- Chemoselective hydrogenation of 4-nitrostyrene to 4-aminostyrene by highly efficient TiO2 supported Ni3Sn2 alloy catalyst
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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
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- Polymeric PEG35k-Pd nanoparticles: Efficient and recyclable catalyst for reduction of nitro compounds
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The small size polymeric PEG35k-Pd nanoparticles are key attractions for catalysis due to their large surface to volume ratio, non-toxicity, inexpensive, thermal stability, and recoverability. Polymeric PEG35k-Pd nanoparticles in the absence of phosphine ligands are insensitive to the air and moisture and act as an active heterogeneous catalyst for the reduction of nitroarenes. Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file. Taylor & Francis Group, LLC.
- Yadav, Veena,Gupta, Shweta,Kumar, Rupesh,Singh, Gajendra,Lagarkha, Rekha
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- A nonmetal catalyst for molecular hydrogen activation with comparable catalytic hydrogenation capability to noble metal catalyst
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(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.
- Li, Baojun,Xu, Zheng
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- Amination-Oxidation Strategy for the Copper-Catalyzed Synthesis of Monoarylamines
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A novel approach for the synthesis of monoarylamines from aryl halides is presented. This method employs an inexpensive, nontoxic metal source (copper) and incorporates a stable ammonia surrogate (α-amino acids), obviating the need for special experimental setup or handling of ammonia reagents. This process, which is proposed to proceed via an amination-oxidation sequence, selectively promotes the transformation of a range of aryl and heteroaryl iodides as well as bromides to the corresponding monoarylamines.
- Thomas, Christopher,Wu, Marvin,Billingsley, Kelvin L.
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- HIGH SITE-SELECTIVITY IN THE CHLORINATION OF ELECTRON-RICH AROMATIC COMPOUNDS BY N-CHLORAMMONIUM SALTS.
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N-Chlorammonium salts are efficient and very site-selective monochlorinating agents for electron-rich aromatic compounds.
- Smith, John R. Lindsay,McKeer, Linda C.
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- Ultrasound-assisted diversion of nitrobenzene derivatives to their aniline equivalents through a heterogeneous magnetic Ag/Fe3O4-IT nanocomposite catalyst
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A heterogeneous magnetic catalytic system is fabricated and suitably applied for the fast and direct conversion of nitrobenzene (NB) derivatives to their aniline forms. For this purpose, different conditions and methods have been checked with numerous catalytic amounts of the nanocatalyst composite, which was constructed of iron oxide and silver nanoparticles and possessed an isothiazolone organic structure. Herein, the mechanistic aspect of the catalytic functioning of this highly efficient nanocatalyst is highlighted and discussed. Firstly, a convenient preparation route assisted by ultrasonication for this metal and metal oxide nanocomposite is presented. Further, a fast and direct reduction strategy for NBs is investigated using ultrasound irradiation (50 kHz, 200 W L-1). As two great advantages of this catalyst, high magnetic property and excellent reusability are also mentioned. This report well reveals that a really convenient conversion of NBs to anilines can be achieved with a high yield during the rapid reaction time in presence of mild reaction conditions. This journal is
- Taheri-Ledari, Reza,Rahimi, Jamal,Maleki, Ali,Shalan, Ahmed Esmail
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- Sustainable and Scalable Fe/ppm Pd Nanoparticle Nitro Group Reductions in Water at Room Temperature
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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).
- Gabriel, Christopher M.,Parmentier, Michael,Riegert, Christian,Lanz, Marian,Handa, Sachin,Lipshutz, Bruce H.,Gallou, Fabrice
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- A phosphorus-carbon framework over activated carbon supported palladium nanoparticles for the chemoselective hydrogenation of para-chloronitrobenzene
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A novel Pd-P-C framework structure was fabricated by supporting Pd on a P-doped carbon layer coated with activated carbon. A P-doped carbon layer was generated via calcination of sodium hypophosphite and ethanediol under inert gas atmosphere. The catalysts were characterized by Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) and were evaluated in the selective hydrogenation of p-CNB to p-CAN. The results indicate that the carbon layer generated via calcination of ethanediol presents a higher disordered structure and then the P-doped carbon layer becomes more ordered due to the formation of a P-C framework. Some electrons were transferred from C atoms adjacent to the P atoms to P atoms, which favors the formation of stable Pd-P species such as the Pd15P2 phase. Pd in the Pd-P-C framework structure possesses electron-rich properties resulting from electron transfer from C atoms to Pd atoms via P atoms, which induces the formation of electron-rich hydrogen (H-) when hydrogen was absorbed on the Pd particles. The produced electron-rich H- might prefer the nucleophilic attack on the nitro group rather than the electrophilic attack on the C-Cl bond. We suggest that it is responsible for the superior selectivity of up to 99.9% to p-CAN for the hydrogenation of p-CNB. The catalytic performance of the Pd particles supported on the P-doped carbon layer remains unchanged after five cycles indicating excellent stability.
- Lu, Chunshan,Wang, Mengjun,Feng, Zhenlong,Qi, Yani,Feng, Feng,Ma, Lei,Zhang, Qunfeng,Li, Xiaonian
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- Sustainable Hydrogenation of Nitroarenes to Anilines with Highly Active in-situ Generated Copper Nanoparticles
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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.
- Kinik, F. Pelin,Nguyen, Tu N.,Mensi, Mounir,Ireland, Christopher P.,Stylianou, Kyriakos C.,Smit, Berend
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- Deficient copper decorated platinum nanoparticles for selective hydrogenation of chloronitrobenzene
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Two types of model Pt-Cu catalysts are designed and prepared to explore the contribution of the geometric and electronic effects from copper to the catalytic performance of Pt nanoparticles in the selective hydrogenation of p-chloronitrobenzene (p-CNB). One model Pt-Cu catalyst (called Cu/C-Pt) is Pt nanoparticles deposited on ultra-small copper particle-decorated activated carbon, and the other is copper particle-decorated Pt/C catalyst (called Pt/C-Cu). Cu/C-Pt catalyst has an activity lower than that of Pt/C, but the selectivity of the desired product p-chloroaniline (p-CAN) on the Cu/C-Pt catalyst is much higher than that on Pt/C. On the Pt/C-Cu catalyst, p-CNB cannot be completely converted into p-CAN. The dechlorination rates of p-CAN on Cu/C-Pt catalysts are three orders of magnitude lower than that on Pt/C. More interestingly, the dechlorination reaction of p-CAN on Pt/C-Cu cannot be observed. High resolution TEM images of our Pt-Cu catalysts show that Pt nanoparticles keep their crystalline structure after incorporation with copper. The dispersions of Pt in 2Pt/C, 5Cu/C-2Pt, and 2Pt/C-5Cu reach 0.106, 0.083 and 0.027, respectively (the numbers before Pt and Cu represent their percentages), revealing that Pt nanoparticles in Cu/C-Pt have a larger exposed surface than those in Pt/C-Cu. It can be deduced that copper mainly exerts an electronic effect on the catalytic performance of Pt nanoparticles in Cu/C-Pt. On the other hand, the geometric effect on Pt from copper in Pt/C-Cu leads to not only a low dispersion of Pt nanoparticles but a weak activity in catalytic hydrogenation of p-CNB and dechlorination of p-CAN. The interaction between Pt nanoparticles and Cu nanoparticles at room temperature is also discussed.
- Li, Xin,Wang, Yue,Li, Liqun,Huang, Wenqing,Xiao, Zicheng,Wu, Pingfan,Zhao, Wenbo,Guo, Wei,Jiang, Peng,Liang, Minghui
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- Acid-base properties of arylnitrenium ions
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This study uses a combination of laser flash photolysis (LFP) and product analysis to show that singlet nitrenes from the irradiation of phenyl, 4-biphenylyl, and 2-fluorenyl azide can be trapped by protonation in aqueous solutions forming nitrenium ions. With phenyl azide, the phenylnitrenium ion is indicated by the formation of ring-substituted anilines in yields of up to 50% in 1 M acids. The acidity dependence furnishes the ratio k(H):k(exp) = 1.1, where k(H) refers to H+-trapping of singlet phenylnitrene and k(exp) to ring expansion of this species. With k(H) expected to be 2-4 x 1010 M-1 s-1, k(exp) is therefore estimated as 2-4 x 1010 s-1. Protonation by solvent water also occurs, but even though the rate constant is of the order of 109 s-1, it constitutes a minor pathway in competition with the ring expansion. LFP studies in acids reveal a transient that is assigned the structure of N-protonated 4-hydroxy-2,5-cyclohexadienone imine, the intermediate formed by water addition to the para position of the phenylnitrenium ion. With 4-biphenylyl- and 2-fluorenylnitrene, ring expansion (and intersystem crossing) occurs more slowly and protonation by water is faster, with the consequence that there are substantial yields of nitrenium ion without added acids. These nitrenium ions are detected with ns LFP, and their formation from singlet nitrene is observed with ps LFP. Combining the LFP experiments with product analysis furnishes a pK(a) value of 16 for the 4-biphenylylnitrenium ion deprotonating to singlet nitrene in 20% acetonitrile. Thus singlet 4-biphenylylnitrene falls close to the category of a strong base in this solution. LFP experiments in acids show behavior consistent with N-protonation of the nitrenium ion forming an aniline dication. Kinetic analyses furnish pK(a) values of 0.1 (4-aminobiphenyl dication) and 0.6 (2-aminofluorene dication) in 20% acetonitrile with 1 M ionic strength. This and other pieces of evidence are consistent with these arylnitrenium ions being better regarded as 6-iminocyclohexadienyl carbocations. Overall, arylnitrenium ions (ArNH+) are very weak acids in water in their deprotonation to singlet nitrenes. They are also weak bases, accepting a proton to form the aniline dication - 1ArN ? 1ArNH+ ? (ArNH2)2+.
