- Catalysis of polymer-protected Ni/Pd bimetallic nano-clusters for hydrogenation of nitrobenzene derivatives
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Poly(N-vinyl-2-pyrrolidone)-protected Ni/Pd bimetallic colloidal nanoparticles, prepared by the polyol reduction method, have been proved to have a nanometer-sized alloy structure with both metals at zerovalent state by our previous study of TEM, XRD, EXAFS, and XPS analyses. Here, dispersions of these bimetallic nanoclusters with different composition ratios are extensively examined as catalysts for the hydrogenation of various nitrobenzene derivatives: i.e., p-nitrotoluene, p-nitroanisole, 1- nitronaphthalene, p-nitrobenzonitrile, and methyl p-nitrobenzoate, at 30 °C under an atmospheric pressure of hydrogen. These bimetallic nanoclusters exhibit excellent catalytic properties for the reduction of a nitro group to an amino group with high selectivity. The catalytic activity strongly depends on the metal composition of the particles. The maximum catalytic activity can be observed at a certain intermediate composition ratio, being 3-4 times greater than that of a monometallic colloidal Pd catalyst. A bimetallic nanocluster with the mole ratio of Ni: Pd = 1/4 was the most active catalyst for the hydrogenation of para-substituted nitrobenzenes. An approximately linear relationship exists between the hydrogenation rate of the substrate with an electron-donating or electron-withdrawing group and the corresponding Hammett constant of the substituent, as well as between the hydrogenation rate and the LUMO energy level of the substrate.
- Lu, Ping,Toshima, Naoki
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Read Online
- A State-of-the-Art Heterogeneous Catalyst for Efficient and General Nitrile Hydrogenation
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Cobalt-doped hybrid materials consisting of metal oxides and carbon derived from chitin were prepared, characterized and tested for industrially relevant nitrile hydrogenations. The optimal catalyst supported onto MgO showed, after pyrolysis at 700 °C, magnesium oxide nanocubes decorated with carbon-enveloped Co nanoparticles. This special structure allows for the selective hydrogenation of diverse and demanding nitriles to the corresponding primary amines under mild conditions (e.g. 70 °C, 20 bar H2). The advantage of this novel catalytic material is showcased for industrially important substrates, including adipodinitrile, picolinonitrile, and fatty acid nitriles. Notably, the developed system outperformed all other tested commercial catalysts, for example, Raney Nickel and even noble-metal-based systems in these transformations.
- Formenti, Dario,Mocci, Rita,Atia, Hanan,Dastgir, Sarim,Anwar, Muhammad,Bachmann, Stephan,Scalone, Michelangelo,Junge, Kathrin,Beller, Matthias
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supporting information
p. 15589 - 15595
(2020/10/02)
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- Cobalt pincer complexes for catalytic reduction of nitriles to primary amines
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Various cobalt pincer type complexes 1-6 were applied for the catalytic hydrogenation of nitriles to amines. Among these, catalyst 4 is the most efficient, allowing the reduction of aromatic as well as aliphatic nitriles in moderate to excellent yields.
- Schneek?nig, Jacob,Tannert, Bianca,Hornke, Helen,Beller, Matthias,Junge, Kathrin
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p. 1779 - 1783
(2019/04/27)
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- Mild palladium-catalysed highly efficient hydrogenation of CN, C-NO2, and CO bonds using H2 of 1 atm in H2O
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Here we present the first example of a mild and high-efficiency protocol enabling a process in water using 1 atm of H2 for the efficient and selective hydrogenation of nitriles, nitro compounds, ketones, and aldehydes to yield primary amines and alcohols with satisfactory yields of up to >99%. Several palladium-based nanoparticle catalysts were prepared from K2PdCl4 and ligands, and one of them was found to be the best and most suitable for the hydrogenation of CN, C-NO2, and CO bonds. In addition, the catalyst Pd-NPs can be easily recycled and reused without losing their activity and selectivity. A plausible mechanism for the hydrogenation of a CN bond was also proposed, representing the first example that possesses great potential for sustainable industrial purposes.
