatives. They also readily condense with benzene in the presence of HBr-AlBr3 or HCl-AlCl3 to provide 5,6,7,8-tetrahydro-5,7-diphenylquinoline (10) and 5,6,7,8-tetrahydro-6, 8-diphenylisoquinoline (12), respectively.
- Koltunov, Konstantin Yu.,Prakash, G.K. Surya,Rasul, Golam,Olah, George A.
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- Convenient synthesis of cobalt nanoparticles for the hydrogenation of quinolines in water
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Easily accessible cobalt nanoparticles are prepared by hydrolysis of NaBH4 in the presence of inexpensive Co(ii) salts. The resulting material is an efficient catalyst for the hydrogenation of quinoline derivatives in water. The activity and chemoselectivity of this catalyst are comparable to other cobalt-based heterogeneous catalysts.
- Beller, Matthias,Dorcet, Vincent,Fischmeister, Cedric,Hervochon, Julien,Junge, Kathrin
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- N-doped hierarchical porous carbon anchored tiny Pd NPs: A mild and efficient quinolines selective hydrogenation catalyst
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Chemoselective hydrogenation of quinolines is often subjected to the problems of leaching and poisoning of catalytic active site as well as harsh reaction conditions. Developing a novel and high-performance heterogeneous catalyst is of paramount importance yet a huge challenge. Herein, we report a facile and efficient strategy for preparing the large surface area and highly N-doped hierarchical porous carbon anchored tiny Pd NPs catalyst, in which the low-cost chitosan, nitrogen-rich ionic liquids are served as composite precursors and KZ molten salt as friendly pore-forming agent. And a series of Pd@CIL-T (C refers to chitosan, IL refers to ionic liquid, T = 600–900 °C) catalysts are successfully fabricated via pyrolyzing aforesaid composites at different temperatures followed by anchoring the highly dispersed and small-sized Pd NPs on their surface. Among all the prepared catalysts, Pd@CIL-900 exhibits the optimal catalytic performance towards the selective hydrogenation of quinoline under extremely mild conditions (0.6 mol% Pd, 0.1 MPa H2 and 50 °C). The kinetic experiments further reveal that such hydrogenation is subject to a pseudo-first order reaction and the apparent activation energy is as low as 41.1 kJ/mol, demonstrating excellent hydrogenation reaction rate. Moreover, the catalytic activity and selectivity are well maintained even after being reused for fifth reaction cycles.
- Zhang, Fengwei,Ma, Chunlan,Chen, Shuai,Zhang, Jianfei,Li, Zhihong,Zhang, Xian-Ming
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- Proton Magnetic Resonance Studies of Compounds with Bridgehead Nitrogen. Part 39. Stereochemistry of Perhydropyrido-benzoxazines and the Conformational Equilibrium for Perhydropyridooxazine
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The four diastereoisomeric perhydropyridobenzoxazines have been synthesised and their configurations assigned by 1H n.m.r. and i.r. spectroscopy and by kinetic studies of N-methylation.Comparisons of the 1H n.m.r. chemical shifts of proton α to nitrogen in these isomers suggested an equilibrium (CDCl3,25 deg C) for perhydropyridooxazine containing ca. 90percent of the trans-fused conformer.
- Crabb, Trevor A.,Turner, Christopher H.
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- Pyrolysis of Phenylalkylsulphonyl Azides and 2-Phenethyl Azidoformate. Selectivity of Sulphonylnitrenes and Contrast between Sulphonyl- and Carbonyl-nitrenes
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Flash vacuum pyrolysis and solution thermolysis of PhnSO2N3 indicate that intramolecular addition to the phenyl group is preferred in solution, provided that up to an eight-membered sultam ring is formed, otherwise side-chain insertion results, while in the gas phase the latter process is favoured when n = 4, 5, but not 3; some 5,6,7,8-tetrahydroquinoline is obtained when n = 3 at 990 deg C, but 2-phenethyl azidoformate gave monomeric tetrahydro-1,3-oxazinoazepin-2-one and 4-phenyloxazolidinone, but no dihydrocyclopentapyridine, even at 900 deg C.
- Abramovitch, Rudolph A.,Hendi, Shivakumar B.,Kress, Albert O.
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- Ruthenium nanoparticles supported on magnesium oxide: A versatile and recyclable dual-site catalyst for hydrogenation of mono- and poly-cyclic arenes, N-heteroaromatics, and S-heteroaromatics
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The development of catalysts capable of promoting hydrogenation of aromatics while being resistant to poisoning by nitrogen- and sulfur-containing species is of much interest in connection with hydrotreating of fossil fuels. We report a catalyst composed of ruthenium nanoparticles supported on magnesia, designed to promote heterolytic hydrogen splitting and surface ionic hydrogenation pathways. The catalyst, prepared through a one-pot procedure, promotes the hydrogenation of mono- and poly-cyclic arenes, as well as N- and S-heteroaromatics representative of fossil fuels components. Of particular significance are the superior activity and wider substrate scope of the catalyst, in relation to other known supported noble metals, and the excellent recyclability and long catalyst lifetime. Based on our experimental data, a dual-site catalyst structure and an associated dual-pathway mechanism are proposed, which may have interesting implications for the development of new poison-tolerant noble metal catalytic systems.
- Fang, Minfeng,Sanchez-Delgado, Roberto A.
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- RhNPs supported onN-functionalized mesoporous silica: effect on catalyst stabilization and catalytic activity
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Amine and nicotinamide groups grafted on ordered mesoporous silica (OMS) were investigated as stabilizers for RhNPs used as catalysts in the hydrogenation of several substrates, including carbonyl and aryl groups. Supported RhNPs on functionalized OMS were prepared by controlled decomposition of an organometallic precursor of rhodium under dihydrogen pressure. The resulting materials were characterized thoroughly by spectroscopic and physical techniques (FTIR, TGA, BET, SEM, TEM, EDX, XPS) to confirm the formation of spherical rhodium nanoparticles with a narrow size distribution supported on the silica surface. The use of nicotinamide functionalized OMS as a support afforded small RhNPs (2.3 ± 0.3 nm), and their size and shape were maintained after the catalyzed acetophenone hydrogenation. In contrast, amine-functionalized OMS formed RhNP aggregates after the catalytic reaction. The supported RhNPs could selectively reduce alkenyl, carbonyl, aryl and heteroaryl groups and were active in the reductive amination of phenol and morpholine, using a low concentration of the precious metal (0.07-0.18 mol%).