- McClelland, Robert A.,Kahley, Mary Jo,Davidse, P. Adriaan,Hadzialic, Gordana
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- A Remarkable Synergic Effect of Polymer-anchored Bimetallic Palladium-Ruthenium Catalysts in the Selective Hydrogenation of p-Chloronitrobenzene
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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.
- Yu, Zhengkun,Liao, Shijian,Xu, Yun,Yang, Bin,Yu, Daorong
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- Superelectrophilic activation of 1-nitronaphthalene in the presence of aluminum chloride. Reactions with benzene and cyclohexane
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1-Nitronaphthalene smoothly reacts with benzene and undergoes selective reduction with cyclohexane in the presence of aluminum chloride to give 2,4,4-triphenyl-3,4-dihydronaphthalen-1(2H)-one oxime and 5,6,7,8-tetrahydro-1-naphthylamine, respectively. The mechanistic aspects of these and related reactions are discussed on the basis of DFT, providing insight into the protonation behavior of 1-nitronaphthalene coordinated to AlCl3.
- Zhu, Zhongwei,Genaev, Alexander M.,Salnikov, George E.,Koltunov, Konstantin Yu.
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- Organic-inorganic hybrid SiO2 supported gold nanoparticles: Facile preparation and catalytic hydrogenation of aromatic nitro compounds
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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.
- Tan, Xiaoying,Zhang, Zhixin,Xiao, Zihui,Xu, Qiang,Liang, Changhai,Wang, Xinkui
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- Xenon difluoride-trimethylsilyl isocyanate-triflic acid as a new system for the amination of aromatic compounds
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In the title system, OCNXeOSO2CF3 is formed, which readily oxidises iodobenzene to [PhI+-NCO -OTf]. The direct amination of aromatic substrates is possible with the use of XeF2-Me3SiNCO-CF3SO3H.
- Pirkuliev,Brel,Akhmedov,Zefirov,Stang
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- pH Dependence on reduction rate of 4-Cl-nitrobenzene by Fe(II)/montmorillonite systems
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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.
- Schultz, Christopher A.,Grundl, Timothy J.
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- Pd-Co catalysts prepared from palladium-doped cobalt titanate precursors for chemoselective hydrogenation of halonitroarenes
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Bimetallic Pd-Co catalysts supported on the mixed oxides CoTiO3-CoO-TiO2 (CTO) were synthesized via the thermal reduction of Pd-doped cobalt titanates PdxCo1-xTiO3 and evaluated for the chemoselective hydrogenation of halonitroarenes to haloarene-amines. The nominal Pd mass percentage of the Pd-Co/CTO systems was varied from 0.0 to 0.50. After the thermal reduction of PdxCo1-xTiO3 at 500 °C for 3 h, Pd was completely reduced and Co was partially reduced, producing a mixture of ionic Co, metallic Co, and TiO2-rutile species to give the supported bimetallic catalysts. The metallic cobalt content increased with the Pd content of the precursor. The catalytic activity toward 4-chloronitrobenzene increased with the Pd content; however, >0.1 mass% Pd decreased the chemoselectivity toward 4-chloroaniline due to the formation of the hydrodehalogenation product—aniline. The 0.1Pd-Co/CTO system was used as a model catalyst to produce haloarene-amine building blocks for linezolid, loxapine, lapatinib, and sorafenib with >98% conversion, 96% chemoselectivity, and no hydrohalogenation products. Finally, recycling tests of the 0.1Pd-Co/CTO catalyst showed loss of activity and selectivity during the third cycle due to catalyst deactivation. Regeneration treatments, every two catalytic cycles, allowed six operation cycles without loss of chemoselectivity and only a slight decrease in catalytic activity during the last cycle.
- Bustamante, Tatiana M.,Dinamarca, Robinson,Torres, Cecilia C.,Pecchi, Gina,Campos, Cristian H.
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- Pd0.01Ru0.01Ce0.98O2-δ: A highly active and selective catalyst for the liquid phase hydrogenation of p-chloronitrobenzene under ambient conditions
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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.
- Mistri, Rajib,Llorca, Jordi,Ray, Bidhan Chandra,Gayen, Arup
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- Pathways of Nitrosobenzene Reduction by Thiols in Alcoholic Media
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The biologically important reaction of nitrosobenzenes with thiols has been investigated in 2-propanol solution at room temperature, experimental conditions which allow for the detection and characterization of key intermediates. Final stable products of such complex reactions include azoxybenzenes and anilines, formed in relative proportions and at a rate which depend on the reagents initial molar ratio. A detailed description of the reaction of 4-chloronitrosobenzene with benzenethiol in 2-propanol was achieved by means of 1H NMR in situ analysis. The reaction is initiated by rapid and quantitative coupling of the two reagents into a covalent adduct, an N-ydroxysulfenamide (N(OH)S), which decays to N-(4-chlorophenyl)hydroxylamine. This second intermediate is then converted via competing paths to 4,4′-dichloroazoxybenzene and to N-(4-chlorophenyl)benzenesulfenamide (4-ClC6H4NHSPh), which in turn decays to 4-chloroaniline. Interestingly, sulfinamides (ArNHS(O)R), major products of the reaction in aqueous media, do not form in 2-propanol.
- Montanari, Stefano,Paradisi, Cristina,Scorrano, Gianfranco
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- Heavy-Atom Kinetic Isotope Effects and Mechanism of the Acid-Catalyzed o-Semidine and p-Semidine Rearrangements and Disproportionation of 4,4'-Dichlorohydrazobenzene
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In acidic 60percent aqueous dioxane solution at 0 deg C, 4,4'-dichlorohydrazobenzene (18) undergoes concurrent disproportionation, to p-chloroaniline (19) and 4,4'-dichloroazobenzene (20), and o- (21) and p-semidine (22) rearrangement.In the p-semidine rearrangement one of the chlorine atoms of 18 is displaced, in essence, as Cl+.This requires participation of a second molecule of 18 in a redox reaction.The overall fate of 18, therefore, is to give 11percent o- and 12percent p-semidine rearrangement (along with 12percent of 20) and 60percent disproportionation, accounting for 95percent of the 18.Nitrogen and carbon kinetic isotope effects (KIE) have been determined for each of these reactions, using 18, 18, 18, and 18.Isotope ratios were obtained, measured on the trifluoroacetyl derivatives of 19, 21, and 22, with a combination of scintillation counting, whole-molecule-ion mass spectrometry (WMIMS), and isotope-ratio mass spectrometry (IRMS).Nitrogen KIE were obtained by WMIMS for two 15N atoms in disproportionation (1.0260) and p-semidine rearrangement (1.0282) and by IRMS for one (naturally abundant) 15N atom in disproportionation (1.0141) and o-(1.0155) and p-semide (1.0162) rearrangement. 13C (IRMS) and 14C KIE were measured for all reactions, but in no case was a KIE other than, effectively, unity obtained.These results show that o-semidine formation from 18 complies with exceptations of sigmatropic shifts; that is, that this 1,3-sigmatropic shift is not a concerted process.The results suggest that, although a concerted 1,5-sigmatropic shift is possible, the p-semidine rearrangement of 18 is not characterized by one.It this case, however, a firm decision is not possible.Finally, the results indicate that disproportionation involves one (or both) of the two semidine rearrangement intermediates.The most likely one is that of the p-semidine.Rapid redox reaction of this intermediate (26), formed in the rate-determining step, with a second molecule of 18 can then lead to the p-semidine by removal of Cl+ and to disproportionation by scission of the central C-C bond of the intermediate.These paths account for the distribution of the products formed and the KIE of their formation.
- Rhee, Eun Sook,Shine, Henry J.
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- Mg-Fe Hydrotalcite as a Catalyst for the Reduction of Aromatic Nitro Compounds with Hydrazine Hydrate
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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
- Kumbhar, Pramod S.,Sanchez-Valente, Jaime,Millet, Jean Marc M.,Figueras, Francois
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- Pd-promoted selective gas phase hydrogenation of p-chloronitrobenzene over alumina supported Au
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The gas phase hydrogenation of p-chloronitrobenzene has been investigated over alumina supported Au (ca. 1%, w/w) prepared by deposition-precipitation with urea (DP) and impregnation in excess solvent (IMP). Both catalysts were 100% selective in terms of
- Cardenas-Lizana, Fernando,Gomez-Quero, Santiago,Hugon, Antoine,Delannoy, Laurent,Louis, Catherine,Keane, Mark A.
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- Reactivity of Fe(II)-Bearing Minerals toward Reductive Transformation of Organic Contaminants
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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.
