T:Toxic;
106-47-8Relevant articles and documents
Chemoselective hydrogenation of 4-nitrostyrene to 4-aminostyrene by highly efficient TiO2 supported Ni3Sn2 alloy catalyst
Yamanaka, Nobutaka,Hara, Takayoshi,Ichikuni, Nobuyuki,Shimazu, Shogo
, p. 811 - 816 (2019)
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.
A nonmetal catalyst for molecular hydrogen activation with comparable catalytic hydrogenation capability to noble metal catalyst
Li, Baojun,Xu, Zheng
, p. 16380 - 16382 (2009)
(Chemical Equation Presented) Fullerene can activate molecular hydrogen and is a novel nonmetal hydrogenation catalyst. The hydrogenation of aromatic nitro compounds to amino aromatics is achieved on this catalyst with high conversion and selectivity under 1 atmospheric pressure of H2 and light irradiation at room temperature or under conditions of 120-160°C and 4-5 MPa H2 pressure without light irradiation, which is comparable to the case with a noble metal catalyst.
-
Kovacic,Sparks
, p. 2541 (1961)
-
HIGH SITE-SELECTIVITY IN THE CHLORINATION OF ELECTRON-RICH AROMATIC COMPOUNDS BY N-CHLORAMMONIUM SALTS.
Smith, John R. Lindsay,McKeer, Linda C.
, p. 3117 - 3120 (1983)
N-Chlorammonium salts are efficient and very site-selective monochlorinating agents for electron-rich aromatic compounds.
Sustainable and Scalable Fe/ppm Pd Nanoparticle Nitro Group Reductions in Water at Room Temperature
Gabriel, Christopher M.,Parmentier, Michael,Riegert, Christian,Lanz, Marian,Handa, Sachin,Lipshutz, Bruce H.,Gallou, Fabrice
, p. 247 - 252 (2017)
An operationally simple and general process for the safe and selective reduction of nitro groups utilizing ppm Pd supported on Fe nanomaterials in aqueous solution of designer surfactant TPGS-750-M has been developed and successfully carried out at a 100 mmol scale. Preferred use of KBH4 as the hydride source, at ambient temperature and pressure, lends this process suitable for a standard reaction vessel alleviating the need for specialized hydrogenation equipment. Calorimetry data parallel those expected for a classical nitro group reduction when measuring the heat of reaction (-896 to -850 kJ/mol).
Sustainable Hydrogenation of Nitroarenes to Anilines with Highly Active in-situ Generated Copper Nanoparticles
Kinik, F. Pelin,Nguyen, Tu N.,Mensi, Mounir,Ireland, Christopher P.,Stylianou, Kyriakos C.,Smit, Berend
, p. 2833 - 2839 (2020)
Metal nanoparticles (NPs) are usually stabilized by a capping agent, a surfactant, or a support material, to maintain their integrity. However, these strategies can impact their intrinsic catalytic activity. Here, we demonstrate that the in-situ formation of copper NPs (Cu0NPs) upon the reduction of the earth-abundant Jacquesdietrichite mineral with ammonia borane (NH3BH3, AB) can provide an alternative solution for stability issues. During the formation of Cu0NPs, hydrogen gas is released from AB, and utilized for the reduction of nitroarenes to their corresponding anilines, at room temperature and under ambient pressure. After the nitroarene-to-aniline conversion is completed, regeneration of the mineral occurs upon the exposure of Cu0NPs to air. Thus, the hydrogenation reaction can be performed multiple times without the loss of the Cu0NPs’ activity. As a proof-of-concept, the hydrogenation of drug molecules “flutamide” and “nimesulide” was also performed and their corresponding amino-compounds were isolated in high selectivity and yield.
-
Banthorpe,Cooper
, p. 618 (1968)
-
A Remarkable Synergic Effect of Polymer-anchored Bimetallic Palladium-Ruthenium Catalysts in the Selective Hydrogenation of p-Chloronitrobenzene
Yu, Zhengkun,Liao, Shijian,Xu, Yun,Yang, Bin,Yu, Daorong
, p. 1155 - 1156 (1995)
A synergic effect of the polymer-anchored bimetallic palladium-ruthenium catalysts can lead to a remarkable increase in the selectivity for p-chloroaniline in the selective hydrogenation of p-chloronitrobenzene under atmospheric pressure and in the presence of a small amount of base.
