- Synthesis of magnetic silver cyclodextrin nanocomposite as catalyst for reduction of nitro aromatics and organic dyes
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Nanocomposites decorated with metallic nanoparticles in their matrix are important class of heterogeneous catalyst with high catalytic activity. Functionalized polymers are low cost materials which offer excellent supports for catalysts to render stability to metallic nanoparticles. Herein we report synthesis of Silver nanocomposite using β-cyclodextrin (b-CD) maleic anhydride crosslinked polymer anchored on the surface of magnetic nanoparticles. The nanocomposite was characterized using sophisticated analytical techniques and its role as a catalyst for reduction of nitroaromatics and organic dyes was investigated. This catalytic system exhibited comparatively lower Ea value of 18 kJ mol?1 and followed pseudo first order kinetics. Simultaneous reduction of 4-Nitrophenol and Methylene Blue could be achieved in a time interval of 7 minutes. Being magnetically separable, the catalyst exhibited high recycling efficiency (up to 5 cycles) and ease of operation under mild conditions.
- Nariya, Pratik,Das, Manita,Shukla, Falguni,Thakore, Sonal
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- Porous noria polymer: a cage-to-network approach toward a robust catalyst for CO2fixation and nitroarene reduction
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The advantages of the cage-to-network design strategy were demonstrated by knitting a waterwheel-like preporous molecular cage, noria, with a rigid aromatic linker to obtain a highly microporous organic polymer (NPOP,SBET: 748 ± 25 m2g?1). The NPOP was employed for the catalytic conversion of CO2to cyclic carbonates under solvent-free reaction conditions. Furthermore, a silver nanoparticle encapsulated NPOP exhibited remarkable catalytic activity for nitroarene reduction with excellent recyclability.
- Giri, Arkaprabha,Patil, Niraj Nitish,Patra, Abhijit
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- Synthesis of graphene quantum dots stabilized bimetallic AgRh nanoparticles and their applications
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The design and synthesis of highly efficient and ultrafine bimetallic nanoparticles catalysts is challenging. Here we report the synthesis of AgRh bimetallic nanoparticles (AgRh BNPs) stabilized by graphene quantum dots (GQDs) and their exceptional catalytic activities in the reduction of 4-nitrophenol, 2,4-dinitrophenol and 4-nitrobenzene diazonium tetrafluoroborate and generation of hydroxyl radicals. Construction of AgRh BNPs nanocomposites is accomplished by mixing of GQDs and sodium borohydride, followed by the addition of simple commercial Ag and Rh salt at 0 °C in water. Among them, AgRh BNPs 4 exhibits excellent catalytic performance owing to a positive synergistic effects between the Ag and Rh atoms on GQDs, and its catalytic activity is better than those of both monometallic counterparts.
- Li, Ning,Chen, Weifeng,Shen,Chen, Shaona,Liu
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- Yolk@Shell Nanoreactors Carrying a Cluster of Metal Nanocrystals Stabilized Inside the Hollow Carbon Shell
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Synthesis and stabilization of ultrasmall metal nanocrystals at high temperature have always been challenging due to their self-aggregating behavior. Here, we introduce a strategy to synthesize a cluster of tiny metal nanocrystals (~3 nm) inside a hollow carbon shell as yolk@shell-type architecture following a metal-coordination-based nanocrystal stabilization at high temperature (500?°C). The successful catalytic reduction of 2-amino-4-nitrophenol demonstrates the efficiency of such nanoreactor in chemical transformation. Further adaptation of this strategy helps in synthesizing bimetallic (Au/Pt, Au/Pd, and Au/Ru) nanocrystals, which unfolds the possibilities to design advanced new-generation catalysts.
- Acharya, Anubhab,Kumar, Amit,Lee, In Su
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- Galactose Grafted Two-Dimensional Nanosheets as a Scaffold for the In Situ Synthesis of Silver Nanoparticles: A Potential Catalyst for the Reduction of Nitroaromatics
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Two major hurdles in NP-based catalysis are the aggregation of the NPs and their recycling. Immobilization of NPs onto a 2D support is the most promising strategy to overcome these difficulties. Herein, amphiphilicity-driven self-assembly of galactose-hexaphenylbenzene-based amphiphiles into galactose-decorated 2D nanosheet is reported. The extremely dense decoration of reducing sugar on the surface of the sheets is used for the in situ synthesis and immobilization of ultrafine catalytically active AgNPs by using Tollens’ reaction. The potential of the system as a catalyst for the reduction of various nitroaromatics is demonstrated. Enhanced catalytic activity is observed for the immobilized AgNPs when compared to the corresponding discrete AgNPs. Recovery of the catalytic system from the reaction mixture by ultrafiltration and its subsequent recycling for several cycles without dropping its activity is shown. This is the first report demonstrating the in situ synthesis and immobilization of ultrafine AgNPs onto a 2D nanosheet that exhibits excellent catalytic performance for the reduction of nitroaromatics.