- Elsner, Martin,Schwarzenbach, Rene P.,Haderlein, Stefan B.
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- Dediazoniations of Arenediazonium Ions in Homogeneous Solutions. Part XV. Products of Dediazonation of p-Chlorobenzenediazonium Tetrafluorobarate in Weakly Alkaline Aqueous Solutions
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The products of decomposition of solutions of p-chlorobenzenediazonium tetrafluoroborate in aqueous buffer solutions (pH 9.0-10.3; ionic strength 0.1-0.5) at 20.0 deg C have been analyzed quantitatively.Up to eleven low molecular weight compounds could be identified besides the major product, the complex polimeric diazo tar.The distribution of products is influenced by trace amount of oxygen as well as by p-chlorophenol and the radical trapping reagent iodoacetic acid.Mechanisms of formation of the products are discussed.
- Besse, Jacques,Schwarz, Wolfgang,Zollinger, Heinrich
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- Highly porous copper-supported magnetic nanocatalysts: made of volcanic pumice textured by cellulose and applied for the reduction of nitrobenzene derivatives
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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.
- Fazeli, Atefeh,Maleki, Ali,Qazi, Fateme Sadat,Saeidirad, Mahdi,Shalan, Ahmed Esmail,Taheri-Ledari, Reza
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- Enhanced reduction of nitrobenzene derivatives: Effective strategy executed by Fe3O4/PVA-10%Ag as a versatile hybrid nanocatalyst
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Herein, we present an organic–inorganic hybrid nanocomposite constructed of polyvinyl alcohol (PVA), iron oxide (Fe3O4), and 10% of silver nanoparticles (Ag NPs). First, a convenient in situ method is introduced for the preparation of this efficient catalytic system (Fe3O4/PVA-10%Ag). Further, we study the high catalytic performance for the reduction of nitrobenzene (NB) derivatives as a hazardous species of chemicals and the significant biological activity (antibacterial effects) of the nanocomposite. However, high reaction yields (99%) have been obtained in short reaction times (~15 min). A plausible mechanism is suggested, and all the required characterizations of the presented nanocatalyst are investigated in this study.
- Rahimi, Jamal,Taheri-Ledari, Reza,Niksefat, Maryam,Maleki, Ali
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- Selective gas phase hydrogenation of p-chloronitrobenzene over Pd catalysts: Role of the support
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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.
- Cárdenas-Lizana, Fernando,Hao, Yufen,Crespo-Quesada, Micaela,Yuranov, Igor,Wang, Xiaodong,Keane, Mark A.,Kiwi-Minsker, Lioubov
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- Highly efficient aqueous phase reduction of nitroarenes catalyzed by phosphine-decorated polymer immobilized ionic liquid stabilized PdNPs
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Palladium nanoparticles stabilized by lightly cross-linked phosphine-decorated polymer immobilized ionic liquids (PIIL) and their PEGylated counterparts (PEGPIIL) are highly effective catalysts for the aqueous phase hydrogenation and sodium borohydride-based reduction of a wide range of nitroaromatic and heteroaromatic compounds under mild conditions with low catalyst loadings. Introduction of extensive cross-linking with tris(4-vinylphenyl)phosphine to isolate the phosphine-based heteroatom and limit the number of surface Pd?P interactions did not have a significant influence on catalyst performance. Comparative testing revealed PdNPs immobilized on lightly cross-linked phsophine-decoarted PEGylated polymer to be a highly efficient catalyst for the aqueous phase reduction of nitroarenes with a TON of 36000 (TOF = 2580 h-1) for hydrogenation and a TON of 274000 (TOF = 17125 h-1) for transfer hydrogenation. Even though these reactions occur under diffusion control due the poor solubility of the substrate these values are the highest to be reported for the room temperature aqueous phase reduction of nitroarenes catalyzed by a nanoparticle-based system. A continuous flow reduction of nitrobenzene in a packed bed reactor operated over a period of 250 min with no sign of catalyst deactivation and the corresponding space-time-yield of 0.738 g L-1 min-1 is a marked improvement on that of 0.384 g L-1 min-1 obtained in batch. The same system also catalyzes a tandem Suzuki-Miyaura cross coupling-nitroarene reduction sequence to afford high yields of biaryl amine in an operationally straightforward single-pot procedure. This is a highly versatile protocol which will enable the aromatic nitro fragment to be introduced as a nitro-substituted aryl or heteroaryl halide and as such will lend itself to rapid diversification for the synthesis of a wide range of amines.
- Doherty,Knight,Backhouse,Bradford,Saunders,Bourne,Chamberlain,Stones,Clayton,Lovelock
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- Kinetically stabilized Pd@Pt core-shell octahedral nanoparticles with thin Pt layers for enhanced catalytic hydrogenation performance
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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.
- Zhang, Peipei,Hu, Yibo,Li, Baihai,Zhang, Qiuju,Zhou, Chen,Yu, Hongbo,Zhang, Xuejun,Chen, Liang,Eichhorn, Bryan,Zhou, Shenghu
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- Amino-Modified Silica-Supported Copper-Palladium Alloy. Synthesis and Use in Selective Hydrogenation of Disubstituted Nitroarenes in a Flow Micro Reactor
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A copper-palladium catalyst supported on amino-modified silica has been synthesized by chemical reduction. It has been found that submicron particles of a copper-palladium alloy are formed on the silica surface. Unlike commercially available palladium catalysts (Pd/Al2O3, Pd/C, Pd/BaSO4), the synthesized copper-palladium catalyst makes it possible to selectively reduce the nitro group in 3-nitrobenzaldehyde and 1-chloro-4-nitrobenzene.
- Nurmukhametova,Belov,Sultanova,Vorob’ev,Osin, Yu. N.,Burilov,Antipin
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- Pd modified prussian blue frameworks: Multiple electron transfer pathways for improving catalytic activity toward hydrogenation of nitroaromatics
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Prussian blue analogs (PBAs) exhibit potential as low-cost and eco-friendly nanocatalysts that can be fabricated with ease. However, the PBA framework structure suffers from poor electronic conductivity, which limits the catalytic efficiency for this clas
- Cha, Joo Hwan,Farha, Omar K.,Jang, Ho Won,Jeon, Se Yeon,Kirlikovali, Kent O.,Ostadhassan, Mehdi,Rasouli, Vamegh,Shokouhimehr, Mohammadreza,Varma, Rajender S.,Zhang, Kaiqiang
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- Architecture controlled PtNi@mSiO2 and Pt-NiO@mSiO2 mesoporous core-shell nanocatalysts for enhanced p-chloronitrobenzene hydrogenation selectivity
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Architecture controlled PtNi@mSiO2 and Pt-NiO@mSiO2 mesoporous core-shell nanocatalysts were synthesized for selective p-chloronitrobenzene hydrogenation to p-chloroaniline. Tetradecyl trimethyl ammonium bromide (TTAB) capped PtNi nanoparticles (NPs) were coated by SiO2 through the hydrolysis of tetraethylorthosilicate. The resultant PtNi@SiO2 core-shell NPs were calcined to remove TTAB to obtain mesoporous Pt-NiO@SiO2 core-shell nanocatalysts (Pt-NiO@mSiO2), which were subsequently reduced by hydrogen to form mesoporous PtNi@SiO2 core-shell nanocatalysts (PtNi@mSiO2). The relevant characterizations such as XRD, TEM, H2-TPR, and BET confirm that the PtNi@mSiO2 NPs consist of PtNi alloy nanoparticle cores and mesoporous SiO2 shells while the Pt-NiO@mSiO2 NPs contain Pt-NiO heteroaggregate nanoparticle cores and mesoporous SiO2 shells. The catalytic results for selective hydrogenation of p-chloronitrobenzene show that the selectivity of p-chloroaniline formation over the PtNi@mSiO2 and Pt-NiO@mSiO2 nanocatalysts is significantly improved relative to that of control Pt@mSiO2 nanocatalysts. Moreover, the PtNi@mSiO2 and Pt-NiO@mSiO2 nanocatalysts demonstrate high stability during multiple cycles of catalytic hydrogenation reactions. The enhanced catalytic performance is ascribed to the metal-metal interaction for the PtNi@mSiO2 catalysts and metal-oxide interaction for the Pt-NiO@mSiO2 catalysts. This journal is
- Liu, Hongmei,Yu, Hongbo,Xiong, Chunrong,Zhou, Shenghu
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- Metalloporphyrins as cytochrome P450 models for chlorhexidine metabolite prediction
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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.
- Palaretti, Vinicius,Dos Santos, Joicy Santamalvina,Guedes, Débora Fernandes Costa,De Moraes, Luiz Alberto Beraldo,Das Dores Assis, Marilda
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- AuPd@Mesoporous SiO2: Synthesis and selectivity in catalytic hydrogenation/hydrodechlorination of p-chloronitrobenzene
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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.