- Pulido-Díaz, Israel T.,Serrano-Maldonado, Alejandro,López-Suárez, Carlos César,Méndez-Ocampo, Pedro A.,Portales-Martínez, Benjamín,Gutiérrez-Alejandre, Aída,Salas-Martin, Karla P.,Guerrero-Ríos, Itzel
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p. 3289 - 3298
(2021/03/16)
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- Pincerlike manganese complex and preparation method thereof, related ligand and preparation method thereof, catalyst composition and application
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The invention discloses a pincerlike manganese complex, a preparation method thereof, a ligand for preparation, a preparation method of the ligand, a catalyst composition taking the complex as an active component and application of the catalyst composition. According to the pincerlike manganese complex, a cycloalkyl ring is introduced into a ligand framework, and by regulating and controlling the cyclic tension, flexibility and steric hindrance of the cycloalkyl ring, the reactivity and stability of the manganese metal center can be effectively adjusted, and the catalytic activity and substrate applicability of a manganese metal system are remarkably improved. The catalyst composition taking the pincerlike manganese complex as an active component has the advantages of high catalyst activity, wide substrate application range, mild reaction conditions and the like in the process of preparing quinoline or pyridine derivatives by catalyzing dehydrogenation coupling reaction of o-amino aromatic alcohol or gamma-amino alcohol, ketone or secondary alcohol; and the synthesis advantages of low cost and stable performance are embodied, the operation is simple, and the yield is high.
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Paragraph 0159-0165
(2021/07/31)
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- Direct synthesis of ring-fused quinolines and pyridines catalyzed byNNHY-ligated manganese complexes (Y = NR2or SR)
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Four cationic manganese(i) complexes, [(fac-NNHN)Mn(CO)3]Br (Mn-1-Mn-3) and [(fac-NNHS)Mn(CO)3]Br (Mn-4) (whereNNHis a 5,6,7,8-tetrahydro-8-quinolinamine moiety), have been synthesized and evaluated as catalysts for the direct synthesis of quinolines and pyridines by the reaction of a γ-amino alcohol with a ketone or secondary alcohol;NNHS-ligatedMn-4proved the most effective of the four catalysts. The reactions proceeded well in the presence of catalyst loadings in the range 0.5-5.0 mol% and tolerated diverse functional groups such as alkyl, cycloalkyl, alkoxy, chloride and hetero-aryl. A mechanism involving acceptorless dehydrogenation coupling (ADC) has been proposed on the basis of DFT calculations and experimental evidence. Significantly, this manganese-based catalytic protocol provides a promising green and environmentally friendly route to a wide range of synthetically important substituted monocyclic, bicyclic as well as tricyclicN-heterocycles (including 50 quinoline and 26 pyridine examples) with isolated yields of up to 93%.
- Han, Mingyang,Lin, Qing,Liu, Qingbin,Liu, Song,Ma, Ning,Solan, Gregory A.,Sun, Wen-Hua,Wang, Zheng,Yan, Xiuli
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p. 8026 - 8036
(2021/12/27)
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- Metal-Free Deoxygenation of Amine N-Oxides: Synthetic and Mechanistic Studies
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We report herein an unprecedented combination of light and P(III)/P(V) redox cycling for the efficient deoxygenation of aromatic amine N-oxides. Moreover, we discovered that a large variety of aliphatic amine N-oxides can easily be deoxygenated by using only phenylsilane. These practically simple approaches proceed well under metal-free conditions, tolerate many functionalities and are highly chemoselective. Combined experimental and computational studies enabled a deep understanding of factors controlling the reactivity of both aromatic and aliphatic amine N-oxides.
- Lecroq, William,Schleinitz, Jules,Billoue, Mallaury,Perfetto, Anna,Gaumont, Annie-Claude,Lalevée, Jacques,Ciofini, Ilaria,Grimaud, Laurence,Lakhdar, Sami
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p. 1237 - 1242
(2021/06/01)
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- Cu-Catalyzed Pyridine Synthesis via Oxidative Annulation of Cyclic Ketones with Propargylamine
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A Cu-catalyzed, easily scalable one-pot synthesis of fused pyridines by the reaction of cyclic ketones with propargylamine is described. The protocol was optimized based on the results of more than 30 experiments. The highest product yields were achieved in i-PrOH as a solvent in the presence of 5.0 mol % CuCl2 in air. In contrast to the well-known Au-catalyzed protocol, our procedure is "laboratory friendly", cost-effective, and suitable for preparing dozens of grams of fused pyridine-based building blocks and does not require a high-pressure autoclave technique. Decreasing the catalyst amount in the reaction to 1.25 mol % CuCl2 provided a yield comparable to that achieved with 5 mol % catalyst, though a longer reaction time was required. A plausible reaction mechanism was proposed. The scope and limitation of the reaction were studied using 24 different cyclic ketones as starting materials. The fused pyridine yield decreased among cyclic ketones in the following order: six-membered ? eight-membered > five-membered ～seven-membered. The elaborated reaction conditions demonstrated tolerance to a number of protective functional groups in ketone such as ester, tert-butoxycarbonyl (Boc)-protected amine, and acetal moieties.
- Sotnik, Svitlana O.,Subota, Andrii I.,Kliuchynskyi, Anton Y.,Yehorov, Dmytro V.,Lytvynenko, Anton S.,Rozhenko, Alexander B.,Kolotilov, Sergey V.,Ryabukhin, Sergey V.,Volochnyuk, Dmitriy M.