- Liu, Yaxu,He, Shaopo,Quan, Ziyi,Cai, Huizhuo,Zhao, Yang,Wang, Bo
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supporting information
p. 830 - 838
(2019/02/27)
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- A ppm level Rh-based composite as an ecofriendly catalyst for transfer hydrogenation of nitriles: Triple guarantee of selectivity for primary amines
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Hydrogenation of nitriles to afford amines under mild conditions is a challenging task with an inexpensive heterogeneous catalyst, and it is even more difficult to obtain primary amines selectively because of the accompanying self-coupling side reactions. An efficient catalytic system was designed as Fe3O4@nSiO2-NH2-RhCu@mSiO2 to prepare primary amines through the transfer hydrogenation of nitrile compounds with economical HCOOH as the hydrogen donor. The loading of rhodium in the catalyst could be at the ppm level, and the TOF reaches 6803 h-1 for Rh. This catalytic system has a wide substrate range including some nitriles that could not proceed in the previous literature. The experimental results demonstrate that the excellent selectivity for primary amines is guaranteed by three tactics, which are the strong active site, the inhibition of side products by the hydrogen source and the special pore structure of the catalyst. In addition, the catalyst could be reused ten times without activity loss through convenient magnetic recovery.
- Liu, Lei,Li, Jifan,Ai, Yongjian,Liu, Yuhong,Xiong, Jialiang,Wang, Hongdong,Qiao, Yijun,Liu, Wenrui,Tan, Shanchao,Feng, Shaofei,Wang, Kunpeng,Sun, Hongbin,Liang, Qionglin
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p. 1390 - 1395
(2019/03/26)
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- Preparation of a magnetic mesoporous Fe3O4-Pd@TiO2 photocatalyst for the efficient selective reduction of aromatic cyanides
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Herein, a hierarchical magnetic mesoporous microsphere was successfully prepared as a photocatalyst via a simple and reproducible route. Typically, Pd nanoparticles (NPs) were evenly dispersed on the surface of a magnetic Fe3O4 microsphere and then coated with a porous anatase-TiO2 shell to form Fe3O4-Pd@TiO2. The core-shell structure could efficiently suppress the conglomeration of Pd NPs during the calcination process at high temperatures as well as the shedding of Pd during the catalytic reaction process in the liquid phase. The as-prepared photocatalyst was characterized by TEM, XRD, XPS, VSM, and N2 adsorption-desorption. Fe3O4-Pd@TiO2 exhibits high photocatalytic activity for the selective reduction of aromatic cyanides to aromatic primary amines in an acidic aqueous solution. Moreover, this magnetic photocatalyst could be easily recovered from the reaction mixture by an external magnet and reused five times without significant reduction in its activity. The superior photocatalytic efficiency of the proposed photocatalyst may be attributed to its high charge separation efficiency and charge transfer rate, which are caused by the Schottky junction and large interface area. The results indicate that the strategy of coating the active noble metal sites with a mesoporous semiconductor shell has a significant potential for application in metal-semiconductor-based photocatalytic reactions.
- Zhao, Ziming,Long, Yu,Luo, Sha,Wu, Wei,Ma, Jiantai
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p. 6294 - 6302
(2019/04/25)
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- Old Concepts, New Application – Additive-Free Hydrogenation of Nitriles Catalyzed by an Air Stable Alkyl Mn(I) Complex
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An efficient additive-free manganese-catalyzed hydrogenation of nitriles to primary amines with molecular hydrogen is described. The pre-catalyst, a well-defined bench-stable alkyl bisphosphine Mn(I) complex fac-[Mn(dpre)(CO)3(CH3)] (dpre=1,2-bis(di-n-propylphosphino)ethane), undergoes CO migratory insertion into the manganese-alkyl bond to form acyl complexes which upon hydrogenolysis yields the active coordinatively unsaturated Mn(I) hydride catalyst [Mn(dpre)(CO)2(H)]. A range of aromatic and aliphatic nitriles were efficiently and selectively converted into primary amines in good to excellent yields. The hydrogenation of nitriles proceeds at 100 °C with a catalyst loading of 2 mol % and a hydrogen pressure of 50 bar. Mechanistic insights are provided by means of DFT calculations. (Figure presented.).
- Weber, Stefan,Veiros, Luis F.,Kirchner, Karl
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p. 5412 - 5420
(2019/11/13)
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- Development of a novel protocol for chemoselective deprotection of N/O-benzyloxycarbonyl (Cbz) at ambient temperature
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Abstract: A novel protocol for the deprotection of N-benzyloxycarbonyl and O-benzyloxycarbonyl groups by nickel boride generated in situ from NaBH4 and NiCl2·6H2O in methanol at room temperature has been developed to give the corresponding amines and phenols. This protocol is chemoselective as groups like chloro, bromo, amide, ester, pyridine, and tert-butyloxycarbonyl moiety are unaffected under these conditions. The deprotection has also been validated in gram scale reactions, to establish the wider appropriateness of this protocol. Graphical abstract: [Figure not available: see fulltext.].
- Saroha, Mohit,Aggarwal, Komal,Bartwal, Gaurav,Khurana, Jitender M.