Organic-inorganic hybrid SiO2 supported gold nanoparticles: Facile preparation and catalytic hydrogenation of aromatic nitro compounds
Tan, Xiaoying,Zhang, Zhixin,Xiao, Zihui,Xu, Qiang,Liang, Changhai,Wang, Xinkui
, p. 788 - 793 (2012)
Highly dispersed gold nanoparticles supported on organic-inorganic hybrid silica have been successfully prepared through a novel and facile approach. In the process, 3-aminopropyltriethoxysilane was hydrolyzed in HCHO aqueous solution to prepare silica with organic functional groups (-SiCH 2CH2CH2NHCH2OH) formed through the reaction between -NH2 and HCHO, then the silica reacted with HAuCl4 in aqueous solution. Due to the reducibility of -SiCH2CH 2CH2NHCH2OH, the gold precursor was in situ reduced on the silica. The materials were characterized by powder X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectroscopy, solid-state nuclear magnetic resonance spectroscopy, and X-ray photoelectron spectroscopy techniques. The results indicated Au nanoparticles were highly dispersed on silica with an average particles size 1.8 ± 0.5 nm. The asobtained Au/SiO2-org exhibited good catalytic activity and stability for liquid phase catalytic hydrogenation of aromatic nitro compounds with H2.
pH Dependence on reduction rate of 4-Cl-nitrobenzene by Fe(II)/montmorillonite systems
Schultz, Christopher A.,Grundl, Timothy J.
, p. 3641 - 3648 (2000)
The pseudo-first-order reduction of 4-Cl-nitrobenzene by Fe(II) in aqueous systems containing montmorillonite clays is investigated over the pH range 6.00-8.00. Silica and alumina is also investigated as simple analogues to aluminosilicate mineral surfaces. At pH 7.25, montmorillonite clays were found to be as much as 1000 times less effective than ferric oxides at mediating the reaction when expressed on a surface area basis. Reaction rates increase dramatically as the pH rises and at pHs above 7.5 approach those previously reported for surface bound Fe(II) on ferric oxides at pH 7.22. This increase in reactivity is attributed to both an increase in concentration of the FeOH+ ion and to the increased sorption of Fe(II) at high pH. Sorption isotherms for Fe(II) to montmorillonite clays at pH 7.00 are reported. Two surface sites are suggested on clay minerals and incorporated into a kinetics model for the pH dependence of the reaction. The overall reaction is modeled as the sum of the reactions between 4-Cl-NB and three reductants; FeOH+ and Fe(II) bound to the two surface sites. FeOH+ is found to be the most effective reductant in our systems. Intrinsic rate constants for both surface sites and FeOH+ are presented. Although the minerals investigated are much less effective at mediating the reaction than ferric oxides, the rates are sufficiently fast to be of importance to environmental processes. At neutral pHs, half-lives are less than a week and decrease to the scale of hours above pH 7.5. This is quite rapid in the context of groundwater systems in which residence times can be months or years. The pseudo-first-order reduction of 4-Cl-nitrobenzene by Fe(II) in aqueous systems containing montmorillonite clays is investigated over the pH range 6.00-8.00. Silica and alumina is also investigated as simple analogues to aluminosilicate mineral surfaces. At pH 7.25, montmorillonite clays were found to be as much as 1000 times less effective than ferric oxides at mediating the reaction when expressed on a surface area basis. Reaction rates increase dramatically as the pH rises and at pHs above 7.5 approach those previously reported for surface bound Fe(II) on ferric oxides at pH 7.22. This increase in reactivity is attributed to both an increase in concentration of the FeOH+ ion and to the increased sorption of Fe(II) at high pH. Sorption isotherms for Fe(II) to montmorillonite clays at pH 7.00 are reported. Two surface sites are suggested on clay minerals and incorporated into a kinetics model for the pH dependence of the reaction. The overall reaction is modeled as the sum of the reactions between 4-Cl-NB and three reductants; FeOH+ and Fe(II) bound to the two surface sites. FeOH+ is found to be the most effective reductant in our systems. Intrinsic rate constants for both surface sites and FeOH+ are presented. Although the minerals investigated are much less effective at mediating the reaction than ferric oxides, the rates are sufficiently fast to be of importance to environmental processes. At neutral pHs, half-lives are less than a week and decrease to the scale of hours above pH 7.5. This is quite rapid in the context of groundwater systems in which residence times can be months or years. Reduction of 4-chloronitrobenzene (CNB) by divalent iron was studied in aqueous systems containing montmorillonite clays over the 6-8 pH range. The clays proved as much as 1000 times less effective than ferric oxides at pH 7.25 at mediating the reaction. Reaction rates increased significantly as pH increased, and sorption isotherms for Fe(II) to montmorillonite clays at pH 7 are reported. The silica and alumina minerals studied were much less effective at mediating the reaction than ferric oxides but the rates were sufficiently fast to be of importance to environmental processes.
