- Rescuing auxotrophic microorganisms with nonenzymatic chemistry
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Organic chemistry to the rescue: Two unrelated nonenzymatic chemical reactions can support the growth of auxotrophic E.-coli strains by generating essential nutrients in-situ. These biocompatible reactions, which take place in the presence of the organisms and are designed to interface with cellular metabolic processes, provide a means of linking the growth of an organism to the success of a nonbiological chemical transformation. Copyright
- Lee, Yunmi,Umeano, Afoma,Balskus, Emily P.
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- A general Staudinger protocol for solution-phase parallel synthesis
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The Staudinger reaction has been adapted for parallel synthesis by the application of fluorous-tethered triphenyl phosphine. The fluorous-tethered triphenylphosphine is expediently removed in parallel by FluoroFlash SPE columns to afford functionalized amines in high yields and purities.
- Lindsley, Craig W,Zhao, Zhijian,Newton, Randall C,Leister, William H,Strauss, Kimberly A
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- Sulfonated covalent triazine polymer loaded with Pd nanoparticles as a bifunctional catalyst for one pot hydrogenation esterification reaction
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Highly dispersed Pd nanoparticles over covalent triazine polymer functionalized with sulfonic acid groups (CTP-SO3H/Pd) were prepared by facile Friedel-Crafts reaction, post synthetic sulfonation and Pd immobilization method. The prepared catalyst was characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption, inductively coupled plasma - optical emission spectrometry (ICP-OES), elemental analysis and X-ray photoelectron spectroscopy (XPS). The sulfonic acid groups were grafted into the terphenyl backbone and the presence of triazine functionality within the framework enabled the uniform dispersion of palladium nanoparticles over the polymer network. When used as a bifunctional catalyst in one pot hydrogenation-esterification (OHE) reaction, the CTP-SO3H/Pd exhibited good activity and stability. The performance of CTP-SO3H/Pd is due to the surface-active acid/metal sites and was evident from the yield of the product in the reaction. The catalyst was easily recovered by filtration and recycle tests showed that it could be re-used for at least five repetitive runs with minor loss of catalytic activity suggesting its potential utility in OHE reaction. A plausible mechanistic pathway for OHE reaction over CTP-SO3H/Pd was also proposed.
- Ravi, S.,Raza, A. Ahmed,Sheriff, A. K. Ibrahim,Tajudeen, S. Syed
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- Gold(II) Porphyrins in Photoinduced Electron Transfer Reactions
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In the context of solar-to-chemical energy conversion, inspired by natural photosynthesis, the synthesis, electrochemical properties and photoinduced electron-transfer processes of three novel zinc(II)-gold(III) bis(porphyrin) dyads [ZnII(P)–AuIII(P)]+ are presented (P: tetraaryl porphyrin). Time-resolved spectroscopic studies indicated ultrafast dynamics (kET1>1010 s?1) after visible-light excitation, which finally yielded a charge-shifted state [ZnII(P?+)–AuII(P)]+ featuring a gold(II) center. The lifetime of this excited state is quite long due to a comparably slow charge recombination (kBET2 ≈3×108 s?1). The [ZnII(P?+)–AuII(P)]+ charge-shifted state is reductively quenched by amines in bimolecular reactions, yielding the neutral zinc(II)–gold(II) bis(porphyrin) ZnII(P)–AuII(P). The electronic nature of this key gold(II) intermediate, prepared by chemical or photochemical reduction, is elucidated by UV/Vis, X-band EPR, gold L3-edge X-ray absorption near edge structure (XANES) and paramagnetic 1H NMR spectroscopy as well as by quantum chemical calculations. Finally, the gold(II) site in ZnII(P)–AuII(P) is thermodynamically and kinetically competent to reduce an aryl azide to the corresponding aryl amine, paving the way to catalytic applications of gold(III) porphyrins in photoredox catalysis involving the gold(III/II) redox couple.
- Prei?, Sebastian,P?pcke, Ayla,Burkhardt, Lukas,Gro?mann, Luca,Lochbrunner, Stefan,Bauer, Matthias,Opatz, Till,Heinze, Katja
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- A facile reduction of nitroarenes to anilines using FeCl 3·6H2O/indium
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Reduction of a variety of nitroaromatic compounds to the corresponding anilines occurs chemoselectively in high yields upon treatment with a new reduction system consisting of FeCl3·6H2O/indium in aqueous methanol.
- Yoo, Byung Woo,Choi, Jin Woo,Hwang, Sun Kyun,Kim, Dong Yoon,Baek, Heung Soo,Choi, Kyung Il,Kim, Joong Hyup
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- Possible role of hydroxyl radicals in the oxidative degradation of folic acid
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An unprecedented .OH radical-induced N-dealkylation of amines including folic acid is reported, the reaction proceeding via a direct hydrogen atom abstraction mechanism as revealed by pulse radiolysis experiments. Hydroxyl radicals have been found to cause oxidative N-dealkylation of amines including folic acid via a hydrogen atom transfer mechanism.
- Patro, Birija S.,Adhikari, Soumyakanti,Mukherjee, Tulsi,Chattopadhyay, Subrata
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- Characterization of the folate salvage enzyme p-aminobenzoylglutamate hydrolase in plants
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Folates break down in vivo to give pterin and p-aminobenzoylglutamate (pABAGlu) fragments, the latter usually having a polyglutamyl tail. Pilot studies have shown that plants can hydrolyze pABAGlu and its polyglutamates to p-aminobenzoate, a folate biosynthesis precursor. The enzymatic basis of this hydrolysis was further investigated. pABAGlu hydrolase activity was found in all species and organs tested; activity levels implied that the proteins responsible are very rare. The activity was located in cytosol/vacuole and mitochondrial fractions of pea (Pisum sativum L.) leaves, and column chromatography of the activity from Arabidopsis tissues indicated at least three peaks. A major activity peak from Arabidopsis roots was purified 86-fold by a three-column procedure; activity loss during purification exceeded 95%. Size exclusion chromatography gave a molecular mass of ～200 kDa. Partially purified preparations showed a pH optimum near 7.5, a Km value for pABAGlu of 370 μM, and activity against folic acid. Activity was relatively insensitive to thiol and serine reagents, but was strongly inhibited by 8-hydroxyquinoline-5-sulfonic acid and stimulated by Mn2+, pointing to a metalloenzyme. The Arabidopsis genome was searched for proteins similar to Pseudomonas carboxypeptidase G, which contains zinc and is the only enzyme yet confirmed to attack pABAGlu. The sole significant matches were auxin conjugate hydrolase family members and the At4g17830 protein. None was found to have significant pABAGlu hydrolase activity, suggesting that this activity resides in hitherto unrecognized enzymes. The finding that Arabidopsis has folate-hydrolyzing activity points to an enzymatic component of folate degradation in plants.
- Bozzo, Gale G.,Basset, Gilles J.C.,Naponelli, Valeria,Noiriel, Alexandre,Gregory III, Jesse F.,Hanson, Andrew D.
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- FAST Hydrogenations as a Continuous Platform for Green Aromatic Nitroreductions
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A continuous-flow packed-bed catalytic reactor has been developed for hydrogenation of aromatic nitrobenzoic acids in water to produce the corresponding anilines. These hydrogenations are green, more efficient, less consumptive, and safer than the conventional reduction process. Various industrially important aromatic amines have been produced in excellent yields and with high throughput. The optimized continuous-flow reduction process produces no detectable genotoxic intermediates, unlike the corresponding batch reduction. The reactor is modular in design and can be scaled up to produce several kilograms of product per day without extensive redesign.