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p. 2231 - 2235
(2018/10/02)
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- A Co2B Mediated NaBH4 Reduction Protocol Applicable to a Selection of Functional Groups in Organic Synthesis
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A high-yielding and high-rate reduction method that operates with alkenes, alkynes, azides, nitriles, and nitroarenes was developed and optimized. The method makes use of sodium borohydride reduction of CoSO4 under release of hydrogen along with the formation of Co2B as a nanoparticle material. The produced Co2B activates the various functional groups for hydride reduction. The protocol was proven to operate with an assortment of functional groups to provide good to excellent yields. Furthermore, the reduction method was successfully adapted, implemented, and developed for a continuous flow approach using the multi-jet oscillating disk (MJOD) flow reactor platform at atmospheric pressure.
- Lundevall, Frida Johanne,Elumalai, Vijayaragavan,Drageset, Audun,Totland, Christian,Bj?rsvik, Hans-René
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supporting information
p. 3416 - 3425
(2018/07/29)
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- Hydrogenation of Nitriles and Ketones Catalyzed by an Air-Stable Bisphosphine Mn(I) Complex
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Efficient hydrogenations of nitriles and ketones with molecular hydrogen catalyzed by a well-defined bench-stable bisphosphine Mn(I) complex are described. These reactions are environmentally benign and atomically economic, implementing an inexpensive, earth-abundant nonprecious metal catalyst. A range of aromatic and aliphatic nitriles and ketones were efficiently converted into primary amines and alcohols, respectively, in good to excellent yields. The hydrogenation of nitriles proceeds at 100 °C with catalyst loading of 2 mol % and 20 mol % base (t-BuOK), while the hydrogenation of ketones takes place already at 50 °C, with a catalyst loading of 1 mol % and 5 mol % of base. In both cases, a hydrogen pressure of 50 bar was applied.
- Weber, Stefan,St?ger, Berthold,Kirchner, Karl
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supporting information
p. 7212 - 7215
(2018/11/25)
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- Single-Site Cobalt Catalysts at New Zr12(μ3-O)8(μ3-OH)8(μ2-OH)6 Metal-Organic Framework Nodes for Highly Active Hydrogenation of Nitroarenes, Nitriles, and Isocyanides
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We report here the synthesis of a robust and porous metal-organic framework (MOF), Zr12-TPDC, constructed from triphenyldicarboxylic acid (H2TPDC) and an unprecedented Zr12 secondary building unit (SBU): Zr12(μ3-O)8(μ3-OH)8(μ2-OH)6. The Zr12-SBU can be viewed as an inorganic node dimerized from two commonly observed Zr6 clusters via six μ2-OH groups. The metalation of Zr12-TPDC SBUs with CoCl2 followed by treatment with NaBEt3H afforded a highly active and reusable solid Zr12-TPDC-Co catalyst for the hydrogenation of nitroarenes, nitriles, and isocyanides to corresponding amines with excellent activity and selectivity. This work highlights the opportunity in designing novel MOF-supported single-site solid catalysts by tuning the electronic and steric properties of the SBUs.
- Ji, Pengfei,Manna, Kuntal,Lin, Zekai,Feng, Xuanyu,Urban, Ania,Song, Yang,Lin, Wenbin
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p. 7004 - 7011
(2017/05/31)
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- Selective Hydrogenation of Nitriles to Primary Amines by using a Cobalt Phosphine Catalyst
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A general procedure for the catalytic hydrogenation of nitriles to primary amines by using a non-noble metal-based system is presented. Co(acac)3 in combination with tris[2-(dicyclohexylphosphino)ethyl]phosphine efficiently catalyzes the selective hydrogenation of a wide range of (hetero)aromatic and aliphatic nitriles to give the corresponding amines.
- Adam, Rosa,Bheeter, Charles Beromeo,Cabrero-Antonino, Jose R.,Junge, Kathrin,Jackstell, Ralf,Beller, Matthias
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p. 842 - 846
(2017/03/17)
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- Cobalt-Catalyzed and Lewis Acid-Assisted Nitrile Hydrogenation to Primary Amines: A Combined Effort
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The selective hydrogenation of nitriles to primary amines using a bench-stable cobalt precatalyst under 4 atm of H2 is reported herein. The catalyst precursor was reduced in situ using NaHBEt3, and the resulting Lewis acid formed, BEt3, was found to be integral to the observed catalysis. Mechanistic insights gleaned from para-hydrogen induced polarization (PHIP) transfer NMR studies revealed that the pairwise hydrogenation of nitriles proceeded through a Co(I/III) redox process.