- Yang, Guangming,Yu, Hongbo,Zhang, Jianfeng,Yin, Hongfeng,Ma, Zhen,Zhou, Shenghu
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- Selective Photocatalytic Synthesis of Haloanilines from Halonitrobenzenes over Multifunctional AuPt/Monolayer Titanate Nanosheet
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Bimetallic alloy AuPt nanoclusters supported on monolayer H1.07Ti1.73O4·H2O nanosheets (AuPt/TN) jointly complete a rapid catalytic reaction toward hydrogenation of halonitrobenzene to haloaniline in methanol under ambient conditions using HCOONH4 as a hydrogen source. Especially, AuPt/TN with a Au/Pt molar ratio of 1:2 exhibits the high catalytic conversion efficiency for halonitrobenzene (>99%) with a high selectivity of haloaniline (>99%). In situ FTIR spectra suggest that the TN affords surface Br?nsted acid sites to chemisorb and activate the halonitrobenzene molecules via the surface hydrogen bond coordination. In situ ESR experiments indicate that HCOONH4 would be decomposed to H+ and a ?CO2- radical by photogenerated holes, serving as the hydrogen source and reducing species for the reduction of the -NO2 group, respectively. Experimental results reveal that atom Pt in alloy is responsible for the hydrogenation, while Au represses the dehalogenation of haloanilines. Finally, a possible synergetic mechanism is discussed. This work highlights that the multifunctional AuPt/TN catalyst with multiple active sites exerts the respective functions to cooperatively catalyze organic transformations toward desired target products.
- Song, Yujie,Wang, Huan,Wang, Zhitong,Guo, Binbin,Jing, Kaiqiang,Li, Yanjun,Wu, Ling
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- Transfer hydrogenation of aromatic nitro compounds using polymer-supported formate and Pd-C
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Transfer hydrogenation of aromatic nitro compounds using recyclable polymer-supported formate as hydrogen donor and Pd-C as a catalyst produces corresponding amines in excellent yields (90-98%).
- Abiraj,Srinivasa,Gowda, D. Channe
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- Hydrogenation of p-chloronitrobenzene over nanostructured-carbon-supported ruthenium catalysts
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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.
- Oubenali, Mustapha,Vanucci, Giuditta,MacHado, Bruno,Kacimi, Mohammed,Ziyad, Mahfoud,Faria, Joaquim,Raspolli-Galetti, Anna,Serp, Philippe
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- Pt-NH2-Fe3O4 catalyst with excellent catalytic performance for hydrogenation of nitroarenes in aqueous medium
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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.
- Fan, Guangyin,Wang, Yinhu
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- The Photochemistry of para-Substituted Phenylsulphamates - Photo-Fries Rearrangements
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The photolysis (254 nm) of a series of para-substituted phenylsulphamates, XC6H4NHSO3Na in degassed methanolic solutions has been examined.For 1a and 1b photo-Fries type rearrangements to sulphonic acids and photodegradation to anilines have been observed.The halogenosulphamates 1c-1e do not rearrange but degrade to anilines and are photosolvolysed to p-methoxyphenylsulphamic acid.No notable spectral changes took place during the irradiation of 1f over relatively long period.Substrate concentration studies, radical scavenging and sensitization and quenching experiments on 1b indicate that, as previously found for 1a, its photolysis involves an intramolecular radical mechanism with the participation of two triplet states.
- Lally, John M.,Spillane, William J.
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- An exceptionally active and selective Pt-Au/TiO2 catalyst for hydrogenation of the nitro group in chloronitrobenzene
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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.
- He, Daiping,Jiao, Xiangdong,Jiang, Ping,Wang, Jian,Xu, Bo-Qing
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- Chemoselective hydrogenation of substituted nitroaromatics using novel water-soluble iron complex catalysts
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Chemoselective hydrogenation of substituted nitroaromatic compounds by water-soluble iron complex catalysts with molecular hydrogen has been reported for the first time. This biphasic catalyst presents an opportunity for a solvent-free hydrogenation. This catalyst system provides a low-cost, efficient alternative to the selective but environmentally unacceptable stoichiometric reductions as well as the supported noble metal catalysts used for hydrogenation. An efficient recycling strategy has resulted in a cumulative turnover number above 6000.
- Deshpande, Raj. M.,Mahajan, Avinash. N.,Diwakar, Makarand. M.,Ozarde, Prakash. S.,Chaudhari
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- 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
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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.]
- Dong, Zhenhua,Pan, Hongguo,Gao, Pengwei,Xiao, Yongmei,Fan, Lulu,Chen, Jing,Wang, Wentao
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p. 299 - 306
(2021/05/10)
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- Coordination Chemistry of Borane in Solution: Application to a STING Agonist
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Equilibrium constants were determined for ligand exchange reactions of borane complexes with various oxygen, sulfur, nitrogen, and phosphorus nucleophiles in solution, and a binding affinity scale was built spanning a range of 12 orders of magnitude. While the Keq are minimally dependent on the solvent, the rate of ligand exchange varies significantly. The fastest and slowest rates were observed in THF and CDCl3, respectively. Moreover, the ligand exchange rate differs in a very broad range depending on stability of the starting complex. Binding of BH3 was found to be much more sensitive to steric factors than protonation. Comparing nitrogen bases having equal steric properties, a linear correlation of BH3 binding affinity vs. Br?nsted acidity was found. This correlation can be used to quickly estimate the BH3 binding affinity of a substrate if pKa is known. Kinetic studies suggest the ligand exchange to occur as a bimolecular SN2 reaction unless other nucleophilic species were present in the reaction mixture.
- Lemaire, Sébastien,Zhdanko, Alexander,van der Worp, Boris A.
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- Catalytic Hydrogenation of Urea Derivatives and Polyureas
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We present herein the catalytic hydrogenation of various urea derivatives to amines and methanol. The reaction is catalyzed by a ruthenium or an iridium Macho pincer complex and produces amine and methanol in very good to excellent yields. Moreover, we also expand this concept to demonstrate the first example of the hydrogenative depolymerization of polyureas to produce diamines and methanol in moderate yields.
- Kumar, Amit,Luk, James
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supporting information
p. 4546 - 4550
(2021/08/30)
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- A convenient Hofmann reaction of carboxamides and cyclic imides mediated by trihaloisocyanuric acids
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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.
- Bastos, Gustavo A.,de Mattos, Marcio C.S.
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- Halogenated method of aromatic compound
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The invention belongs to the field of organic synthesis, and particularly relates to synthesis of aromatic halogens, in particular to arylamine. The invention discloses a synthesis method of a corresponding ortho-halogenated product from aromatic compounds such as carbazole and phenol. The method comprises the following steps: adding a metal sulfonate salt catalyst, aromatic amine, carbazole, phenol and other hydrogen - heteroatom-containing aromatic compound reaction substrates, a halogenation reagent and a reaction solvent at a specific reaction temperature. After the drying agent is dried, the yield of the reaction product and the nuclear magnetic characterization determining structure are determined by column chromatography. The reaction product yield is determined by gas chromatography. By adopting the method, under the cheap metal salt catalyst, a plurality of ortho-substituted brominated and chloro products can be obtained with moderate to excellent yield.
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Paragraph 0082-0085
(2021/11/10)
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- Synthesis method of metolachlor intermediate
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The synthesis method comprises the following steps: S1) nitration reaction of chlorobenzene in a nitration reagent to obtain a mixture of o-chloronitrobenzene and p-chloronitrobenzene without separation. S2) The mixture of o-chloronitrobenzene and p-chloronitrobenzene is subjected to catalytic hydrogenation reaction to obtain the mixture of o-chloroaniline and p-chloroaniline, and the product does not need to be separated. S3) The mixture of o-chloroaniline and chloroaniline is subjected to diazotization reaction to obtain the mixture of o-chlorophenylhydrazine and p-chlorophenylhydrazine, and the product does not need to be separated. S4) The mixture of o-chlorophenylhydrazine and p-chlorophenylhydrazine and aldehyde are subjected to a condensation reaction to obtain a triazole ring mixture of Formulae I through a and I through b. S5) The triazole ring mixture is subjected to chlorination reaction to obtain the metolachlor intermediate shown in the formula I. 2, 4 - Dichloroaniline is used as a raw material, the production cost of the metolachlor is reduced, and the supply limitation of the raw material is avoided.
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Paragraph 0078-0086; 0097-0105
(2021/09/21)
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- Rhodium nanoparticles supported on 2-(aminomethyl)phenols-modified Fe3O4 spheres as a magnetically recoverable catalyst for reduction of nitroarenes and the degradation of dyes in water
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A magnetic nanostructured catalyst (Fe3O4@SiO2-Amp-Rh) modified with 2-(aminomethyl)phenols (Amp) was designed and prepared, which is used to catalyze the reduction of aromatic nitro compounds into corresponding amines and the degradation of dyes. The 2-aminomethylphenol motif plays a vital role in the immobilization of rhodium nanoparticles to offer extraordinary stability, which has been characterized by using various techniques, including transmission electron microscopy (TEM), thermal gravimetric analyzer (TGA), X-Ray Diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). A variety of nitroaromatic derivatives have been reduced to the corresponding anilines in water with up to yields of 99% within 1?h at room temperature. In addition, the catalyst system is effective in catalyzing the reduction of toxic pollutant 4-nitrophenol and the degradation of MO, MB and RhB dyes. Importantly, this catalyst Fe3O4@SiO2-Amp-Rh can be easily recovered by an external magnetic field because of the presence of magnetic core of Fe3O4, and the activity of Fe3O4@SiO2-Amp-Rh does not decrease significantly after 7 times’ recycling, which indicates that the catalyst performed high reactivity as well as stability. Graphical abstract: [Figure not available: see fulltext.]