- Manyar, Haresh,Moody, Thomas S.,Rahman, Md Taifur,Smyth, Megan,Wharry, Scott
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- Synthesis of six 8-quinolinate-based ruthenium complexes with high catalytic activity for nitroarene reduction
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Six ruthenium complexes were synthesized by treating different 2-substituted 8-hydroxyquinolinate ligands with [Ru(p-cymene)(μ-Cl)Cl]2. Their structures were fully characterized by a variety of techniques, including 1H and 13C NMR spectra, elemental analyses and infrared spectrometry. Additionally, single-crystal X-ray diffraction reveals that these ruthenium complexes possess similar half-sandwich structures. The mononuclear ruthenium building units are further linked into 1D or 2D supramolecular structures through non-covalent interactions, such as π?π stacking, hydrogen-bonding and C–H? halogen interactions. The catalytic activities of the six half-sandwich ruthenium complexes towards the hydrogenation of nitroarenes were explored under mild conditions. The ruthenium complexes displayed high catalytic activities in the synthesis of aromatic anilines from nitroarenes in the presence of NaBH4.
- Jia, Wei-Guo,Cheng, Ming-Xia,Xu, Qiu-Tong,Gao, Li-Li,Yuan, Guozan
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- Oxidation of procainamide by diperiodatocuprate(III) complex in aqueous alkaline medium: a comparative kinetic study
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A comparative study of uncatalysed and ruthenium(III) catalyzed oxidation of procainamide(PAH) was carried out spectrophotometrically using diperiodatocuprate(III) in aqueous alkali. Stoichiometry observed was 1:2 (PAH: DPC). The reaction was of first order in both catalyzed and uncatalyzed cases, with respect to [DPC] & [Ru(III)], less than unit order in [PAH] and [alkali]. Negative fraction in [periodate]. Other kinetic parameters viz., ionic strength, dielectric constant, temperature effect and intervention of free radical were also studied. The main oxidation products were characterized by different techniques. The activation parameters with respect to slow step of the mechanism, also the thermodynamic quantities were determined.
- Meti, Manjunath D.,Nandibewoor, Sharanappa T.,Chimatadar, Shivamurti A.
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- Cytochrome P450 CYP199A4 from Rhodopseudomonas palustris Catalyzes Heteroatom Dealkylations, Sulfoxidation, and Amide and Cyclic Hemiacetal Formation
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The cytochrome P450 enzymes execute a range of selective oxidative biotransformations across many biological systems. The bacterial enzyme CYP199A4 catalyzes the oxidative demethylation of 4-methoxybenzoic acid. The benzoic acid moiety of the molecule binds in the active site of the enzyme such that the functional group at the para-position is held close to the heme iron. Therefore, CYP199A4 has the potential to catalyze alternative monooxygenase reactions with different para-substituted benzoic acid substrates such as thioethers and alkylamines. The oxidation of 4-methyl- and 4-ethyl-thiobenzoic acids by CYP199A4 resulted in sulfur oxidation. 4-Ethylthiobenzoic acid sulfoxidation and 4-ethylbenzoic acid hydroxylation by CYP199A4 occurred with high enantioselectivity (>74% enantiomeric excess). By way of contrast, CYP199A4 catalyzed exclusive oxidative N-demethylation over N-oxide formation with 4-methyl- and 4-dimethylaminobenzoic acids. Unexpectedly acetamide formation by CYP199A4 competes with dealkylation in the turnover of 4-ethyl- and diethyl-aminobenzoic acids. No oxidative dealkylation was observed with 3,4-ethylenedioxybenzoic with only hydroxylation to form a cyclic hemiacetal being detected. The X-ray crystal structures of four substrate-bound forms of the enzyme were solved and revealed subtle changes in the location of the para substituent which, when combined with the reactivity of the substituents, provided a basis for understanding the changes in selectivity. Furthermore, in the 4-ethylthiobenzoic acid-bound structure, the active site residue Phe298 moves to accommodate the substituent which points away from the heme iron. As such, the CYP199A4 enzyme provides ready access to a combination of structural, binding, and activity data with which to study a variety of reactions which are catalyzed by the P450 superfamily of enzymes.
- Coleman, Tom,Wong, Siew Hoon,Podgorski, Matthew N.,Bruning, John B.,De Voss, James J.,Bell, Stephen G.
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- Ruthenium nanoparticles supported over mesoporous TiO2 as an efficient bifunctional nanocatalyst for esterification of biomass-derived levulinic acid and transfer-hydrogenation reactions
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We have supported ruthenium nanoparticles (NPs) over a mesoporous TiO2 material (Ru@MTiO2) having nanoscale porosity and a high BET surface area. Wide-angle powder X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible absorption spectra (UV-vis) and N2 sorption studies are used to characterize the Ru@MTiO2 material. This nanostructured ruthenium supported over a TiO2 material exhibited excellent bifunctional catalytic activity in the esterification of levulinic acid and selective transfer hydrogenation reactions of nitroarenes under mild reaction conditions. This Ru@MTiO2 catalyst can be easily recovered from the reaction mixtures and reused five times without a significant loss of its reactivity and selectivity.
- Mandi, Usha,Salam, Noor,Kundu, Sudipta K.,Bhaumik, Asim,Islam, Sk. Manirul
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- Kinetic and mechanistic investigations and thermodynamic quantities for different steps involved in the mechanism of oxidation of procainamide by hexacyanoferrate(III) in aqueous alkaline medium: a spectrophotometric study
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The kinetics of oxidation of procainamide by alkaline hexacyanoferrate(III) at a constant ionic strength of 1.10 mol dm-3 has been studied spectrophotometrically at 25°C. The stoichiometric analysis indicates that one mole of procainamide requires two moles of hexacyanoferrate(III). The reaction products are identified and confirmed by IR, NMR, and GC-MS spectral studies. The reaction is first order with respect to oxidant, Fe(CN) 6 3- and less than unit order with respect to procainamide and alkali concentrations. Increasing ionic strength and decreasing dielectric constant of the medium increases the rate of reaction. The added products did not have any significant effect on the rate of reaction. Based on the experimental results, a suitable mechanism is proposed and the following rate law is derived and verified. Activation parameters are evaluated with respect to the slow step of the mechanism and thermodynamic quantities are also calculated. Voltammetric behavior of procainamide is also made.
- Meti,Lamani,Naikar,Sutar,Nandibewoor,Chimatadar
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- Highly Stable and Active Palladium Nanoparticles Supported on a Mesoporous UiO66@reduced Graphene Oxide Complex for Practical Catalytic Applications
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A metal–organic framework-based composite with reduced graphene oxide was successfully designed, prepared and used for the first time as a support for Pd nanoparticles. The as-synthesized UiO66@RGO-Pd composite was characterized by powder X-ray diffractio
- Liu, Xiang,Zhao, Xiaohua,Zhou, Ming,Cao, Yuanyuan,Wu, Haiyan,Zhu, Jianjun
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- Selective Hydration of Nitriles to Amides Over Titania Supported Palladium Exchanged Vanadium Incorporated Molybdophosphoric Acid Catalysts
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Abstract: Titania supported palladium exchanged vanadium incorporated molybdophosphoric acid (PdMPAV1) catalysts were prepared and characterized by FT-IR, X-ray diffraction and Laser Raman spectroscopy. The characterization results confirmed the presence of vanadium and palladium into the primary and secondary structure of Keggin ion of heteropoly molybdate respectively. The PdMPAV1 was dispersed on support with intact Keggin ion structure. These catalysts were studied for selective hydration of nitriles to amides. The PdMPAV1was highly active compared to the molybdophosphoric acid containing either vanadium or palladium. The catalyst with 20?% PdMPAV1 dispersed on TiO2 showed highest activity compare to other catalysts. A variety of nitriles were tested over this catalyst and found that the catalyst was active to yield corresponding amides. Different reaction parameters were studied and optimum conditions were established. The PdMPAV1/TiO2 catalyst exhibited consistent activity during reuse. Graphical Abstract: [Figure not available: see fulltext.]