- Tokmic, Kenan,Jackson, Bailey J.,Salazar, Andrea,Woods, Toby J.,Fout, Alison R.
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supporting information
p. 13554 - 13561
(2017/10/05)
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- NNP-Type Pincer Imidazolylphosphine Ruthenium Complexes: Efficient Base-Free Hydrogenation of Aromatic and Aliphatic Nitriles under Mild Conditions
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A series of seven novel NImNHP-type pincer imidazolylphosphine ruthenium complexes has been synthesized and fully characterized. The use of hydrogenation of benzonitrile as a benchmark test identified [RuHCl(CO)(NImNHPtBu)] as the most active catalyst. With its stable Ru-BH4 analogue, in which chloride is replaced by BH4, a broad range of (hetero)aromatic and aliphatic nitriles, including industrially interesting adiponitrile, has been hydrogenated under mild and base-free conditions.
- Adam, Rosa,Alberico, Elisabetta,Baumann, Wolfgang,Drexler, Hans-Joachim,Jackstell, Ralf,Junge, Henrik,Beller, Matthias
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p. 4991 - 5002
(2016/04/05)
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- Selective Catalytic Hydrogenations of Nitriles, Ketones, and Aldehydes by Well-Defined Manganese Pincer Complexes
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Hydrogenations constitute fundamental processes in organic chemistry and allow for atom-efficient and clean functional group transformations. In fact, the selective reduction of nitriles, ketones, and aldehydes with molecular hydrogen permits access to a green synthesis of valuable amines and alcohols. Despite more than a century of developments in homogeneous and heterogeneous catalysis, efforts toward the creation of new useful and broadly applicable catalyst systems are ongoing. Recently, Earth-abundant metals have attracted significant interest in this area. In the present study, we describe for the first time specific molecular-defined manganese complexes that allow for the hydrogenation of various polar functional groups. Under optimal conditions, we achieve good functional group tolerance, and industrially important substrates, e.g., for the flavor and fragrance industry, are selectively reduced.
- Elangovan, Saravanakumar,Topf, Christoph,Fischer, Steffen,Jiao, Haijun,Spannenberg, Anke,Baumann, Wolfgang,Ludwig, Ralf,Junge, Kathrin,Beller, Matthias
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supporting information
p. 8809 - 8814
(2016/07/29)
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- A Mild and Base-Free Protocol for the Ruthenium-Catalyzed Hydrogenation of Aliphatic and Aromatic Nitriles with Tridentate Phosphine Ligands
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A novel protocol for the general hydrogenation of nitriles in the absence of basic additives is described. The system is based on the combination of [Ru(cod)(methylallyl)2] (cod=cyclooctadiene) and L2. A variety of aromatic and aliphatic nitriles is hydrogenated under mild conditions (50 °C and 15 bar H2) with this system. Kinetic studies revealed higher activity in the case of aromatic nitriles compared with aliphatic ones.
- Adam, Rosa,Bheeter, Charles Beromeo,Jackstell, Ralf,Beller, Matthias
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p. 1329 - 1334
(2016/04/20)
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- Ruthenium(II) 9,10-phenanthrenequinone thiosemicarbazone complexes: Synthesis, characterization, and catalytic activity towards the reduction as well as condensation of nitriles
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The ligands 9,10-phenanthrenequinone-N4-substituted thiosemicarbazones (HL1-3) and their ruthenium(II) complexes were synthesized and characterized by elemental and spectroscopic methods. The ligands are tridentate, monobasic chelating ligands with O, N, and S as the donor sites and are in the thiol form in all the complexes. Catalytic studies showed that all the complexes displayed good catalytic activity towards the reduction of nitriles and also the condensation of nitriles with 2-aminoalcohol under solvent-free conditions.
- Anitha, Panneerselvam,Viswanathamurthi, Periasamy,Kesavan, Devarayan,Butcher, Ray Jay
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p. 321 - 334
(2015/10/20)
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- Selective Hydrogenation of Nitriles to Primary Amines Catalyzed by a Cobalt Pincer Complex
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The catalytic hydrogenation of nitriles to primary amines represents an atom-efficient and environmentally benign reduction methodology in organic chemistry. This has been accomplished in recent years mainly with precious-metal-based catalysts, with a single exception. Here we report the first homogeneous Co-catalyzed hydrogenation of nitriles to primary amines. Several (hetero)aromatic, benzylic, and aliphatic nitriles undergo hydrogenation to the corresponding primary amines in good to excellent yields under the reaction conditions.