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p. 7315 - 7325
(2021/05/29)
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- Highly efficient one-pot multi-directional selective hydrogenation and N-alkylation catalyzed by Ru/LDH under mild conditions
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Atomic economy, non-toxicity, harmlessness and multidirectional selectivity advocated by green chemistry have increasingly become a hot and difficult research topic. Herein, we present a highly efficient, one-pot tandem and easy-to-operate method through which we could directly produce a broad range of multi-directional selective hydrogenated amines or N-alkyl aliphatic amines using aromatic nitro compounds as raw materials. Ru/LDH with characteristics of layered mesoporous structure, well dispersed small Ru nanoparticles and LDH stabilization to the Ru NPs was employed as the catalyst. It is remarkable that multi-directional superb chemoselectivity to aromatic amines, alicyclic amines as well as N-alkyl aliphatic amines could be achieved with excellent catalytic activity and recyclability by tuning reaction conditions over 5wt%Ru/LDH-2. Additionally, this catalytic system also exhibited attractive activity and multi-directional chemoselectivity in the hydrogenation of quinoline and its derivatives with solvents of different polarity. Chemoselectivity to 5,6,7,8-tetrahydroquinoline derivatives could reach as high as 95.6 %.
- Zhang, Sishi,Xu, Jie,Cheng, Hongmei,Zang, Cuicui,Sun, Bin,Jiang, Heyan,Bian, Fengxia
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supporting information
(2020/03/30)
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- Synthesis of Pyridines, Quinolines, and Pyrimidines via Acceptorless Dehydrogenative Coupling Catalyzed by a Simple Bidentate P^ N Ligand Supported Ru Complex
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A ruthenium hydrido chloride complex (1) supported by a simple, heteroleptic bidentate P^N ligand (L1) containing a diarylphosphine and a benzannulated phenanthridine donor arm is reported. In the presence of base, complex 1 catalyzes multicomponent reactions using alcohol precursors to produce structurally diverse molecules including pyridines, quinolines, and pyrimidines via acceptorless dehydrogenative coupling pathways. Notably, L1 does not bear readily (de)protonated Br?nsted acidic or basic groups common to transition metal catalysts capable of these sorts of transformations, suggesting metal-ligand cooperativity does not play a significant role in the catalytic reactivity of 1. A rare example of an η2-aldehyde adduct of ruthenium was isolated and structurally characterized, and its role in acceptorless dehydrogenative coupling reactions is discussed.
- Mondal, Rajarshi,Herbert, David E.
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supporting information
p. 1310 - 1317
(2020/04/15)
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- Hydrogenation of N-Heteroarenes Using Rhodium Precatalysts: Reductive Elimination Leads to Formation of Multimetallic Clusters
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A rhodium-catalyzed method for the hydrogenation of N-heteroarenes is described. A diverse array of unsubstituted N-heteroarenes including pyridine, pyrrole, and pyrazine, traditionally challenging substrates for hydrogenation, were successfully hydrogenated using the organometallic precatalysts, [(η5-C5Me5)Rh(N-C)H] (N-C = 2-phenylpyridinyl (ppy) or benzo[h]quinolinyl (bq)). In addition, the hydrogenation of polyaromatic N-heteroarenes exhibited uncommon chemoselectivity. Studies into catalyst activation revealed that photochemical or thermal activation of [(η5-C5Me5)Rh(bq)H] induced C(sp2)-H reductive elimination and generated the bimetallic complex, [(η5-C5Me5)Rh(μ2,η2-bq)Rh(η5-C5Me5)H]. In the presence of H2, both of the [(η5-C5Me5)Rh(N-C)H] precursors and [(η5-C5Me5)Rh(μ2,η2-bq)Rh(η5-C5Me5)H] converted to a pentametallic rhodium hydride cluster, [(η5-C5Me5)4Rh5H7], the structure of which was established by NMR spectroscopy, X-ray diffraction, and neutron diffraction. Kinetic studies on pyridine hydrogenation were conducted with each of the isolated rhodium complexes to identify catalytically relevant species. The data are most consistent with hydrogenation catalysis prompted by an unobserved multimetallic cluster with formation of [(η5-C5Me5)4Rh5H7] serving as a deactivation pathway.
- Kim, Sangmin,Loose, Florian,Bezdek, Máté J.,Wang, Xiaoping,Chirik, Paul J.
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p. 17900 - 17908
(2019/11/19)
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- Quinoline derivatives and its preparation method and in the application of neural protection in
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The invention discloses a quinoline derivative and its preparation method and in the application of neural protection in, quinoline derivatives of the formula is Wherein R1 , R2 , R3 , R4 Independently selected from - H, - F or - OCH3 . Anti-A β25 - 35 Induced PC12 cell protective action of injury the experimental results show that, in the dosage is 100μmol/L under the condition of, KL201, KL202 and KL208 with the survival rate of the model set of differences are statistical significance (p25 - 35 Induced neurotoxicity, obviously improve the survival rate of the cells, with nerve protection function, can be used as neuroprotective agents for more in-depth research.
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Paragraph 0024; 0028-0030
(2019/02/19)
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- Palladium acetate-catalyzed one-pot synthesis of mono- And disubstitued pyridines
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A Pd-catalyzed one-pot synthesis of mono- and disubstituted pyridines was developed. The substituted pyridines were obtained from ketones or an aldehyde and 1,3-diaminopropane using a combination of catalytic Pd(OAc)2 and Cu(OAc)2. High-concentration reaction conditions enabled this catalytic reaction to be acid-free.
