- Origin and Abatement of Heterogeneity at the Support Granule Scale of Silver on Silica Catalysts
-
Incipient wetness impregnation is used commonly to form supported metal nanoparticle catalysts. Recently, it has been revealed that this approach may induce severe heterogeneity between catalyst granules of the same batch. At least a 10-fold variation in metal loading was observed, which affect the catalytic performance of individual catalyst granules severely. However, the origin of this heterogeneity is still unclear. Here we show that every elementary step in the preparation procedure of a Ag on silica catalyst has an effect on the resulting interparticle heterogeneity, but the influence of the drying step is the most important. This is because drying by capillary force results in a heterogeneous sample. Specifically, the position of a granule in the stagnant drying bed influences the resulting color and, thus, Ag loading significantly. This is further demonstrated by varying the drying conditions: freeze-drying and fluidized-bed drying led to a more homogeneous Ag loading. An investigation of the fluidized-bed-dried sample by using optical microscopy revealed a large fraction of transparent granules (94 %), which indicates that almost all the Ag nanoparticles in this sample are confined within the 6 nm pores. The optimized supported Ag on silica catalyst shows a good catalytic performance. This adaptation of the drying step can be implemented easily on a laboratory scale, is scalable, and does not require the use of expensive solvents or metal precursors.
- Plessers, Eva,van den Reijen, Jeroen E.,de Jongh, Petra E.,de Jong, Krijn P.,Roeffaers, Maarten B. J.
-
-
Read Online
- Room-Temperature Chemoselective Reduction of 3-Nitrostyrene to 3-Vinylaniline by Ammonia Borane over Cu Nanoparticles
-
We report a new strategy of controlling catalytic activity and selectivity of Cu nanoparticles (NPs) for the ammonia borane initiated hydrogenation reaction. Cu NPs are active and selective for chemoselective reduction of nitrostyrene to vinylaniline under ambient conditions. Their activity, selectivity, and more importantly, stability are greatly enhanced by their anchoring on WO2.72 nanorods, providing a room-temperature full conversion of nitrostyrene selectively to vinylaniline (>99% yield). Compared with all other catalysts developed thus far, our new Cu/WO2.72 catalyst shows much enhanced hydrogenation selectivity and stability without the use of pressured hydrogen. The synthetic approach demonstrated here can be extended to prepare various M/WO2.72 catalysts (M = Fe, Co, Ni), with M being stabilized for many chemical reactions.
- Shen, Mengqi,Liu, Hu,Yu, Chao,Yin, Zhouyang,Muzzio, Michelle,Li, Junrui,Xi, Zheng,Yu, Yongsheng,Sun, Shouheng
-
-
Read Online
- Robust Synthesis of Gold-Based Multishell Structures as Plasmonic Catalysts for Selective Hydrogenation of 4-Nitrostyrene
-
A robust self-template strategy is used for facile and large-scale synthesis of porous multishell gold with controllable shell number, sphere size, and in situ surface modification. The process involved the rapid reduction of novel Au-melamine colloidal templates with a great amount of NaBH4 in presence of poly(sodium-p-styrenesulfonate) (PSS). After soaking the templates in other metal salt solution, the obtained bimetallic templates could also be generally converted into bimetallic multishell structures by same reduction process. In the hydrogenation of 4-nitrostyrene using NH3BH3 as a reducing agent, the porous triple-shell Au with surface modification (S-PTSAu) exhibited excellent selectivity (97 %) for 4-aminostyrene in contrast with unmodified triple-shell Au. Furthermore, it also showed higher enhancement of catalytic activity under irradiation of visible light as compared to similar catalysts with fewer shells.
- Li, Jian,Long, Yan,Liu, Yu,Zhang, Lingling,Wang, Qishun,Wang, Xiao,Song, Shuyan,Zhang, Hongjie
-
-
Read Online
- Shape-selective synthesis of Sn(MoO4)2 nanomaterials for catalysis and supercapacitor applications
-
Size and shape-selective Sn(MoO4)2 nanomaterials have been synthesized for the first time using a simple hydrothermal route by the reaction of Sn(ii) chloride salt with sodium molybdate in CTAB micellar media under stirring at 60 °C temperature for about three hours. Needle-like and flake-like Sn(MoO4)2 nanomaterials were synthesized by optimizing the CTAB to metal salt molar ratio and by controlling other reaction parameters. The eventual diameter and length of the nanoneedles are ～100 ± 10 nm and ～850 ± 100 nm respectively. The average diameter of the flakes is ～250 ± 50 nm. The synthesized Sn(MoO4)2 nanomaterials can be used in two potential applications, namely, catalytic reduction of nitroarenes and as an anodic material in electrochemical supercapacitors. From the catalysis study, it was observed that the Sn(MoO4)2 nanomaterials could act as a potential catalyst for the successful photochemical reduction of nitroarenes into their respective aminoarenes within a short reaction time. From the supercapacitor study, it was observed that the Sn(MoO4)2 nanomaterials of different shapes show different specific capacitance (Cs) values and the highest Cs value was observed for Sn(MoO4)2 nanomaterials having a flake-like morphology. The highest Cs value observed was 109 F g-1 at a scan rate of 5 mV s-1 for the flake-like Sn(MoO4)2 nanomaterials. The capacitor shows an excellent long cycle life along with 70% retention of the Cs value, even after 4000 consecutive cycles at a current density of 8 mA cm-2. Other than the applications in catalysis and supercapacitors, the synthesized nanomaterials can find further applications in photoluminescence, sensor and other energy-related devices.
- Sakthikumar,Ede, Sivasankara Rao,Mishra, Soumyaranjan,Kundu, Subrata
-
-
Read Online
- Base-free chemoselective transfer hydrogenation of nitroarenes to anilines with formic acid as hydrogen source by a reusable heterogeneous Pd/ZrP catalyst
-
A highly efficient, chemoselective, environmentally-benign method is developed for the catalytic transfer hydrogenation (CTH) of nitroarenes using FA as a hydrogen source. Various supported Pd catalysts were examined for this transformation, and Pd supported ZrP (Pd/ZrP) proved to be the best catalyst for CTH of nitrobenzene. Applicability of the Pd/ZrP catalyst is also explored for hydrogenation of various substituted nitroarenes. The Pd/ZrP catalyst showed high specificity for hydrogenation of nitro groups even in the presence of other reducible functional groups such as -CC, -COOCH3, and -CN. To investigate the reaction mechanism, a Hammett plot was obtained for CTH of p-substituted nitroarenes. The active site is thought to be in situ generated Pd(0) species as seen from XRD and TEM data. The Pd/ZrP catalyst is reusable at least up to 4 times while maintaining the same activity and selectivity. To the best of our knowledge, this is one of the best methodologies for CTH of nitroarenes under base-free conditions with high activity and chemoselectivity over heterogeneous Pd-based catalysts. the Partner Organisations 2014.
- Tuteja, Jaya,Nishimura, Shun,Ebitani, Kohki
-
-
Read Online
- Co based N, S co-doped carbon hybrids for catalytic hydrogenation: Role of cobalt salt and doped S
-
A series of Co-based N, S dual-doped carbon catalysts were prepared successfully via the pyrolysis of porous organic polymers (POPs)impregnated with cobalt salt and characterized by TEM, XRD, XPS, etc. The successful construction of cobalt-nitrogen (Co-Nx)sites is confirmed by XPS spectra. It was found that the content of Co-Nx sites is markedly affected by the type of cobalt salt, and the catalyst derived by the pyrolysis of the complex of POPs with Co(NO3)2·6H2O displays the best activity and outstanding selectivity for catalytic hydrogenation of various aromatic nitro compounds, it also demonstrates good recyclability. According to the results of control experiments, the activity for catalytic hydrogenation is mainly attributed to the Co-Nx sites. In addition, the doped S species in carbon shells can promote the formation of the active sites, which can effectively improve the performance of catalysts. Thus, this work can provide an effective and green approach for design highly effective transition metal-based multi-doped carbon catalysts with abundant metal-Nx sites.
- Gao, Ruixiao,Guo, Haotian,Wang, Bowei,Qiu, Pengzhi,Sun, Mingming,Chen, Ligong
-
-
Read Online
- Selective Liquid-Phase Hydrogenation of a Nitro Group in Substituted Nitrobenzenes over Au/Al2O3 Catalyst in a Packed-Bed Flow Reactor
-
A series of substituted nitrobenzenes with the general formula XC6H4NO2 (X=Cl, CH=CH2, or C(O)CH3) dissolved in toluene were reduced with hydrogen over the 1.9 % Au/Al2O3 catalyst at 60-110 C and 10-20 bar in a three-phase packed-bed reactor operating in up-flow mode. Under these conditions, hydrogenation of isomeric ClC6H4NO2 gives exclusively chloroanilines. Hydrogenation of 3-CH2CHC6H4NO2 and 4-CH3C(O)C6H4NO2 leads to the formation of 3-CH2CHC6H4NH2 and 4-CH3C(O)C6H4NH2 with selectivities of up to 93 and 97 % at substrate conversions of 98 and 100 %, respectively. Smooth catalyst deactivation was observed regardless of which substituted nitrobenzene was taken for hydrogenation. According to the results obtained by temperature-programmed oxidation of the spent catalyst, a carbonaceous deposit formed that might block the catalyst surface. Almost complete regeneration of the supported gold catalyst with retention of its high selectivity to hydrogenation of a nitro group was achieved in a flow of air at temperatures up to 400 C to eliminate carbonaceous deposits.
- Nuzhdin, Alexey L.,Moroz, Boris L.,Bukhtiyarova, Galina A.,Reshetnikov, Sergey I.,Pyrjaev, Pavel A.,Aleksandrov, Pavel V.,Bukhtiyarov, Valerii I.