- Mukherjee, Arup,Srimani, Dipankar,Chakraborty, Subrata,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 8888 - 8891
(2015/08/03)
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- Ruthenium/imidazolylphosphine catalysis: Hydrogenation of aliphatic and aromatic nitriles to form amines
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A convenient and efficient catalyst system for the hydrogenation of aliphatic nitriles towards the corresponding primary amines in high to excellent yields is presented. In addition, aromatic nitriles are reduced smoothly, too. The use of low catalyst loadings and molecular hydrogen make this protocol an attractive methodology. It's not complicated: A general and easy homogeneous catalyst system based on [Ru(cod)(methylallyl)2] and a cyclohexyl-substituted imidazolylphosphine ligand for selective hydrogenation of aliphatic nitriles is presented. In addition, by using an isopropyl-substituted imidazolylphosphine ligand, selected aromatic nitriles were reduced with excellent yields towards the primary amine. Furthermore, two new crystal structures give an insight of possible pre-catalysts.
- Werkmeister, Svenja,Junge, Kathrin,Wendt, Bianca,Spannenberg, Anke,Jiao, Haijun,Bornschein, Christoph,Beller, Matthias
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supporting information
p. 4227 - 4231
(2014/05/06)
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- Chemoselective reduction of a nitro group through transfer hydrogenation catalysed by Ru0-nanoparticles stabilized on modified Montmorillonite clay
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Ru0-nanoparticles of approximately 5 nm size were generated by incipient impregnation of RuCl3 into the nanopores of the acid activated Montmorillonite clay followed by polyol reduction. Acid activation of the clay increases the surface area by generating nanopores (0-10 nm), which act as a host and stabilize nanoparticles in the pores. The generated Ru 0-nanoparticles exhibit inter-planar lattice fringe spacing of 0.21 nm of the face centered cubic lattice of Ru0 crystals, and show efficient catalytic activity in the chemoselective transfer hydrogenation reduction of substituted nitrobenzenes to corresponding anilines with high yield of conversion (56-97%) and selectivity (91-100%) depending upon the nature of the substituents. The reactions were carried out in the presence of isopropanol, which served as the solvent as well as the reductant. The catalysts were found to be active for several catalytic runs.
- Sarmah, Podma Pollov,Dutta, Dipak Kumar
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experimental part
p. 1086 - 1093
(2012/06/01)
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- Two iron catalysts are better than one: A general and convenient reduction of aromatic and aliphatic primary amides
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It takes two: For the reduction of amides to amines iron catalysts were developed. A combination of two different iron catalysts made possible the challenging reduction of primary amides (see picture). Copyright
- Das, Shoubhik,Wendt, Bianca,Moeller, Konstanze,Junge, Kathrin,Beller, Matthias
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supporting information; experimental part
p. 1662 - 1666
(2012/05/05)
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- Hydrogen transfer reduction of nitriles in DBU based ionic liquids
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Raney nickel catalyzed transfer hydrogenation of nitrile was proposed, with formats as hydrogen donor. Three ionic liquids, including [DBUH +][C2H5COO-], [DBUH +][C3H7COO-], and [DBUH +][C4H9COO-], were prepared as reaction medium, and [DBUH+][C4H9COO -] showed the best performance. Various nitriles were reduced with potassium formate as hydrogen donor, and considerable to excellent yields of amines were given. The ionic liquid can be used for 6 times at least, and the reaction process is clean. ARKAT-USA, Inc.
- Chen, Xinzhi,Zhou, Shaodong,Qian, Chao
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experimental part
p. 128 - 136
(2012/09/11)
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- Application of alkoxide in catalytic transfer hydrogenation of unsaturated nitrogen compounds
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Alcoholate was utilized in catalytic transfer hydrogenation of unsaturated nitrogen compounds. In the reduction of nitro compounds, oximes and imines, alkoxide was used as the promoter, with alcohol as the hydrogen source, while in the reduction of nitriles, alkoxide was used as the hydrogen source. Springer Science+Business Media B.V. 2012.