Pd0.01Ru0.01Ce0.98O2-δ: A highly active and selective catalyst for the liquid phase hydrogenation of p-chloronitrobenzene under ambient conditions
Mistri, Rajib,Llorca, Jordi,Ray, Bidhan Chandra,Gayen, Arup
, p. 111 - 119 (2013)
Nanostructured bimetal ion substituted ceria, Pd0.01Ru 0.01Ce0.98O2-δ (PdRuC2), prepared for the first time by a novel solution combustion synthesis and characterized employing XRD, BET, HRTEM and XPS has been shown to be very active and selective than the monometal ion substituted analogue Pd0.02Ce0.98O 2-δ (PdC2), whereas Ru0.02Ce0.98O 2-δ (RuC2) is inactive towards liquid phase hydrogenation of p-chloronitrobenzene to p-chloroaniline under ambient conditions. Structural studies show metal ion substituted ceria as the predominant phase. The hydrogenation over PdRuC2 is completed beyond 75 min with 100% selectivity. Conversely, PdC2 hydrogenates ~40% of p-chloronitrobenzene with 82% selectivity. Increase of temperature from 35 C to 80 C showed a little higher activity of PdRuC2 but with a lower selectivity. The as-prepared and aged forms of PdRuC2 showed similar activity, whereas PdRuC2 heat-treated at 500 C increased the conversion and the 800 C heated catalyst reduced it (both ~2%) indicating high thermal stability. Maximum hydrogenation activity has been observed in ethanol as compared to methanol and butanol. The PdRuC2 catalyst also shows excellent hydrogenation activity towards o-, m-chloronitrobenzene and nitrobenzene. The enhancement of activity and selectivity of Pd in presence of Ru in the PdRu bimetal ionic catalyst for the hydrogenation reaction has been attributed to involvement of remarkable Ru4+-promotion in Pd0.01Ru 0.01Ce0.98O2-δ.
-
Gilman et al.
, p. 906 (1935)
-
Mg-Fe Hydrotalcite as a Catalyst for the Reduction of Aromatic Nitro Compounds with Hydrazine Hydrate
Kumbhar, Pramod S.,Sanchez-Valente, Jaime,Millet, Jean Marc M.,Figueras, Francois
, p. 467 - 473 (2000)
Catalysts consisting of mixed oxides of Fe3+ and Mg2+ were prepared by decarbonation of Mg-Fe hydrotalcite-like precursors. They show high activity and selectivity for the selective reduction of aromatic nitro compounds under mild re
Reactivity of Fe(II)-Bearing Minerals toward Reductive Transformation of Organic Contaminants
Elsner, Martin,Schwarzenbach, Rene P.,Haderlein, Stefan B.