-
-
Read Online
- Efficient and highly selective boron-doped carbon materials-catalyzed reduction of nitroarenes
-
Exploring the potential catalytic applications of boron-doped carbon materials is a fascinating challenge. Here we describe that boron-doped onion-like carbon and carbon nanotubes as metal-free catalysts exhibit excellent catalytic activity and stability in nitroarene reduction under a stoichiometric amount of reductant.
- Lin, Yangming,Wu, Shuchang,Shi, Wen,Zhang, Bingsen,Wang, Jia,Kim, Yoong Ahm,Endo, Morinobu,Su, Dang Sheng
-
-
Read Online
- Bimetallic Platinum-Tin Nanoparticles on Hydrogenated Molybdenum Oxide for the Selective Hydrogenation of Functionalized Nitroarenes
-
The hydrogenation of functionalized nitroarenes to the corresponding anilines is of great importance in the fine chemical industry and requires high-performance catalysts with a good activity and selectivity. Herein, hydrogenated MoOx (H-MoOx) supported bimetallic Pt-Sn (Pt-Sn/H-MoOx) was developed to accomplish selective and efficient hydrogenation. In the case of 4-nitrostyrene, an outstanding selectivity to 4-vinylaniline (≈93 %) with a high turnover frequency (0.094 s?1) was achieved under mild conditions (T=30 °C, PH2 =1 atm). The metal–support interactions contributed to the efficient turnover on the ultrafine nanoparticles, and the atom-rearranged bimetallic Pt-Sn surface promoted the selectivity because of the preferred adsorption of the nitro group. The good efficiency for various functionalized nitroarenes further verified the promise of Pt-Sn/H-MoOx in chemoselective hydrogenation.
- Shu, Yijin,Chan, Hang Cheong,Xie, Lifang,Shi, Zhangping,Tang, Yi,Gao, Qingsheng
-
-
Read Online
- Resolving Interparticle Heterogeneities in Composition and Hydrogenation Performance between Individual Supported Silver on Silica Catalysts
-
Supported metal nanoparticle catalysts are commonly obtained through deposition of metal precursors onto the support using incipient wetness impregnation. Typically, empirical relations between metal nanoparticle structure and catalytic performance are inferred from ensemble averaged data in combination with high-resolution electron microscopy. This approach clearly underestimates the importance of heterogeneities present in a supported metal catalyst batch. Here we show for the first time how incipient wetness impregnation leads to 10-fold variations in silver loading between individual submillimeter-sized silica support granules. This heterogeneity has a profound impact on the catalytic performance, with 100-fold variations in hydrogenation performance at the same level. In a straightforward fashion, optical microscopy interlinks single support particle level catalytic measurements to structural and compositional information. These detailed correlations reveal the optimal silver loading. A thorough consideration of catalyst heterogeneity and the impact thereof on the catalytic performance is indispensable in the development of catalysts.
- Plessers, Eva,Stassen, Ivo,Sree, Sreeprasanth Pulinthanathu,Janssen, Kris P. F.,Yuan, Haifeng,Martens, Johan,Hofkens, Johan,De Vos, Dirk,Roeffaers, Maarten B. J.
-
-
Read Online
- Boronate self-assemblies with embedded Au nanoparticles: Preparation, characterization and their catalytic activities for the reduction of nitroaromatic compounds
-
Sequential boronate esterification of benzene-1,4-diboronic acid with pentaerythritol induced hierarchical molecular self-assembly to produce mono-dispersed flower-like microparticles. ATR-FT-IR, PXRD, 13C-CP- MAS and 11B-DD-MAS NMR spectra indicate that the particles consist of zigzag-shaped packing structures of polymeric 2,4,8,10-tetraoxa-3,9- diboraspiro[5.5]undecane. Au nanoparticles (Au NPs) with a mean diameter of 2.7 nm were successfully deposited on the microparticles by the deposition reduction (DR) method. It is noteworthy that the resulting novel hybrids exhibited an efficient catalytic activity for the reduction of nitroaromatic compounds; in particular, high chemoselectivity in the hydrogenation of 4-nitrostyrene to the corresponding aniline was attained without reduction of the vinyl bond. Careful investigation of the catalyst suggested a synergistic effect between Au NPs and the boronate support in the selective hydrogenation. These findings strongly suggest that boronate self-assemblies are advantageous as support materials for preparation of heterogeneous catalysts based on polymer-Au hybrids. The Royal Society of Chemistry 2012.
- Matsushima, Yusuke,Nishiyabu, Ryuhei,Takanashi, Naoto,Haruta, Masatake,Kimura, Hideaki,Kubo, Yuji
-
-
Read Online
- Effect of Fe, Co and Ni promoters on MoS2 based catalysts for chemoselective hydrogenation of nitroarenes
-
The effect of Fe, Co and Ni promoters on supported MoS2 catalysts for hydrogenation of nitroarenes were systematically investigated via experiment, characterization and DFT calculation. It was found that the addition of promoters remarkably improved the reaction activity in a sequence of Ni > Co > Fe > Mo. Meanwhile Ni promoted catalyst with the best performance showed good recyclability and chemoselectivity for a wide substrate scope. The characterization results revealed that the addition of promoters decreased the interaction between Mo and support and facilitated the reductive sulfidation of Mo species to produce more coordinated unsaturated sites (CUS). DFT calculations showed that the addition of promoters increased the formation of CUS, and enhanced the adsorption of hydrogen. The influence degree of promoters followed the sequence Ni > Co > Fe > Mo, which was consistent with those of the activities. Nitrobenzene hydrogenation and hydrogen activation occurred at the S and Mo edge, respectively. The adsorbed hydrogen diffused from the Mo edge to the S edge to participate in the hydrogenation reaction. Mechanism investigation showed that the main reason for increased activity by the addition of promoters was the increase of amounts of CUS and the secondary reason was the augmentation of intrinsic activity of CUS. The present studies give a new understanding for promoter modified MoS2 catalysts applied for hydrogenation of nitroarenes.
- Du, Mingxian,Ge, Hui,Han, Wenpeng,Li, Xuekuan,Ma, Ben,Wang, Shanmin,Yang, Ying,Zhang, Ye,Zhou, Ligong
-
-
Read Online
- Co/N-codoped porous carbons derived from poly(Schiff base)/Co(II) complex as ultrahighly efficient catalysts for CTH of nitroarenes
-
Herein we report the scalable synthesis of Co/N-codoped porous carbon (Co/N-C) catalysts by pyrolyzing poly(Schiff base)/Co(II) complex. The strong Co(II)-binding affinity of poly(Schiff base) leads to the formation of uniformly distributed Co(0) nanoparticles, Co-Nx species, and N–C configurations, in which their catalytic contributions are confirmed and estimated by ligand-poisoning and acid-etching experiments and the Co-Nx species has been proved to be highly active for catalytic transfer hydrogenation (CTH) reaction. Consequently, the as-prepared Co-N/C-950 catalyst exhibits an ultrahigh activity for the CTH of 4-nitrophenol (4-NP) with a TOF of 226 mol4-NP molCo?1 min?1 (13560 h?1) together with an excellent selectivity for CTH of challenging nitroarenes. Moreover, the Co(0) nanoparticles embedded in the Co-N/C-950 catalyst can be further transformed to Co4N phase by a facile nitridation reaction, yielding Co4N-N/C-950 catalyst with even higher activity for the CTH of 4-NP (TOF up to 310 mol4-NP molCo?1 min?1).
- Chen, Hongbiao,Li, Huaming,Liu, Bei,Liu, Yijiang,Xie, Weichao,Yang, Mei
-
-
Read Online
- Surfactant Assembly within Pickering Emulsion Droplets for Fabrication of Interior-Structured Mesoporous Carbon Microspheres
-
Large-sized carbon spheres with controllable interior architecture are highly desired, but there is no method to synthesize these materials. Here, we develop a novel method to synthesize interior-structured mesoporous carbon microspheres (MCMs), based on the surfactant assembly within water droplet-confined spaces. Our approach is shown to access a library of unprecedented MCMs such as hollow MCMs, multi-chambered MCMs, bijel-structured MCMs, multi-cored MCMs, “solid” MCMs, and honeycombed MCMs. These novel structures, unattainable for the conventional bulk synthesis even at the same conditions, suggest an intriguing effect arising from the droplet-confined spaces. This synthesis method and the hitherto unfound impact of the droplet-confined spaces on the microstructural evolution open up new horizons in exploring novel materials for innovative applications.
- Liu, Dawei,Xue, Nan,Wei, Lijuan,Zhang, Ye,Qin, Zhangfeng,Li, Xuekuan,Binks, Bernard P.,Yang, Hengquan
-
-
Read Online
- Reduction of 4-nitrostyrene to 4-aminostyrene
-
Reduction of 4-nitrostyrene with Fe0, Fe2+, and S2O 4 2- was studied. A new method of 4-aminostyrene synthesis was developed.
- Shul'Tsev
-
-
Read Online
- Highly Chemoselective Reduction of Nitroarenes Using a Titania-Supported Platinum-Nanoparticle Catalyst under a CO Atmosphere
-
The discovery that supported gold catalysts can promote CO/H2O-mediated reduction at ambient temperatures is important to chemoselective synthesis and has gained significant attention in recent years. Whether the alternative Pt group metal (PGM) catalysts can exhibit such exceptional performance is thus an interesting research issue. So far, no PGM catalyst shows activity for CO/H2O-mediated reduction at ambient temperatures. Here, we demonstrate that it is possible to transform nonactive into highly active and selective catalysts for CO/H2O-mediated reduction by modulating the interfacial structure and electronic properties at the metal-support interfaces. Thus, highly active and chemoselective hydrogenation Pt, Ir, Rh and Pd catalysts can be prepared by decorating the exposed metal faces with partially reduced support species by means of a simple catalyst activation procedure. In this way, it has been possible to dramatically facilitate the previously unappreciated PGM-catalyzed activation of CO molecules under mild conditions, which can make a significant contribution not only to reveal the intrinsic catalytic potential of supported PGMs but also to establish a more sustainable and industrially-relevant process.