- Harikrishnan, Kaloor S.,Krishnan, Nithiyanandan,Kumar, Nilima Manoj,Krishna, Anusree,Raj, Gowtham,Perumal, Devanathan,Kalathil, Jemshiya,Krishna, Jithu,Varghese, Reji
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p. 14100 - 14107
(2021/09/06)
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- Chemoselective reduction of nitro and nitrile compounds using an Fe3O4-MWCNTs?PEI-Ag nanocomposite as a reusable catalyst
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Multi-walled carbon nanotubes (MWNTs) were modified with carboxylic acid functional groups (MWCNTs-(COOH)n) prior to decoration with Fe3O4 nanoparticles. A further modification step by polyethyleneimine (PEI) resulted in Fe3O4-MWCNTs?PEI which provided a suitable platform for coordination and in situ reduction of silver ions to obtain an Fe3O4-MWCNTs?PEI-Ag nanocomposite with highly dispersed Ag nanoparticles. The Fe3O4-MWCNTs?PEI-Ag hybrid material was characterized by various techniques such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA), and was used as an efficient catalyst for chemoselective reduction of nitroaromatic and nitrile compounds to their corresponding amines in aqueous solution at ambient temperature. Nitrofurazone, a cytotoxic antibiotic, as a non-aromatic example was also reduced selectively at the nitro group without reduction of the other functionalities in the presence of Fe3O4-MWCNTs?PEI-Ag. The catalyst was magnetically recoverable and maintained its activity for at least six cycles without considerable loss of efficiency.
- Ansari, Sara,Khorshidi, Alireza,Shariati, Shahab
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p. 3554 - 3565
(2020/02/04)
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- A Pd confined hierarchically conjugated covalent organic polymer for hydrogenation of nitroaromatics: Catalysis, kinetics, thermodynamics and mechanism
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Herein, we propose a fast and scalable synthesis of a triazine based hierarchically conjugated covalent organic polymer under solvent and additive free conditions through a single step process. The synthesized material CCTP (Cyanuric Chloride-Thiourea-Polymer) was thoroughly characterized by various physicochemical techniques. The CCTP exhibited regular sponginess and excellent chemical as well as thermal stability. The solvent and additive free approach for CCTP synthesis provides a sustainable alternative for classical solvothermal methods. The CCTP was immobilized with Pd (0) and subsequently a heterogeneous material Pd&at;CCTP was obtained, which was used as an efficient catalyst for the hydrogenation of nitroarenes. The rate constant and Ea were measured to be 2.08 × 10-2 s-1 and 15.67 kJ mol-1 respectively and thereafter other thermodynamic parameters like ΔH, ΔS and ΔG for the hydrogenation of p-nitrophenol were also calculated. The obtained results indicate that the catalytic hydrogenation of p-nitrophenol is a non-spontaneous and endothermic process. We have also investigated the effect of surfactants (NH4OH, FA, and N2) on the reaction performance, and consequently NH4OH and FA both slow down the reaction while N2 doesn't affect the reaction medium. Further, we calculated the rate constant for the hydrogenation of 2,4-dinitrophenol and 2,4,6-trinitrophenol. An array of nitroarenes were further reduced to extend the substrate scope at RT; high TOFs were observed. Besides, Pd&at;CCTP showed excellent reusability in hydrogenation reactions without evident performance falloff.
- Awasthi, Satish Kumar,Yadav, Deepika
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p. 4295 - 4303
(2020/07/30)
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- Record-high catalytic hydrogenated activity in nitroarenes reduction derived from in-situ nascent active metals enabled by constructing bimetallic phosphate
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Herein, we report an excellent in-situ exsolution triggered hydrogenated catalyst F-Ni/Cu-P-RT started from bimetallic phosphate Ni/Cu-P-RT, affording an ultrafast catalytic hydrogenated rate (20 s even 5 s) in nitrophenol reduction. In the first catalytic cycle, we proved the enhanced catalytic reduction activity of bimetallic Ni/Cu-P-RT within 50 s compared to monometallic counterparts. The kinetics results revealed Ni/Cu-P-RT affords the reaction rate K of 2.85/4.23/6.6 min?1 at 20, 30, and 40 °C with the activation energy 32 kJ/mol. Impressively, the involved reaction induction period is visibly observed and interpreted by reconstruction and evolution of active metal during the reaction, but was eliminated through integrating two metal Cu-Ni by regulation of electronic band energy of phosphate from 4.1–3.5 eV. The nascent Cu and Ni nanoparticles as reaction-preferred active species were in-situ exsolved partially after adding NaBH4, triggering the resulted higher active and stable F-Ni/Cu-P-RT(20 s, 14.1 min?1) in later multiple cycles.
- Yang, Fu,Wang, Jin,Gao, Shuying,Zhou, Shijian,Kong, Yan
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- Pd-Pt/modified GO as an efficient and selective heterogeneous catalyst for the reduction of nitroaromatic compounds to amino aromatic compounds by the hydrogen source
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In this work, different nitroaromatic compounds were successfully reduced to their corresponding aromatic amines with excellent conversion and selectivity in methanol at 50?°C by using Pd-Pt nanoparticles immobilized on the modified grapheme oxide (m-GO) and hydrogen as the reducing source. The catalytic efficiency of Pd and Pd-Pt loading on the modified GO was investigated for the reduction of various nitroaromatic compounds, and the Pd-Pt/m-GO system demonstrated the highest conversion and selectivity. The catalyst was characterized by different techniques including FT-IR, Raman, UV–Vis, XRD, BET, XPS, FESEM, EDS, and TEM. The metal nanoparticles with the size of less than 10?nm were uniformly distributed on the m-GO. The catalyst could be reused at least five times without losing activity, showing the stability of the catalyst structure. Finally, the efficiency of the prepared catalyst was compared with Pd-Pt/AC, and Pd-Pt/GO catalysts.