- Srinivasa Rao,Srivani,Dhana Lakshmi,Lingaiah
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- Multiway partial least-squares coupled to residual trilinearization: A genuine multidimensional tool for the study of third-order data. Simultaneous analysis of procaine and its metabolite p-aminobenzoic acid in equine serum
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A new third-order multivariate calibration approach, based on the combination of multiway-partial least-squares with a separate procedure called residual trilinearization (N-PLS/RTL), is presented and applied to multicomponent analysis using third-order data. The proposed chemometric algorithm is able to predict analyte concentrations in the presence of unexpected sample components, which require strict adherence to the second-order advantage. Results for the determination of procaine and its metabolite p-aminobenzoic acid in equine serum are discussed, based on kinetic fluorescence excitation-emission four-way measurements and application of the newly developed multiway methodology. Since the analytes are also the reagent and product of the hydrolysis reaction followed by fast-scanning fluorescence spectroscopy, the classical approach based on parallel factor analysis is challenged by strong linear dependencies and multilinearity losses. In comparison, N-PLS/RTL appears an appealing genuine multiway alternative that avoids the latter complications, yielding analytical results that are statistically comparable to those rendered by related unfolded algorithms, which are also able to process four-way data. Prediction was made on validation samples with a qualitative composition similar to the calibration set and also on test samples containing unexpected equine serum components.
- Damiani, Patricia C.,Duran-Meras, Isabel,Garcia-Reiriz, Alejandro,Jimenez-Giron, Ana,De La Pena, Arsenio Munoz,Olivieri, Alejandro C.
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- Magnetic graphene nanocomposite as an efficient catalyst for hydrogenation of nitroarenes
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Graphene-Fe3O4 nanocomposite (G-Fe3O 4) was synthesized by a chemical co-precipitation method which was used as an efficient catalyst for the reduction of nitroarenes with hydrazine hydrate. The method has been
- Feng, Cheng,Zhang, Hai-Yan,Shang, Ning-Zhao,Gao, Shu-Tao,Wang, Chun
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- Nickel Boride Catalyzed Reductions of Nitro Compounds and Azides: Nanocellulose-Supported Catalysts in Tandem Reactions
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Nickel boride catalyst prepared in situ from NiCl2 and sodium borohydride allowed, in the presence of an aqueous solution of TEMPO-oxidized nanocellulose (0.01 wt%), the reduction of a wide range of nitroarenes and aliphatic nitro compounds. Here we describe how the modified nanocellulose has a stabilizing effect on the catalyst that enables low loading of the nickel salt pre-catalyst. Ni-B prepared in situ from a methanolic solution was also used to develop a greener and facile reduction of organic azides, offering a substantially lowered catalyst loading with respect to reported methods in the literature. Both aromatic and aliphatic azides were reduced, and the protocol is compatible with a one-pot Boc-protection of the obtained amine yielding the corresponding carbamates. Finally, bacterial crystalline nanocellulose was chosen as a support for the Ni-B catalyst to allow an easy recovery step of the catalyst and its recyclability for new reduction cycles.
- Proietti, Giampiero,Prathap, Kaniraj Jeya,Ye, Xinchen,Olsson, Richard T.,Dinér, Peter
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p. 133 - 146
(2021/11/04)
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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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- UiO-66/btb/Pd as a stable catalyst reduction of 4-nitrophenol into 4-aminophenol
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In order to synthesize highly sparse nanoparticles, UiO-66-NH2 can be utilized as an appropriate support. It has great surface area, which is functionalized by 1,3-bis(dimethylthiocarbamoyloxy)benzene compounds that can act as the powerful performers, hence, the Pd (II) is a complex without aggregate over the UiO-66-NH2 microspheres structures (UiO-66/btb/Pd). Nitro-aromatic pollution in industrial waste streams threat wellbeing of water resources. The produced UiO-66/btb/Pd nanocatalyst showed appropriate catalytic activity for reduce nitro-aromatic compounds in aqueous solution. XRD, EDS, SEM, FT-IR, and TEM were utilized for characterizing the nanostructures UiO-66/btb/Pd.
- Kiani, Zahra,Zhiani, Rahele,Khosroyar, Susan,Motavalizadehkakhky, Alireza,Hosseiny, Malihesadat
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- Magnetically‐recoverable Schiff base complex of Pd(II) immobilized on Fe3O4@SiO2 nanoparticles: an efficient catalyst for the reduction of aromatic nitro compounds to aniline derivatives
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Fe3O4@SiO2/Schiff base/Pd(II) is reported as a magnetically recoverable heterogeneous catalyst for the chemoselective reduction of aromatic nitro compounds to the corresponding amines through catalytic transfer hydrogenation (CTH). In this regard, a small amount of the nanocatalyst (0.52?mol% Pd) and hydrazine hydrate, showing safe characteristics and perfect ability as the hydrogen donor, were added to the nitro substrates. The experiments described the successful reduction of aromatic nitro compounds with good to excellent yields and short reaction times. The catalyst, due to its magnetic property, could be simply separated from the reaction mixture by a permanent magnet and reused in seven consecutive reactions without considerable loss in its activity. Moreover, the leaching of Pd was only 3.6% after the seventh run. Thus, the most striking feature of this method is to use a small amount of the magnetic nanocatalyst along with a cheap and safe hydrogen source to produce the important amine substances selectively, which makes the method economical, cheap, environmentally friendly, and simple. Graphic abstract: [Figure not available: see fulltext.]
- Azadi, Sedigheh,Esmaeilpour, Mohsen,Sardarian, Ali Reza
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p. 809 - 821
(2021/07/20)
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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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p. 25284 - 25295
(2021/08/05)
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- Synthesis of CoFe2O4@Pd/Activated carbon nanocomposite as a recoverable catalyst for the reduction of nitroarenes in water
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Efficient reduction of nitro compounds into amines is an important industrial transformation. So, it is a great deal to design new catalysts for efficient reduction of the nitro compounds especially in water. In this work, a new magnetic Pd/activated carbon nanocomposite (CoFe2O4@Pd/AC) was synthesized via metal-impregnation-pyrolysis method. The CoFe2O4@Pd/AC was fully characterized by FT-IR, PXRD, FESEM, TEM, VSM, EDX-mapping and BET techniques. The results showed that CoFe2O4@Pd/AC is a highly reactive and easily recoverable magnetic catalyst for the reduction of the nitro compounds by using NaBH4 in water. For instance, aniline was obtained in high yield (99%) after 75 ?min at 25 ?C by using just 6 ?mg of the catalyst. In addition, CoFe2O4@Pd/AC was recovered by a simple magnetic decantation and it exhibits stable activity and remains intact during the catalytic process with no significant loss in activity (8 cycles).
- Hamadi, Hosein,Kazeminezhad, Iraj,Mohammadian, Sara
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- A highly effective green catalyst Ni/Cu bimetallic nanoparticles supported by dendritic ligand for chemoselective oxidation and reduction reaction
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The highly active Ni/Cu bimetallic nanoparticles (NPs) of the different molar ratios of Ni and Cu (1:1, 1:3, 3:1) assisted by dendritic ligand 2,4,6-Tris (di-4-chlorobenzamido)-1,3-diazine were synthesized successfully confirmed by Scanning Electron Microscopy (SEM), Electron Diffraction X-ray (EDX), X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), and Transmission Electron Microscopy (TEM) analysis. These NPs were studied as a heterogeneous catalyst for the chemoselective oxidation of alcohol to the corresponding aldehyde at 30?min and chemoselective reduction of aromatic nitro substituents to the corresponding amino substituents at 20?min, while the Ni/Cu (3:1) NPs were found to be the most effective among other Ni/Cu?(1:1)?and Ni/Cu?(1:3)?NPs at room temperature under mild conditions. The Ni/Cu (3:1) NPs can be recycled for at least five successive runs with no perceptible decrease in catalytic activity. Graphic abstract: [Figure not available: see fulltext.]
- Islam, Md. Sayedul,Khan, Md. Wahab
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p. 2353 - 2369
(2021/01/07)
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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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- Copper nanoparticles (CuNPs) catalyzed chemoselective reduction of nitroarenes in aqueous medium
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Abstract: A procedure for practical synthesis of CuNPs from CuSO4·5H2O is established, under appropriate reaction conditions, using rice (Oryza sativa) as an economic source of reducing as well as a stabilizing agent. Optical and microscopic techniques are employed for the characterization of the synthesized CuNPs and the sizes of the particles were found to be in the range of 8 ± 2 nm. The nanoparticles are used as a catalyst for chemoselective reduction of aromatic nitro compounds to corresponding amines under ambient conditions and water as a reaction medium. Graphic abstract: CuNPs are synthesized using hydrolysed rice and used as catalyst for chemoselective reduction of nitroarenes to their corresponding amines in water. [Figure not available: see fulltext.]