- Chen, Tian,Chen, Zhangpei,Hu, Jianshe,Lv, Kexin,Reheman, Aikebaier,Wang, Gongshu
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- In situcreation of multi-metallic species inside porous silicate materials with tunable catalytic properties
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Porous metal silicate (PMS) material PMS-11, consisting of uniformly distributed multi-metallic species inside the pores, is synthesized by using a discrete multi-metal coordination complex as the template, demonstrating high catalytic activity and selectivity in hydrogenation of halogenated nitrobenzenes by synergistically activating different reactant moleculesviaNi and Co transition metal centers, while GdIIILewis acid sites play a role in tuning the catalytic properties.
- Liu, Yang-Yang,Wu, Chuan-De,Zhan, Guo-Peng
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supporting information
p. 6185 - 6188
(2021/06/30)
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- A novel water-dispersible and magnetically recyclable nickel nanoparticles for the one-pot reduction-Schiff base condensation of nitroarenes in pure water
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In this work, a heterogeneous nanocatalyst called Ni-Fe3O4@Pectin~PPA ~ Piconal was first synthesized, which was investigated as a bifunctional catalyst containing nickel functional groups. On the other hand, this Ni-Fe3O4@Pectin~PPA ~ Piconal catalyst in aqueous solvents shows a very effective performance at ambient temperature for the nitroarene reduction reaction with sodium borohydride, for which NaBH4 is considered as a reducing agent. This is a novelty magnetic catalyst that was approved by various methods, including Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), Dynamic light scattering (DLS), Transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), Inductively coupled plasma (ICP), Energy-dispersive X-ray spectroscopy (EDX), and Field emission scanning electron microscopy (FESEM) analyses. From the satisfactory results obtained from the reduction of nitrogen, this catalytic system is used for a one-pot protocol containing a reduction-Schiff base concentration of diverse nitroarenes. It was corroborated with the heterogeneous catalytic experiments on the one-pot tandem synthesis of imines from nitroarenes and aldehydes. Finally, the novel Ni-Fe3O4@Pectin~PPA ~ Piconal catalyst could function as a more economically desirable and environmentally amicable in the catalysis field. The favorable products are acquired in good to high performance in the attendance of Ni-Fe3O4@Pectin~PPA ~ Piconal as a bifunctional catalyst. This catalyst can be recycled up to six steps without losing a sharp drop.
- Ghamari Kargar, Pouya,Ravanjamjah, Asiye,Bagherzade, Ghodsieh
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p. 1916 - 1933
(2021/07/10)
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- Hydrophilic nickel phosphate nanoparticles: An efficient catalyst for the hydrogenation of nitroarenes
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A clean and highly efficient chemical method was developed for the synthesis of hydrophilic nickel phosphate nanoparticles and the formation of nanoparticles was confirmed by discrete spectral techniques. The synthesized nanoparticles were found to be an
- Muthuvinothini, Alagesan,Stella, Selvaraj
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supporting information
p. 2613 - 2627
(2021/07/16)
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- Highly efficient hydrogenation reduction of aromatic nitro compounds using MOF derivative Co-N/C catalyst
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The direct hydrogenation reduction of aromatic nitro compounds to aromatic amines with non-noble metals is an attractive area. Herein, the pyrolysis of Co(2-methylimidazole)2 metal-organic framework successfully produces a magnetic Co-N/C nanocomposite, which exhibits a porous structure with a high specific area and uniform Co nanoparticle distribution in nitrogen-doped graphite. In addition, the Co-N/C catalysts possess high cobalt content (23%) with highly active β-Co as the main existing form and high nitrogen content (3%). These interesting characteristics endow the Co-N/C nanocomposite with excellent catalytic activity for the hydrogenation reduction of nitro compounds under mild conditions. In addition, the obtained Co-N/C nanocomposites possess a broad substrate scope and good cycle stability for the reduction of halogen-substituted or carbonyl substituted phenyl nitrates. This journal is
- Dai, Yuyu,Li, Xiaoqing,Wang, Likai,Xu, Xiangsheng
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p. 22908 - 22914
(2021/12/24)
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- Integration of Pd nanoparticles with engineered pore walls in MOFs for enhanced catalysis
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Achieving free-access metal sites with the ability to regulate interactions with substrates is highly desired yet remains a grand challenge in catalysis. Herein, naked Pd nanoparticles were encapsulated inside a metal-organic framework (MOF), giving Pd@MIL-101-NH2. Its activity and selectivity toward de/hydrogenation reactions can be greatly promoted via the MOF pore wall engineering to regulate Pd surrounding microenvironment and substrate adsorption behavior. Creating free-access active sites and regulating their interaction with substrates are crucial for efficient catalysis, yet remain a grand challenge. Herein, naked Pd nanoparticles (NPs) have been encapsulated in a metal-organic framework (MOF), MIL-101-NH2, to afford Pd@MIL-101-NH2. The hydrophobic perfluoroalkyls were post-synthetically modified onto -NH2 group to yield Pd@MIL-101-Fx (x = 3, 5, 7, 11, 15), which engineer the MOF pore walls to regulate Pd surrounding microenvironment and interaction with substrates. As a result, both the dehydrogenation coupling of organosilane and hydrogenation of halogenated nitrobenzenes show that their activity and selectivity can be greatly promoted upon hydrophobic modification due to the favorable substrate enrichment and regulated interactions between Pd and the modified MOF hosts, far surpassing the traditional supported or surfactant-protected Pd NPs. We envision metal NPs@MOF composites would be an ideal platform integrating the inherent activity of well-accessible metal sites with engineered microenvironment via readily tunable MOFs. Regulating the interaction between active sites and substrates is of great importance in catalysis. The common strategy is to modify the surface of active sites (mostly, metal nanoparticles/NPs in heterogeneous catalysts) with diverse molecules, which, unfortunately, is unfavorable to substrate accessibility and, thus, detrimental to activity. Therefore, it is highly desired to develop heterogeneous catalysts featuring naked metal NPs, which are simultaneously able to regulate interaction with substrates. This puts forward long-standing contradictory challenges on metal NP-based catalysts: (1) exposed active sites, requiring naked metal surface, for their good accessibility; (2) functional molecules around active sites, affording tunable interaction with substrates, for enhanced activity and selectivity. To meet the above challenges, we judiciously encapsulate surface-naked metal NPs into MOFs, achieving tunable interaction with substrates by engineering the MOF pore wall microenvironment.
- Li, Luyan,Li, Zhixin,Yang, Weijie,Huang, Yamin,Huang, Gang,Guan, Qiaoqiao,Dong, Yemin,Lu, Junling,Yu, Shu-Hong,Jiang, Hai-Long
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p. 686 - 698
(2021/02/27)
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- COPPER NANOPARTICLE BASED CHEMOSELECTIVE REDUCTION
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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)
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- Selective Reduction of Nitroarenes to Arylamines by the Cooperative Action of Methylhydrazine and a Tris(N-heterocyclic thioamidate) Cobalt(III) Complex
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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.
- Ioannou, Dimitris I.,Gioftsidou, Dimitra K.,Tsina, Vasiliki E.,Kallitsakis, Michael G.,Hatzidimitriou, Antonios G.,Terzidis, Michael A.,Angaridis, Panagiotis A.,Lykakis, Ioannis N.
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supporting information
p. 2895 - 2906
(2021/02/27)
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- Enhanced strong metal-support interactions between Pt and WO3-xnanowires for the selective hydrogenation ofp-chloronitrobenzene
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WO3-xnanowires with oxygen vacancies synthesized by a hydrothermal method were employed as supports to deposit Pt nanoparticles (NPs)viaa deposition-reduction method with NaBH4. The Pt/WO3-xnanocomposites exhibit an excellent catalytic hydrogenation performance in the selective hydrogenation ofp-chloronitrobenzene due to the interaction between Pt NPs and WO3-xnanowires.
- Yan, Xuedong,Yang, Fan,Yin, Hongfeng,Yu, Hongbo,Yu, Zhiyong
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supporting information
p. 18065 - 18069
(2021/10/12)
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- Selective Carbon-Carbon Bond Amination with Redox-Active Aminating Reagents: A Direct Approach to Anilines?
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Amines are among the most fundamental motifs in chemical synthesis, and the introduction of amine building blocks via selective C—C bond cleavage allows the construction of nitrogen compounds from simple hydrocarbons through direct skeleton modification. Herein, we report a novel method for the preparation of anilines from alkylarenes via Schmidt-type rearrangement using redox-active amination reagents, which are easily prepared from hydroxylamine. Primary amines and secondary amines were prepared from corresponding alkylarenes or benzyl alcohols under mild conditions. Good compatibility and valuable applications of the transformation were also displayed.