- Salahshournia, Hossein,Ghiaci, Mehran
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- Synthesis of Ultrafine Silver Nanoparticles on the Surface of Fe3O4@SiO2@KIT-6-NH2 Nanocomposite and Their Application as a Highly Efficient and Reusable Catalyst for Reduction of Nitrofurazone and Aromatic Nitro Compounds Under Mild Conditions
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Uniform dispersion of ultrafine spherical silver nanoparticles (NPs) was obtained over the surface of Fe3O4@SiO2@KIT-6 core–shell support via functionalization of the mesoporous KIT-6 shell by aminopropyltriethoxysilane, followed by coordination of Ag+ ions and in situ chemical reduction with sodium borohydride. The obtained hybrid material, Fe3O4@SiO2@KIT-6-Ag nanocomposite, was fully characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, and used as an efficient catalyst for selective reduction of nitroaromatic compounds in aqueous solution at ambient temperature and neutral pH [nine examples, apparent rate constants at 25?°C, k (min?1), 0.112–0.628]. As a non-aromatic example, nitrofurazone which is a cytotoxic antibiotic was also reduced selectively at nitro group without reduction of other functionalities. Fe3O4@SiO2@KIT-6-Ag NPs also showed potential ability to act as catalyst for reduction of nitromethane in aqueous solution which can provide a colorimetric method for detection of nitromethane in solution down to 0.9 × 10?4?mol?L?1. Fe3O4@SiO2@KIT-6-Ag nanocomposite was also screened for its antibacterial activity, and satisfactory results were obtained in comparison with drug references including Tetracycline, Chloramphenicol and Cefotaxime as positive controls, on gram negative Escherichia coli and Pseudomonas aeroginosa. Ease of recycling of the Fe3O4@SiO2@KIT-6-Ag is another benefit of this nanocatalyst. Under the optimized conditions, the recycled catalyst showed 15% loss of efficiency after five successive runs. Graphical Abstract: [Figure not available: see fulltext.].
- Ansari, Sara,Khorshidi, Alireza,Shariati, Shahab
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p. 410 - 418
(2018/11/23)
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- Novel perovskite nanocatalyst (BiFeO3) for the photodegradation of rhodamine B/tartrazine and swift reduction of nitro compounds
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Design and synthesis of visible light respondent photocatalyst with high separation efficiency is of great importance due to its application in practical point of view. In this presentation, novel perovskite-structured BiFeO3 nanoparticles have been successfully synthesized by simple, cost-effective and eco-friendly technique. The BiFeO3 nanoparticles were prepared by using different chelating agents (sucrose, citric acid, tartaric acid and urea) and under different range of calcination temperature (150–850?°C). Different characterization techniques such as FT-IR, XRD, VSM, BET, TEM and UV–Vis spectroscopy have been used for its structure evaluation. Further, by using this catalyst, a green approach has been developed for the removal of harmful organic compounds from the industrial waste. The catalytic activity was assessed by the catalytic degradation of industrial waste dyes such as rhodamine B and tartrazine (first time by perovskite-structured material) in aqueous media under sunlight irradiation and reduction of various nitro compounds to corresponding amines (in s) by using NaBH4 in green solvent water at room temperature. Effect of all types of BiFeO3 nanoparticles on catalytic degradation and reduction was investigated. BiFeO3 nanoparticles prepared by sucrose as chelating agent and calcinated at 650° were selected as a better catalyst on the basis of its performance in degradation and reduction experiment. Thus, the present approach provides a promising way to prepare noble catalyst for extensive applications in degradation/reduction of organic pollutants. The examination of degraded products of dye has been carried out by using FT-IR; mass spectroscopy and UV–Vis spectroscopy and confirmation of reduction of nitrocompounds with UV–Vis spectroscopy.
- Singh, Harminder,Rajput, Jaspreet Kaur
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p. 2409 - 2432
(2019/07/03)
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- Synthesis method for disperse dye intermediate
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The invention discloses a synthesis method for a disperse dye intermediate. The synthesis method comprises the following steps: preparing 2,4-diaminophenol through reduction reaction of 2,4-dinitrophenol and hydrogen gas; enabling 2,4-diaminophenol and iodomethane to generate etherification reaction under action of a catalyst tributyl methyl ammonium carbonate to prepare 2,4-diaminoanisole; and enabling 2,4-diaminoanisole and acetic anhydride to generate acylation reaction to prepare a target product 3-amino-4-methoxya-cetanilide. Compared with a 2,4-diaminoanisole hydrogenation reduction process, the 2,4-dinitrophenol hydrogenation reduction process is adopted, so that the conversation rate is high and the side reactions are fewer.
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Paragraph 0037-0046
(2018/09/13)
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- Facile Fabrication of Nickel/Heazlewoodite@Carbon Nanosheets and their Superior Catalytic Performance of 4-Nitrophenol Reduction
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A facile molten salt method was utilized for the synthesis of carbon anchored nickel/heazlewoodite nanoparticles (Ni/Ni3S2@C nanosheets) with potassium humate as the carbon and sulfur source and NaCl as template. The morphology, particle size and crystallinity of the products were characterized by various techniques containing TEM, FE-SEM and XRD. Furthermore, the mesoporous Ni/Ni3S2@C own easy accessibility of active sites and high surface area (149.04 m2 g?1). Thus, the as-prepared Ni/Ni3S2@C exhibited prominent performance for catalytic reduction of 4-nitrophenol (4-NP). Catalytic reduction of other nitrophenols (NPs) were also tested which can prove that the catalyst own selectivity on reduction of NPs. For durability, the property of the catalyst does not decrease obviously after five cycles. More significant correlations concerning effect of activation parameters (Ea=37.21 kJ mol?1) on 4-NP reduction were scrutinized and discussed. Hence, we provide a facile method for fabrication of metal/metal sulfide@C which own better dispersity, small dimension and excellent catalytic performance for further studies.