- Chand, Dillip Kumar,Rai, Randhir
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- Alkali-modified heterogeneous Pd-catalyzed synthesis of acids, amides and esters from aryl halides using formic acid as the CO precursor
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To establish an environmentally friendly green chemical process, we minimized and resolved a significant proportion of waste and hazards associated with conventional organic acids and molecular gases, such as carbon monoxide (CO). Herein, we report a facile and milder reaction procedure, using low temperatures/pressures and shorter reaction time for the carboxyl- and carbonylation of diverse arrays of aryl halides over a newly developed cationic Lewis-acid promoted Pd/Co3O4catalyst. Furthermore, the reaction proceeded in the absence of acid co-catalysts, and anhydrides for CO release. Catalyst reusability was achievedviascalable, safer, and practical reactions that provided moderate to high yields, paving the way for developing a novel environmentally benign method for synthesizing carboxylic acids, amides, and esters.
- Fapojuwo, Dele Peter,Maqunga, Nomathamsanqa Prudence,Meijboom, Reinout,Mogudi, Batsile M.,Molokoane, Pule Petrus,Onisuru, Oluwatayo Racheal,Oseghale, Charles O.
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p. 26937 - 26948
(2021/08/17)
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- Catalytic production of anilines by nitro-compounds hydrogenation over highly recyclable platinum nanoparticles supported on halloysite nanotubes
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Pt-nanoparticles supported on halloysite-nanotubes (HNTs) were selectively deposited onto the inner (Pt(IN)/HNT) or outer (Pt(OUT)/HNT) surface of the support to evaluate their operational stability on the cleaner and efficient hydrogenation of nitro compounds to produce their corresponding anilines. The formation of Pt0-aggregates on the inner or outer surfaces was observed, with mean particles sizes of 2.4–2.9 nm. The catalysts were evaluated using ethanol as solvent and nitrobenzene as a model substrate at a temperature of 298 K, under 1 bar of H2 pressure. The Pt(IN)/HNT catalyst showed better catalytic performance than Pt(OUT)/HNT, which was mainly attributed to the confinement effect of the Pt-nanoparticles inside the HNTs. However, the operational stability showed that Pt(OUT)/HNT retained its catalytic performance after 15 cycles, while the Pt(IN)/HNT catalyst suffered deactivation after the 5th cycle. The best catalytic system showed a moderate-to-high efficiency in the efficient hydrogenation of 7 nitro compounds used to produce their corresponding anilines, which are important pharmaceutical building blocks.
- Aepuru, Radhamanohar,Bustamante, Tatiana M.,Campos, Cristian H.,Leal-Villarroel, Edgardo,Mangalaraja, Ramalinga Viswanathan,Shanmugaraj, Krishnamoorthy,Torres, Cecilia C.,Vinoth, Victor
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- Preparation method of 4-aminobenzoic acid and derivatives thereof
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The invention discloses a preparation method of 4-aminobenzoic acid and derivatives thereof. The method comprises the following steps: (1) reacting an acid ester raw material, namely 1, 4-phthalic acid monoester or 1, 4-phthalic acid diester or 1, 4-phthalic acid monoester monoamide, with hydroxylamine to obtain a 4-carboxyl benzoyl hydroxamic acid inorganic salt, a 4-alkoxyacyl benzoyl hydroxamic acid inorganic salt and a 4-carbamoyl benzoyl hydroxamic acid inorganic salt respectively; and (2), enabling the 4-carboxyl benzoyl hydroxamic acid inorganic salt, the 4-alkoxyacyl benzoyl hydroxamic acid inorganic salt or the 4-carbamoyl benzoyl hydroxamic acid inorganic salt to be subjected to rearrangement reaction, so as to obtain the 4-aminobenzoate, the 4-aminobenzoate ester and the 4-aminobenzamide; and acidifying the 4-aminobenzoate to obtain the 4-aminobenzoic acid. Nitrification and reduction reactions are not used, and hidden dangers of waste acid pollution and explosive polynitrobenzene are eliminated.
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Paragraph 0027; 0048-0050
(2021/05/05)
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- Hydrolysis of amides to carboxylic acids catalyzed by Nb2O5
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Hydrolysis of amides to carboxylic acids is an industrially important reaction but is challenging due to the difficulty of cleaving the resonance stabilized amidic C-N bond. Twenty-three heterogeneous and homogenous catalysts were examined in the hydrolysis of acetamide. Results showed that Nb2O5was the most effective heterogeneous catalyst with the greatest yield of acetic acid. A series of Nb2O5catalysts calcined at various temperatures were characterized and tested in the hydrolysis of acetamide to determine the effects of crystal phase and surface properties of Nb2O5on catalytic performance. The high catalytic performance observed was attributed mainly to the facile activation of the carbonyl bond by Lewis acid sites that function even in the presence of basic inhibitors (NH3and H2O). The catalytic studies showed the synthetic advantages of the present method, such as simple operation, catalyst recyclability, additive free, solvent free, and wide substrate scope (>40 examples; up to 95% isolated yield).
- Siddiki,Rashed, Md. Nurnobi,Touchy, Abeda Sultana,Jamil, Md. A. R.,Jing, Yuan,Toyao, Takashi,Maeno, Zen,Shimizu, Ken-Ichi
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p. 1949 - 1960
(2021/03/26)
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- Switching on prodrugs using radiotherapy
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Chemotherapy is a powerful tool in the armoury against cancer, but it is fraught with problems due to its global systemic toxicity. Here we report the proof of concept of a chemistry-based strategy, whereby gamma/X-ray irradiation mediates the activation of a cancer prodrug, thereby enabling simultaneous chemo-radiotherapy with radiotherapy locally activating a prodrug. In an initial demonstration, we show the activation of a fluorescent probe using this approach. Expanding on this, we show how sulfonyl azide- and phenyl azide-caged prodrugs of pazopanib and doxorubicin can be liberated using clinically relevant doses of ionizing radiation. This strategy is different to conventional chemo-radiotherapy radiation, where chemo-sensitization of the cancer takes place so that subsequent radiotherapy is more effective. This approach could enable site-directed chemotherapy, rather than systemic chemotherapy, with ‘real time’ drug decaging at the tumour site. As such, it opens up a new era in targeted and directed chemotherapy. [Figure not available: see fulltext.].
- Geng, Jin,Zhang, Yichuan,Gao, Quan,Neumann, Kevin,Dong, Hua,Porter, Hamish,Potter, Mark,Ren, Hua,Argyle, David,Bradley, Mark
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p. 805 - 810
(2021/06/14)
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- Synthesis and characterization of a novel TEMPO?FeNi3/DFNS-laccase magnetic nanocomposite for the reduction of nitro compounds
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Water is an essential substance for life on earth and for all living things. Plants and animals need almost pure water to live; if it is contaminated with harmful chemicals and micro organisms, it will be impossible for them to survive. This study has tried to investigate the performance of catalyst to reduce nitro-aromatic combinations in the attendance of NaBH4 solution duo to the hydrogen source. TEMPO?FeNi3/DFNS-laccase MNPs was prepared, and its features were reviewed using SEM, TEM, XRD, TGA, VSM, AFM, and FTIR. Then, its strength as a nanocatalyst for removal of nitro-aromatic combinations was tested in contact time, initial concentration, the effects of pH and nanocatalyst amount was study. The results of this research proved that TEMPO?FeNi3/DFNS-laccase MNPs has a good return in removal of nitro-aromatic combinations, as its easy synthesis and reliable recovery.