- Chen, Xinzhi,Zhou, Shaodong,Chen, Yuehan,Dong, Zehan,Gao, Yeyu,Qian, Chao,He, Chaohong
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p. 2255 - 2269
(2013/02/23)
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- The conversion of a phenol to an aniline occurs in the biochemical formation of the 1-(4-aminophenyl)-1-deoxy- d -ribitol moiety in methanopterin
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Recent work has demonstrated that 4-hydroxybenzoic acid is the in vivo precursor to the 1-(4-aminophenyl)-1-deoxy-d-ribitol (APDR) moiety present in the C1 carrier coenzyme methanopterin present in the methanogenic archaea. For this transformation to occur, the hydroxyl group of the 4-hydroxybenzoic acid must be replaced with an amino group at some point in the biosynthetic pathway. Using stable isotopically labeled precursors and liquid chromatography with electrospray-ionization mass spectroscopy, the first step of this transformation in Methanocaldococcus jannaschii occurs by the reaction of 4-hydroxybenzoic acid with phosphoribosyl pyrophosphate (PRPP) to form 4-(β-d-ribofuranosyl)hydroxybenzene 5′-phosphate (β-RAH-P). The β-RAH-P then condenses with l-aspartate in the presence of ATP to form 4-(β-d-ribofuranosyl)-N-succinylaminobenzene 5′-phosphate (β-RFSA-P). Elimination of fumarate from β-RFSA-P produces 4-(β-d-ribofuranosyl)aminobenzene 5′-phosphate (β-RFA-P), the known precursor to the APDR moiety of methanopterin [White, R. H. (1996) Biochemistry 35, 3447-3456]. This work represents the first biochemical example of the conversion of a phenol to an aniline.
- White, Robert H.
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experimental part
p. 6041 - 6052
(2012/06/04)
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- A rapid and practical protocol for solvent-free reduction of oximes to amines with NaBH4/ZrCl4/Al2O3 system
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Solvent-free reduction of various aldoximes and ketoximes to the corresponding amines was performed easily and efficiently with NaBH4 in the presence of ZrCl4 supported on Al2O3. The reactions were carried out rapidly (within 2 min) at room temperature to afford the amines in high to excellent yields.
- Zeynizadeh, Behzad,Kouhkan, Mehri
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experimental part
p. 3448 - 3452
(2012/02/01)
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- A general and environmentally benign catalytic reduction of nitriles to primary amines
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An easily accessible in situ catalyst composed of [Ru(cod)methylallyl 2] and DPPF was developed for the environmentally benign hydrogenation of various nitriles to give primary amines. A solution of benzonitrile in toluene was transferred by syringe into an autoclave that contained argon and KOtBu. The catalyst was generated in situ by stirring [Ru(cod)methylallyl2] and DPPF in toluene for 10 min and transferring the solution by syringe into the autoclave. the reaction mixture was filtered through a short plug of silica gel and the yield was measured by GC. A superior catalyst activity with a TOF of up to 5783 h-1 is achieved in the model reaction under optimized conditions. The results also show that [Ru(cod)methylallyl2]/DPPF catalyst system exhibit a broad functional group tolerance.
- Enthaler, Stephan,Addis, Daniele,Junge, Kathrin,Erre, Giulia,Beller, Matthias
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experimental part
p. 9491 - 9494
(2009/10/14)
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- First report for the efficient reduction of oximes to amines with zinc borohydride in the form of (Pyridine)(tetrahydroborato)zinc complex
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(Pyridine)(tetrahydroborato)zinc complex, (Py)Zn(BH4) 2, as a stable modification of zinc borohydride can easily reduce a variety of aromatic and aliphaticaldoximes or ketoximes to their corresponding amines in high to excellent yields in refluxing THF.
- Zeynizadeh, Behzad,Zahmatkesh, Karam
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p. 109 - 112
(2007/10/03)
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- Magnesium-Catalyzed Proficient Reduction of Oximes to Amines Using Ammonium Formate
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Various aldoximes and ketoximes were selectively reduced to the corresponding amines by catalytic transfer hydrogenation employing low cost magnesium powder and ammonium formate at room temperature. Many other functionalities such as halogens, -OH, -OCH3, -COOH and -CH 3 remained unaffected. The hydrogenation is fast, mild, clean, cost effective and high yielding.
- Abiraj,Gowda, D. Channe
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p. 599 - 605
(2007/10/03)
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- Zinc/ammonium formate: A new facile system for the rapid and selective reduction of oximes to amines
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Various oximes, both aldoximes and ketoximes, are selectively reduced to corresponding amines employing low cost zinc dust and ammonium formate despite presence of other functional groups such as halogens, -OH, -OCH3, -COOH, -CN, > C = C 3.
- Abiraj,Gowda, D. Channe
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p. 332 - 334
(2007/10/03)
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- Rapid reduction of nitriles to primary amines with nickel boride at ambient temperature
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Reduction of a variety of nitriles to their corresponding primary amines can be achieved with nickel boride generated in situ in dry ethanol at ambient temperature. The reductions are very rapid and chemoselective.