- Wang, Xinyu,Lu, Jing,Zhao, Yunlong,Wang, Xiaopeng,Lin, Zhang,Liu, Xueming,Wu, Ronglan,Yang, Chao,Su, Xintai
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p. 4143 - 4153
(2018/09/06)
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- Metastable Bi2Zr2O7 with Pyrochlore-like Structure: Stabilization, Oxygen Ion Conductivity, and Catalytic Properties
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Equimolar concentrations of Zr4+ and Bi3+ were chelated with ethylenediaminetetraacetic acid ligand with the purpose of using it as a precursor to generate pyrochlore-like Bi2Zr2O7. When the X-ray amorphous precursor was calcined at 750 °C for 3 h in air, pyrochlore-like product with superstructure reflections was identified by powder X-ray diffraction (PXRD) along with one minor reflection due to β-Bi2O3. This phase was found to be metastable from additional experiments conducted by varying calcination conditions. Structural refinement of PXRD pattern by Le Bail method in Fd3m space group yielded cubic lattice constant of 10.8421(27) ?. Flower-petal-like morphology of the sample was evident in its field-emission scanning electron microscopy image and energy-dispersive X-ray analysis performed at various locations of the specimen confirmed nearly equal concentration of zirconium and bismuth. Six bands at 260, 320, 448, 531, 597, and 828 cm-1 were observed for this sample in its Raman spectrum and supported our claim of pyrochlore-like structure. Indexation of bright spots present in selected area electron diffraction pattern and observed distances of lattice fringes in high-resolution transmission electron microscopy image were in conformity with the results from PXRD measurements. Absorbance maxima at 312, 372, and 423 nm with a broad tailing stretching up to visible region was noticed in the UV-visible spectrum of this sample. Direct band gap of 2 eV was estimated for this sample from Tauc plot. The oxygen ion conductivity of the sample in the temperature range of 333-773 K was examined, and the highest conductivity at 773 K was 3.071 × 10-6 S/cm. From activation energy estimation and dielectric loss analysis, thermally activated process related to the mobility of oxygen ion vacancy was found responsible for the observed ionic conductivity. A similar conclusion was reached after careful analysis of dielectric spectroscopy data of this sample. High surface area (125.04 m2/g) and mesoporosity (pore diameter of 3.81 nm) were possessed by this sample, which paved way for studying its catalytic role in the reduction of nitroaromatics and carcinogenic Cr6+. Cyclability experiments showed the retainment of catalytic activity up to five cycles by the sample without undergoing any structural change.
- Pandey, Jyoti,Shrivastava, Vipul,Nagarajan, Rajamani
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p. 13667 - 13678
(2018/10/24)
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- Preparation and characterization of copper chloride supported on citric acid-modified magnetite nanoparticles (Cu2+-CA@Fe3O4) and evaluation of its catalytic activity in the reduction of nitroarene compounds
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A new, powerful and recyclable copper catalyst were prepared by heterogenization of copper chloride using of Fe3O4 nano particles modified with citric acid as a linker. This system can catalyze reduction of nitroaren compound to aniline derivatives in the presence of Sodium borohydride as a reduction agent in moderate to good yields. In addition, easy separation and recoverable with an external permanent magnet is the dominant properties of this catalyst (Cu2+-CA@Fe3O4).
- Ghonchepour, Ehsan,Yazdani, Elahe,Saberi, Dariush,Arefi, Marzban,Heydari, Akbar
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- Magnetically Recoverable Gold Nanorods as a Novel Catalyst for the Facile Reduction of Nitroarenes Under Aqueous Conditions
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Abstract: In this work, cysteine-functionalized Fe3O4@Carbon magnetic nanoparticles were used for the synthesis of gold nanorods. Fe3O4@C nanoparticles were first prepared by synthesis of Fe3O4magnetic nanoparticles (MNPs), and then carbon-coated MNPs (Fe3O4@C) were synthesized by glucose carbonization using a hydrothermal method. Finally, the gold NRs were loaded on the modified surface of Fe3O4@C MNPs. The designed magnetically recoverable gold nanorods, after full characterization by FTIR, SEM, TEM, TGA, VSM, XRD, and ICP-OES, were applied to the reduction of nitroarenes. The Fe3O4@C@Cys–Au nanorods showed higher performance than Fe3O4@C@Cys–Au nanospheres in a selective facile reduction of nitroarenes to the corresponding aminoarenes in aqueous medium at room temperature using NaBH4. Graphical Abstract: [Figure not available: see fulltext.]
- Lamei, Kamran,Eshghi, Hossein,Bakavoli, Mehdi,Rostamnia, Sadegh
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p. 491 - 501
(2017/02/18)
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- A normal pressure catalytic synthesis of aniline compounds and the use of catalyst (by machine translation)
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A normal pressure catalytic synthesis of aniline compounds is the nitrobenzene compound and solvent after mixing, adding catalyst to form suspension, then transfer to the with a quartz window in the high-pressure reactor, reactor for sealing and hydrogen purge after washing, maintaining a hydrogen under normal pressure conditions, under stirring condition, heating the reaction system to10-50oC, in strength is0.01-5W/cm2under the illumination of the reaction, the reaction time is 5 - 180min. This invention has mild condition, environmental protection, low cost, simple operation, reaction period is short, high product yield, selectivity is good. (by machine translation)
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Paragraph 0047-0050
(2017/04/14)
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- A smart approach to achieve an exceptionally high loading of metal nanoparticles supported by functionalized extended frameworks for efficient catalysis
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The problem associated with metal nanoparticle (NP) agglomeration when trying to achieve a high loading amount has been solved by a new method of functionalization of MOFs' pores with terminal alkyne moieties. The alkynophilicity of the Au3+ ions has been utilized successfully for an exceptionally high loading (~50 wt%) of Au-NPs on supported functionalized MOFs.