- Mehrzad, Jamshid,Motavalizadehkakhky, Alireza,Saberi, Shima,Zhiani, Rahele
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p. 27297 - 27304
(2020/09/01)
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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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p. 19827 - 19835
(2020/12/04)
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- Convenient conversion of hazardous nitrobenzene derivatives to aniline analogues by Ag nanoparticles, stabilized on a naturally magnetic pumice/chitosan substrate
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Herein, silver nanoparticles (Ag NPs), as an effective catalyst for the reduction process of nitrobenzene derivatives to non-hazardous and useful aniline derivatives, are conveniently synthesized on an inherently magnetic substrate. For this purpose, an efficient combination of volcanic pumice (VP), which is an extremely porous igneous rock, and a chitosan (CTS) polymeric network is prepared and suitably used for the stabilization of the Ag NPs. High magnetic properties of the fabricated Ag@VP/CTS composite, which have been confirmed via vibrating-sample magnetometer (VSM) analysis, are the first and foremost advantage of the introduced catalytic system since it gives us the opportunity to easily separate the particles and perform purification processes. Briefly, higher yields were obtained in the reduction reactions of nitrobenzenes (NBs) under very mild conditions in a short reaction time. Also, along with the natural biocompatible ingredients (VP and CTS) in the structure, excellent recyclability has been observed for the fabricated Ag@VP/CTS catalytic system, which convinces us to do scaling-up and suggests the presented system can be used for industrial applications. This journal is
- Taheri-Ledari, Reza,Mirmohammadi, Seyedeh Shadi,Valadi, Kobra,Maleki, Ali,Shalan, Ahmed Esmail
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p. 43670 - 43681
(2020/12/25)
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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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- Generation and characterization of palladium nanocatalyst anchored on a novel polyazomethine support: Application in highly efficient and quick catalytic reduction of environmental contaminant nitroarenes
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Removal of toxic nitroarenes, which threaten all living organisms and environment, from wastewaters has been an important and prior issue. Therefore, the focus of the present study was to fabricate an effective, fast, reusable, and easily recoverable heterogeneous Pd nanoparticles (Pd NPs) supported on a novel polyazomethine having phenol group (Pd NPs? P(3-M-4-PAP)) for removal of several hazardous nitroarenes by catalytic reduction from water. Firstly, a novel polyazomethine featuring phenol group was prepared as a stabilizer and then, Pd NPs were anchored on it. Characterizations of the materials were performed by XRD, UV–Vis, FTIR, 1H-NMR, TGA, FE-SEM, EDS and TEM techniques. The obtained TEM analysis results showed that the size of Pd NPs was about 50 nm. Then, catalytic ability of Pd NPs?P(3-M-4-PAP) was investigated in reduction of harmful nitroarenes to useful aniline derivatives in water. Catalytic tests revealed that Pd NPs?P(3-M-4-PAP) had outstanding catalytic efficiency against reduction of different nitroarenes by giving excellent yields (up to 98%), in very short time (between 22s and 70s) with 2 mg nanocatalyst. Moreover, performed reusability test results demonstrated that the Pd NPs?P(3-M-4-PAP) could be recurrently reusable and easily recoverable.
- Y?lmaz Baran, Nuray
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- Synthesis and characterization of go-chit-ni nanocomposite as a recoverable nanocatalyst for reducing nitroarenes in water
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In the present study, nickel nanoparticles (Ni-NPs) immobilized on graphene oxide-chitosan (GO-Chit-Ni) have been synthesized and characterized as a catalyst for reduction of nitroarenes in water. For this purpose, GO has been functionalized with chitosan (GO-Chit). Then, Ni-NPs were immobilized on the surface of GO-Chit using a simple method. The GO-Chi-Ni nanocomposites were characterized using Fourier Transforms Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), X-Ray Diffraction Measurements (XRD), and Atomic Adsorption Spectrometry (AAS). The GO-Chi-Ni nanoparticles demonstrated appropriate catalytic activity in reducing nitroarenes to aryl amines in the existence of sodium borohydride (NaBH4) aqueous solution as a hydrogen source at 80oC. This catalytic system applies environmentally benign water as a solvent that is cheap, easily accessible, non-toxic, non-volatile, non-flammable and thermally stable. This type of catalyst can be applied several times with no considerable change in its performance.
- Azadi, Roya,Sarvestani, Mosayeb
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p. 523 - 531
(2020/07/17)
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- Rice husk-SiO2supported bimetallic Fe-Ni nanoparticles: as a new, powerful magnetic nanocomposite for the aqueous reduction of nitro compounds to amines
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This paper reports a novel green procedure for immobilization of bimetallic Fe/Ni on amorphous silica nanoparticles extracted from rice husk (RH-SiO2). The heterogeneous nanocomposite (Fe/Ni?RH-SiO2) was identified using SEM, EDX, TEM, BET, H2-TPR, TGA, XRD, VSM, ICP-OES, and FT-IR analyses. The Fe/Ni?RH-SiO2nanocomposite was applied as a powerful catalyst for the reduction of structurally diverse nitro compounds with sodium borohydride (NaBH4) in green conditions. This procedure suggests some benefits such as green chemistry-based properties, short reaction times, non-explosive materials, easy to handle, fast separation and simple work-up method. The catalyst was separated by an external magnet from the reaction mixture and was reused for 9 successive cycles with no detectable changes of its catalytic efficiency.
- Ghadermazi, Mohammad,Moradi, Setareh,Mozafari, Roya
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p. 33389 - 33400
(2020/09/21)
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- Immobilization of Au nanoparticles on poly(glycidyl methacrylate)-functionalized magnetic nanoparticles for enhanced catalytic application in the reduction of nitroarenes and Suzuki reaction
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We report a novel strategy for the synthesis of magnetic nanocomposite for highly efficient catalysis. Poly(glycidyl methacrylate) (PGMA) chains were grafted to the surface of magnetic nanoparticles (MNPs) through surface-initiated reversible addition-fragmentation chain transfer polymerization. Then, the oxirane rings in the PGMA chains were opened with 2,6-diamino pyridine (DAP) molecules as ligands to prepare the solid support. Finally, this magnetic nanocomposite was used for the immobilization of gold nanoparticles. Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, transmission electron microscopy, scanning electron microscopy, gel permeation chromatography, vibrating sample magnetometry, and atomic absorption spectroscopy were used for characterization of the catalyst. The loading of gold nanoparticles on the solid support was 0.52 mmol/g. The catalytic activity of the prepared catalyst (MNP@PGMA@DAP@Au) was evaluated for the reduction of nitro compounds and C–C coupling reaction in water. The catalyst can be easily recovered and reused seven times without significant loss of catalytic activity.
- Pourjavadi, Ali,Kohestanian, Mohammad,Keshavarzi, Nahid
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- Copper and L-(?)-quebrachitol catalyzed hydroxylation and amination of aryl halides under air
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L-(?)-Quebrachitol, a natural product obtained from waste water of the rubber industry, was utilized as an efficient ligand for the copper-catalyzed hydroxylation and amination of aryl halides to selectively give phenols and aryl amines in water or 95percent ethanol. In addition, the hydroxylation of 2-chloro-4-hydroxybenzoic acid was validated on a 100-g scale under air.