- Mikami, Shunya,Toyota, Masahiro
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p. 1315 - 1321
(2019/08/01)
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- Selective hydrogenation of quinolines into 1,2,3,4-tetrahydroquinolines over a nitrogen-doped carbon-supported Pd catalyst
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In this study, we have developed a sustainable method for the hydrogenation of quinolines to 1,2,3,4-tetrahydroquinolines under mild conditions over a nitrogen-doped carbon-supported Pd catalyst with abundant porous structures (abbreviated as Pd/CN). The mesoporous structure of the nitrogen-doped carbon support was prepared by the pyrolysis of glucose and melamine using eutectic salts of KCl and ZnCl2 as the porogen. Due to the high nitrogen content in the support, Pd nanoparticles were homogeneously dispersed on the surface of nitrogen-doped carbon materials with an ultra-small size of 1.9 nm in a narrow size distribution. The as-prepared Pd/CN catalyst showed high catalytic activity towards the hydrogenation of quinolines at 50 °C and 20 bar H2, affording the corresponding 1,2,3,4-tetrahydroquinolines with yields in the range of 86.6-97.8%. More importantly, the Pd/CN catalyst was highly stable without the loss of its catalytic activity during the recycling experiments. The use of renewable resources to prepare the catalyst makes this method promising for the sustainable 1,2,3,4-tetrahydroquinolines from the hydrogenation of quinolines.
- Ren, Yongshen,Wang, Yanxin,Li, Xun,Zhang, Zehui,Chi, Quan
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p. 16694 - 16702
(2018/10/23)
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- STABILIZATION OF ACTIVE METAL CATALYSTS AT METAL-ORGANIC FRAMEWORK NODES FOR HIGHLY EFFICIENT ORGANIC TRANSFORMATIONS
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Metal-organic framework (MOFs) compositions based on post?synthetic metalation of secondary building unit (SBU) terminal or bridging OH or OH2 groups with metal precursors or other post-synthetic manipulations are described. The MOFs provide a versatile family of recyclable and reusable single-site solid catalysts for catalyzing a variety of asymmetric organic transformations, including the regioselective boryiation and siiylation of benzyiic C—H bonds, the hydrogenation of aikenes, imines, carbonyls, nitroarenes, and heterocycles, hydroboration, hydrophosphination, and cyclization reactions. The solid catalysts can also be integrated into a flow reactor or a supercritical fluid reactor.
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Paragraph 0349
(2019/01/07)
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- 2-furan aldehyde compounds and application to Alzheimer's disease drugs thereof
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The invention discloses a 2-furan aldehyde compound and application to Alzheimer's disease drugs thereof. The structural formula of the 2-furan aldehyde compound is shown in the specification, and inthe structural formula, R1, R2, R3 and R4 are each independently selected from the group consisting of -H, -F or -OCH3. A protective effect experiment result of A[beta][25-35]-induced PC12 cell injuryshows that the differences between the survival rate of a model group and the survival rates of FN201, FN202, FN208 and FN209 are statistically significant(p0.01) at a dose of 50 [mu]mol/L. Therefore, the experiment result proves that compared with the model group, the compound of the present invention can significantly reduce the neurotoxicity induced by A[beta][25-35], the cell survival rate is obviously improved, and the compound has a neuroprotective effect, can be used as a neuroprotective agent for further research, and can also be used as a therapeutic and/or a more in-depth study ofdrugs to prevent Alzheimer's disease.
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Paragraph 0025; 0029; 0030; 0031
(2019/01/05)
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- Quinoline derivative with neuroprotective effect and preparation method of quinoline derivative
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The invention discloses a quinoline derivative with a neuroprotective effect and a preparation method of the quinoline derivative. The quinoline derivative has a structural formula as shown in the specification. In the formula, R1, R2, R3 and R4 are respectively independently selected from -H, -F or -OH. Experimental results of protective effects on anti-Abeta 25-35 induced PC12 cellular damage show that under the condition that the dosage of compounds in an experimental group is 50umol/L, the survival rate differences of KL301, KL303 and KL306 and the model group have statistical significance(p0.01). Compared with the model group, the compound disclosed by the invention has the advantages that the Abeta 25-35 induced neurotoxicity can be obviously reduced, the cell survival rate is obviously improved, and the compound has the neuroprotective effect, can serve as a neuroprotective agent for in-depth study, and can serve as a medicine for treating and/or preventing Alzheimer's diseasefor more in-depth study.
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Paragraph 0028-0030
(2019/01/08)
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- Synthesis of Arylamines via Non-Aerobic Dehydrogenation Using a Palladium/Carbon-Ethylene System
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The reaction of cyclohexanones with amines proceeded under an ethylene atmosphere in the presence of a catalytic amount of palladium/carbon to afford a variety of arylamines in good to high yields. The present reaction was carried out under completely non-aerobic conditions, and which is in contrast with the previously reported aerobic system. has wide applicability affording a variety of aromatic amines, and co-product of the reaction is only gaseous ethane. Thus, this method is environmentally friendly. This protocol was applied intramolecularly to provide a novel method for the construction of quinoline and isoquinoline compounds. (Figure presented.).
- Shimomoto, Yuya,Matsubara, Ryosuke,Hayashi, Masahiko
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supporting information
p. 3297 - 3305
(2018/08/07)
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- NHC-stabilised Rh nanoparticles: Surface study and application in the catalytic hydrogenation of aromatic substrates
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New Rh-NPs stabilised by N-Heterocyclic Carbenes (NHC) were synthesized by decomposition of [Rh(η3-C3H5)3] under H2 atmosphere and fully characterized. Surface studies by FT-IR and NMR spectroscopy employing isotopically labelled ligands were also performed. The Rh0.2 NPs are active catalysts in the reduction of various aromatic substrates. In the reduction of phenol, high selectivities to cyclohexanone or cyclohexanol were obtained depending on the reaction conditions. However, this catalytic system exhibited much lower activity in the hydrogenation of substituted phenols. Pyridine was easily hydrogenated under mild conditions and interestingly, the hydrogenation of 4-methyl and 4-trifluoromethylpyridine resulted slower than that of 2-methylpyridine. The hydrogenation of 1-(pyridin-2-yl)propan-2-one provided the β-enaminone 13a in high yield as a consequence of the partial reduction of the pyridine ring followed by isomerization. Quinoline could be either partially hydrogenated to 1,2,3,4-tetrahydroquinoline or fully reduced to decahydroquinoline by adjusting the reaction conditions.