- Gole, Bappaditya,Sanyal, Udishnu,Mukherjee, Partha Sarathi
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supporting information
p. 4872 - 4875
(2015/03/18)
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- Selective removal of nitroaromatic compounds from wastewater in an integrated zero valent iron (ZVI) reduction and ZVI/H2O2 oxidation process
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In this study, an integrated system comprised of zero-valent iron (ZVI) reduction and ZVI-based Fenton oxidation processes (ZVI-ZVI/H2O2) was applied for the selective removal of nitroaromatic compounds (NACs) from 2,4-dinitroanisole (DNAN) producing wastewater. For the ZVI reduction process, at a hydraulic retention time (HRT) of 6 h and neutral pH of 7.2, removal efficiencies of 2,4-dinitroanisole (DNAN), 2,4-dinitrophenol (DNP) and 2,4-dinitrochlorobenzene (DNCB) were as high as 81.3 ± 3.6%, 80.6 ± 1.8% and 90.9 ± 3.5%, respectively, demonstrating the excellent performance of ZVI. For the ZVI/H2O2 oxidation process, the optimal pH and H2O2 dosage were found to be 3.0 and 100 mmol L-1, respectively. Under these optimal conditions, NACs and their degradation intermediates could be removed selectively and effectively in the coupled ZVI reduction and ZVI/H2O2 oxidation process, as was indicated by the low UV254 value of 0.104 ± 0.003 and the low TOC removal efficiency of 32.4 ± 0.7% in the effluent. Ferrous ions could be generated in situ through the corrosion of the metal iron in both the ZVI reduction process and the ZVI/H2O2 oxidation process, giving rise to a potent Fenton-type reaction. In addition, the enhanced Fenton reaction with the aid of reaction between Fe0 and Fe3+ was probably due to the presence of Fe0 in the ZVI/H2O2 oxidation process, which promoted the utilization efficiency of the Fenton catalyst, i.e., Fe2+. Compared to the sequential ZVI reduction and homogeneous Fenton oxidation process (ZVI-Fe2+/H2O2), the low consumption of iron shavings, the reduced H2O2 consumption and the low yield of ferric sludge made the integrated ZVI-ZVI/H2O2 process promising for the treatment of NAC containing wastewater.
- Liu, Jianguo,Ou, Changjin,Han, Weiqing,Faheem,Shen, Jinyou,Bi, Huiping,Sun, Xiuyun,Li, Jiansheng,Wang, Lianjun
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p. 57444 - 57452
(2015/07/20)
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- Pd nanoparticles partially embedded in the inner wall of nitrogen-doped carbon hollow spheres as nanoreactors for catalytic reduction of 4-nitrophenol
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Pd@nitrogen-doped carbon nanoreactors (Pd@NC) were synthesized by partially embedding small Pd nanoparticles in the inner wall of the nitrogen-doped carbon shells. Such embedment is critical for improving catalytic activity and stability.
- Bian, Shao-Wei,Liu, Si,Guo, Mei-Xia,Xu, Ling-Li,Chang, Lan
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p. 11913 - 11916
(2015/02/19)
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- Catalytic hydrogenation of nitrophenols and nitrotoluenes over a palladium/graphene nanocomposite
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We report a stable palladium/graphene (Pd/G) nanocomposite with differing Pd content for use in the catalytic hydrogenation of nitrophenols and nitrotoluenes. Various microscopic and spectroscopic techniques were employed to characterize the as-prepared catalysts. Catalytic hydrogenation reactions of nitrophenols were conducted in aqueous solution by adding NaBH4, while the nitrotoluene hydrogenation was carried out in methanol in the presence of H2 because of the poor solubility in water. The Pd/G hybrids exhibited much higher activity and higher stability than the commercial Pd/C. Due to the presence of a large excess of NaBH4 compared to p-nitrophenol, the kinetic data can be explained by the assumption of a pseudo-first-order reaction with regard to p-nitrophenol. The resulting high catalytic activity can be attributed to the graphene sheets' strong dispersion effect for Pd nanoparticles and good adsorption ability for nitrobenzene derivatives via π-π stacking interactions. A plausible mechanism is proposed. Considering inductive and conjugation effects that may affect the reactions, the reactivity of nitrophenols in this study is expected to follow the order m-NP > o-NP > p-NP > 2,4-DNP > 2,4,6-TNP, which is in good agreement with the experimental results. This journal is the Partner Organisations 2014.