, p. 799 - 807 (2004)
Fe(II) present at surfaces of iron-containing minerals can play a significant role in the overall attenuation of reducible contaminants in the subsurface. As the chemical environment, i.e., the type and arrangement of ligands, strongly affects the redox potential of Fe(II), the presence of various mineral sorbents is expected to modulate the reactivity of surficial Fe(II)-species in aqueous systems. In a comparative study we evaluated the reactivity of ferrous iron in aqueous suspensions of siderite (FeCO 3), nontronite (ferruginous smectite SWa-1), hematite (α-Fe2O3), lepidocrocite (γ-FeOOH), goethite (α-FeOOH), magnetite (Fe3O4), sulfate green rust (FeII4FeIII2(OH)12SO 4·4H2O), pyrite (FeS2), and mackinawite (FeS) under similar conditions (pH 7.2, 25 m2 mineral/L, 1 mM Fe(II)aq, O2 (aq) 0.1 g/L). Surface-area-normalized pseudo first-order rate constants are reported for the reduction of hexachloroethane and 4-chloronitrobenzene representing two classes of environmentally relevant transformation reactions of pollutants, i.e., dehalogenation and nitroaryl reduction. The reactivities of the different Fe(II) mineral systems varied greatly and systematically both within and between the two data sets obtained with the two probe compounds. As a general trend, surface-area-normalized reaction rates increased in the order Fe(II) + siderite Fe(II) + iron oxides Fe(II) + iron sulfides. 4-Chloronitrobenzene was transformed by mineral-bound Fe(II) much more rapidly than hexachloroethane, except for suspensions of hematite, pyrite, and nontronite. The results demonstrate that abiotic reactions with surface-bound Fe(II) may affect or even dominate the long-term behavior of reducible pollutants in the subsurface, particularly in the presence of Fe(III) bearing minerals. As such reactions can be dominated by specific interactions of the oxidant with the surface, care must be taken in extrapolating reactivity data of surface-bound Fe(II) between different compound classes.
Highly porous copper-supported magnetic nanocatalysts: made of volcanic pumice textured by cellulose and applied for the reduction of nitrobenzene derivatives
Fazeli, Atefeh,Maleki, Ali,Qazi, Fateme Sadat,Saeidirad, Mahdi,Shalan, Ahmed Esmail,Taheri-Ledari, Reza
, p. 25284 - 25295 (2021)
Herein, a novel designed heterogeneous catalytic system constructed of volcanic pumice magnetic particles (VPMPs), cellulose (CLS) as a natural polymeric matrix, and copper nanoparticles (Cu NPs) is presented. Also, to enhance the inherent magnetic property of VPMP, iron oxide (Fe3O4) nanoparticles have been prepared and incorporated in the structureviaanin situprocess. As its first and foremost excellent property, the designed composite is in great accordance with green chemistry principles because it contains natural ingredients. Another brilliant point in the architecture of the designed composite is the noticeable porosity of VPMP as the core of the composite structure (surface area: 84.473 m2g?1). This great porosity leads to the use of a small amount (0.05 g) of the particles for catalytic purposes. However, the main characterization methods, such as Fourier-transform infrared and energy-dispersive X-ray spectroscopy, thermogravimetric analysis, and electron microscopy, revealed that the spherical metallic particles (Fe and Cu oxides) were successfully distributed onto the surface of the VPMP and CLS matrices. Further, vibrating-sample magnetometer analysis confirmed the enhancement of the magnetic property (1.5 emu g?1) of the composite through the addition of Fe3O4nanoparticles. Further, the prepared (Fe3O4@VPMP/CLS-Cu) nanocomposite has been applied to facilitate the reduction reaction of hazardous nitrobenzene derivatives (NBDs) to their aniline analogs, with 98% conversion efficiency in eight minutes under mild conditions. Moreover, the good reusability of the catalytic system has been verified after recycling it ten times without any significant decrease in the performance.
Selective gas phase hydrogenation of p-chloronitrobenzene over Pd catalysts: Role of the support
Cárdenas-Lizana, Fernando,Hao, Yufen,Crespo-Quesada, Micaela,Yuranov, Igor,Wang, Xiaodong,Keane, Mark A.,Kiwi-Minsker, Lioubov
, p. 1386 - 1396 (2013)
The gas phase (1 atm, 453 K) hydrogenation of p-chloronitrobenzene (p-CNB) over a series of laboratory-synthesized and commercial Pd (1-10% wt) supported on activated carbon (AC) and non-reducible (SiO2 and Al 2O3) and reducible (ZnO) oxides has been examined. Reaction over these catalysts generated the target p-chloroaniline (p-CAN) (via selective hydrogenation) and nitrobenzene (NB)/aniline (AN) as a result of a combined hydrodechlorination/hydrogenation. A range of Pd nanoparticles with mean sizes 2.4-12.6 nm (from HRTEM and H2/CO chemisorption) were generated. Both the p-CNB transformation rate and H2 chemisorption increased with decreasing Pd size. Residual Mo (from the stabilizer used in the synthesis of Pd colloids) suppressed activity, but this was circumvented by the use of poly(N-vinyl-2-pyrrolidone) (PVP). Pd/AC generated p-CAN and AN as principal products, Pd on SiO2 and Al2O3 exhibited hydrodechlorination character generating AN and NB, and Pd/ZnO promoted the sole formation of p-CAN at all levels of conversion. Reaction selectivity is linked to Pd electron density with the formation of Pd δ+ on AC and the occurrence of Pdδ- on SiO2 and Al2O3. Reaction exclusivity to p-CAN over Pd/ZnO is attributed to the formation of PdZn alloy (demonstrated by XPS), which selectively activates the -NO2 group. This is the first report that demonstrates 100% selectivity for p-CNB → p-CAN over supported Pd.