- Qiu, Xu,Wang, Yachong,Su, Lingyu,Jin, Rui,Song, Song,Qin, Qixue,Li, Junhua,Zong, Baoning,Jiao, Ning
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p. 3011 - 3016
(2021/09/13)
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- Manganese Catalyzed Hydrogenation of Azo (N=N) Bonds to Amines
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We report the first example of homogeneously catalyzed hydrogenation of the N=N bond of azo compounds using a complex of an earth-abundant-metal. The hydrogenation reaction is catalyzed by a manganese pincer complex, proceeds under mild conditions, and yields amines, which makes this methodology a sustainable alternative route for the conversion of azo compounds. A plausible mechanism involving metal-ligand cooperation and hydrazine intermediacy is proposed based on mechanistic studies. (Figure presented.).
- Ben-David, Yehoshoa,Das, Uttam Kumar,Diskin-Posner, Yael,Kar, Sayan,Milstein, David
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supporting information
p. 3744 - 3749
(2021/07/09)
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- Iridium-Triggered Allylcarbamate Uncaging in Living Cells
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Designing a metal catalyst that addresses the major issues of solubility, stability, toxicity, cell uptake, and reactivity within complex biological milieu for bioorthogonal controlled transformation reactions is a highly formidable challenge. Herein, we report an organoiridium complex that is nontoxic and capable of the uncaging of allyloxycarbonyl-protected amines under biologically relevant conditions and within living cells. The potential applications of this uncaging chemistry have been demonstrated by the generation of diagnostic and therapeutic agents upon the activation of profluorophore and prodrug in a controlled fashion within HeLa cells, providing a valuable tool for numerous potential biological and therapeutic applications.
- Gupta, Ajay,Gupta, Shalini,Mahawar, Pritam,Prasad, Puja,Sasmal, Pijus K.,Singh, Neelu
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supporting information
p. 12644 - 12650
(2021/09/06)
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- The graphite-catalyzed: ipso -functionalization of arylboronic acids in an aqueous medium: metal-free access to phenols, anilines, nitroarenes, and haloarenes
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An efficient, metal-free, and sustainable strategy has been described for the ipso-functionalization of phenylboronic acids using air as an oxidant in an aqueous medium. A range of carbon materials has been tested as carbocatalysts. To our surprise, graphite was found to be the best catalyst in terms of the turnover frequency. A broad range of valuable substituted aromatic compounds, i.e., phenols, anilines, nitroarenes, and haloarenes, has been prepared via the functionalization of the C-B bond into C-N, C-O, and many other C-X bonds. The vital role of the aromatic π-conjugation system of graphite in this protocol has been established and was observed via numerous analytic techniques. The heterogeneous nature of graphite facilitates the high recyclability of the carbocatalyst. This effective and easy system provides a multipurpose approach for the production of valuable substituted aromatic compounds without using any metals, ligands, bases, or harsh oxidants.
- Badgoti, Ranveer Singh,Dandia, Anshu,Parewa, Vijay,Rathore, Kuldeep S.,Saini, Pratibha,Sharma, Ruchi
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p. 18040 - 18049
(2021/05/29)
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- Room-temperature copper-catalyzed electrophilic amination of arylcadmium iodides with ketoximes
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We started our study by preparation two ketoximes. Later, there were studies to reveal these ketoximes' effects in the electrophilic amination reaction with organocadmium reagents. Primarily, it was observed that arylcadmium iodides could not be reacted with ketoximes at room temperature in the absence of a catalyst. CuCN was a suitable catalyst for this electrophilic amination reaction of arylcadmium iodides and allowed the preparation of functionalized aniline derivatives in good yields under mild reaction conditions. We obtained the results indicated that the yield of primary arylamines was strongly dependent on the steric and electronic effects of organocadmium reagent and amination agent. In the case of both amination reagents, meta-substituted arylamines were obtained in higher yields than para-substituted arylamines. We observed that acetone O-(4-chlorophenylsulfonyl)oxime, 1, as an aminating agent, was more successful than acetone O-(2-Naphthylsulfonyl)oxime, 2, in the synthesis of functionalized arylamines by electrophilic amination of corresponding aryl cadmium iodides. In this method, there is no cadmium release to the environment.
- Korkmaz, Adem
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p. 3119 - 3125
(2021/05/10)
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- High yielding electrophilic amination with lower order and?higher order organocuprates: Application of acetone O-(4-Chlorophenylsulfonyl)oxime in the construction of the C?N bond at room temperature
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Electrophilic amination reaction was performed with lower order and?higher order organocuprates using acetone O-(4-Chlorophenylsulfonyl)oxime (1). It was proceeded smoothly at room temperature in the presence of organocuprates to provide the corresponding primary amines in good yields with 10 and 60 min, respectively. The primary amine yields of the electrophilic amination of bromomagnesium organocyanocuprates and dibromomagnesium diorganocyanocuprates were obtained 52–72% and 58–83%, respectively. We observed that higher order organocuprates were more successful than lower order organocuprates in the synthesis of functionalized arylamines by electrophilic amination.
- Duran, Serdar,Korkmaz, Adem
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p. 2077 - 2087
(2021/05/27)
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- Catalytic Decarboxylative C?N Formation to Generate Alkyl, Alkenyl, and Aryl Amines
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Transition-metal-catalyzed sp2 C?N bond formation is a reliable method for the synthesis of aryl amines. Catalytic sp3 C?N formation reactions have been reported occasionally, and methods that can realize both sp2 and sp3 C?N formation are relatively unexplored. Herein, we address this challenge with a method of catalytic decarboxylative C?N formation that proceeds through a cascade carboxylic acid activation, acyl azide formation, Curtius rearrangement and nucleophilic addition reaction. The reaction uses naturally abundant organic carboxylic acids as carbon sources, readily prepared azidoformates as the nitrogen sources, and 4-dimethylaminopyridine (DMAP) and Cu(OAc)2 as catalysts with as low as 0.1 mol % loading, providing protected alkyl, alkenyl and aryl amines in high yields with gaseous N2 and CO2 as the only byproducts. Examples are demonstrated of the late-stage functionalization of natural products and drug molecules, stereospecific synthesis of useful α-chiral alkyl amines, and rapid construction of different ureas and primary amines.
- Zhang, Yipin,Ge, Xia,Lu, Hongjian,Li, Guigen
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supporting information
p. 1845 - 1852
(2020/12/01)
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- Method for synthesizing heteroatom- substituted aromatic compound from styrene compound
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The invention discloses a method for synthesizing a heteroatom-substituted aromatic compound from a styrene compound, which comprises the following steps of: mixing a styrene compound with a general formula (I) and a heteroatom-containing compound with a general formula (II), and reacting in the presence of an acid additive and an organic solvent to obtain a heteroatom-substituted compound with ageneral formula (III). According to the synthesis method disclosed by the invention, a large amount of styrene compounds are used as raw materials and react to generate aromatic amine or phenol compounds under the action of no metal catalysis; and compared with the traditional aromatic amine and phenol synthesis method, the method has the advantages of high yield, simple conditions, low waste discharge amount, no metal participation, simple reaction equipment, easiness in industrial production and the like.
- -
-
Paragraph 0133-0136
(2021/02/06)
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- Visible-light induced one-pot hydrogenation and amidation of nitroaromatics with carboxylic acids over 2D MXene-derived Pt/N-TiO2/Ti3C2
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Pt nanoparticles supported on N doped titanium dioxide/titanium carbide (MXene) heterojunctions were employed as photocatalysts for the tandem reactions between aromatic nitro compounds and carboxylic acids to produce amide products. The 3%Pt/N-TiO2/Ti3C2 heterojunction was prepared by in situ grew TiO2 on Ti3C2 nanosheets and then N doped TiO2 with melamine, Pt nanoparticles with 3.3 nm mean diameter well dispersed on N-TiO2/Ti3C2. 3%Pt/N-TiO2/Ti3C2 had excellent amidation activity and chemoselectivity under visible-light irradiation. The elevated catalytic performance of 3%Pt/N-TiO2/Ti3C2 was owing to the improvement in photogenerated electron and hole separation efficiency through charge short-range directional transmission caused by the intimate contact between the TiO2 and the conductive Ti3C2. This direct hydrogenation along with amidation between nitroaromatics and carboxylic acids own actual merits in the amides produce with no harmful byproducts. In situ DRIFTS spectra verified that the amidation activation with visible light irradiation at 25 °C was much faster than heating.
- Jiang, Heyan,Hu, Zujie,Gan, Chuan,Sun, Bin,Kong, Shuzhen,Bian, Fengxia
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- Minimization of Back-Electron Transfer Enables the Elusive sp3 C?H Functionalization of Secondary Anilines
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Anilines are some of the most used class of substrates for application in photoinduced electron transfer. N,N-Dialkyl-derivatives enable radical generation α to the N-atom by oxidation followed by deprotonation. This approach is however elusive to monosubstituted anilines owing to fast back-electron transfer (BET). Here we demonstrate that BET can be minimised by using photoredox catalysis in the presence of an exogenous alkylamine. This approach synergistically aids aniline SET oxidation and then accelerates the following deprotonation. In this way, the generation of α-anilinoalkyl radicals is now possible and these species can be used in a general sense to achieve divergent sp3 C?H functionalization.