- Khurana, Jitender M.,Kukreja, Gagan
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p. 1265 - 1269
(2007/10/03)
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- Selective nitrolytic deprotection of N-BOC-amines and N-BOC-amino acids derivatives
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The extension of the deprotection procedure using HNO3 in CH2Cl2 to a number of appropriately selected N-BOC-masked amines and derivatives of natural amino acids was investigated. The method was found to work effectively with almost all tested substrates, with the exception of activated aromatic amines and heterocycles which underwent unavoidable faster oxidation. Alanine, phenylalanine, serine and lysine derivatives were efficiently deprotected, as well as dipeptide Ala-Phe, preserving the configuration of the substrates and without affecting copresent Z and ester functions, with a remarkable selectivity towards acid sensitive t-butyl esters. The obtained amino acids esters, isolated and characterized in the form of nitrates salts, proved to be suitable intermediates to be used in peptide synthesis.
- Strazzolini, Paolo,Melloni, Tiziana,Giumanini, Angelo G
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p. 9033 - 9043
(2007/10/03)
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- 1,4-diazacycloheptane derivatives and their use in hair oxidation dyes
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A 1,4-diazacycloheptane derivative and an oxidative hair colorant containing the derivative as a primary intermediate is presented. The 1,4-diazacycloheptane derivative is of the formula: STR1 where R1, R2, R3 and R4 independently of one another represent hydrogen, a C1-4 alkyl or hydroxyalkyl group or a C2-4, dihydroxyalkyl group, X and Y independently of one another represent hydrogen, chlorine, fluorine, a C1-4 alkyl, hydroxyalkyl, aminoakyl or alkoxy group, a C2-4 dihydroxyalkyl group or an allyl group and R5 and R6 independently of one another represent hydrogen or a C1-4 alkyl group. Natural color tones can be obtained in keratin fibers with oxidative hair colorants containing the 1,4-diazacycloheptane derivative, without the use of additional primary intermediates.
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- AMIDINE DERIVATIVES WITH NITRIC OXIDE SYNTHETASE ACTIVITIES
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Amidine derivative compounds of formula I as defined in the Specification having nitric oxide synthetase inhibitory activity as well as processes for the preparation of and compositions containing said compounds are described
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- Oxidation dye composition for keratinous fibres comprising a para-aminophenol, a meta-aminophenol and a para-phenylenediamine and/or a bis(phenylalkylenediamine)
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The invention relates to a dyeing composition for keratinous fibres and in particular for human keratinous fibres such as hair, comprising, in a suitable media for dyeing, at least one oxidation dye precursor chosen from 3-methyl-para-aminophenol, 2-methyl-para-aminophenol and 2-hydroxymethyl-para-aminophenol, and their addition salts with an acid; at least one coupling agent chosen from the 2-methyl-5-aminophenols of formula (I): STR1 in which R is methyl, ethyl, β-hydroxyethyl or γ-hydroxypropyl, and their addition salts with an acid; and at least one para-phenylenediamine and/or one bis(phenylalkylenediamine) or one of their addition salts with an acid as oxidation dye precursor.
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- pH optimization of nucleophilic reactions in water
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We present a way of prescribing the pH for a reaction so as to obtain either (a) maximum yield in competition with hydrolysis or (b) selective reaction at either of two sites in such nucleophile-electrophile reactions as C-alkylation of acidic ketones and the acylation and sulfonylation of amines. First, we derive the following general equation for pHmax, the pH giving the highest yield of the product (P) of the reaction of a nucleophile (Nu) with a hydrolyzable electrophile (E) in water: pHmax = 1/2[log (kw/kOH) + PKw + pKw] (kw and kOH refer to the water- and hydroxide-promoted hydrolyses of E, Kw is the autoprotolysis constant of water, and Ka is the acid dissociation constant of NuH+, the conjugate acid of Nu). pHmax thus depends on a property of E (namely, kw/kOH) and a property of Nu (the pKa of NuH+), but not on the rate constant for the reaction of E with Nu or the concentration of Nu. We then deduce analogous approximate equations for maximum selectivity for reaction at either of two nucleophilic sites, specifically, equations giving pHxmax and pHymax, the pH values for the maximum yields of the respective products (Px and Py) of the reactions of E with the two nucleophiles. We find that (a) pH-yield profiles calculated from the equations concur with observed yields for reactions under pseudo-first-order conditions and (b) preparative experiments at the estimated pH values give good to excellent yields of clean products and high selectivity in both the C-alkylation and Schotten-Baumann reactions.
- King,Rathore,Lam,Guo,Klassen
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p. 3028 - 3033
(2007/10/02)
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- Process for producing aminobenzylamines
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Aminobenzylamines are produced by catalytically reducing o-, m- or p-nitrobenzaldoxime in an organic solvent in the presence of a compound selected from the group consisting of (a) boric acid, phosphoric acid and/or anhydrides thereof, (b) CO2 gas and (c) an organic acid. The starting material, nitrobenzaldoxime is produced by reaction of the corresponding nitrobenzaldehyde with hydroxylamine.