Kinetically stabilized Pd@Pt core-shell octahedral nanoparticles with thin Pt layers for enhanced catalytic hydrogenation performance
Zhang, Peipei,Hu, Yibo,Li, Baihai,Zhang, Qiuju,Zhou, Chen,Yu, Hongbo,Zhang, Xuejun,Chen, Liang,Eichhorn, Bryan,Zhou, Shenghu
, p. 1335 - 1343 (2015)
This study investigates the structural stability of small Pd@Pt core@shell octahedral nanoparticles (NPs) and their shell thickness dependent catalytic performance for p-chloronitrobenzene hydrogenation with H2. The 6-8 nm Pd@Pt octahedral NPs are prepared by a sequential reduction method, and the characterization results confirm that Pd@Pt octahedral NPs with one to four atomic Pt layers can be controllably synthesized. The Pd@Pt octahedral NPs with one atomic Pt layer demonstrate excellent structural stability with the maintenance of core-shell structures as well as high catalytic stability during cycle to cycle catalytic p-chloronitrobenzene hydrogenation reactions. The alumina-supported Pd@Pt octahedral NPs illustrate a superior catalytic performance relative to individual Pt and Pd and their physical mixtures. Theoretical calculations by density functional theory suggest that the unexpected structural stability for Pd@Pt octahedral NPs with thin Pt shells and their corresponding catalytic stability during hydrogenation reactions can be ascribed to the strong binding between Pt surfaces and reactants/products in catalytic reactions. The enhanced catalytic performance of Pd@Pt octahedral NPs possibly originates from the core-shell interaction, which adjusts the electronic state of surface Pt atoms to be suitable for selective p-chloronitrobenzene hydrogenation.
-
Ho,Olah
, p. 815 (1976)
-
-
Robertson,Evans
, p. 142,143 (1940)
-
Metalloporphyrins as cytochrome P450 models for chlorhexidine metabolite prediction
Palaretti, Vinicius,Dos Santos, Joicy Santamalvina,Guedes, Débora Fernandes Costa,De Moraes, Luiz Alberto Beraldo,Das Dores Assis, Marilda
, p. 7 - 13 (2012)
The catalytic oxidation of chlorhexidine (CHX, a strong microbicidal agent) mediated by ironporphyrins has been investigated by using hydrogen peroxide, mCPBA, tBuOOH, or NaOCl as oxidant. All of these oxygen donors yielded p-chloroaniline (pCA) as the main product. The higher pCA yields amounted to 71% in the following conditions: catalyst/oxidant/substrate molar ratio of 1:150:50, aqueous medium, FeTMPyP as catalyst. The medium pH also had a strong effect on the pCA yields; in physiological pH, formation of this product was specially favored in the presence of the catalysts, with yields 58% higher than those achieved in control reactions. This provided strong evidence that CHX is metabolized to pCA upon ingestion.
AuPd@Mesoporous SiO2: Synthesis and selectivity in catalytic hydrogenation/hydrodechlorination of p-chloronitrobenzene
Yang, Guangming,Yu, Hongbo,Zhang, Jianfeng,Yin, Hongfeng,Ma, Zhen,Zhou, Shenghu
, p. 3744 - 3750 (2017)
AuPd nanoparticles (NPs) protected by tetradecyl trimethyl ammonium bromide (TTAB) were coated with SiO2 through hydrolysis of tetraethylorthosilicate (TEOS). The as-synthesized AuPd@SiO2 core-shell NPs were calcined in air at 500°C to remove TTAB and open up mesopores within the SiO2 shells. The obtained Au-PdO@m-SiO2 NPs were reduced by H2 at 300°C to obtain AuPd@m-SiO2 NPs with AuPd NP cores (diameter: ～3 nm) and SiO2 shells (thickness: ～18 nm). Results from relevant characterization indicated that these SiO2-protected core-shell NPs were highly stable during calcination and subsequent reduction. Au@m-SiO2, Au10Pd@m-SiO2, Au5Pd@m-SiO2, AuPd5@m-SiO2, AuPd10@m-SiO2, and Pd@m-SiO2 NPs with similar core sizes and shell thicknesses were also synthesized. These samples were tested in the catalytic hydrogenation of p-chloronitrobenzene. The activity and selectivity were found to be tunable, depending on the composition of the bimetallic alloys. AuPd@m-SiO2 NPs with a 1/1 molar ratio of Au/Pd showed the highest selectivity for the hydrodechlorination of p-chloronitrobenzene.