- Li, Shushuang,Wang, Fuzerong,Liu, Yongmei,Cao, Yong
-
-
Read Online
- Half-Sandwich Ruthenium Complexes of Amide-Phosphine Based Ligands: H-Bonding Cavity Assisted Binding and Reduction of Nitro-substrates
-
We present synthesis and characterization of two half-sandwich Ru(II) complexes supported with amide-phosphine based ligands. These complexes presented a pyridine-2,6-dicarboxamide based pincer cavity, decorated with hydrogen bonds, that participated in the binding of nitro-substrates closer to the Ru(II) centers, which is further supported with binding and docking studies. These ruthenium complexes functioned as the noteworthy catalysts for the borohydride mediated reduction of assorted nitro-substrates. Mechanistic studies not only confirmed the intermediacy of [Ru-H] in the reduction but also asserted the involvement of several organic intermediates during the course of the catalysis. A similar Ru(II) complex that lacked pyridine-2,6-dicarboxamide based pincer cavity substantiated its unique role both in the substrate binding and the subsequent catalysis.
- Pachisia, Sanya,Kishan, Ram,Yadav, Samanta,Gupta, Rajeev
-
-
Read Online
- A Top-Down Strategy to Realize Surface Reconstruction of Small-Sized Platinum-Based Nanoparticles for Selective Hydrogenation
-
Over the past decades, despite the substantial efforts that have been devoted to the modifications of Pt nanoparticles (NPs) to tailor their selectivities for hydrogenation reactions, there are still a lack of facile strategies for precisely regulation of the surface properties of NPs, especially for those with small sizes. In this work, we propose a top-down thermal annealing strategy for tuning the surface properties of Pt-based NPs (≈4 nm) without the occurrence of aggregation. Compared to conventional bottom-up methods, the present top-down strategy can precisely regulate the surface compositions of Pt-Cd NPs and other ternary Pt-Cd-M NPs (M=Fe, Ni, Co, Mn, and Sn). The optimized Pt-Cd NPs exhibit excellent selectivity toward phenylacetylene and 4-nitrostyrene hydrogenations with a styrene selectivity and 4-aminophenyl styrene selectivity of 95.2 % and 94.5 %, respectively. This work provides a general strategy for the surface reconstructions of Pt-based NPs, and promotes fundamental research on catalyst design for heterogeneous catalysis.
- Huang, Xiaoqing,Jin, Yu,Li, Leigang,Liu, Shangheng,Mao, Xinnan,Shao, Qi,Wang, Lu,Wang, Pengtang,Xu, Yong
-
-
Read Online
- Size- and support-dependent silver cluster catalysis for chemoselective hydrogenation of nitroaromatics
-
Silver clusters on θ-Al2O3 support catalyze highly chemoselective reduction of a nitro group for the reduction of substituted nitroaromatics such as nitrostyrene. These catalysts show higher selectivity than conventional platinum-group metal-based heterogeneous catalysts. Systematic studies on the influence of the metal particle size and support oxides show that the intrinsic activity increases with decrease in the silver particle size, and acid-base bifunctional supports such as Al2O3 give higher activity than acidic or basic supports. Kinetic and in situ infrared studies provide a reaction mechanism which explains fundamental reasons of these tendencies. Cooperation of the acid-base pair site on Al2O3 and the coordinatively unsaturated Ag sites on the silver cluster is responsible for the rate-limiting H2 dissociation to yield a H+/H- pair at metal/support interface, while the basic site on oxides acts as an adsorption site of nitroaromatics. High chemoselectivity could be attributed to a preferential transfer of the H+/H- pair to the polar bonds in the nitro group.
- Shimizu, Ken-ichi,Miyamoto, Yuji,Satsuma, Atsushi
-
-
Read Online
- COPPER NANOPARTICLE BASED CHEMOSELECTIVE REDUCTION
-
The instant invention provides processes for a chemo selective reduction of a nitro group within a compound in the presence of other groups which can also be reduced. This aspect of the present invention provides an ammonia borane (AB) initiated chemoselective reduction process of a nitro group contained within a compound in the presence of a copper (Cu) nanoparticle based catalyst. The invention is also directed to Copper (Cu) nanoparticle (NP) based catalysts, selected from Cu/WOx, Cu/SiO2, and Cu/C; wherein x represents an integer having a value of from about 2 to about 3.5, used in the chemo selective reduction of a nitro group contained within a compound in the presence of other groups which can also be reduced.
- -
-
Paragraph 0050; 0051
(2021/11/20)
-
- Cyclic (Alkyl)(amino)carbene Ligand-Promoted Nitro Deoxygenative Hydroboration with Chromium Catalysis: Scope, Mechanism, and Applications
-
Transition metal catalysis that utilizes N-heterocyclic carbenes as noninnocent ligands in promoting transformations has not been well studied. We report here a cyclic (alkyl)(amino)carbene (CAAC) ligand-promoted nitro deoxygenative hydroboration with cost-effective chromium catalysis. Using 1 mol % of CAAC-Cr precatalyst, the addition of HBpin to nitro scaffolds leads to deoxygenation, allowing for the retention of various reducible functionalities and the compatibility of sensitive groups toward hydroboration, thereby providing a mild, chemoselective, and facile strategy to form anilines, as well as heteroaryl and aliphatic amine derivatives, with broad scope and particularly high turnover numbers (up to 1.8 × 106). Mechanistic studies, based on theoretical calculations, indicate that the CAAC ligand plays an important role in promoting polarity reversal of hydride of HBpin; it serves as an H-shuttle to facilitate deoxygenative hydroboration. The preparation of several commercially available pharmaceuticals by means of this strategy highlights its potential application in medicinal chemistry.
- Zhao, Lixing,Hu, Chenyang,Cong, Xuefeng,Deng, Gongda,Liu, Liu Leo,Luo, Meiming,Zeng, Xiaoming
-
supporting information
p. 1618 - 1629
(2021/01/25)
-
- Boosting chemoselective reduction of 4-nitrostyreneviaphotoinduced energetic electrons fromin situformed Cu nanoparticles on carbon dots
-
Chemoselective hydrogenation of structurally diverse nitroarenes is a challenging process that often requires precious metal catalysts and proceeds in an organic solvent. Herein, a convenient and stable hybrid nanocatalyst combining carbon dots and copper nanoparticles is developed as an ideal alternative for this transformation. The as-prepared nanocatalyst achieves over 99% selectivity for the formation of 4-aminostyrene at 100% conversion of 4-nitrostyrene in an aqueous solvent under visible light irradiation. Compared with other reported catalysts, our presented catalyst shows more superior hydrogenation selectivity and stability as well as lower material cost. This high efficiency could be originated from the nanocatalyst's ability to synergistically control surface hydrogen species released from ammonia borane and energetic “hot” electrons induced by visible light irradiation for the selective reduction reaction. Compared with other reported catalysts, our presented nanocatalyst is better for the realization of energy-saving chemical processes by introducing solar energy.
- Ren, Yuqi,Hao, Caihong,Chang, Qing,Li, Ning,Yang, Jinlong,Hu, Shengliang
-
supporting information
p. 2938 - 2943
(2021/05/05)
-
- Microwave-assisted reduction of aromatic nitro compounds with novel oxo-rhenium complexes
-
The reduction of several aromatic nitro compounds to amines by means of the two novel catalytic systems ([IMes]2ReOBr3)/PhSiH3 and ([Py]3ReNOBr2)/PhSiH3 under microwave irradiation is here reported. These two systems were able to perform the reduction of nitro groups with higher TON and TOF when compared with previously reported systems based on oxo-rhenium core under standard heating, although they showed a lesser broad reaction scope compared with the known systems.
- Blacque, Olivier,Grieco, Gabriele
-
-
- Fabrication of magnetically separable ruthenium nanoparticles decorated on channelled silica microspheres: Efficient catalysts for chemoselective hydrogenation of nitroarenes
-
Fe3O4-SiO2microspheres were synthesized by a three-step synthetic procedure involving silica coating, surface capping, and surface modification. These magnetic mesoporous microspheres were employed as sorbents for the incorporation of ultrasmall Ru nanoparticles (2-5 nm) followed by thermal aggregation of the microspheres for achieving better heterogeneity and low leaching. The Ru decorated Fe3O4-SiO2microspheres (Ru@Fe3O4-CSM) were applied as chemoselective catalysts to convert more than 20 substituted nitroarenes to corresponding amines with good-to-excellent conversion (77-99%) and selectivity (70-100%) under mild conditions; the catalyst can be magnetically recovered within a frame of 90s (recovery time-lapse) and reused up to 5 times without significant decrease in activity or selectivity. Magnetic hysteresis studies were performed to elucidate the magnetic behavior of the ruthenium decorated materials.
- Das, Manash R.,Das, Pankaj,Kalita, Gauravjyoti D.
-
p. 13483 - 13496
(2021/10/12)
-
- Highly Efficient and Chemoselective Hydrogenation of Nitro Compounds into Amines by Nitrogen-Doped Porous Carbon-Supported Co/Ni Bimetallic Nanoparticles
-
A novel Co/Ni bimetallic nanoparticle supported by nitrogen-doped porous carbon (NPC), Co5/Ni@NPC-700, exhibits high conversion, chemoselectivity, and recyclability in the hydrogenation of 16 different nitro compounds into desired amines with hydrazine hydrate under mild conditions. The synergistic effects of Co/Ni bimetal nanoparticles and the NPC-supported porous honeycomb structure with more accessible active sites may be responsible for the high catalytic hydrogenation performance.