- Zhao, Huaibo,Leonori, Daniele
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supporting information
p. 7669 - 7674
(2021/03/08)
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- Reductive Formylation of Nitroarenes using HCOOH over Bimetallic C?N Framework Derived from the Integration of MOF and COF
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CoZn embedded C?N framework is prepared by the carbonization of CoZn containing MOF integrated with COF porous architecture in Ar atmosphere. The graphitic nature of porous carbon is confirmed from Raman analysis. The porosity and nanostructure information are retrieved from N2-sorption and transmission electron microscopic analysis, respectively. The incorporation of different metals and their oxidation states and types of nitrogen present in the C?N framework are confirmed from X-ray photoelectron spectroscopy. The basicity of the materials is determined from a CO2-temperature programmed desorption. ZnCo embedded C?N framework exhibits excellent activity in the selective reductive formylation using HCOOH. For comparison, more than 15 materials are prepared, and their activities are compared. Several control experiments are performed to establish a structure-activity relation. The recycling experiment, hot-filtration test, and poisoning experiment demonstrate the metal embedded porous C?N framework‘s recyclability and stability. A reaction mechanism for the reductive N-formylation of nitroaromatics is presented based on structure-activity relationship, control reactions, and physicochemical characterizations. The development of interesting MOF-COF-derived metal nanoclusters embedded C?N framework for selective reductive formylation of nitroaromatics using formic acid will be highly attractive to catalysis researchers and industrialists.
- Kumar Kar, Ashish,Srivastava, Rajendra
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p. 3174 - 3183
(2021/05/27)
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- Cu-Catalyzed Cross-Coupling of Nitroarenes with Aryl Boronic Acids to Construct Diarylamines
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The development and study of a simple copper-catalyzed reaction of nitroarenes with aryl boronic acids to form diarylamines that uses phenyl silane as the stoichiometric terminal reductant is described. This cross-coupling reaction requires as little as 2 mol % of CuX and 4 mol % of diphosphine for success and tolerates a broad range of functional groups on either the nitroarene or the aryl boronic acid to afford the amine in good yield. Mechanistic investigations established that the cross-coupling reaction proceeds via a nitrosoarene intermediate and that copper is required to catalyze both the deoxygenation of the nitroarene to afford the nitrosoarene and C-NAr bond formation of the nitrosoarene with the aryl boronic acid.
- Guan, Xinyu,Zhu, Haoran,Driver, Tom G.
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p. 12417 - 12422
(2021/10/12)
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- Unlocking Amides through Selective C–N Bond Cleavage: Allyl Bromide-Mediated Divergent Synthesis of Nitrogen-Containing Functional Groups
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We report a new set of reactions based on the unlocking of amides through simple treatment with allyl bromide, creating a common platform for accessing a diverse range of nitrogen-containing functional groups such as primary amides, sulfonamides, primary amines, N-acyl compounds (esters, thioesters, amides), and N-sulfonyl esters. The method has potential industrial applicability, as demonstrated through gram-scale syntheses in batch and in a continuous flow system.
- Govindan, Karthick,Chen, Nian-Qi,Chuang, Yu-Wei,Lin, Wei-Yu
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p. 9419 - 9424
(2021/11/30)
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- Copper catalyzed reduction of azides with diboron under mild conditions
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We report herein the first Cu catalyzed reduction of azides with B2pin2 (pin = pinacolato) as the reductant under very mild conditions. A series of primary amines and amides were obtained in moderate to excellent yields with high chemoselectivity and good functional group tolerance. This reaction can be performed with a cheap copper salt, a simple NHC ligand and a diboron reagent.
- Chen, Yang,Deng, Shengqi,Gao, Yihua,Liu, Liwen,Liu, Yu,Lu, Da,Wang, Qianwen,Zhang, Xiao
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supporting information
(2020/02/27)
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- Heterogeneous photocatalysis of azides: Extending nitrene photochemistry to longer wavelengths
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The photodecomposition of azides to generate nitrenes usually requires wavelengths in the 300 nm region. In this study, we show that this reaction can be readily performed in the UVA region (368 nm) when catalyzed by Pd-decorated TiO2. In aqueous medium the reaction leads to amines, with water acting as the H source; however, in non-protic and non-nucleophilic media, such as acetonitrile, nitrenes recombine to yield azo compounds, while azirine-mediated trapping occurs in the presence of nucleophiles. The heterogeneous process facilitates catalyst separation while showing great chemoselectivity and high yields.
- Argüello, Juan E.,Lanterna, Anabel E.,Lemir, Ignacio D.,Scaiano, Juan C.
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supporting information
p. 10239 - 10242
(2020/10/02)
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- Copper(II) complex with oxazoline ligand: Synthesis, structures and catalytic activity for nitro compounds reduction
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The Cu(II) complexes bearing bisoxazolines, tridentate pincer pybox and terpyridine ligands have been synthesized and fully characterized. The molecular structures of copper complexes 1a and 1c were confirmed by single-crystal X-ray diffraction methods. These copper complexes highly catalyzed nitro compounds reduction to aniline and its derivatives in the presence of NaBH4 reducing agent in water solvent. The complex 1e was an efficient catalyst toward nitro compounds reduction with wide functional group substrate scope and aliphatic nitro compounds.
- Du, Jun,Gao, Li-Li,Jia, Wei-Guo,Li, Mei,Zhi, Xue-Ting
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- Synthesis, characterization, and catalytic activity of half-sandwich ruthenium complexes with pyridine/phenylene bridged NHC = E (NHC = N-heterocyclic carbene, E = S, Se) ligands
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Three half-sandwichruthenium(II) complexes with pyridine/phenylene bridged NHC = E (NHC = N-heterocyclic carbene, E = S, Se) ligands [Ru(p-cymene)L](PF6)1–2 (1a–1c, L = ligand) were synthesized and characterized. All ruthenium complexes were fully characterized by 1H and 13C NMR spectra, mass spectrometry, and single-crystalX-ray diffraction methods. Moreover, the half-sandwich ruthenium complexes with NHC = E ligands showed highly catalytic activities towards to the tandem dehydrogenation of ammonia borane (AB) and hydrogenation of R–NO2 to R–NH2 at 353 K in water.
- Jia, Wei-Guo,Du, Teng-Teng,Gao, Li-Li,Du, Jun
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- Promotional effect of palladium in Co-SiO2 core@shell nanocatalysts for selective liquid phase hydrogenation of chloronitroarenes
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This study describes the synthesis of palladium-promoted Co@SiO2 catalyst developed by electrostatic immobilization of Pd ionic precursor onto Co3O4 nanoparticles core, coated with a mesoporous SiO2 shell. The oxidized Pd-Co3O4@SiO2 (xPdCo-ox) and partially reduced Pd-Co@SiO2 (xPdCo-red) nanocatalysts were used in the direct synthesis of chloro-arylamines from chloronitroarenes employing heterogeneous hydrogenation process. The effect of palladium content (xPdCo; x = 0.0, 0.5, 1.0 and 3.0 Pd wt%) in the Co3O4 core of the structures on catalytic performance for the hydrogenation of 4-chloronitrobenzene (CNB) to 4-chloroaniline (CAN) was systematically studied. It was found that the incorporation of palladium ionic precursor promotes both Co3O4 core nanoparticles flocculation and an increase in the mesoporous shell thickness in the Pd-promoted catalysts compared to the pristine Co-SiO2 core-shell structure. The TPR, XRD, XPS and magnetic measurements results indicated that the palladium addition promoted the reduction of Co3O4 core during the isothermal H2 treatment at 873 K rendering metallic Pd° and Co° species. The catalytic CNB hydrogenation experiments showed that the 0.5PdCo-red catalyst inhibited both the hydrodechlorination and intermediates accumulation reaching 99% yield in CAN compared to 1.0PdCo-red and 3.0PdCo-red catalysts which provided aniline as undesired product. Additionally, the 0.5PdCo-red catalyst was easily recycled with a moderate catalytic activity after five consecutive reaction cycles. Finally, the catalytic hydrogenation performance of the 0.5PdCo-red catalyst for different pharmaceutical substituted chloro-nitroarenes such as 1-(4-chlorophenoxy)-2-nitrobenzene, 2-chloro-1-((3-fluorobenzyl)oxy)-4-nitrobenzene and 2-chloro-5nitrobenzotrifluoride was also evaluated and revealed high activity (>99% at 3 h of reaction) and selectivity towards the desired chloro-arylmines production, highlighting the potential of this catalyst in these processes.
- Bustamante, Tatiana M.,Campos, Cristian H.,Fraga, Marco A.,Fierro,Pecchi, Gina
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p. 224 - 237
(2020/04/08)
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- Atomically Dispersed Co Catalyst for Efficient Hydrodeoxygenation of Lignin-Derived Species and Hydrogenation of Nitroaromatics
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Single-atom catalysts (SACs) have attracted much attention due to their outstanding catalytic performance in heterogeneous catalysis. Here, we report a template sacrificial method to fabricate an atomically dispersed Co catalyst; three kinds of silica templates with different microstructures (MCM-41, SBA-15, and FDU-12) were employed and the effect of pore structure of the templates on the dispersity of Co was investigated. The catalysts fabricated with different templates presented different Co dispersities, leading to distinguishing catalytic performance. The optimized Co1?NC-(SBA) catalyst with atomically dispersed Co displayed outstanding catalytic activity for the hydrodeoxygenation (HDO) of lignin-derived species as well as the hydrogenation of various nitroaromatics. The reaction mechanism of the HDO of vanillin was investigated by using density functional theory calculations as well.