- Bao, Xuefei,Chen, Guoliang,Dong, Jinhua,Du, Fangyu,Li, Hui,Liang, Xinjie,Wu, Ying,Zhang, Yongsheng
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supporting information
(2020/08/03)
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- Discovery and characterization of an acridine radical photoreductant
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Photoinduced electron transfer (PET) is a phenomenon whereby the absorption of light by a chemical species provides an energetic driving force for an electron-transfer reaction1–4. This mechanism is relevant in many areas of chemistry, including the study of natural and artificial photosynthesis, photovoltaics and photosensitive materials. In recent years, research in the area of photoredox catalysis has enabled the use of PET for the catalytic generation of both neutral and charged organic free-radical species. These technologies have enabled previously inaccessible chemical transformations and have been widely used in both academic and industrial settings. Such reactions are often catalysed by visible-light-absorbing organic molecules or transition-metal complexes of ruthenium, iridium, chromium or copper5,6. Although various closed-shell organic molecules have been shown to behave as competent electron-transfer catalysts in photoredox reactions, there are only limited reports of PET reactions involving neutral organic radicals as excited-state donors or acceptors. This is unsurprising because the lifetimes of doublet excited states of neutral organic radicals are typically several orders of magnitude shorter than the singlet lifetimes of known transition-metal photoredox catalysts7–11. Here we document the discovery, characterization and reactivity of a neutral acridine radical with a maximum excited-state oxidation potential of ?3.36 volts versus a saturated calomel electrode, which is similarly reducing to elemental lithium, making this radical one of the most potent chemical reductants reported12. Spectroscopic, computational and chemical studies indicate that the formation of a twisted intramolecular charge-transfer species enables the population of higher-energy doublet excited states, leading to the observed potent photoreducing behaviour. We demonstrate that this catalytically generated PET catalyst facilitates several chemical reactions that typically require alkali metal reductants and can be used in other organic transformations that require dissolving metal reductants.
- MacKenzie, Ian A.,Wang, Leifeng,Onuska, Nicholas P. R.,Williams, Olivia F.,Begam, Khadiza,Moran, Andrew M.,Dunietz, Barry D.,Nicewicz, David A.
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- Acceptorless dehydrogenative oxidation of primary alcohols to carboxylic acids and reduction of nitroarenes via hydrogen borrowing catalyzed by a novel nanomagnetic silver catalyst
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A novel silver nano magnetic catalyst was devised for dehydrogenative oxidation of aromatic and aliphatic alcohols to the corresponding acid with water as the sole oxygen source and hydrogen gas as the only by-product. The designed catalytic system advantages from easy recovery of magnetic materials i.e. magnetic decantation, being economically viable and environmentally friendly. Furthermore, the catalytic reaction is able to reduce aryl nitro compounds in the absence of any reducing agent.
- Yazdani, Elahe,Heydari, Akbar
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supporting information
(2020/08/14)
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- A cyclometalated Ir(iii)-NHC complex as a recyclable catalyst for acceptorless dehydrogenation of alcohols to carboxylic acids
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In this work, we have synthesized two new [C, C] cyclometalated Ir(iii)-NHC complexes, [IrCp?(C∧C:NHC)Br](1a,b), [Cp? = pentamethylcyclopentadienyl; NHC = (2-flurobenzyl)-1-(4-methoxyphenyl)-1H-imidazoline-2-ylidene (a); (2-flurobenzyl)-1-(4-formylphenyl)-1H-imidazoline-2-ylidene (b)] via intramolecular C-H bond activation. The molecular structure of complex 1a was determined by X-ray single crystal analysis. The catalytic potentials of the complexes were explored for acceptorless dehydrogenation of alcohols to carboxylic acids with concomitant hydrogen gas evolution. Under similar experimental conditions, complex 1a was found to be slightly more efficient than complex 1b. Using 0.1 mol% of complex 1a, good-to-excellent yields of carboxylic acids/carboxylates have been obtained for a wide range of alcohols, both aliphatic and aromatic, including those involving heterocycles, in a short reaction time with a low loading of catalyst. Remarkably, our method can produce benzoic acid from benzyl alcohol on a gram scale with a catalyst-to-substrate ratio as low as 1?:?5000 and exhibit a TON of 4550. Furthermore, the catalyst could be recycled at least three times without losing its activity. A mechanism has been proposed based on controlled experiments and in situ NMR study.
- Borah, Dhrubajit,Das, Pankaj,Saha, Biswajit,Sarma, Bipul
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p. 16866 - 16876
(2020/12/18)
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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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- Atomically dispersed Ni as the active site towards selective hydrogenation of nitroarenes
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Rational design of heterogeneous non-noble metal catalysts as highly efficient and selective catalysts for hydrogenation of nitroarenes with hydrogen as the reducing agent is currently a great challenge, which has attracted a great deal of attention. Herein, a new strategy for achieving atomic dispersion of Ni atoms on nitrogen-doped porous carbon (Ni-N-C) with a specific surface area of up to 810 m2 g-1 and nickel loading as high as 4.4 wt% is developed, yielding high activity, chemoselectivity, and reusability of catalysts in the hydrogenation of nitroarenes using hydrogen as the reductant with a turnover of number (TON) value of 84 and a turnover of frequency (TOF) value of 8.4 h-1 for the first time. The Ni single atoms anchored on N-doped porous carbon by binding with nitrogen/carbon have been proved to be the active sites. Importantly, the Ni-N3 active species is found to contribute more activity compared with Ni-N2 and Ni-N4. Density functional theory (DFT) calculations also reveal that the Ni-N3 structure exhibits the highest activity according to the lowest adsorption energy and the longest elongation N-O bonds of nitrobenzene, which originated from the induced charge transfer. This work opens a new route for rational design and accurate modulation of nanostructured organic molecular transformation catalysts at the atomic scale.
- Yang, Fan,Wang, Minjian,Liu, Wei,Yang, Bin,Wang, Ying,Luo, Jun,Tang, Yushu,Hou, Liqiang,Li, Yun,Li, Zihui,Zhang, Bing,Yang, Wang,Li, Yongfeng
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supporting information
p. 704 - 711
(2019/02/14)
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- Selective Reduction of Nitroarenes Catalyzed by Sustainable and Reusable DNA-supported Nickel Nanoparticles in Water at Room Temperature
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Abstract: In this research, a novel, biodegradable and environmentally friendly catalyst composed of nickel nanoparticles supported on DNA was prepared and fully characterized by Fourier transform infrared spectroscopy, high resolution transmission electron microscopy, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, UV–vis spectroscopy, inductively coupled plasma optical emission spectroscopy, and elemental analysis. The catalyst exhibited remarkable catalytic activity and chemoselectivity for the reduction of various substituted nitroarenes with sodium borohydride (NaBH4) as the source of inexpensive hydride in water at room temperature. High turnover frequency and selectivity were observed for the reduction of all tested substrates. Interestingly, the catalyst could be recovered conveniently for multiple recycling reactions with sustained activity. Furthermore, nearly no nickel species was leached out from the catalyst during the course of reaction, proving the true heterogeneity in the present catalytic protocol. Graphical Abstract: The reduction of various nitroaromatic compounds into their corresponding amines is achieved by DNA supported nickel nanoparticles with the sodium borohydride as the reducing agent in water at room temperature. [Figure not available: see fulltext.].
- Niakan, Mahsa,Asadi, Zahra
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- Diruthenium complex catalyzed reduction of nitroarenes-investigation of reaction pathway
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A diruthenium complex, [(L)Ru2(η6-C6H6)2Cl2](PF6)2 (1) (L = 5-phenyl-2,8-di-2-pyridinylanthyridine), was prepared and characterized. This diruthenium complex 1 was found to be an efficient catalyst for the reduction of aromatic nitro compounds leading to the corresponding aniline derivatives with the use of hydrazine as the reducing agent at 80 °C in an ethanol solution. Catalytic activity of 1 towards various possible intermediates leading to anilines was investigated to understand the reaction pathway. These studies indicate that this reduction proceeds via a direct route as evidenced by hydroxylamines being observed as the major intermediate followed by the appearance of aniline under the catalytic conditions. Thus, the reaction pathway of this catalytic system is discussed.
- Lin, Shih-Chieh Aaron,Liu, Yi-Hung,Peng, Shie-Ming,Liu, Shiuh-Tzung
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- Hydroxyl Assisted Rhodium Catalyst Supported on Goethite Nanoflower for Chemoselective Catalytic Transfer Hydrogenation of Fully Converted Nitrostyrenes
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Control of chemoselectivity is a special challenge for the reduction of nitroarenes bearing one or more unsaturated groups. Here, we report a flower-like Rh/α-FeOOH catalyst for the chemoselective hydrogenation of nitrostyrene to vinylaniline over full conversion, which benefits the new functionalized aminostyrene because the multisubstituted aminostyrenes are usually commercially unavailable. This catalyst does not only show desirable selectivity for the vinylanilines, but also exhibits the inertness to various other reducible groups over wide reaction duration. The catalytic selectivity for the reduction of the nitro group towards vinyl group was investigated by the control experiments and FT-IR analysis. We have found that the abundant hydroxyl groups in the α-FeOOH may contribute to the improvement of catalytic activity and selectivity. Furthermore, the catalyst exhibits excellent stability and keeps its catalytic performance even after 6 cycles. (Figure presented.).