- Shen, Zeyu,Hong, Lirui,Zheng, Baishu,Wang, Guanyu,Zhang, Beibei,Wang, Zhaoxu,Zhan, Feiyang,Shen, Shaohua,Yun, Ruirui
-
supporting information
p. 16834 - 16839
(2021/11/17)
-
- Unsaturated Mo in Mo4O4N3for efficient catalytic transfer hydrogenation of nitrobenzene using stoichiometric hydrazine hydrate
-
Transfer hydrogenation of nitroarenes to the corresponding anilines using hydrazine hydrate and non-noble metal catalysts has already been widely studied. However, the toxicity resulting from excess hydrazine hydrate and the high reaction temperature limit its industrial application. Herein, a novel N-doped molybdenum oxide compound (Mo4O4N3) was in situ prepared from g-C3N4 and (NH4)6Mo7O24·4H2O (AHM). The as-prepared Mo4O4N3 can achieve a 99% yield of aniline using a stoichiometric molar ratio of hydrazine hydrate (-NO2?:?N2H4·H2O = 1?:?1.5) at room temperature for 50 minutes. Mechanistic experiments and characterization techniques indicate that the acidic sites of unsaturated Mo in Mo4O4N3 can efficiently activate N2H4 molecules to form active hydrogen species for catalytic transfer hydrogenation of nitroarenes without the generation of hazardous NH3. Besides, Mo4O4N3 still exhibited excellent catalytic performance for the large-scale reaction without solvent. This work may offer a feasible and efficient strategy for arylamine production. This journal is
- Li, Jing,Liang, Kun,Long, Yu,Luo, Shicheng,Ma, Jiantai,Qiao, Yi,Qin, Jiaheng,Yang, Guangxue
-
supporting information
p. 8545 - 8553
(2021/11/17)
-
- Synergistic effects for enhanced catalysis in a dual single-atom catalyst
-
Synergistic effects have been discussed extensively in bimetallic heterogeneous catalysis, but it remains unclear how the effects function at the atomic scale. Here, we report a dual single-atom catalyst (DSAC) Ir1Mo1/TiO2 displaying much greater catalytic chemoselectivity (>96%, at 100% conversion) than comparable single-atom catalysts (SACs) Ir1/TiO2 (38%, at 87% conversion) and Mo1/TiO2 (no activity) for the hydrogenation of 4-nitrostyrene (4-NS) to 4-vinylaniline (4-VA). Activation of the TiO2-supported bimetallic carbonyl cluster Ir2Mo2(CO)10(η5- C5H5)2 in an Ar atmosphere affords the DSAC Ir1Mo1/TiO2. Characterization of the dual single-atom structure confirms that it consists of well-dispersed Ir single atoms (Ir1) and Mo single atoms (Mo1) on TiO2. Density functional theory studies reveal that Ir1 sites effect H2 activation while Mo1 sites are responsible for 4-NS adsorption, with synergistic cooperation between the two sets of single atoms contributing to the better catalytic performance for the hydrogenation of 4-NS. This work provides a deep understanding of synergistic effects in dual single-atom catalysis.
- Fu, Junhong,Dong, Jinhu,Si, Rui,Sun, Keju,Zhang, Junying,Li, Mingrun,Yu, Nana,Zhang, Bingsen,Humphrey, Mark G.,Fu, Qiang,Huang, Jiahui
-
p. 1952 - 1961
(2021/02/16)
-
- Solar-accelerated chemoselective hydrogenation of 4-nitrostyrene to 4-vinylaniline with carbon dot-induced Cu over Cu3P in the absence of any sacrificial reagent
-
We present an efficient method toward rational design and fabrication of multicomponent photocatalysts using carbon dots (CDs) for solar-driven chemical reactions with super selectivity and activity. CDs act not only as a reductant to enable metallic Cu formation but also as a hole trapping agent to hinder side reactions. By simple pyrolysis of the mixture of the Cu source, CDs and NaH2PO2, the Cu3P-CDs-Cu nanocomposite is produced and shows a good sunlight harvesting property. Under one sun irradiation, Cu3P-CDs-Cu can catalyze ammonia borane (AB) for selective hydrogenation of 4-nitrostyrene (4-NS) to 4-aminostyrene (4-AS) in an aqueous solvent at room temperature, achieving 100% selectivity and beyond 99% conversion rate within a few short minutes of reaction time. The superior performance of Cu3P-CDs-Cu is attributed to the formation of the all-solid-state Z-scheme photocatalytic system, eliminating the high-energy holes - active species attacking CC groups in 4-NS - from Cu3P. Meanwhile, metallic Cu promotes the migration and transport of excited electrons from the interior to the surface and interface, accelerating the activation of AB for selective reduction of 4-NS to 4-AS.
- Chang, Qing,Hao, Caihong,Hu, Shengliang,Li, Ning,Ren, Yuqi,Yang, Jinlong
-
supporting information
p. 25374 - 25380
(2021/12/07)
-
- Phosphorus and nitrogen-doped palladium nanomaterials support on coral-like carbon materials as the catalyst for semi-hydrogenation of phenylacetylene and mechanism study
-
In this work, two types of polyporous and coral-like materials (CN) with high specific surface area are prepared using sodium glutamate as a carrier. At the same time, a CN-supported phosphorus-nitrogen-doped palladium nanomaterial CN-P-Pd is synthesized and applied to the preparation of styrene by selective hydrogenation of phenylacetylene under mild conditions. As shown in the TEM images, Pd nanoparticles with a particle size of about 4.4 nm are uniformly dispersed on the surface of the carrier. The results of N2 adsorption–desorption reveal that the surface area of the prepared catalyst (CN-P-Pd) is 1307 m2g?1. In addition, the experimental exploration shows the intervention of P in carbon-nitrogen materials can contribute to improve the selectivity of the reaction, which can be attributed to the fact that P element can change the electron density of Pd. Meanwhile, it is found that the solvent not only affects the activity of catalyst, but also the selectivity of the reaction. Kinetic study shows the activation energy of the reaction is 4.5 kJ/mol. With the increase of the reaction temperature, the dissolution rate of hydrogen in the solvent gradually slows down, which inhibits the progress of the reduction reaction. Mechanistic studies demonstrate that the carbon-nitrogen materials have strong adsorption capacity for substrates, and also provide more adsorption sites for phenylacetylene. Additionally, the optimal catalyst (CN-P-Pd) also has high reaction activity to other alkynes and the conversion can reach at 95%. Moreover, the optimal catalyst can be reused several times without significant reduction in reaction activity.
- Ma, Lei,Jiang, Pengbo,Wang, Kaizhi,Lan, Kai,Huang, Xiaokang,Yang, Ming,Gong, Li,Jia, Qi,Mu, Xiao,Xiong, Yucong,Li, Rong
-
-
- Highly selective hydrogenation of aromatic ketones to alcohols in water: effect of PdO and ZrO2
-
Pd/ZrO2and PdO/ZrO2composites, containing Pd or PdO nanoparticles, were prepared using an original one-step methodology. These nanocomposites catalyze the hydrogenation of acetophenone (AP) at 1 bar and 10 bar of H2in an aqueous solution. Compared to unsupported Pd or PdO nanoparticles, a remarkable increase in their activity was achieved as a result of interaction with zirconia. An unsupported PdO hydrogenated AP mainly to ethylbenzene (EB), while excellent regioselectivity towards 1-phenylethanol (PE) was obtained with PdO/ZrO2and it was preserved during recycling. Similarly, regioselectivity to PE was higher with Pd/ZrO2compared to unsupported Pd NPs. PdO and zirconia resulted in high selectivity to alcohols in the hydrogenation of substituted acetophenones.
- Alsalahi, W.,Trzeciak, A. M.,Tylus, W.
-
p. 10386 - 10393
(2021/08/09)
-
- Method for preparing amine through catalytic reduction of nitro compound by cyclic (alkyl) (amino) carbene chromium complex
-
The cyclic (alkyl) (amino) carbene chromium complex is prepared from corresponding ligand salt, alkali and CrCl3 and used for catalyzing pinacol borane to reduce nitro compounds in an ether solvent under mild conditions to generate corresponding amine. The method for preparing amine has the advantages of cheap and accessible raw materials, mild reaction conditions, wide substrate application range, high selectivity and the like, and is simple to operate.
- -
-
Paragraph 0015
(2021/04/17)
-
- Design and synthesis of water-soluble chelating polymeric materials for heavy metal ion sequestration from aqueous waste
-
Sequestration and removal of dissolved heavy metal ions from aqueous waste streams is a challenging task. Ethylenediaminetetraacetic acid (EDTA) is a hexadentate chelating ligand capable of forming 1:1 complex with various heavy metal ions while iminodiacetic acid (IDA) is analogous to half a unit of EDTA. A new styrene based monomer M1 bearing dimethyl iminodiacetate group was designed and synthesized in good yield to meet this objective. Free radical polymerization of M1 generated the homopolymer, which upon base hydrolysis generated the water-soluble chelating homopolymer P10, bearing sodium salt of IDA as the chelating group. The overall yield of P10 was 76.80% and the solubility was 5 mg/mL at room temperature. The water soluble polymer P10 was investigated for its ability to bind various heavy metal ions by UV–vis spectroscopy and was found to efficiently sequester Cu2+, Cd2+, Zn2+, Pb2+, Ni2+, Co2+, Cr3+, Fe2+ and Fe3+. The effect of pH on Cu2+ binding with P10 showed that every two IDA bearing monomeric repeat units binds with one Cu2+ ion at pH 7 suggesting that it forms complexes analogous to EDTA. Thermogravimetric analysis showed that the synthesized polymer possesses high thermal stability up to 400 °C. The potential for recovery and reuse of the polymer has been demonstrated with Cu2+ ion. The reported results suggest that this water-soluble chelating homopolymer is an excellent material with very high potential for application in wastewater treatment.