EFFECT OF HYDROGEN PRESSURE ON THE KINETICS OF THE LIQUID-PHASE CATALYTIC HYDROGENATION OF AROMATIC NITRO COMPOUNDS
Makaryan, I. A.,Savchenko, V. I.,Brikenshtein, Kh. A.
, p. 742 - 744 (1981)
-
Hydrogenation of p-chloronitrobenzene over nanostructured-carbon-supported ruthenium catalysts
Oubenali, Mustapha,Vanucci, Giuditta,MacHado, Bruno,Kacimi, Mohammed,Ziyad, Mahfoud,Faria, Joaquim,Raspolli-Galetti, Anna,Serp, Philippe
, p. 950 - 956 (2011)
Carbon nanotubes (CNTs) and carbon nanofibers (CNFs) have been used for the first time to support ruthenium nanoparticles for the hydrogenation of p-chloronitrobenzene (p-CNB) to produce selectively p-chloroaniline. The preparation of well-dispersed ruthenium catalysts from the [Ru 3(CO)12] precursor required activation of the purified supports by nitric acid oxidation. The supports, purified and functionalized, and the supported catalysts have been characterized by a range of techniques. The catalytic activity of these materials for the hydrogenation of p-CNB at 35bar and 60°C is shown to reach as high as 18molp-CNB g Ru-1 h-1, which is one order of magnitude higher than a commercial Ru/Al2O3 catalyst. Selectivities between 92 and 94 % are systematically obtained, the major byproduct being aniline. Carbon nanotubes and carbon nanofibers act as supports for ruthenium nanoparticles in the hydrogenation of p-chloronitrobenzene to selectively produce p-chloroaniline. The preparation of well-dispersed ruthenium catalysts from a [Ru3(CO)12] precursor requires activation of the purified supports by nitric acid oxidation. The catalytic activity is one order of magnitude higher than that of a commercial Ru/Al2O3 catalyst.
Pt-NH2-Fe3O4 catalyst with excellent catalytic performance for hydrogenation of nitroarenes in aqueous medium
Fan, Guangyin,Wang, Yinhu
, p. 967 - 973 (2014)
Catalytic hydrogenation of aromatic nitro compounds was carried out in neat water with Pt nanoparticles deposited on surface amine-functionalized magnetite. The hydrophilic Pt-NH2-Fe3O4 catalyst exhibited excellent activity as well as superior selectivity to the corresponding amines. 99.9% yield of p-chloroaniline (p-CAN) was obtained at 303 K under an H2 atmosphere in aqueous media; the turnover frequency value reached 500 h-1 in the absence of any additives or promoters. Furthermore, the novel nanocomposites can be readily isolated from the reaction system by a magnet and recycled at least six times without any loss in activity.
An exceptionally active and selective Pt-Au/TiO2 catalyst for hydrogenation of the nitro group in chloronitrobenzene
He, Daiping,Jiao, Xiangdong,Jiang, Ping,Wang, Jian,Xu, Bo-Qing
, p. 111 - 116 (2012)
Adding a very small amount of Pt entities (0.01-0.03 wt%) onto the Au surface of a Au/TiO2 catalyst is found to be an efficient approach to improve the catalytic activity of Au for the hydrogenation of p-chloronitrobenzene (p-CNB), without loss of selectivity towards p-chloroaniline (p-CAN). The effect of catalyst amount, reaction temperature, H2 pressure and reaction time on p-CNB hydrogenation was studied with 0.02wt%Pt-0.5wt%Au/TiO2 (Pt0.0002-Au0.005/ TiO2). The selectivity to p-CAN could be up to 100% at complete conversion of p-CNB with reaction temperatures at or below 333 K. The catalyst also exhibited perfect stability. The catalyst structure was characterized by TEM and XRD, and the mechanism of the high activity of the catalyst was discussed.