- Du, Congcong,Gao, Shutao,Gao, Yongjun,Huang, Jianyu,Meng, Tao,Qiao, Yuqing,Shang, Ningzhao,Shen, Tongde,Wang, Chun,Wang, Haijun,Wang, Junmin,Wang, Zhi,Wu, Qiuhua,Zhang, Longkang
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p. 8672 - 8682
(2020/09/18)
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- Cycloglutaramide-based ligand, synthetic method of ligand, application of ligand in coupling reaction for synthesizing arylamine derivative and catalytic system
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The invention discloses a cycloglutaramide-based ligand having a general formula I shown in the specification, a synthetic method of the ligand, an application of the ligand in a coupling reaction forsynthesizing an arylamine derivative, and a catalytic system. The compounds represented by the formula I can be used as a ligand in the coupling reaction of synthesizing the arylamine derivative by using an aryl halide under catalysis of copper, especially the coupling reaction of aryl halide and an amine source to form a C-N bond under catalysis. Under mild reaction conditions, the high-yield arylamine derivative is obtained, and the ligand has a simple structure, convenient preparation and a less use amount.
- -
-
Paragraph 0106; 0107; 0108; 0109; 0110
(2020/03/12)
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- Selective Photoinduced Reduction of Nitroarenes to N-Arylhydroxylamines
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We report the selective photoinduced reduction of nitroarenes to N-arylhydroxylamines. The present methodology facilitates this transformation in the absence of catalyst or additives and uses only light and methylhydrazine. This noncatalytic photoinduced transformation proceeds with a broad scope, excellent functional-group tolerance, and high yields. The potential of this protocol reflects on the selective and straightforward conversion of two general antibiotics, azomycin and chloramphenicol, to the bioactive hydroxylamine species.
- Kallitsakis, Michael G.,Ioannou, Dimitris I.,Terzidis, Michael A.,Kostakis, George E.,Lykakis, Ioannis N.
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supporting information
p. 4339 - 4343
(2020/06/08)
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- Shape-dependent reactivity and chemoselectivity of nanogold towards nitrophenol reduction in water
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Although the catalytic activity of nano-gold surfaces for the reduction of nitro compounds has been known, the effect of their shape has been rarely evaluated. Here, the synthesis, characterization, and application of both gold nanoworms (GNW) and gold nanospheres (GNS) are described. Both GNW and GNS were characterized using SEM, TEM, UV–Vis, FTIR, and XPS spectroscopy. The catalytic efficiency of GNW with an average dimensions of 2 × 250 nm (D × L) towards the hydrogenation of nitrophenol, a pollutant present in industrial wastewater, is higher (TOF 3675 h?1) than that of spherical GNS (10 ± 1 nm), for which TOF is 1838 h?1 in water using NaBH4 as the reductant. The selectivity of 4-aminophenol is 100% for both GNS and GNW.
- Aziz, Md Abdul,Nafiu, Sodiq Adeyeye,Shaikh, M. Nasiruzzaman
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- Zn(0)-Catalysed mild and selective hydrogenation of nitroarenes
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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
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supporting information
p. 4640 - 4644
(2020/08/10)
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- Exploring Opportunities for Platinum Nanoparticles Encapsulated in Porous Liquids as Hydrogenation Catalysts
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The unusual combination of characteristics observed for porous liquids, which are typically associated with either porous solids or liquids, has led to considerable interest in this new class of materials. However, these porous liquids have so far only been investigated for their ability to separate and store gases. Herein, the catalytic capability of Pt nanoparticles encapsulated within a Type I porous liquid (Pt@HS-SiO2 PL) is explored for the hydrogenation of several alkenes and nitroarenes under mild conditions (T=40 °C, PH2=1 atm). The different intermediates in the porous liquid synthesis (i.e., the initial Pt@HS-SiO2, the organosilane-functionalized intermediate, and the final porous liquid) are employed as catalysts in order to understand the effect of each component of the porous liquid on the catalysis. For the hydrogenation of 1-decene, the Pt@HS-SiO2 PL catalyst in ethanol has the fastest reaction rate if normalized with respect to the concentration of Pt. The reaction rate slows if the reaction is completed in a “neat” porous liquid system, probably because of the high viscosity of the system. These systems may find application in cascade reactions, in particular, for those with mutually incompatible catalysts.
- Hemming, Ellen B.,Masters, Anthony F.,Maschmeyer, Thomas
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p. 7059 - 7064
(2020/03/24)
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- Highly efficient one-pot multi-directional selective hydrogenation and N-alkylation catalyzed by Ru/LDH under mild conditions
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Atomic economy, non-toxicity, harmlessness and multidirectional selectivity advocated by green chemistry have increasingly become a hot and difficult research topic. Herein, we present a highly efficient, one-pot tandem and easy-to-operate method through which we could directly produce a broad range of multi-directional selective hydrogenated amines or N-alkyl aliphatic amines using aromatic nitro compounds as raw materials. Ru/LDH with characteristics of layered mesoporous structure, well dispersed small Ru nanoparticles and LDH stabilization to the Ru NPs was employed as the catalyst. It is remarkable that multi-directional superb chemoselectivity to aromatic amines, alicyclic amines as well as N-alkyl aliphatic amines could be achieved with excellent catalytic activity and recyclability by tuning reaction conditions over 5wt%Ru/LDH-2. Additionally, this catalytic system also exhibited attractive activity and multi-directional chemoselectivity in the hydrogenation of quinoline and its derivatives with solvents of different polarity. Chemoselectivity to 5,6,7,8-tetrahydroquinoline derivatives could reach as high as 95.6 %.
- Zhang, Sishi,Xu, Jie,Cheng, Hongmei,Zang, Cuicui,Sun, Bin,Jiang, Heyan,Bian, Fengxia
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supporting information
(2020/03/30)
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- A new ligand for copper-catalyzed amination of aryl halides to primary(hetero)aryl amines
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N,N′-Bis(3,5-dimethoxyphenyl)cyclopentane-1,1-dicarboxamide was found as a new ligand for copper-catalyzed amination of aryl iodides, bromides and chlorides to afford various primary (hetero)aryl amines. These reactions proceeded efficiently under mild conditions when inexpensive aqueous ammonia (28% NH3 in H2O) was used as the amino source.
- Chen, Dong,Dong, Xinrui,Jiang, Shang,Jiang, Sheng,Qiu, Yatao,Wu, Xiaoxing
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supporting information
(2020/02/11)
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- Pt nanoparticles on Ti3C2T: X -based MXenes as efficient catalysts for the selective hydrogenation of nitroaromatic compounds to amines
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The development of Pt nanocatalysts for the selective hydrogenation of nitroaromatic compounds to the corresponding amines is of great significance to solve the drawbacks associated with a low reserve of Pt. Herein, we develop a protocol for the preparation of a Pt/titanium carbide-based MXene heterostructure for the selective reduction of nitroaromatic compounds. In the heterostructure, well-defined and nano-sized metallic Pt crystallites are uniformly decorated on Ti3C2Tx nanosheets using a mild reducing agent of ammonia borane without additional stabilizing agents. The selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN) was employed as a model reaction to investigate the catalytic performance of the as-synthesized heterostructure, denoted as Pt/Ti3C2Tx-D-AB. Notably, this catalyst can catalyze the complete conversion of p-CNB to p-CAN with 99.5% selectivity, superior to that of Pt/Ti3C2Tx-D-SB synthesized with sodium borohydride. The high performance of the present catalytic system can be ascribed to the well-dispersed Pt nanoparticles, the abundant surface electron-efficient Pt(0), and the synergistic catalysis between Pt/Ti3C2Tx-D-AB and water. This catalyst also shows generality toward the selective hydrogenation of a series of nitroaromatic compounds to the corresponding amines with high efficiency. The present study provides a strategy to synthesize efficient catalysts for catalytic applications.
- Chen, Qian,Fan, Guangyin,Jiang, Weidong
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supporting information
p. 14914 - 14920
(2020/11/11)
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- Selective Room-Temperature Hydrogenation of Amides to Amines and Alcohols Catalyzed by a Ruthenium Pincer Complex and Mechanistic Insight
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We report a room-temperature protocol for the hydrogenation of various amides to produce amines and alcohols. Compared with most previous reports for this transformation, which use high temperatures (typically, 100-200 °C) and H2 pressures (10-100 bar), this system proceeds under extremely mild conditions (RT, 5-10 bar of H2). The hydrogenation is catalyzed by well-defined ruthenium-PNNH pincer complexes (0.5 mol %) with potential dual modes of metal-ligand cooperation. An unusual Ru-amidate complex was formed and crystallographically characterized. Mechanistic investigations indicate that the room-temperature hydrogenation proceeds predominantly via the Ru-N amido/amine metal-ligand cooperation.
- Ben-David, Yehoshoa,Kar, Sayan,Kumar, Amit,Leitus, Gregory,Milstein, David,Rauch, Michael
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p. 5511 - 5515
(2020/07/21)
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