- Jacob, Josemon,Tyagi, Reshu
-
-
- Pyridinimine derivative/8-hydroxyquinoline derivative cadmium complex dye sensitizer as well as preparation method and application thereof
-
The invention relates to a D(-A-pi-A) type pyridinimine derivative/8-hydroxyquinoline derivative cadmium complex dye sensitizer (BDTT-im-Cd) as shown in a formula 1, and a preparation method and application thereof. The dye sensitizer is a D(-A-pi-A) complex synthesized by reacting a pyridinimine derivative/8-hydroxyquinoline derivative cadmium complex containing functional groups such as anauxiliary electron acceptor (A), a pi bridge, a main electron acceptor (A), an anchoring group and the like with an electron donor (D), namely, benzodithiophene bithiophene (BDTT) through a Heck coupling reaction. Experiments show that a dye-sensitized solar cell with the BDTT-im-Cd as the dye sensitizer shows good effects in photovoltaic performance tests, wherein photoelectric conversion efficiency (PCE) reaches 9.13%, the thermal decomposition temperature of a dye reaches 300 DEG C or above, thermal stability is high, the requirements of photovoltaic materials can be met, and the dye sensitizer has a certain prospect in the development and application of the dye-sensitized solar cell. The formula 1 shows the structure of the complex BDTT-im-Cd.
- -
-
-
- Differences in the selective reduction mechanism of 4-nitroacetophenone catalysed by rutile- And anatase-supported ruthenium catalysts
-
Ru/TiO2 catalysts exhibit excellent catalytic performance for selective reduction of 4-nitroacetophenone to 4-aminoacetophenone at normal temperature and atmospheric hydrogen pressure. Moreover, 99.9% selectivity to 4-aminoacetophenone can be obtained over 2.7 wt% Ru/TiO2(anatase) catalyst even in a relatively wide temperature (55-115 °C) and time (1-12 h) range. Its excellent catalytic performance is derived from the activation of H2 on the Ru nanoparticles at atmospheric pressure and the strong interaction of nitro groups with the support surface. Additionally, Ru nanoparticles supported on different crystalline TiO2 phases (anatase and rutile) result in different reaction pathways for 4-nitroacetophenone. Since the Ti-Ti distance on the rutile surface is smaller than that on the anatase surface, the hydroxylamine species adsorbed on the Ti atoms of rutile are more susceptible to the coupling reaction. Therefore, Ru/TiO2(rutile) causes a series of intermediates to accumulate during the conversion process, while Ru/TiO2(anatase) allows the highly selective conversion of 4-nitroacetophenone to 4-aminophenone. In addition, Ru/TiO2(anatase) can achieve chemoselective reduction of nitroaromatics to the corresponding anilines in the presence of -CN, -CHO, and -COOH, especially nitroaromatics containing CC and CC, indicating the excellent applicability.
- Gu, Xianmo,Pei, Linjuan,Wang, Jie,Zhang, Jin,Zheng, Zhanfeng,Zhu, Pengqi
-
p. 1518 - 1528
(2020/03/26)
-
- Highly Efficient Ultralow Pd Loading Supported on MAX Phases for Chemoselective Hydrogenation
-
Palladium is one of the most efficient metals for the hydrogenation of organic compounds. However, when molecules, such as nitroaromatics, with several reducible functionalities, are hydrogenated, Pd, like any other very active metal, such as nickel or platinum, often behaves unselectively. One strategy to render Pd more selective is to choose the proper support. Herein, we show that MAX phase powders of Ti3SiC2, Ti2AlC, or Ti3AlC2 can chemoselectively hydrogenate 4-nitrostyrene to 4-aminostyrene, with 100% selectivity, at around 3-4% conversion. To boost the latter, we loaded Ti3SiC2 with 0.0005 wt % Pd and increased the conversion to 100% while maintaining the 4-AS selectivity at >90%. By optimizing the Pd loading, we were also able to increase the turnover frequency 100-fold relative to previous literature results. The identification of this highly efficient and chemoselective system has broad implications for the design of cost-effective, earth-abundant, nontoxic, metal catalysts, with ultralow noble metal loadings.
- Barsoum, Michel W.,Chirica, Iuliana M.,Cucolea, Elena I.,Florea, Mihaela,Kuncser, Andrei C.,Natu, Varun,Nea?u, ?tefan,Nea?u, Florentina,Trandafir, Mihaela M.
-
p. 5899 - 5908
(2020/06/09)
-
- Zn(0)-Catalysed mild and selective hydrogenation of nitroarenes
-
The hydrogenation of nitroarenes is one of the most important strategies for the preparation of anilines. However, it is still a great challenge to develop mild and efficient synthetic routes toward aniline synthesis, particularly those employing both non-precious metal catalysts and low-pressure H2. Herein, we report a highly efficient protocol for the selective hydrogenation of nitroarenes in neutral H2O using H2 (1 atm) over a heterogeneous Zn(0) catalyst under mild conditions. The nitro groups of an array of nitroarenes can be converted into -NH2 with up to 99percent conversions and a selectivity of >99percent, even when functionalized with easily reducible substituents, or in the presence of aromatic ketones or styrene. This study might open an avenue for the selective hydrogenation of nitroarenes over a zinc catalyst using 1 atm H2.
- Du, Muyao,Hu, Pan,Jv, Xinchun,Sun, Shuting,Wang, Bo,Zhang, Qun,Zhao, Ruixiang
-
supporting information
p. 4640 - 4644
(2020/08/10)
-
- Selective hydrogenation of nitroarenes under mild conditions by the optimization of active sites in a well defined Co?NC catalyst
-
The catalytic hydrogenation of aromatic nitro compounds containing multiple functional groups into amino compounds with high conversion rates, selectivity, and stability under mild conditions is a great challenge. Herein, a well defined catalyst (Co?NC) is prepared through the pyrolysis of the Co-centered metal-organic framework (MOF) at the optimized temperature. The as-synthesized catalyst exhibits a high conversion rate and selectivity for the hydrogenation of 12 aromatic nitro compounds with different competing groups into desired amino compounds with hydrazine hydrate under mild conditions (80 °C, 30 min, and 1 atm). The catalyst also shows excellent stability and can be reused over 20 times without considerably losing its activity. It is found that the Co-Nx site is the main active site for catalytic hydrogenation, and the Mott-Schottky effect between the surface Co NPs and N-doped carbon can further promote the hydrogenation reaction. EXAFS, TEM, XPS, and Raman analyses confirm that cobalt nanoparticles (NPs) are properly encapsulated by the N-doped carbon matrix at the optimized temperature, and the Co species maintain a high spin state after the catalysis, which may be responsible for the high performance of Co?NC. This work demonstrates not only a highly efficient catalyst for hydrogenation under mild conditions, but also provides insight into the active sites in Co-based catalysts for hydrogenation.
- Chen, Shuo,Jiang, Hong,Jiang, Shun-Feng,Ling, Li-Li
-
p. 5730 - 5741
(2020/09/21)
-
- On-Demand, Ultraselective Hydrogenation System Enabled by Precisely Modulated Pd-Cd Nanocubes
-
The pursuit of efficient hydrogenation nanocatalysts with a desirable selectivity toward intricate substrates is state-of-the-art research but remains a formidable challenge. Herein, we report a series of novel PdCdx nanocubes (NCs) for ultraselective hydrogenation reactions with flexible tuning features. Obtaining a desirable conversion level of the substrates (e.g., 4-nitrophenylacetylene (NPA), 4-nitrobenzaldehyde (NBAD), and 4-nitrostyrene (NS)) and competitive selectivity for all potential hydrogenation products have been achieved one by one under optimized hydrogenation conditions. The performance of these PdCdx NCs displays an evident dependence on both the composition and the use of Cd and a need for a distinct hydrogen source (H2 or HCOONH4). Additionally, for the selectivity of hydrogen to be suitably high, the morphology of the NCs has a very well-defined effect. Density functional theory calculations confirmed the variation of adsorption energy for the substrate and hydrogenation products by carefully controlled introduction of Cd, leading to a desirable level of selectivity for all potential hydrogenation products. The PdCdx NCs also exhibit excellent reusability with negligible activity/selectivity decay and structural/composition changes after consecutive reactions. The present study provides an advanced strategy for the rational design of superior hydrogenation nanocatalysts to achieve a practical application for desirable and selective hydrogenation reaction efficiency.
- Feng, Yonggang,Xu, Weiwei,Huang, Bolong,Shao, Qi,Xu, Lai,Yang, Shize,Huang, Xiaoqing
-
supporting information
p. 962 - 972
(2020/02/20)
-
- In Situ Construction of Pt–Ni NF?Ni-MOF-74 for Selective Hydrogenation of p-Nitrostyrene by Ammonia Borane
-
Pt–Ni nanoframes (Pt–Ni NFs) exhibit outstanding catalytic properties for several reactions owing to the large numbers of exposed surface active sites, but its stability and selectivity need to be improved. Herein, an in situ method for construction of a core–shell structured Pt-Ni NF?Ni-MOF-74 is reported using Pt–Ni rhombic dodecahedral as self-sacrificial template. The obtained sample exhibits not only 100 % conversion for the selective hydrogenation of p-nitrostyrene to p-aminostyrene conducted at room temperature, but also good selectivity (92 %) and high stability (no activity loss after fifteen runs) during the reaction. This is attributed to the Ni-MOF-74 shell in situ formed in the preparation process, which can stabilize the evolved Pt–Ni NF and donate electrons to the Pt metals that facilitate the preferential adsorption of electrophilic NO2 group. This study opens up new vistas for the design of highly active, selective, and stable noble-metal-containing materials for selective hydrogenation reactions.