- Martinez-Espinar, Francisco,Blondeau, Pascal,Nolis, Pau,Chaudret, Bruno,Claver, Carmen,Castillón, Sergio,Godard, Cyril
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p. 113 - 127
(2017/09/08)
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- Uncoordinated Amine Groups of Metal-Organic Frameworks to Anchor Single Ru Sites as Chemoselective Catalysts toward the Hydrogenation of Quinoline
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Here we report a precise control of isolated single ruthenium site supported on nitrogen-doped porous carbon (Ru SAs/N-C) through a coordination-assisted strategy. This synthesis is based on the utilization of strong coordination between Ru3+ and the free amine groups (-NH2) at the skeleton of a metal-organic framework, which plays a critical role to access the atomically isolated dispersion of Ru sites. Without the assistance of the amino groups, the Ru precursor is prone to aggregation during the pyrolysis process, resulting in the formation of Ru clusters. The atomic dispersion of Ru on N-doped carbon can be verified by the spherical aberration correction electron microscopy and X-ray absorption fine structure measurements. Most importantly, this single Ru sites with single-mind N coordination can serve as a semihomogeneous catalyst to catalyze effectively chemoselective hydrogenation of functionalized quinolones.
- Wang, Xin,Chen, Wenxing,Zhang, Lei,Yao, Tao,Liu, Wei,Lin, Yue,Ju, Huanxin,Dong, Juncai,Zheng, Lirong,Yan, Wensheng,Zheng, Xusheng,Li, Zhijun,Wang, Xiaoqian,Yang, Jian,He, Dongsheng,Wang, Yu,Deng, Zhaoxiang,Wu, Yuen,Li, Yadong
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supporting information
p. 9419 - 9422
(2017/07/24)
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- Single-Site Cobalt Catalysts at New Zr8(μ2-O)8(μ2-OH)4 Metal-Organic Framework Nodes for Highly Active Hydrogenation of Alkenes, Imines, Carbonyls, and Heterocycles
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We report here the synthesis of robust and porous metal-organic frameworks (MOFs), M-MTBC (M = Zr or Hf), constructed from the tetrahedral linker methane-tetrakis(p-biphenylcarboxylate) (MTBC) and two types of secondary building units (SBUs): cubic M8(μ2-O)8(μ2-OH)4 and octahedral M6(μ3-O)4(μ3-OH)4. While the M6-SBU is isostructural with the 12-connected octahedral SBUs of UiO-type MOFs, the M8-SBU is composed of eight MIV ions in a cubic fashion linked by eight μ2-oxo and four μ2-OH groups. The metalation of Zr-MTBC SBUs with CoCl2, followed by treatment with NaBEt3H, afforded highly active and reusable solid Zr-MTBC-CoH catalysts for the hydrogenation of alkenes, imines, carbonyls, and heterocycles. Zr-MTBC-CoH was impressively tolerant of a range of functional groups and displayed high activity in the hydrogenation of tri- and tetra-substituted alkenes with TON > 8000 for the hydrogenation of 2,3-dimethyl-2-butene. Our structural and spectroscopic studies show that site isolation of and open environments around the cobalt-hydride catalytic species at Zr8-SBUs are responsible for high catalytic activity in the hydrogenation of a wide range of challenging substrates. MOFs thus provide a novel platform for discovering and studying new single-site base-metal solid catalysts with enormous potential for sustainable chemical synthesis.
- Ji, Pengfei,Manna, Kuntal,Lin, Zekai,Urban, Ania,Greene, Francis X.,Lan, Guangxu,Lin, Wenbin
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supporting information
p. 12234 - 12242
(2016/09/28)
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- Preparation and characterization of NiW supported on Al-modified MCM-48 catalyst and its high hydrodenitrogenation activity and stability
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Al-containing MCM-48 with different Si/Al ratios and aluminum free MCM-48 materials were successfully prepared with hexadecyl trimethyl ammonium bromide (CTAB) and poly(ethylene oxide) poly(propylene oxide)-poly(ethylene oxide) triblock copolymer (P123) as a co-template. A series of characterizations show that both the supports and the NiW supported catalysts are highly ordered. The acid strength of the supports is enhanced when Al is introduced and when its content is increased. The acid amount and strength is further improved by supporting the NiW species. The oxide precursors show a high degree of sulfidation under mild sulfidation conditions. The activity of the Al-modified catalysts for quinoline hydrodenitrogenation (HDN) is much higher than that of aluminum free NiW/MCM-48 and NiW/γ-Al2O3 catalysts. The addition of CS2 to the feed could boost the conversion of quinoline HDN and change the product distribution due to modification of the active site distribution of hydrogenation and C-N bond cleavage. Moreover, the stability of the resulting catalysts was also investigated, and no dramatic decrease in HDN conversion was observed in 960 h, which suggests that they could be candidates for industrial HDN catalysts.
- Shao, Mingqiang,Cui, Haitao,Guo, Shaoqing,Zhao, Liangfu,Tan, Yisheng
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p. 61747 - 61757
(2016/07/11)
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- A Ruthenium Catalyst with Unprecedented Effectiveness for the Coupling Cyclization of - Amino Alcohols and Secondary Alcohols
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The ruthenium complex (8-(2-diphenylphosphinoethyl)aminotrihydroquinolinyl)(carbonyl)(hydrido)ruthenium chloride exhibited extremely high efficiency toward the coupling cyclization of -amino alcohols with secondary alcohols. The corresponding products, pyridine or quinoline derivatives, are obtained in good to high isolated yields. On comparison with literature catalysts whose noble-metal loading with respect to -amino alcohols reached 0.5-1.0 mol % for Ru and a record lowest of 0.04 mol % for Ir, the current catalyst achieves the same efficiency with a loading of 0.025 mol % for Ru. The mechanism of acceptorless dehydrogenative condensation (ADC) was proposed on the basis of DFT calculations; in addition, the reactive intermediates were determined by GC-MS, NMR, and single-crystal X-ray diffraction. The catalytic process is potentially suitable for industrial applications.