- Sun, Jingwen,Fu, Yongsheng,He, Guangyu,Sun, Xiaoqiang,Wang, Xin
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p. 1742 - 1748
(2014/06/09)
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- Metallic nanoparticles immobilized in magnetic metal-organic frameworks: Preparation and application as highly active, magnetically isolable and reusable catalysts
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Separation and recycling of catalysts after catalytic reactions are critically required to reduce the cost of catalysts as well as to avoid the generation of waste in industrial applications. In this paper, ultrafine noble metallic nanoparticles are incorporated into cauliflower-like porous magnetic metal-organic frameworks (MOFs). With the restriction effects of the pore/surface structure in the MOFs, "surfactant-free" metallic nanoparticles are successfully obtained on a 2-3 nm scale. In addition, both the thickness of MOFs shell and the content of noble metallic NPs are tunable on the MOFs coating. Moreover, the microspheres exhibit excellent performance for the catalytic reduction of p-nitrophenol with a turnover frequency of 3094 h-1. The uniform cavities in the MOFs shell provide docking sites for p-nitrophenol and act as confinement nanoreactors, which greatly improves the catalytic performance. Most importantly, the magnetically responsive microspheres can be easily recovered by a magnetic field and show excellent reusability. The as-prepared catalyst also shows good activity for the reduction of other nitrobenzenes. Consequently, this work provides a highly active, magnetically isolable, and recyclable catalyst, which can be used for various catalytic industrial processes. The fundamental model can be further employed in a variety of biomedical fields including drug delivery and biological molecules separation. the Partner Organisations 2014.
- Zhang, Hai-Juan,Qi, Sheng-Da,Niu, Xiao-Ying,Hu, Jing,Ren, Cui-Ling,Chen, Hong-Li,Chen, Xing-Guo
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p. 3013 - 3024
(2014/08/18)
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- In situ formed metal nanoparticle systems for catalytic reduction of nitroaromatic compounds
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Developing robust and facile catalytic systems for converting nitroaromatic compounds to NH2-containing compounds are of importance to decrease or even eliminate their toxicity or risk in the environment. In view of in situ formed metal nanoparticles, the metal ion (Cu2+, Ag+, AuCl4-, Co2+ and Ni2+)/NaBH4 systems were employed to catalyze the reduction reaction of nitroaromatic compounds. By employing the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) as a model reaction, the effects of concentration of NaBH4, 4-NP and metal ions on the rate constants of the catalytic reduction reactions were systematically investigated. Apparent activation energies of these metal ion/NaBH4 catalytic systems were further measured and compared. In situ formed metal NPs could be characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Furthermore, these metal ion/NaBH4 systems were successfully employed to catalyze the reduction reaction of a series of other nitroaromatic compounds. These metal ion/NaBH4 catalytic systems investigated in this protocol are simple and do not require the preparation of metal nanoparticles in advance, compared with previous related reports. This journal is
- Wu, Xiao-Qiong,Wu, Xing-Wen,Shen, Jiang-Shan,Zhang, Hong-Wu
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p. 49287 - 49294
(2014/12/11)
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- One pot green synthesis of polyaniline coated gold nanorods and its applications
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Morphology controlled high aspect ratio worm-like polyaniline (PANI) layer coated Au-nanostructures (Au/PANI) have been successively synthesized by in situ polymerisation techniques using aniline as a monomer with HAuCl4 as an oxidising agent in the absence and presence of citric acid (CA). Synthesized composites were characterized by HRTEM, FESEM, XRD, XPS, UV-vis and FTIR study. Spherical morphologies are seen in the absence of CA and Au nanoparticles are coated by a PANI thin layer with ~30 nm thickness. In the presence of CA, as well as depending upon the CA to aniline molar ratio, morphology varies from irregular assembly to regular fiber to spherical-like nanostructures. The nanostructures show fibrous morphology with an average diameter of ~100 nm and lengths of more than 5 μm when CA to aniline molar ratios are 1.0 and 0.2. When the ratios are 2.0 and 0.1, the nanostructure represents the granularlike morphology. Nanofiber formation takes place by the assembly of the CA capped tiny Au-nanorods in the presence of aniline during the polymerisation, and all Au-nanorods are finely coated by a PANI thin layer of ~5 nm thickness. Importantly, fibrous Au/PANI nanostructures show superior catalytic activity compared to spherical/irregular Au/PANI nanostructures towards the reduction of toxic aromatic nitro compounds like 4-nitrophenol (4-NP), 4-nitroaniline (4-NA), 2,4-dinitrophenol (2,4-DNP) and 2,4,6-trinitrophenol (2,4,6-TNP). This is because of the coating thickness of PANI over Au-nanoparticles in fibrous Au/PANI nanostructures as well as enhanced surface area.
- Mondal, Sanjoy,Rana, Utpal,Ranjan Bhattacharjee, Rama,Malik, Sudip
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p. 57282 - 57289
(2015/02/05)
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- Palladium nanoparticles supported on nitrogen-functionalized active carbon: A stable and highly efficient catalyst for the selective hydrogenation of nitroarenes
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Nitrogen-functionalized active carbon-supported ultrasmall Pd nanoparticles were conveniently prepared by using a postloading method. The Pd catalyst was highly active and selective for the hydrogenation of nitroarenes at room temperature under ambient pressure. Reducible groups such as ketone, carboxylic acid, and ester were not hydrogenated, and the corresponding anilines were obtained quantitatively. The Pd catalyst demonstrated high stability and could be reused 10 times without the loss of catalytic performance. Be active, be fit! A facile method to prepare nitrogen-functionalized active carbon (NAC) has been described. The small-sized Pd nanoparticles are supported on NAC by using a postloading method. The representative catalyst Pd@NAC-800 demonstrated high activity and selectivity for the selective hydrogenation of nitroarenes under mild reaction conditions.