- Feng, Jing,Liu, Yu,Long, Yan,Song, Shuyan,Xu, Jinhui,Yang, Xiangguang,Zhang, Hongjie,Zhang, Yibo,Zhu, Junjiang
-
supporting information
(2020/09/21)
-
- Heteroleptic 1,4-Diazabutadiene Complexes of Ruthenium: Synthesis, Characterization and Utilization in Catalytic Transfer Hydrogenation
-
Reaction of [Ru(trpy)Cl3] with 1,4-diazabutadienes (p-RC6H4N=C(H)-(H)C=NC6H4R-p; R = OCH3, CH3, H and Cl; abbreviated as L-R) in refluxing ethanol in the presence of triethylamine has afforded a family of complexes, isolated as perchlorate salts, of type [Ru(trpy)(L-R)Cl]ClO4 [depicted as complexes 1 (R = OCH3), 2 (R = CH3), 3 (R = H) and 4 (R = Cl)]. Crystal structures of complexes 1, 2 and 4 have been determined, and structure of complex 3 has been optimized by DFT method. The 1,4-diazabutadiene ligand in each complex is bound to ruthenium as a N,N-donor forming five-membered chelate. Complexes 1–4 catalyze transfer hydrogenation of aryl aldehydes to the corresponding alcohols with high (ca. 106) TON. They are also found to catalyze transfer hydrogenation of aryl ketones to corresponding secondary alcohols, but with much less efficiency. Catalytic transfer hydrogenation of nitroarenes to the corresponding amines has also been achieved.
- Saha, Rumpa,Mukherjee, Aparajita,Bhattacharya, Samaresh
-
p. 4539 - 4548
(2020/11/30)
-
- Creation of Redox-Active PdSx Nanoparticles Inside the Defect Pores of MOF UiO-66 with Unique Semihydrogenation Catalytic Properties
-
Semihydrogenation of alkynes to produce alkenes is very important in the industry; however, over-hydrogenation heavily complicates the postprocesses, which are highly energy consuming and not environmentally friendly. One of the most efficient pathways to solve this challenging issue is to develop highly selective catalysts that could only hydrogenate alkynes and are inactive in hydrogenation of alkenes. This work presents herein an efficient catalyst, consisting of in situ created PdS0.53 nanoparticles as the redox-active sites inside the defect pores of metal–organic framework UiO-66, which demonstrates very high alkene selectivity (up to 99.5%) in semihydrogenation of easily over-hydrogenated terminal alkynes. In contrast to the traditional catalysts, strict control over the reaction time becomes the nonessential condition because the catalyst system is almost inactive in hydrogenation of alkenes. Therefore, this paradigm work provides a practically applicable pathway for the development of efficient catalysts with unique catalytic properties for selective semihydrogenation reactions.
- Dong, Ming-Jie,Wang, Xuan,Wu, Chuan-De
-
-
- Selective Transfer Semihydrogenation of Alkynes with H2O (D2O) as the H (D) Source over a Pd-P Cathode
-
We reported a selective semihydrogenation (deuteration) of numerous terminal and internal alkynes using H2O (D2O) as the H (D) source over a Pd-P alloy cathode at a lower potential. P-doping caused the enhanced specific adsorption of alkynes and the promoted intrinsic activity for producing adsorbed atomic hydrogen (H*ads) from water electrolysis. The semihydrogenation of alkynes could be accomplished at a lower potential with up to 99 % selectivity and 78 % Faraday efficiency of alkene products, outperforming pure Pd and commercial Pd/C. This electrochemical semihydrogenation of alkynes might proceed via a H*ads addition pathway rather than a proton-coupled electron transfer process. The decreased amount of H*ads at a lower potential and the more preferential adsorption of the Pd-P to C≡C π bond than C=C moiety resulted in the excellent alkene selectivity. This method was capable of producing mono-, di-, and tri-deuterated alkenes with up to 99 % deuterium incorporation.
- Liu, Cuibo,Lu, Siyu,Wang, Changhong,Wu, Yongmeng,Zhang, Bin
-
supporting information
p. 21170 - 21175
(2020/09/11)
-
- Hydroxyl Assisted Rhodium Catalyst Supported on Goethite Nanoflower for Chemoselective Catalytic Transfer Hydrogenation of Fully Converted Nitrostyrenes
-
Control of chemoselectivity is a special challenge for the reduction of nitroarenes bearing one or more unsaturated groups. Here, we report a flower-like Rh/α-FeOOH catalyst for the chemoselective hydrogenation of nitrostyrene to vinylaniline over full conversion, which benefits the new functionalized aminostyrene because the multisubstituted aminostyrenes are usually commercially unavailable. This catalyst does not only show desirable selectivity for the vinylanilines, but also exhibits the inertness to various other reducible groups over wide reaction duration. The catalytic selectivity for the reduction of the nitro group towards vinyl group was investigated by the control experiments and FT-IR analysis. We have found that the abundant hydroxyl groups in the α-FeOOH may contribute to the improvement of catalytic activity and selectivity. Furthermore, the catalyst exhibits excellent stability and keeps its catalytic performance even after 6 cycles. (Figure presented.).
- Hu, Zenan,Ai, Yongjian,Liu, Lei,Zhou, Junjie,Zhang, Gang,Liu, Hongqi,Liu, Xiangyu,Liu, Zhibo,Hu, Jianshe,Sun, Hong-bin,Liang, Qionglin
-
supporting information
p. 3146 - 3154
(2019/05/10)
-
- Hydrogenation of Functionalized Nitroarenes Catalyzed by Single-Phase Pyrite FeS2 Nanoparticles on N,S-Codoped Porous Carbon
-
Catalytic hydrogenation of nitroarenes is an industrially very important and environmentally friendly process for the production of anilines; however, highly chemoselective reduction of nitroarenes decorated with one or more reducible groups in a nitroarene molecule remains a challenge. Herein, a novel hybrid non-noble iron-based nanocatalyst (named as FeS2/NSC) was developed, which was prepared from biomass as C and N source together with inexpensive Fe(NO3)3 as Fe source through high-temperature pyrolysis in a straightforward and cost-effective procedure. Comprehensive characterization revealed that single-phase pyrite FeS2 nanoparticles with precisely defined composition and uniform size were homogeneously dispersed on N,S-codoped porous carbon with large specific surface area, hierarchical porous channels, and high pore volume. The resultant catalyst FeS2/NSC demonstrated good catalytic activity for hydrogenation of functionalized nitroarenes with good tolerance of various functional groups in water as a sustainable and green solvent. Compared with bulk pyrite FeS2 and other non-noble metal-based heterogeneous catalysts reported in the literature, a remarkably enhanced activity was observed under mild reaction conditions. More importantly, FeS2/NSC displayed exclusive chemoselectivity for the reduction of nitro groups for nitroarenes bearing varying readily reducible groups.
- Duan, Yanan,Dong, Xiaosu,Song, Tao,Wang, Zhaozhan,Xiao, Jianliang,Yuan, Youzhu,Yang, Yong
-
-
- Atomically dispersed Ni as the active site towards selective hydrogenation of nitroarenes
-
Rational design of heterogeneous non-noble metal catalysts as highly efficient and selective catalysts for hydrogenation of nitroarenes with hydrogen as the reducing agent is currently a great challenge, which has attracted a great deal of attention. Herein, a new strategy for achieving atomic dispersion of Ni atoms on nitrogen-doped porous carbon (Ni-N-C) with a specific surface area of up to 810 m2 g-1 and nickel loading as high as 4.4 wt% is developed, yielding high activity, chemoselectivity, and reusability of catalysts in the hydrogenation of nitroarenes using hydrogen as the reductant with a turnover of number (TON) value of 84 and a turnover of frequency (TOF) value of 8.4 h-1 for the first time. The Ni single atoms anchored on N-doped porous carbon by binding with nitrogen/carbon have been proved to be the active sites. Importantly, the Ni-N3 active species is found to contribute more activity compared with Ni-N2 and Ni-N4. Density functional theory (DFT) calculations also reveal that the Ni-N3 structure exhibits the highest activity according to the lowest adsorption energy and the longest elongation N-O bonds of nitrobenzene, which originated from the induced charge transfer. This work opens a new route for rational design and accurate modulation of nanostructured organic molecular transformation catalysts at the atomic scale.
- Yang, Fan,Wang, Minjian,Liu, Wei,Yang, Bin,Wang, Ying,Luo, Jun,Tang, Yushu,Hou, Liqiang,Li, Yun,Li, Zihui,Zhang, Bing,Yang, Wang,Li, Yongfeng
-
supporting information
p. 704 - 711
(2019/02/14)
-
- Cobalt Entrapped in N,S-Codoped Porous Carbon: Catalysts for Transfer Hydrogenation with Formic Acid
-
Catalysts with Co nanoparticles (NPs) entrapped in N,S-codoped carbon shells were successfully fabricated by pyrolysis of porous organic polymers (POPs) with cobalt salts. The encapsulated structure consisting of Co NPs and N,S-codoped carbon layers was verified by TEM, XRD, and X-ray photoelectron spectroscopy. The catalysts displayed excellent activity and stability for the catalytic transfer hydrogenation (CTH) of nitrobenzene with formic acid under base-free conditions. Furthermore, the resultant catalysts allowed for highly efficient and selective transfer hydrogenation of various functionalized nitroarenes to the corresponding anilines. Through control experiments, the covered Co NPs were identified as active sites for CTH. The incorporation of S into the N-doped carbon lattice promoted the electron transfer from metallic cobalt NPs to their shells, which played a significant role in the acceleration of CTH. Moreover, the Co-NSPC-850 catalyst pyrolyzed at 850 °C showed excellent stability in the recycling experiments.