- Hu, Zenan,Ai, Yongjian,Liu, Lei,Zhou, Junjie,Zhang, Gang,Liu, Hongqi,Liu, Xiangyu,Liu, Zhibo,Hu, Jianshe,Sun, Hong-bin,Liang, Qionglin
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supporting information
p. 3146 - 3154
(2019/05/10)
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- Metal-free carbocatalyst for catalytic hydrogenation of N-containing unsaturated compounds
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Eco-friendly carbocatalyst is extremely desirable in organic catalysis and wastewater treatment. Herein, we reported a one-pot synchronous hydrothermal process to synthesize a highly efficient N doped holey graphene (NHG) carbocatalyst, in which graphene
- He, Zhaolin,Liu, Jin,Wang, Qijun,Zhao, Meng,Wen, Zhipan,Chen, Jun,Manoj, Devaraj,Xie, Chuyi,Xi, Jiangbo,Yu, Junxia,Tang, Chunyan,Bai, Zhengwu,Wang, Shuai
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p. 199 - 208
(2019/08/07)
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- The immobilized Ni(II)-thiourea complex on silica-layered copper ferrite: A novel and reusable nanocatalyst for one-pot reductive-acetylation of nitroarenes
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In this study, magnetically nanoparticles of CuFe2O4@SiO2@PTMS@Tu@Ni(II) as novel and reusable catalyst were prepared. Synthesis of the Ni (II)-nanocatalyst was carried out through the complexation of Ni(OAc)2·4H2O with the immobilized thiourea on silica-layered CuFe2O4. The prepared nanocomposite system was then characterized using SEM, EDX, XRD, VSM, ICP-OES, Raman, UV–Vis and FT-IR analyses. Catalytic activity of the Ni(II)-CuFe2O4 system was investigated towards rapid reduction of aromatic nitro compounds to arylamines with sodium borohydride as well as one-pot reductive-acetylation of nitroarenes to acetanilides with NaBH4/Ac2O system without the isolation of intermediate arylamines. All reactions were carried out in H2O within 3–7?min to afford the products arylamines/acetanilides in high to excellent yields. Reusability of the Ni(II)-nanocatalyst was examined for seven consecutive cycles without the significant loss of the catalytic activity.
- Zeynizadeh, Behzad,Shokri, Zahra,Hasanpour Galehban, Morteza
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- Sustainable visible light assisted in situ hydrogenation via a magnesium-water system catalyzed by a Pd-g-C3N4 photocatalyst
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A non-hazardous and relatively mild protocol was formulated for an effectual hydrogen generation process via a "magnesium-activated water" system with a Pd-g-C3N4 photocatalyst under visible light at room temperature. Water functions photochemically as a hydrogen donor without any external source with the Pd-g-C3N4 photocatalyst. The synthesized Pd-g-C3N4 photocatalyst is highly efficient under visible light for the selective reduction of a wide range of unsaturated derivatives and nitro compounds to afford excellent yields (>99%). The photocatalyst Pd-g-C3N4 could be easily recovered and reused for several runs without any deactivation during the photochemical hydrogen transfer reaction process.
- Sharma, Priti,Sasson, Yoel
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supporting information
p. 261 - 268
(2019/01/28)
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- Switchable Bifunctional Bistate Reusable ZnO-Cu for Selective Oxidation and Reduction Reaction
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Herein we disclosed the utilization of copper loaded zinc oxide (ZnO-Cu) for its stimuli (O2/light) responsive switchable performance between its reduced (S-1) and oxidized (S-2) state for two antagonistic reactions, namely oxidation of alkyl arenes/heteroarenes to aldehydes/ketones and reduction of nitro arenes/heteroarenes to corresponding amines. The two states of the catalyst showed its switchable performance as highly active and poorly active catalyst for oxidation and reduction, and both reactions could be turned "off" and "on" by changing the stimuli (light and O2/N2). The switching efficiency between the states and their relative reactivity were found to be consistent under variety of reaction conditions and remain unaltered irrespective of oxidation-reduction (or vice versa) sequence and substrates used in the reaction. The photo catalysts (S-1 and S-2) demonstrated good catalytic activity, multiple reusability, broad substrate scope, and reasonable functional group tolerance for both the reactions and probed its quality performance in a large-scale setup. The system was used in an assisted tandem catalysis setup for the synthesis of benzyl amines utilizing both oxidation and reduction reaction by stimuli responsive switching between the states of the catalyst.
- Sarmah, Kasturi,Mukhopadhyay, Subhamoy,Maji, Tarun K.,Pratihar, Sanjay
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p. 732 - 745
(2019/01/11)
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- Catalytic Transfer Hydrodebenzylation with Low Palladium Loading
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A highly-efficient catalytic system for hydrodebenzylation reaction is described. The cleavage of O-benzyl and N-benzyl protecting groups was performed using an uncommonly low palladium loading (0.02–0.3 mol%; TON up to 5000) in a relatively short reaction time. The approach was used for a variety of substrates including pharmaceutically important precursors, and gram-scale deprotection reaction was shown. Transfer conditions together with easy-to-make Pd/C catalyst are the key features of this debenzylation scheme. (Figure presented.).
- Yakukhnov, Sergey A.,Ananikov, Valentine P.
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supporting information
p. 4781 - 4789
(2019/09/16)
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- FUSED HETEROCYCLIC DERIVATIVES, THEIR PREPARATION METHODS THEREOF AND MEDICAL USES THEREOF
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The present invention relates to fused heterocyclic derivatives, processes for their preparation and their use in medicine. Specifically, the present invention relates to a novel derivative represented by the formula (I′), or its pharmaceutically acceptable salt thereof, a pharmaceutical composition containing the derivative or its pharmaceutically acceptable salt thereof, and the method for preparing the derivative and its pharmaceutically acceptable salt thereof. The present invention also relates to the use of the derivative and its pharmaceutically acceptable salt thereof, or a pharmaceutical composition containing the derivative and its pharmaceutically acceptable salt thereof in the preparation of medicines, in particularly as IDO inhibitor medicines, for treating and/or preventing cancers. Wherein each substituent of the formula (I′) is the same as defined in the specification.
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Paragraph 0246; 0735-0738
(2019/07/03)
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- Highly active bidentate N-heterocyclic carbene/ruthenium complexes performing dehydrogenative coupling of alcohols and hydroxides in open air
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Eight bidentate NHC/Ru complexes, namely [Ru]-1-[Ru]-8, were designed and prepared. In particular, [Ru]-2 displayed extraordinary performance even in open air for the dehydrogenative coupling of alcohols and hydroxides. Notably, an unprecedentedly low catalyst loading of 250 ppm and the highest TON of 32 800 and TOF of 3200 until now were obtained.