- Li, Zelong,Li, Jinlei,Liu, Jianhua,Zhao, Zelun,Xia, Chungu,Li, Fuwei
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p. 1333 - 1339
(2014/05/20)
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- A new class of heterogeneous platinum catalysts for the chemoselective hydrogenation of nitroarenes
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A new series of nanostructured platinum catalysts able to catalyze the selective reduction of nitroarenes has been developed. The materials, made of organosilica physically doped with nanostructured platinum(0), are stable and efficient. Reactions in general proceed with high yield and often go to completion, while the catalysts can be reused in further reaction runs. This establishes a new class of relevant solid catalysts for synthetic organic chemistry named SiliaCat Platinum-Hydrogel.
- Pandarus, Valerica,Ciriminna, Rosaria,Beland, Francois,Pagliaro, Mario
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scheme or table
p. 1306 - 1316
(2011/06/25)
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- Homoleptic ruthenium(iii) chalcogenolates: A single precursor to metal chalcogenide nanoparticles catalyst
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Eight homoleptic metal(iii) arylchalcogenolate polymers [M(EPh-p-X) 3]n (M = Ru, Cr, and Mo) were characterized by PXRD. Structural solution of [Ru(SPh-p-tBu)3]n1 was achieved by Rietveld refinement of the PXRD data. Pyrolysis of [Ru(SePh)3] n4 produced nanostructured RuSe2, which selectively catalyzed the reduction of nitro compounds in the presence of other functionalities.
- Chan, Sharon Lai-Fung,Low, Kam-Hung,So, Gary Kwok-Ming,Chui, Stephen Sin-Yin,Che, Chi-Ming
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body text
p. 8808 - 8810
(2011/10/02)
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- Selective reduction of nitro compounds using CeY zeolite under microwaves
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Aliphatic and aromatic nitro compounds were selectively reduced to their corresponding amino derivatives in good yields using formic acid and CeY zeolite under monomode reactor. This system is found to be compatible with several sensitive functionalities. Beside the recycling result showed it had a long catalyst lifetime and could maintain activity even after being used for 20 cycles.
- Arya, Kapil,Dandia, Anshu
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experimental part
p. 55 - 58
(2010/09/05)
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- A new reagent for selective reduction of nitro group
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The nitro group in aromatic nitro compounds containing reducible substitucnts such as methyl, carboxylic acids and phcnols, and halogcns arc selectively and rapidly reduced at room temperature to the corresponding amines in good yield by employing hydrazine glyoxylatc in the presence of zinc powder or magnesium powder. It has been observed that hydrazine glyoxylatc is more effective than hydrazine, glyoxylic acid, hydrazinium monoformate or ammonium monoformate and reduction of the nitro group occurs without hydrogcnolysis in the presence of low-cost magnesium compared to expensive metals like palladium, platinum, ruthenium, etc. The products have been characterized by comparison of their TLC, infrared spectra and melting points.
- Raju,Ragul,Sivasankar
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experimental part
p. 1315 - 1318
(2010/01/16)
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- NaBH4/charcoal: A new synthetic method for mild and convenient reduction of nitroarenes
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NaBH4 in the presence of charcoal (0.4-0.8 g) reduces varieties of nitroarenes to their corresponding amines. Reduction reactions were carried out in a mixture of H2O-THF (1:0.5 mL) at 50-60°C with high to excellent yields of products. Copyright Taylor & Francis Group, LLC.
- Zeynizadeh, Behzad,Setamdideh, Davood
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p. 2699 - 2704
(2007/10/03)
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- One step hair coloring compositions using salts
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A hair coloring composition comprising the following two compositions which are mixed just prior to application to the hair: (a) a composition comprising a water-soluble peroxygen oxidizing agent; and (b) a composition comprising one or more oxidative hair coloring agents selected from the group consisting of an aromatic diamine, an amino phenol, a naphthol, a polyhydric phenol, a catechol and mixtures thereof; wherein the composition comprising one or more oxidative hair coloring agents further comprises al least one water soluble carbonate releasing salts; and optionally a water soluble ammonium salt, is described.
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- Transition metal complexes as dye forming catalysts in hair coloring compositions
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A hair coloring composition comprising a first composition which comprises: (a) a dye forming transition metal salt or complex; which is first applied to the hair; and a second composition which comprises the following two compositions which are mixed just prior to application to the hair: (a) a composition comprising a water-soluble peroxygen oxidizing agent; and (b) a composition comprising one or more oxidative hair coloring agents selected from the group consisting of an aromatic diamine, an aminophenol, a polyhydric phenol a catechol and mixtures thereof.
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- Enhanced color deposition for hair with sequestering agents
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Hair coloring compositions which comprise: (A) non-nitrogenous chelating agents from the group consisting of polyphosphate; phosphonates; hydroxycarboxylates; polyacrylates; zeolite; and mixtures thereof; (B) an oxidative dye primary intermediate; and (C) an oxidative dye coupler; (D) and water are described. The present invention also relates to a method for coloring hair which comprises contacting said hair with a hair coloring composition as described above.
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- Hydrazinium monoformate: A new hydrogen donor. Selective reduction of nitrocompounds catalyzed by commercial zinc dust
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The nitro group in aliphatic and aromatic nitro compounds also containing reducible substituents such as ethene, nitrile, acid, phenol, halogen, ester, etc., are selectively and rapidly reduced at room temperature to corresponding amines in good yields by employing hydrazinium monoformate, in the presence of commercial zinc dust. It was observed that, hydrazinium monoformate is more effective than hydrazine or formic acid and reduction of nitro group occurs without hydrogenolysis in the low cost zinc dust compared to expensive metals like palladium.