- Guo, Haotian,Gao, Ruixiao,Sun, Mingming,Guo, Hao,Wang, Bowei,Chen, Ligong
-
p. 487 - 494
(2019/01/24)
-
- Ammonia borane dehydrogenation and selective hydrogenation of functionalized nitroarene over a porous nickel-cobalt bimetallic catalyst
-
The hydrolysis of ammonia borane is a promising strategy for hydrogen energy exploration and exploitation. The in situ produced hydrogen could be directly utilized in hydrogenation reactions. In this work, a bimetallic nickel-cobalt material with porous structure was developed through the pyrolysis of ZIF-67 incorporated with Ni ions. Through the introduction of Ni(NO3)2 as an etching agent, the ZIF-67 polyhedrons were transformed into hollow nanospheres, and further evolved into irregular nanosheets. The bimetallic NiCo phase was formed after pyrolysis in a nitrogen atmosphere at high temperature, with the decomposition and release of organic ligands as gaseous molecules under flowing nitrogen. The obtained bimetallic NiCo porous materials show superior catalytic performance towards hydrolytic dehydrogenation of ammonia borane, thereby nitrobenzene with reducible functional groups can be reduced with high selectivity to the corresponding aniline.
- Miao, Hui,Ma, Kelong,Zhu, Huiru,Yin, Kun,Zhang, Ying,Cui, Yumin
-
p. 14580 - 14585
(2019/05/24)
-
- Bimetallic Co/Al nanoparticles in an ionic liquid: Synthesis and application in alkyne hydrogenation
-
Herein, we report the microwave-induced decomposition of various organometallic cobalt and aluminum precursors in an ionic liquid (IL), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIm]NTf2), resulting in Co/Al nanoalloys with different molar Co/Al ratios. The dual-source precursor system of dicobalt octacarbonyl (Co2(CO)8) and pentamethylcyclopentadienyl aluminum ([AlCp?]4) in [BMIm]NTf2 afforded CoAl nanoparticles (CoAl-NPs) with a molar Co/Al ratio of 1?:?1. Their size and size distribution were determined via transmission electron microscopy (TEM) to be an average diameter of 3.0 ± 0.5 nm. Furthermore, the dual-source precursor system of cobalt amidinate ([Co(iPr2-MeAMD)2]) and aluminum amidinate [Me2Al(iPr2-MeAMD)] in molar ratios of 1?:?1 and 3?:?1 resulted in CoAl-and Co3Al-NPs with an average diameter of 3 ± 1 and 2.0 ± 0.2 nm, respectively. All the obtained materials were characterized via TEM, energy dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED), together with high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and (high-resolution) X-ray photoelectron spectroscopy ((HR-)XPS). Phase-pure Co/Al-NPs were not obtained since the concomitant formation of Co-NPs and Al2O3 occurred in this wet-chemical synthesis. The as-prepared Co/Al nanoalloys were evaluated as catalysts in the hydrogenation of phenylacetylene under mild conditions (2 bar H2, 30 °C in THF). In comparison to the monometallic Co-NPs, the Co/Al-NPs showed a significantly higher catalytic hydrogenation activity. The Co-and Co/Al-NPs were also active under harsher reaction conditions (80 bar H2, 80 °C) without the addition of the activating co-catalyst DIBAL-H.
- Schmolke, Laura,Gregori, Bernhard J.,Giesen, Beatriz,Schmitz, Alexa,Barthel, Juri,Staiger, Lena,Fischer, Roland A.,Jacobi Von Wangelin, Axel,Janiak, Christoph
-
p. 16583 - 16594
(2019/11/11)
-
- Pt Nanoparticles Supported over Porous Porphyrin Nanospheres for Chemoselective Hydrogenation Reactions
-
Optimizing the chemoselectivity in a chemical reaction catalyzed by metallic nanoparticles (NPs) hosted over a solid support is a big challenge, especially in the context of the sustainability of the process. Here we showed that chemoselectivity in the hydrogenation of 4-nitrostyrene can be tailored on Pt-loaded porphyrin nanospheres through the functionalization with sulfonic acid groups at the catalyst surface. 4-Nitrostyrene is transformed to 4-aminostyrene over sulfonated Pt-POP-SO3H, with ～77.8 % selectivity at conversion of ～90 %, whereas the pristine catalyst selectively produced ～80 % 4-ethylnitrobenezene at almost complete conversion level. The reversal of the selectivity could be attributed to the effect of the introduction of sulfonic acid group over the supported Pt NPs. Presence of sulfonic acid groups in the functionalized Pt-porphyrin material has been confirmed from XPS, FT-IR and elemental analysis data. Moreover, these catalysts are recyclable, suggesting their durability and chemical-stability for long-term sustainable operations.
- Modak, Arindam,Bhanja, Piyali,Bhaumik, Asim
-
p. 1977 - 1985
(2019/03/21)
-
- Chemoselective hydrogenation of 4-nitrostyrene to 4-aminostyrene by highly efficient TiO2 supported Ni3Sn2 alloy catalyst
-
Ni3Sn2 alloy catalysts supported on various metal oxides (TiO2, Al2O3, ZrO2, SnO2, and CeO2) were successfully prepared by simple hydrothermal method and then applied to the hydrogenation of 4-nitrostyrene under H2 3.0 MPa at 423 K. All the supported catalysts hydrogenated the nitro group more preferentially than the olefin group from the initial reaction stages, showing 100% chemoselectivities towards the desired 4-aminostyrene. This may be attributed to -interaction between the oxygen lone pairs in the nitro group and Sn atoms in Ni3Sn2 alloy. By prolonging the reaction times, the 4- aminostyrene yields increased and finally reached the maximum yields. Among the catalysts, Ni3Sn2/TiO2 alloy catalyst showed the highest catalytic activity with remarkably high chemoselectivity towards 4-aminostyrene. The conversion and chemoselectivity were 100% and 79%, respectively, at a reaction time of only 2.5 h. From the physical and chemical characterization of the supported catalysts, it was clear that the catalytic activity was correlated with H2 uptake. The application of the best catalyst for the hydrogenation of a wide variety of substituted nitroarenes resulted in the chemoselective formation of the corresponding aminoarenes.
- Yamanaka, Nobutaka,Hara, Takayoshi,Ichikuni, Nobuyuki,Shimazu, Shogo
-
supporting information
p. 811 - 816
(2019/05/21)
-
- Efficient and Practical Transfer Hydrogenation of Ketones Catalyzed by a Simple Bidentate Mn?NHC Complex
-
Catalytic reductions of carbonyl-containing compounds are highly important for the safe, sustainable, and economical production of alcohols. Herein, we report on the efficient transfer hydrogenation of ketones catalyzed by a highly potent Mn(I)?NHC complex. Mn?NHC 1 is practical at metal concentrations as low as 75 ppm, thus approaching loadings more conventionally reserved for noble metal based systems. With these low Mn concentrations, catalyst deactivation is found to be highly temperature dependent and becomes especially prominent at increased reaction temperature. Ultimately, understanding of deactivation pathways could help close the activity/stability-gap with Ru and Ir catalysts towards the practical implementation of sustainable earth-abundant Mn-complexes.
- van Putten, Robbert,Benschop, Joeri,de Munck, Vincent J.,Weber, Manuela,Müller, Christian,Filonenko, Georgy A.,Pidko, Evgeny A.
-
p. 5232 - 5235
(2019/07/18)
-
- Chemoselective hydrogenation of nitroarenes catalyzed by cellulose-supported Pd NPs
-
Cellulose-supported palladium nanoparticles (NPs) were prepared by straightforward deposition of metal NPs on modified cellulose. The catalyst exhibited excellent catalytic activity and selectivity in room-temperature hydrogenation of various nitroarenes to arylamines under atmospheric hydrogen pressure in neat water without any additives. High chemoselectivity was also achieved in the hydrogenation of substituted nitroarenes with multiple reducible groups. The catalyst can be recycled by simple centrifugation and reused for at least 4 times without significant decline of yields.
- Li, Dan-dan,Zhang, Jia-wei,Cai, Chun
-
-
- Nitrogen-doped graphene-activated metallic nanoparticle-incorporated ordered mesoporous carbon nanocomposites for the hydrogenation of nitroarenes
-
Herein, nanoscale metallic nanoparticle-incorporated ordered mesoporous carbon catalysts activated by nitrogen-doped graphene (NGr) were fabricated via an efficient multi-component co-assembly of a phenolic resin, nitrate, acetylacetone, the nitrogen-containing compound 1,10-phenanthroline, and Pluronic F127, followed by carbonization. The obtained well-dispersed nitrogen-doped graphene-activated transition metal nanocatalysts possess a 2-D hexagonally arranged pore structure with a high surface area (～500 m2 g-1) and uniform pore size (～4.0 nm) and show excellent activity for the selective hydrogenation-reduction of substituted nitroarenes to anilines in an environmentally friendly aqueous solution. The high catalytic performance and durability is attributed to the synergistic effects among the components, the unique structure of the nitrogen-doped graphene layer-coated metallic nanoparticles, and electronic activation of the doped nitrogen.