- Wang, Zhi-Qin,Tang, Xiao-Sheng,Yang, Zhao-Qi,Yu, Bao-Yi,Wang, Hua-Jing,Sang, Wei,Yuan, Ye,Chen, Cheng,Verpoort, Francis
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supporting information
p. 8591 - 8594
(2019/07/25)
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- Gold nanodots self-assembled polyelectrolyte film as reusable catalyst for reduction of nitroaromatics
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Separation of homogeneous catalyst from the reaction mixture is a crucial and difficult process in any catalytic process. To address this issue, a new class of multifunctional catalyst in the form of film was developed using a facile approach to enjoy the advantages of homogeneous catalyst with the versatility of heterogeneous catalyst. To achieve the same, methionine-capped gold nanodots (AuNDs) were self-assembled on a cationic polyelectrolyte modified glass plate for the catalytic reduction of nitro functional groups in the presence of olefinic double bond at mild conditions. Separation of this reusable catalytic film from the reaction mixture is very simple and advantageous when compared to the currently available and conventional catalytic systems. Kinetics of nitro reduction was monitored using absorption spectroscopy and the product formation was confirmed by 1H and 13CNMR analyses. Prepared AuNDs catalyst was characterized using UV-Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), cyclic voltammetry and atomic force microscopy (AFM) techniques. Graphical Abstract: SYNOPSIS?Colloidal gold nanoparticles are efficient catalysts for organic reactions. But the removal of homogeneous gold colloids from the reaction mixture is very difficult. To address this issue, gold nanodots were synthesized and self-assembled over polyelectrolyte film to form catalytic plates. Removal of these reusable catalytic plates from the reaction mixture is facile.[Figure not available: see fulltext.].
- Viswanathan, Perumal,Ramaraj, Ramasamy
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- Mechanochemical catalytic transfer hydrogenation of aromatic nitro derivatives
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Mechanochemical ball milling catalytic transfer hydrogenation (CTH) of aromatic nitro compounds using readily available and cheap ammonium formate as the hydrogen source is demonstrated as a simple, facile and clean approach for the synthesis of substituted anilines and selected pharmaceutically relevant compounds. The scope of mechanochemical CTH is broad, as the reduction conditions tolerate various functionalities, for example nitro, amino, hydroxy, carbonyl, amide, urea, amino acid and heterocyclic. The presented methodology was also successfully integrated with other types of chemical reactions previously carried out mechanochemically, such as amide bond formation by coupling amines with acyl chlorides or anhydrides and click-type coupling reactions between amines and iso(thio)cyanates. In this way, we showed that active pharmaceutical ingredients Procainamide and Paracetamol could be synthesized from the respective nitro-precursors on milligram and gram scale in excellent isolated yields.
- Portada, Tomislav,Margeti?, Davor,?trukil, Vjekoslav
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supporting information
(2018/12/11)
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- Self-Assembled Magnetic Gold Catalysts from Dual-Functional Boron Clusters
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A new class of core–shell magnetic gold nanocomposites is prepared in a raspberry-like fashion by the controlled supramolecular host–guest assembly of γ-cyclodextrins (γ-CDs) and boron clusters. In this work, Cs2[closo-B12H12], a fundamental boron cluster, can play a dual role in the preparation of highly monodispersed Au nanoparticles and in the immobilization of Au nanoparticles on the γ-CDs@Fe3O4 surface as an effective anchor. This facile and spontaneous supramolecular strategy allows for the control of the size and composition of the highly stable gold composites. Furthermore, the obtained AuNPs@Fe3O4 composites exhibit an excellent catalytic activity and recyclability for the selective reduction of nitroaromatics to their corresponding aniline compounds, and the fastest reaction can be achieved within 20 s with a high conversion and selectivity at room temperature, which is better than that obtained previously in studies on metal nanoparticle composites as catalysts.
- Qi, Bin,Wu, Chenchen,Li, Xin,Wang, Dan,Sun, Liang,Chen, Bo,Liu, Wenjing,Zhang, Haibo,Zhou, Xiaohai
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p. 2285 - 2290
(2018/05/15)
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- A new magnetically recyclable heterogeneous palladium(II) as a green catalyst for Suzuki-Miyaura cross-coupling and reduction of nitroarenes in aqueous medium at room temperature
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In the current work, a new stable and powerful magnetic nanoparticle supported Schiff base-palladium(II) (MNPs@SB-Pd) nanomagnetic catalyst was synthesized. The structural feature of the MNPs@SB-Pd nanomagnetic catalyst was properly characterized using a combination of attenuated total reflectance infrared spectroscopy (ATR-IR), ultraviolet–visible spectroscopy (UV–Visible), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), energy-dispersive X-ray spectroscopy (EDS), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller surface area analysis (BET). The air- and moisture stable prepared MNPs@SB-Pd nanomagnetic catalyst was applied in C–C bond formation through Suzuki-Miyaura cross-coupling reactions and reduction of nitroarenes. Use of green medium, eco-friendly, waste-free, efficient preparation leading to high yield of products, short reaction time and cost effective catalyst are the major benefits of the method presented. In addition, the MNPs@SB-Pd nanomagnetic catalyst was easily separated from the reaction mixture with the help of an external magnetic field and reused for five consecutive cycles in Suzuki-Miyaura cross-coupling and ten consecutive cycles in reduction of nitroarene reactions with no significant loss of catalytic efficiency.
- Kandathil, Vishal,Koley, Tuhin S.,Manjunatha,Dateer, Ramesh B.,Keri, Rangappa S.,Sasidhar,Patil, Shivaputra A.,Patil, Siddappa A.
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p. 195 - 210
(2018/04/23)
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- Silver nanoparticles supported on ionic-tagged magnetic hydroxyapatite as a highly efficient and reusable nanocatalyst for hydrogenation of nitroarenes in water
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A novel chemically modified magnetic hydroxyapatite (MHAp) was prepared and used as support and stabilizer for the synthesis of silver nanoparticles. First, 1,4-diazabicyclo[2.2.2]octane (DABCO) was successfully grafted onto the surface of MHAp, and then silver nanoparticles were homogeneously loaded on mesoporous MHAp-DABCO (ionic-tagged MHAp) nanocomposite by in situ chemical reduction of silver nitrate using sodium borohydride. The structure and properties of the resulting MHAp-DABCO-Ag nanocomposite were confirmed using various techniques. The catalytic activity of ionic-tagged MHAp-Ag nanocatalyst was investigated for the hydrogenation reaction of nitroarenes in aqueous media. The results reveal that the Ag-containing inorganic–organic nanocomposite is highly efficient for the reduction of a wide range of aromatic nitro compounds under green conditions. The superparamagnetic nature of the nanocatalyst leads to its being readily removed from solution via application of a magnetic field, and it can be easily stored and reused.
- Pashaei, Mokhtar,Mehdipour, Ebrahim
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- Large-scale preparation of B/N co-doped graphene-like carbon as an efficient metal-free catalyst for the reduction of nitroarenes
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Boron and nitrogen co-doped graphene-like carbon (BNG) is a metal-free catalyst that has been synthesized by combining ball-milling with thermal treatment. Firstly, the edge-selectively-functionalized graphene nanoplatelets (EFGnPs) were prepared by ball
- Yang, Fan,Cao, Yan,Chen, Zhuo,He, Xing,Hou, Liqiang,Li, Yongfeng
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p. 2718 - 2725
(2018/02/19)
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- Silver Nanoparticles Engineered Β-Cyclodextrin/Γ-Fe2O3@ Hydroxyapatite Composite: Efficient, Green and Magnetically Retrievable Nanocatalyst for the Aqueous Reduction of Nitroarenes
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Abstract: Ag nanoparticles incorporated β-cyclodextrin conjugated magnetic hydroxyapatite, γ-Fe2O3@HAp-CD.Ag was conveniently synthesized via the grafting of β-cyclodextrin moieties on the hydroxyapatite surface, followed by reacting of the nanocomposite, γ-Fe2O3, with silver nitrate and then its reduction with sodium borohydride. The cavity of β-cyclodextrin units as host material can stabilize the Ag nanoparticles (particles size: 12–14 nm) effectively and prevent their aggregation and separation from the surface. The nanocomposite obtained appears to have an organized structure, with a magnetic γ-Fe2O3 core surrounded by a layer-structured coating shell. The structure and composition of the nanocomposite were confirmed by FT-IR, FE-SEM, TEM, TGA, XRD, EDS, BET, and VSM. This catalytic system selectively reduces the nitro group even in the presence of other sensitive functional groups in good to excellent yields (85–98%).The organometallic nanocatalyst was easily removed from solution using an external magnet and was successfully examined for five runs, with a slight loss of catalytic activity.
- Azaroon, Maedeh,Kiasat, Ali Reza
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p. 745 - 756
(2017/12/26)
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