Palladium Immobilized on a Polyimide Covalent Organic Framework: An Efficient and Recyclable Heterogeneous Catalyst for the Suzuki–Miyaura Coupling Reaction and Nitroarene Reduction in Water
Dong, Zhenhua,Pan, Hongguo,Gao, Pengwei,Xiao, Yongmei,Fan, Lulu,Chen, Jing,Wang, Wentao
, p. 299 - 306 (2021/05/10)
An efficient and recyclable Pd nano-catalyst was developed via immobilization of Pd nanoparticles on polyimide linked covalent organic frameworks (PCOFs) that was facilely prepared through condensation of melamine and 3,3′,4,4′-biphenyltetracarboxylic dianhydride. The Pd nanoparticles (Pd NPs) catalyst was thoroughly characterized by FT-IR, XRD, SEM, TEM. Furthermore, the catalytic activity of Pd NPs catalyst was evaluated by Suzuki–Miyaura coupling reaction and nitroarene reduction in water, respectively. The excellent yields of corresponding products revealing revealed that the Pd NPs catalyst could be applied as an efficient and reusable heterogeneous catalyst for above two reactions. Graphical Abstract: [Figure not available: see fulltext.]
A convenient Hofmann reaction of carboxamides and cyclic imides mediated by trihaloisocyanuric acids
Bastos, Gustavo A.,de Mattos, Marcio C.S.
, (2021/09/29)
A simple, efficient and pot-economic approach in a single vessel has been developed for conversion of aromatic and aliphatic carboxamides into primary amines with one fewer carbom atom (Hofmann reaction) in 38–89 % yield by reacting with trichloro- or tribromoisocyanuric acid and sodium hydroxide in aqueous acetonitrile. Under the same reaction conditions, cyclic imides gave amino acids (69–83 %). The role of the trihaloisocyanuric acids is the in situ generation of N-haloamides, key-intermediates for the Hofmann reaction. The scalability of the methodology was demonstrated by a multigram-scale transformation of phthalimide into anthranilic acid in 77 % yield.
Selective Reduction of Nitroarenes to Arylamines by the Cooperative Action of Methylhydrazine and a Tris(N-heterocyclic thioamidate) Cobalt(III) Complex
Ioannou, Dimitris I.,Gioftsidou, Dimitra K.,Tsina, Vasiliki E.,Kallitsakis, Michael G.,Hatzidimitriou, Antonios G.,Terzidis, Michael A.,Angaridis, Panagiotis A.,Lykakis, Ioannis N.
supporting information, p. 2895 - 2906 (2021/02/27)
We report an efficient catalytic protocol that chemoselectively reduces nitroarenes to arylamines, by using methylhydrazine as a reducing agent in combination with the easily synthesized and robust catalyst tris(N-heterocyclic thioamidate) Co(III) complex [Co(κS,N-tfmp2S)3], tfmp2S = 4-(trifluoromethyl)-pyrimidine-2-thiolate. A series of arylamines and heterocyclic amines were formed in excellent yields and chemoselectivity. High conversion yields of nitroarenes into the corresponding amines were observed by using polar protic solvents, such as MeOH and iPrOH. Among several hydrogen donors that were examined, methylhydrazine demonstrated the best performance. Preliminary mechanistic investigations, supported by UV-vis and NMR spectroscopy, cyclic voltammetry, and high-resolution mass spectrometry, suggest a cooperative action of methylhydrazine and [Co(κS,N-tfmp2S)3] via a coordination activation pathway that leads to the formation of a reduced cobalt species, responsible for the catalytic transformation. In general, the corresponding N-arylhydroxylamines were identified as the sole intermediates. Nevertheless, the corresponding nitrosoarenes can also be formed as intermediates, which, however, are rapidly transformed into the desired arylamines in the presence of methylhydrazine through a noncatalytic path. On the basis of the observed high chemoselectivity and yields, and the fast and clean reaction processes, the present catalytic system [Co(κS,N-tfmp2S)3]/MeNHNH2 shows promise for the efficient synthesis of aromatic amines that could find various industrial applications.