- Huang, Haigen,Wang, Xueguang,Sheng, Yao,Chen, Chenju,Zou, Xiujing,Shang, Xingfu,Lu, Xionggang
-
p. 8898 - 8909
(2018/03/08)
-
- Chemoselective Hydrogenation with Supported Organoplatinum(IV) Catalyst on Zn(II)-Modified Silica
-
Well-defined organoplatinum(IV) sites were grafted on a Zn(II)-modified SiO2 support via surface organometallic chemistry in toluene at room temperature. Solid-state spectroscopies including XAS, DRIFTS, DRUV-vis, and solid-state (SS) NMR enhanced by dynamic nuclear polarization (DNP), as well as TPR-H2 and TEM techniques revealed highly dispersed (methylcyclopentadienyl)methylplatinum(IV) sites on the surface ((MeCp)PtMe/Zn/SiO2, 1). In addition, computational modeling suggests that the surface reaction of (MeCp)PtMe3 with Zn(II)-modified SiO2 support is thermodynamically favorable (ΔG = -12.4 kcal/mol), likely due to the increased acidity of the hydroxyl group, as indicated by NH3-TPD and DNP-enhanced 17O{1H} SSNMR. In situ DRIFTS and XAS hydrogenation experiments reveal the probable formation of a surface Pt(IV)-H upon hydrogenolysis of Pt-Me groups. The heterogenized organoplatinum(IV)-hydride sites catalyze the selective partial hydrogenation of 1,3-butadiene to butenes (up to 95%) and the reduction of nitrobenzene derivatives to anilines (up to 99%) with excellent tolerance of reduction-sensitive functional groups (olefin, carbonyl, nitrile, halogens) under mild reaction conditions.
- Camacho-Bunquin, Jeffrey,Ferrandon, Magali,Sohn, Hyuntae,Yang, Dali,Liu, Cong,Ignacio-De Leon, Patricia Anne,Perras, Frédéric A.,Pruski, Marek,Stair, Peter C.,Delferro, Massimiliano
-
p. 3940 - 3951
(2018/03/29)
-
- N-doped graphitic carbon-improved Co-MoO3 catalysts on ordered mesoporous SBA-15 for chemoselective reduction of nitroarenes
-
Metallic Co-MoO3 catalysts supported on ordered mesoporous SBA-15 were first prepared through in situ reaction of SBA-15-supported Co-Mo oxides with 1,10-phenanthroline. The resulting Co-MoO3/NC@SBA-15 catalysts with N-doped carbon (NC) exhibited high catalytic activity and chemoselectivity for selective reduction of various functionalized nitroarenes to the corresponding arylamines in ethanol with hydrazine hydrate at near room temperature (30 °C). For reduction of all tested substrates (28 examples), the catalyst could afford a conversion of >99% and arylamine selectivity of >99%. The excellent catalytic performance of the Co-MoO3/NC@SBA-15 was attributed to the Co-Nχ(C)-Mo active sites generated through the interaction between the surface Co-Nχ(C) and MoO3 species, promoting the dissociation of hydrazine molecule into the active H* species for the reduction of nitro groups. After the seventh cycle for reduction of 4-methoxylnitrobenzene, the 2%Co-MoO3/NC@SBA-15 showed little change in catalytic performance, textural properties, size and dispersion of metal species and valence states of elements, indicating high stability and recyclability.
- Huang, Haigen,Liang, Xiangcheng,Wang, Xueguang,Sheng, Yao,Chen, Chenju,Zou, Xiujing,Lu, Xionggang
-
p. 127 - 137
(2018/05/04)
-
- Enhanced catalytic performance of cobalt nanoparticles coated with a N,P-codoped carbon shell derived from biomass for transfer hydrogenation of functionalized nitroarenes
-
The development of abundantly available base metal catalysts for organic transformations remains an important goal of chemical research. Herein, we report the first facile fabrication of active, inexpensive, and reusable cobalt nanoparticles (NPs) coated with a N,P-codoped carbon shell derived from naturally renewable biomass and earth-abundant, low-cost cobalt salt and PPh3. The entire process is operationally simple, straightforward, cost-effective and environmentally benign and can be used in mass production for practical application. The resultant catalysts allow for highly efficient and selective transfer hydrogenation of functionalized nitroarenes to the corresponding anilines using formic acid or ammonium formate as the hydrogen donor. Uniformly incorporated N and P into the carbon lattices exhibited synergistic effects with the encapsulated Co NPs to engineer the structure and composition of the catalyst, thereby substantially boosting the catalytic efficiency. The most active catalyst Co@NPC-800 exhibited outstanding activity and exclusive selectivity for the reduction of functionalized nitroarenes to anilines, especially those decorated with readily reducible functional groups. The catalyst demonstrated high stability and can be easily separated by using an external magnet for successive reuses without significant loss in both activity and selectivity.
- Duan, Yanan,Song, Tao,Dong, Xiaosu,Yang, Yong
-
supporting information
p. 2821 - 2828
(2018/06/29)
-
- Chemoselective hydrogenation of unsaturated nitro compounds to unsaturated amines by Ni-Sn alloy catalysts
-
Ni-Sn alloy catalysts were prepared and applied to the hydrogenation of 4-nitrostyrene at 383423 K using H2 gas as the hydrogen donor. Ni3Sn2 alloy showed a significantly high conversion and selectivity towards 4-aminostyrene (Conv. 100%, Sel. 99%). Various unsaturated nitro compounds were also successfully converted into their corresponding unsaturated amines.
- Yamanaka, Nobutaka,Hara, Takayoshi,Ichikuni, Nobuyuki,Shimazu, Shogo
-
supporting information
p. 971 - 974
(2018/08/24)
-
- Heterogeneous Iron-Catalyzed Hydrogenation of Nitroarenes under Water-Gas Shift Reaction Conditions
-
Reduction of various nitroarenes in the presence of heterogeneous iron oxide-based catalyst Fe 2 O 3 /NGr@C under water-gas shift reaction (WGSR) conditions has been demonstrated. The catalytic material is prepared in a straightforward manner via deposition/pyrolysis of iron-phenanthroline complex on carbon support. It shows high chemoselectivity towards the reduction of nitroarenes in the presence of other reducible and/or poisoning-capable functional groups. Hydrogenation is achieved using CO/H 2 O as a hydrogen source. Furthermore, it is demonstrated that the presence of triethylamine additive has a significant positive effect on the rate of reduction.
- Ryabchuk, Pavel,Junge, Kathrin,Beller, Matthias
-
supporting information
p. 4369 - 4376
(2018/11/21)
-
- Metal-free deoxygenation and reductive disilylation of nitroarenes by organosilicon reducing reagents
-
A metal-free deoxygenation and reductive disilylation of nitroarenes was achieved using N,N’-bis(trime-thylsilyl)-4,4’-bipyridinylidene (1) under mild and neutral reaction conditions, and a broad functional group tolerance was possible in this reaction. Mono-deoxygenation, giving a synthetically valuable N,O-bis(trimethylsilyl)phe-nylhydroxylamine (7a) as a readily available and safe phenylnitrene source from nitrobenzene, and double-deoxy-genation, giving N,N-bis(trimethylsilyl)anilines 8, were easily controlled by varying the amounts of 1 and reaction temperature as well as adding dibenzothiophene (DBTP). Reaction of 2-arylnitrobenzenes with 1 resulted in the formation of the corresponding carbazoles 14 via in situ-gen-erated phenylnitrene species derived by thermolysis of N,O-bis(trimethylsilyl)phenylhydroxylamines 7, followed by their subsequent intramolecular C H insertion. In addition, the intramolecular N N coupling reaction proceeded in the reduction of 2,2’-dinitrobiphenyl derivatives by 1, giving the corresponding benzo[c]cinnolines.
- Bhattacharjee, Argha,Hosoya, Hiromu,Ikeda, Hideaki,Nishi, Kohei,Tsurugi, Hayato,Mashima, Kazushi
-
supporting information
p. 11278 - 11282
(2018/10/20)
-
- Visible-light-driven Efficient Photocatalytic Reduction of Organic Azides to Amines over CdS Sheet–rGO Nanocomposite
-
CdS sheet–rGO nanocomposite as a heterogeneous photocatalyst enables visible-light-induced photocatalytic reduction of aromatic, heteroaromatic, aliphatic and sulfonyl azides to the corresponding amines using hydrazine hydrate as a reductant. The reaction shows excellent conversion and chemoselectivity towards the formation of the amine without self-photoactivated azo compounds. In the adopted strategy, CdS not only accelerates the formation of nitrene through photoactivation of azide but also enhances the decomposition of azide to a certain extent, which entirely suppressed formation of the azo compound. The developed CdS sheet-rGO nanocomposite catalyst is very active, providing excellent results under irradiation with a 40 W simple household CFL lamp.
- Singha, Krishnadipti,Mondal, Aniruddha,Ghosh, Subhash Chandra,Panda, Asit Baran
-
p. 255 - 260
(2018/01/15)
-
- Terminal Alkenes from Acrylic Acid Derivatives via Non-Oxidative Enzymatic Decarboxylation by Ferulic Acid Decarboxylases
-
Fungal ferulic acid decarboxylases (FDCs) belong to the UbiD-family of enzymes and catalyse the reversible (de)carboxylation of cinnamic acid derivatives through the use of a prenylated flavin cofactor. The latter is synthesised by the flavin prenyltransferase UbiX. Herein, we demonstrate the applicability of FDC/UbiX expressing cells for both isolated enzyme and whole-cell biocatalysis. FDCs exhibit high activity with total turnover numbers (TTN) of up to 55000 and turnover frequency (TOF) of up to 370 min?1. Co-solvent compatibility studies revealed FDC's tolerance to some organic solvents up 20 % v/v. Using the in-vitro (de)carboxylase activity of holo-FDC as well as whole-cell biocatalysts, we performed a substrate profiling study of three FDCs, providing insights into structural determinants of activity. FDCs display broad substrate tolerance towards a wide range of acrylic acid derivatives bearing (hetero)cyclic or olefinic substituents at C3 affording conversions of up to >99 %. The synthetic utility of FDCs was demonstrated by a preparative-scale decarboxylation.
- Aleku, Godwin A.,Prause, Christoph,Bradshaw-Allen, Ruth T.,Plasch, Katharina,Glueck, Silvia M.,Bailey, Samuel S.,Payne, Karl A. P.,Parker, David A.,Faber, Kurt,Leys, David
-
p. 3736 - 3745
(2018/08/03)
-