- Gowda, Shankare,Gowda, B. K. Kempe,Gowda, D. Channe
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p. 281 - 289
(2007/10/03)
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- Hydrazine/magnesium mediated cost-effective and selective reduction of nitro compounds
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Hydrazine aided catalytic transfer hydrogenation has been employed for the reduction of both aliphatic and aromatic nitro compounds to corresponding amines. The use of low-cost magnesium, as catalyst leads to high yields of amino compounds under ambient conditions of temperature and pressure. Many commonly encountered functional groups like ethene, nitrile, acid, phenol, halogen etc. are compatible with the present system.
- Srinivasa,Abiraj,Gowda, D. Channe
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p. 2885 - 2887
(2007/10/03)
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- Surfactant-assisted UV-photolysis of nitroarenes
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Photochemical transformations (λ = 254 nm) of 2,4-dinitrotoluene (2,4-DNT) in aqueous solutions containing the cationic surfactant cetyltrimethylammonium (CTA) and the anionic nucleophile borohydride (BH4-) were investigated. The ove
- Diehl, Claude A.,Jafvert, Chad T,Marley, Karen A.,Larson, Richard A.
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p. 553 - 560
(2007/10/03)
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- Zinc-catalyzed ammonium formate reductions: Rapid and selective reduction of aliphatic and aromatic nitro compounds
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Aliphatic and aromatic nitro compounds are selectively and rapidly reduced to their corresponding amino derivatives in good yields using ammonium formate and commercial zinc dust. This system is found to be compatible with several sensitive functionalities such as halogens, -OH, -OCH3, -CHO, -COCH3, -COC6H5, -COOH, COOC2H5, -CONH2, -CN, -CH=CH-COOH, -NHCOCH3. The reduction can be carried out not only with HCOONH4 but also with HCOOH.
- Gowda, D. Channe,Mahesh, B.,Gowda, Shankare
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- Catalytic transfer hydrogenation of aromatic nitro compounds by employing ammonium formate and 5% platinum on carbon
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Aromatic nitro compounds were reduced to respective amines in high yields by using 5% platinum on carbon with ammonium formate or formic acid as hydrogen donor. It was observed that the former was mote efficient donor than the later. Further we have found that reduction of nitro groups occurs without hydrogenolysis of halogens and the reducible substituents which remains unchanged under the reaction conditions.
- Gowda,Mahesh
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p. 3639 - 3644
(2007/10/03)
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- Formic acid with 10% palladium on carbon: A reagent for selective reduction of aromatic nitro compounds
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The nitro group in aromatic nitro compounds also containing reducible substituents such as carbonyl, ethene, ethyne, nitrile, acid, phenol etc, is selectively and rapidly reduced at room temperature to corresponding amino derivatives in good yield employing formic acid in the presence of 10% palladium on carbon. The catalyst could be recovered and reused after washing with water and ethanol, and the results obtained indicate further, there is no apparent loss of catalytic activity.
- Channe Gowda,Gowda
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p. 709 - 711
(2007/10/03)
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- Nickel-catalyzed formic acid reductions. A selective method for the reduction of nitro compounds
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Aliphatic and aromatic nitro compounds were selectively reduced to their corresponding amino derivatives in good yields using formic acid and raney nickel. This system is found to be compatible with several sensitive functionalities such as halogens, -OH, -OCH3, -CHO, -COCH3-COC6H5, -COOH, -COOC2H5, -CONH2, -CN, -CH=CH-COOH, -NHCOCH3. The reduction can be carrid out not only with HCOOH but also with HCOONH4.
- Channe Gowda,Prakasha Gowda,Ramesha Baba,Gowda, Shankare
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p. 2889 - 2895
(2007/10/03)
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- Microwave thermolysis VII: Selective diversity in the reduction using sodium hypophosphite under microwave irradiation
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The selective reduction of nitro group into amine using sodium hypophosphite under microwave irradiation is described. The rapid reaction, solvent free conditions and selectivity over common functional groups like CN, OH, COOH, CONH2 and halogens are the distinct features of the procedure.
- Meshram,Ganesh,Sekhar, K. Chandra,Yadav
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p. 993 - 994
(2007/10/03)
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- Method for preparing 2,4-diaminolphenol or 2,4-diamonophenol dihydrochloride
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A method for preparing 2,4-diaminophenol or 2,4-diaminophenol dihydrochloride comprising hydrogenation of 2,4-dinitrophenol on a membrane catalyst made of an alloy consisting of 90 to 98% by mass of palladium, 2 to 10% by mass of rhodium or ruthenium. Said hydrogenation of 2,4-dinitrophenol is effected by hydrogen diffusing through said membrane catalyst. The starting 2,4-dinitrophenol is used in a medium of water or a 4--37% aqueous solution of hydrochloric acid at a concentration of 2,4-dinitrophenol in said medium ranging from 2 to 50% by mass. The hydrogenation is effected at a temperature within the range of from 50° to 150° C. under a pressure of from 1 to 60 atm. The process is simple and performed on a simple equipment; it makes use of both pure and commercial hydrogen, enables elimination of the formation of waste waters and results in the desired products in a high yield: 2,4-diaminophenol--with a yield of up to 93%, 2,4-diaminophenol dihydrochloride--with a yield of up to 92% as calculated for the starting 2,4-dinitrophenol.
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