- Pan, Bing,Liu, Bo,Yue, Erlin,Liu, Qingbin,Yang, Xinzheng,Wang, Zheng,Sun, Wen-Hua
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p. 1247 - 1253
(2016/02/18)
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- Tuning the chemoselective hydrogenation of aromatic ketones, aromatic aldehydes and quinolines catalyzed by phosphine functionalized ionic liquid stabilized ruthenium nanoparticles
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Ruthenium nanoparticles (Ru NPs) stabilized by phosphine-functionalized ionic liquids (PFILs) were synthesized in an imidazolium-based ionic liquid using H2 as a reductant. Characterization showed well-dispersed particles of about 2.2 nm (TEM) and confirmed the PFIL stabilization of the Ru NPs (NMR). The Ru NPs stabilized by PFILs exhibited excellent activity and switchable chemoselectivity in the heterogeneous selective hydrogenation of aromatic ketones, aromatic aldehydes and quinolines under mild conditions.
- Jiang, He-Yan,Zheng, Xu-Xu
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p. 3728 - 3734
(2015/07/07)
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- Phosphine-functionalized ionic liquid-stabilized rhodium nanoparticles for selective hydrogenation of aromatic compounds
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Phosphine-functionalized, ionic liquid-stabilized rhodium nanoparticles with an average size of about 3.5 nm are very active catalysts for the selective hydrogenation of aromatic compounds, including quinoline and its analogues, and aromatic nitro compounds. Their catalytic performance complements that of classic homogeneous and heterogeneous rhodium catalysis.
- Jiang, He-Yan,Zheng, Xu-Xu
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p. 118 - 123
(2015/09/28)
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- Catalytic asymmetric hydrogenation of quinoline carbocycles: Unusual chemoselectivity in the hydrogenation of quinolines
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The reduction of quinolines selectively took place on their carbocyclic rings to give 5,6,7,8-tetrahydroquinolines, when the hydrogenation was conducted in the presence of a Ru(η3-methallyl)2(cod)-PhTRAP catalyst. The chiral ruthenium catalyst converted 8-substituted quinolines into chiral 5,6,7,8-tetrahydroquinolines with up to 91:9 er. This journal is
- Kuwano, Ryoichi,Ikeda, Ryuhei,Hirasada, Kazuki
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supporting information
p. 7558 - 7561
(2015/05/04)
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- γ-Al2O3-supported and unsupported (Ni)MoS 2 for the hydrodenitrogenation of quinoline in the presence of dibenzothiophene
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Supported MoS2/γ-Al2O3 and Ni-MoS2/γ-Al2O3 as well as unsupported Ni-MoS2 were investigated in the hydrodenitrogenation (HDN) of quinoline in the presence of dibenzothiophene (DBT). The supported oxide catalyst precursors had a well-dispersed amorphous polymolybdate structure that led to the formation of a highly dispersed sulfide phase. In contrast, the unsupported catalyst precursor consisted of a mixture of nickel molybdate and ammonium nickel molybdate phases that formed stacked sulfide slabs after sulfidation. On all catalysts, the reaction pathway for the removal of N in quinoline HDN mainly followed the sequence quinoline→1,2,3,4- tetrahydroquinoline→decahydroquinoline→propylcyclohexylamine→ propylcyclohexene→propylcyclohexane. The hydrodesulfurization of DBT proceeded mainly by direct desulfurization towards biphenyl. For both processes, the activity increased in the order MoS2/γ-Al 2O32/unsupported2/γ-Al2O3. The promotion of the MoS 2 phase with Ni enhances the activity of the unsupported catalyst to a greater extent than the supported one. However, the multiply stacked unsupported Ni-MoS2 exhibited lower rates than Ni-MoS 2/γ-Al2O3 because of its lower dispersion. I want to break free (from your nitrogen): Ni and Al 2O3 exert particular effects on the physicochemical and kinetic features of molybdenum oxide species and the corresponding MoS 2 phase. The support maximizes the concentration of active sites, whereas the promoter changes their intrinsic activity. In turn, the support also influences the promotion mechanism. Copyright
- Hein, Jennifer,Hrabar, Ana,Jentys, Andreas,Gutierrez, Oliver Y.,Lercher, Johannes A.
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p. 485 - 499
(2014/03/21)
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- Copper-catalyzed aerobic synthesis of 2-arylpyridines from acetophenones and 1,3-diaminopropane
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A copper-catalyzed reaction providing direct access to 2-arylpyridines from acetophenones and 1,3-diaminopropane is described. A range of electronically diverse acetophenones undergo this transformation, affording 2-arylpyridines in good yields. (Chemical Equation Presented).
- Xi, Long-Yi,Zhang, Ruo-Yi,Liang, Shuai,Chen, Shan-Yong,Yu, Xiao-Qi
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supporting information
p. 5269 - 5271
(2015/01/09)
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- Competitive hydrodesulfurization of dibenzothiophene and hydrodenitrogenation of quinoline over unsupported MoS2 catalyst
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The hydrodesulfurization of dibenzothiophene and the hydrodenitrogenation of quinoline were investigated both individually and simultaneously as a mixture over an unsupported synthetic MoS2 catalyst. The reactions were carried out in a batch system under 3 MPa H2 at 340 C. Investigations toward the effect of H2S on the hydrodenitrogenation reaction of quinoline revealed that H2S promoted the transformation of 1,2,3,4-tetrahydroquinoline (THQ1) to ortho-propylaniline (OPA), but had a considerable adverse impact on the transformation of OPA to propylbenzene and its derivatives (C9 products). The hydrodesulfurization of dibenzothiophene proceeded predominantly through a hydrogenation pathway to give cyclohexylbenzene. The hydrodesulfurization of dibenzothiophene was found to be completely inhibited during the initial stages of the reaction, when quinoline was added into the feedstock. The inhibition of the reaction persisted until the quinoline was transformed to a sufficiently low level. Thereafter, the hydrodesulfurization of dibenzothiophene recovered and the reaction proceeded with only moderate inhibition. In contrast, the hydrodenitrogenation of quinoline was significantly enhanced by the presence of dibenzothiophene in the reaction feedstock. The THQ1 and C9 products were the main species obtained from the hydrodenitrogenation reaction of quinoline. The presence of dibenzothiophene enhanced the activity and selectivity toward C9 productions. These results suggested that at least two types of active site were involved in the reaction. Dibenzothiophene could interact with distinct coordinative unsaturated sites, and this could stabilize and increase the acidity of the potential active sites assumed to be responsible for the hydrodenitrogenation reactions.