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- Aminobenzylamine composition
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A composition of aminobenzylamine is provided which is mainly composed of m-aminobenzylamine and p-aminobenzylamine in either the presence or absence of a small quantity of o-aminobenzylamine, is liquid at room temperature, and is an excellent cold-setting type curing agent useful for thermosetting resin compositions.
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- Novel monoazo and disazo colorants from aminoalkylanilines and bis(aminoalkyl)anilines
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Water-insoluble azo dyestuffs of the formula STR1 and water-soluble acid addition salts thereof useful for coloring natural fibers, synthetic fiber-forming material and cellulosic materials as well as in the manufacture of paper, varnishes, inks, coatings and plastics in which A represents an azoic coupling radical derived from a coupling component selected from the group consisting of arylides of hydroxy-substituted carbocyclic aromatic carboxylic acids, 1-aryl-5-hydroxy-pyrazoles, 6-amino-1-naphthol-3-sulfonic acid, and compounds having an enolizable ketomethylene group of the formula STR2 R is hydrogen, lower-alkyl, lower-alkoxy or halogen; R2 is hydrogen, lower-alkyl, lower-alkoxy, halogen, aminomethyl or 2-aminoethyl with the proviso that A is other than β-naphthol when R2 is aminomethyl or 2-aminoethyl; R1 and R3 are the same or different and are each hydrogen, lower-alkyl, lower-alkoxy, halogen or aminomethyl with the proviso that at least one of R1 and R3 is aminomethyl when R2 is other than aminomethyl or 2-aminoethyl; and n represents an integer whose value is 1 or 2 and corresponds to the number of azo linkages, which dyestuffs are obtained by coupling a diazotized amine of the formula STR3 in which R, R1, R2 and R3 are as defined above with said coupling component.
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- Monoazo and diazo colorants from aminoalkylanilines and bis(aminoalkyl)anilines
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Water-insoluble azo dyestuffs of the formula STR1 AND WATER-SOLUBLE ACID ADDITION SALTS THEREOF USEFUL FOR COLORING NATURAL FIBERS, SYNTHETIC FIBER-FORMING MATERIAL AND CELLULOSIC MATERIALS AS WELL AS IN THE MANUFACTURE OF PAPER, VARNISHES, INKS, COATINGS AND PLASTICS IN WHICH A represents an azoic coupling radical derived from a coupling component selected from the group consisting of arylides of hydroxysubstituted carbocyclic aromatic carboxylic acids, 1-aryl-5-hydroxypyrazoles, 6-amino-1-naphthol-3-sulfonic acid, and compounds having an enolizable ketomethylene group of the formula STR2 R is hydrogen, lower-alkyl, lower-alkoxy or halogen; R2 is hydrogen, lower-alkyl, lower-alkoxy, halogen, aminomethyl or 2-aminoethyl with the proviso that A is other than β-naphthol when R2 is aminomethyl or 2-aminoethyl; R1 and R3 are the same or different and are each hydrogen, lower-alkyl, lower-alkoxy, halogen or aminomethyl with the proviso that at least one of R1 and R3 is aminomethyl when R2 is other than aminomethyl or 2-aminoethyl; and n represents an integer whose value is 1 or 2 and corresponds to the number of azo linkages, which dyestuffs are obtained by coupling a diazotized amine of the formula STR3 in which R, R1, R2 and R3 are as defined above with said coupling component.
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- Inhibitors of Bacillus subtilis DNA polymerase III. 6-(arylalkylamino)uracils and 6-anilinouracils.
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6-(Benzylamino)uracils and substituted 6-anilinouracils have been found to be potent inhibitors of Bacillus subtilis DNA polymerase III by a mechanism identical with that of 6-(phenylhydrazino)uracils. Higher phenylalkylamino homologues are progressively weaker inhibitors of the enzyme. Examination of the effects of substituents on the activity of 6-(benzylamino)uracils against wild-type and mutant enzymes and preliminary results for 6-anilinouracils have permitted further dissection of the mechanism of inhibition. The experimental results indicate that (1) the polymerase inhibitor binding site is compact, accommodating only small alterations in the distance between the uracil and phenyl rings, (2) the phenyl ring, which provides the major contribution to inhibitor-enzyme binding, adopts a specific active conformation, and (3) an enzyme site which interacts with substituents in the phenyl ring forms a part of the active site of DNA polymerase III.
- Brown et al.
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p. 1186,1189
(2007/10/06)
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