- Farag, Hamdy,Kishida, Masahiro,Al-Megren, Hamid
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p. 173 - 182
(2013/11/19)
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- NanoRu@hectorite: A heterogeneous catalyst with switchable selectivity for the hydrogenation of quinoline Dedicated to Professor Irina Petrovna Beletskaya in recognition of her contributions to the field of metal-catalysed reactions.
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A versatile nano-structured catalyst composed of ruthenium nanoparticles intercalated in hectorite (nanoRu@hectorite) catalyzes the hydrogenation of quinoline (100 C, 30-60 bar H2) with switchable selectivity: In water, 1,2,3,4-tetrahydroquinoline is formed with yields >99%, while in cyclohexane the fully hydrogenated decahydroquinoline is obtained with yields >99%, the mean turnover frequencies being 222 h-1 and 89 h -1, respectively. The reaction in cyclohexane proceeds via both intermediates, 1,2,3,4-tetrahydroquinoline and 5,6,7,8-tetrahydroquinoline.
- Sun, Bing,Khan, Farooq-Ahmad,Vallat, Armelle,Süss-Fink, Georg
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p. 310 - 314
(2013/09/12)
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- Direct synthesis of pyridines and quinolines by coupling of γ-amino-alcohols with secondary alcohols liberating H2 catalyzed by ruthenium pincer complexes
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A novel, one-step synthesis of substituted pyridine- and quinoline-derivatives was achieved by acceptorless dehydrogenative coupling of γ-aminoalcohols with secondary alcohols. The reaction involves consecutive C-N and C-C bond formation, catalyzed by a bipyridyl-based ruthenium pincer complex with a base.
- Srimani, Dipankar,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 6632 - 6634
(2013/07/26)
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- An efficient one pot transfer hydrogenation and N-alkylation of quinolines with alcohols mediated by Pd/C/Zn
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A Pd/C/Zn mixture with alcohols has been revealed to be an efficient transfer hydrogenation system to quinolines. Furthermore, the metals mixture is able to activate alcohols as N-alkylating agents in a hydrogen autotransfer process. 1,2,3,4-Tetrahydroquinolines and N-alkylated tetrahydroquinolines from quinolines have been obtained with excellent yields in one step.
- Abarca, Belen,Adam, Rosa,Ballesteros, Rafael
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p. 1826 - 1833
(2012/04/23)
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- Hydrogenation of arenes and N-heteroaromatic compounds over ruthenium nanoparticles on poly(4-vinylpyridine): A versatile catalyst operating by a substrate-dependent dual site mechanism
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A nanostructured catalyst composed of Ru nanoparticles immobilized on poly(4-vinylpyridine) (PVPy) has been synthesized by NaBH4 reduction of RuCl3·3H2O in the presence of the polymer in methanol at room temperature. TEM measurements show well-dispersed Ru nanoparticles with an average diameter of 3.1 nm. Both powder XRD patterns and XPS data indicate that the Ru particles are predominantly in the zerovalent state. The new catalyst is efficient for the hydrogenation of a wide variety of aromatic hydrocarbons and N-heteroaromatic compounds representative of components of petroleum-derived fuels. The experimental data indicate the existence of two distinct active sites in the nanostructure that lead to two parallel hydrogenation pathways, one for simple aromatics involving conventional homolytic hydrogen splitting on Ru and a second one for N-heteroaromatics taking place via a novel heterolytic hydrogen activation on the catalyst surface, assisted by the basic pyridine groups of the support.
- Fang, Minfeng,MacHalaba, Nataliya,Sanchez-Delgado, Roberto A.
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experimental part
p. 10621 - 10632
(2011/11/29)
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- Inverse electron demand diels-alder reactions of 1,2,3-triazines: Pronounced substituent effects on reactivity and cycloaddition scope
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A systematic study of the inverse electron demand Diels-Alder reactions of 1,2,3-triazines is disclosed, including an examination of the impact of a C5 substituent. Such substituents were found to exhibit a remarkable impact on the cycloaddition reactivity of the 1,2,3-triazine without altering, and perhaps even enhancing, the intrinsic cycloaddition regioselectivity. The study revealed not only that the reactivity may be predictably modulated by a C5 substituent (R = CO2Me > Ph > H) but also that the impact is of a magnitude to convert 1,2,3-triazine (1) and its modest cycloaddition scope into a heterocyclic azadiene system with a reaction scope that portends extensive synthetic utility, expanding the range of participating dienophiles. Significantly, the studies define a now powerful additional heterocyclic azadiene, complementary to the isomeric 1,2,4-triazines and 1,3,5-triazines, capable of dependable participation in inverse electron demand Diels-Alder reactions, extending the number of complementary heterocyclic ring systems accessible with implementation of the methodology.
- Anderson, Erin D.,Boger, Dale L.
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supporting information; experimental part
p. 12285 - 12292
(2011/09/16)
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- Ni2P and CoP catalysts prepared from phosphite-type precursors for HDS-HDN competitive reactions
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Silica-supported nickel and cobalt phosphide catalysts were synthesized with low metal-loading (5 wt%). The formation of Ni2P and CoP phases was achieved by temperature-programmed reduction of phosphite-based precursors, Ni(HPO3H)2 and Co(HPO3H)2, respectively. The catalysts were characterized by X-ray fluorescence (XRFS), N2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and elemental analysis (CNHS). These catalysts were tested in the individual reactions of hydrodesulfurization (HDS) of dibenzothiophene (DBT) and hydrodenitrogenation (HDN) of quinoline (Q), and also in the simultaneous HDS and HDN reactions. These tests were conducted by feeding 3000 ppm of DBT or 3000 ppm of Q. Additional tests were performed with the aim to evaluate S-removal capability by keeping constant Q concentration in the feed (3000 ppm) and varying DBT concentration (200 and 2000 ppm). The catalytic results show that these phosphide catalysts achieve high DBT and Q conversion values at high temperatures though the rate of HDS reaction is higher than that of HDN. In all cases Ni2P is more active than CoP. Moreover, the presence of N-containing molecules in the feed does not affect the S-removal as sulfur is almost completely removed after 48 h on-stream.
- Infantes-Molina,Cecilia,Pawelec,Fierro,Rodríguez-Castellón,Jiménez-López
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scheme or table
p. 253 - 263
(2011/12/21)
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- 6, 7 -DIHYDRO- 5H- PYRROLO [3, 4-D] PYRIMIDIN-4-YL] -QUINOLIN-3 -YLAMINE COMPOUNDS USEFUL AS FAAH MODULATORS AND USES THEREOF
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Compounds are disclosed that have formula I: where A, B, L1, W, Y, R1, and R3 are as defined herein. The compounds and pharmaceutical compositions thereof are useful for the prevention and treatment of a variety of conditions in mammals including humans, including by way of non- limiting example, pain, anxiety, depression, inflammation, cognitive disorders, weight and eating disorders, Parkinson's disease, Alzheimer's disease, spasticity, addiction, glaucoma, and others.
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Page/Page column 63
(2010/07/10)
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- A new type of nonsulfide hydrotreating catalyst: Nickel phosphide on carbon
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Nickel phosphide on carbon is successfully synthesized by temperature-programmed reduction as verified with X-ray diffraction and extended X-ray absorption fine structure measurements; it shows superior activity, selectivity, and stability for sulfur removal from the refractory compound 4,6-dimethyldibenzothiophene with a steady-state conversion of 99%, which is much higher than that of a commercial NiMoS/γ-Al2O3 catalyst of 68%. The Royal Society of Chemistry 2005.
- Shu, Yuying,Oyama, S. Ted
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p. 1143 - 1145
(2007/10/03)
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- Thermal hydrogenolysis of nitrogen-containing (hetero)arenes at elevated temperature and pressure
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The behaviour of the aromatic nitrogen derivatives pyridine P and quinoline Q - and for comparison benzonitrile and azobenzene - was studied under elevated pressure (20 to 30 bar) in a flow reactor with an atmosphere of hydrogen at temperatures ranging from 773 to 1173 K. Compounds were introduced into the reactor admixed with benzene. Efficient removal of the heteroelement was observed, accompanied by deep gasification of the carbon skeletons, at higher temperatures. P reacts much faster than benzene, while Q is a little less reactive than P. The main products were methane, hydrogen cyanide and ammonia. Mechanisms are discussed based on induced decomposition by hydrogen atoms. The facile reaction of P is explained by hydrogen abstraction to give the 2-pyridyl radical followed by ring opening, a reaction with much better thermochemistry than that for benzene and the phenyl radical. Reaction via (partially) hydrogenated intermediates may also play a part. Exocyclic nitrogen - such as in benzonitrile - is readily displaced by hydrogen, while for azobenzene spontaneous fission of the rather weak C-N bond is the major rate- (and product-) determining step. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Cieplik, Mariusz K.,Louw, Robert
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p. 3011 - 3016
(2007/10/03)
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- A comparison between silica-immobilized ruthenium(II) single sites and silica-supported ruthenium nanoparticles in the catalytic hydrogenation of model hetero- and polyaromatics contained in raw oil materials
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HDS and HDN are very important hydrotreating reactions that remove sulfur and nitrogen from fossil fuels where they are contained in various organic compounds, which include polyaromatic heterocycles, aliphatic and aromatic thiols and amines, thioethers, disulfides, and nitriles. A comparative study of the hydrogenation of various heterocycles, model compounds in raw oil materials, by either Ru(II) complex immobilized on mesoporous silica or Ru(0) nanoparticles deposited on the same support was conducted. The single-site catalyst contained the molecular precursor [Ru(NCMe)3(sulphos)](OSO2 CF3) tethered to partially dehydroxylated high-surface-area silica through hydrogen bonds between silanol groups of the support and SO3- groups from the sulphos ligand [-O3S(C6H4) CH2C(CH2PPh2)3] and the triflate counter anion. The heterocycles (benzo[b]thiophene, quinoline, indole, acridine) were hydrogenated to cyclic thioethers or amines. Ru(II)-based catalysts were much more efficient for the hydrogenation of S-heterocycles than for N-heterocycles.
- Bianchini, Claudio,Dal Santo, Vladimiro,Meli, Andrea,Moneti, Simonetta,Moreno, Marta,Oberhauser, Werner,Psaro, Rinaldo,Sordelli, Laura,Vizza, Francesco
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- Photocycloaddition of four-carbon-tethered pyridones. Intramolecular hydrogen bonding and facilitated amide hydrolysis by a proximal secondary alcohol
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Four-carbon-tethered pyridones undergo photocycloaddition to give exclusively trans-[4 + 4] products. The presence of a tether alcohol engenders a solvent-dependent diastereoselectivity for the cycloaddition by intramolecular hydrogen bonding to the adjacent pyridone. Following cycloaddition, the alcohol can deliver a carbonyl group to the proximal, hindered amide nitrogen, leading to a very facile amide hydrolysis.
- Zhu, Man,Qiu, Zhilei,Hiel, Gary P.,Sieburth, Scott McN.
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p. 3487 - 3493
(2007/10/03)
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- Synthesis of pyridine and isoquinoline derivatives by the palladium-catalyzed cyclization of olefinic ketone O-pentafluorobenzoyloximes
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Pyridines and isoquinolines are synthesized from olefinic ketone O-pentafluorobenzoyloximes by treatment with a catalytic amount of Pd(PPh3)4 in the presence of (n-Bu)4NCl and triethylamine.
- Tsutsui, Hironori,Narasaka, Koichi
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p. 526 - 527
(2007/10/03)
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