Reaction Of Nitrobenzene Research Articles

The Study of Photosensitized Reactions of Nitrobenzene and m-Dinitro Benzene Using Benzophenone As a Sensitizer under Visible Light Irradiation

The Study of Photosensitized Reactions of Nitrobenzene and m-Dinitro Benzene Using Benzophenone As a Sensitizer under Visible Light Irradiation

Superhydrophobic biochars as catalysts for efficient hydrogen transfer in N-heterocycles and nitrobenzene reactions

The heteroatom-doped carbon nanomaterials can be the active catalysts in hydrogen transfer reactions, however, carbon-catalyzed hydrogen transfer processes in the absence of additives and cocatalysts have been rarely described. Herein, functional biochar catalysts (FBCs) were successfully fabricated from wheat straw by a simple scalable two-step strategy via reconstructing the catalytic active sites in carbon precursors and subsequently controlled carbonization. The characterization of FBCs was discussed with regard to morphologic structures, chemical constitutions and performance, revealing that the high hydrophobicity is beneficial for obtaining high activity. Wherein the optimized FBC-850 catalyst exhibited high activity and durability toward the reaction of N-heterocycles and nitrobenzene in the aqueous systems due to the synergistic effects that were attributed to the external superhydrophobicity, internal capillary repulsion and hydrogen transfer property, eliminating the need for additional co-catalysts or additives. In the model reaction, the yields of quinoline and aniline were respectively achieved at 92% and 90%. Furthermore, the encapsulated quinone units as the active sites in FBC-850 formed the bipyramidal structure, enabling the hydrogen transfer process through a cyclical hydrogen exchange, which was proved from kinetic studies combined with spectral characterization and theoretical calculation. In addition, a possible reaction mechanism was proposed based on the observation of key intermediates and DFT calculations, also providing a rationale for the existing active site structures.

Zr-Based MOF-Stabilized CO2-Responsive Pickering Emulsions for Efficient Reduction of Nitroarenes.

A Pickering emulsion is a natural microreactor for interfacial catalysis in which an emulsifier is critical. Recently, a metal-organic framework (MOF) has attracted attention to emulsify water-organic mixtures for constructing a Pickering emulsion. However, a few stimuli-responsive Pickering emulsions based on MOFs have been reported, and the MOF emulsifiers cannot be regenerated at room temperature. Herein, the Zr-MOF with a rodlike morphology is synthesized using ionic liquid as a modulator and then modified with n-(trimethoxysilylpropyl)imidazole (C3im) to prepare a series of functionalized Zr-MOFs (MOF-C3im). It is found that MOF-C3im is an excellent emulsifier to construct stable and CO2-responsive Pickering emulsions even at low content (>0.20 wt %). Notably, the emulsification and demulsification of the emulsions can be easily and reversibly switched by bubbling of CO2 and N2 alternatively at room temperature because CO2 and imidazole molecules anchored on the Zr-MOF underwent a reversible acid-base reaction, resulting in an obvious change in the wettability of the emulsifier. As a proof of concept, the reduction reactions of nitrobenzene have been successfully carried out in these Pickering emulsions, demonstrating the efficient integration as a microreactor for chemical reaction, product separation, and emulsifier recycling under ambient conditions. This strategy provides an innovative option to develop stimulus-responsive Pickering emulsions for sustainable chemical processes.

CuII-Hfur–imidazole] compounds as precursors of efficient hydrogenation and reductive alkylation catalysts in flow systems

The reaction of copper(II) acetate with furoic acids (2Hfur / 3Hfur) and imidazole (Im) in methanol resulted in mononuclear complexes [Cu(fur)2(Im)2(H2O)]·L (fur- = 2fur- (1, 2), 3fur- (3); L = MeCN (1)) whose structures were determined by direct single crystal X-ray analysis. It was found for the first time that copper nanoparticles immobilized on the surface of γ-Al2O3 obtained by chemical reduction of 1, 2 and 3 (pre-deposited on the surface from solution) with sodium tetrahydroborate show high selectivity of mono- and dihydrogenation of tricyclo[5.2.1.02,6]deca-3,8-diene (dicyclopentadiene, DCPD). The catalytic activity tests show a high selectivity (97 %) of the catalyst obtained from an ethanolic solution of complex 1 in the reaction of partial hydrogenation to DHDCPD under continuous process conditions even at high conversion values (up to 96 %) and with an excess of hydrogen, whereas the catalyst obtained from an aqueous solution of complex 1 showed 98 % total hydrogenation product (THDCPD) selectivity. The catalysts based on all the complexes 1–3 were successfully used in reactions of nitrobenzene (NB) reduction to aniline (AN) and in the reductive alkylation of nitrobenzene with isobutanol (i-BAN) 100 % yields of aniline and N-isobutylaniline were obtained at LHSV 0.16 h−1.

Hydrogenation of Nitrobenzene in Trickle Bed Reactor over Ni/Sio2 Catalyst

Trickle bed reactor was used to study the hydrogenation of nitrobenzene over Ni/SiO2 catalyst. The catalyst was prepared using the Highly Dispersed Catalyst (HDC) technique. Porous silica particles (capped cylinders, 6x5.5 mm) were used as catalyst support. The catalyst was characterized by TPR, BET surface area and pore volume, X-ray diffraction, and Raman Spectra. The trickle bed reactor was packed with catalyst and diluted with fine glass beads in order to decrease the external effects such as mass transfer, heat transfer and wall effect. The catalyst bed dilution was found to double the liquid holdup, which increased the catalyst wetting and hence, the gas-liquid mass transfer rate. The main product of the hydrogenation reaction of nitrobenzene was aniline. Reaction operating conditions, i.e., temperature, liquid flow rate, and initial feed concentration were investigated to find their influences on the conversion and rate of nitrobenzene hydrogenation. Under normal conditions without bed dilution, the system was mass transfer controlled. In the diluted reactor, on the other hand, the resistance of mass transfer was nearly absent and the system became under surface kinetic control. The catalyst showed significant deactivation during the reaction period due to the adsorption of intermediate amine products on the surface of the catalyst. The kinetic study revealed that the reaction is zero order with respect to nitrobenzene concentration for the range of concentration between 0.58 to 1.17 mol/L while it was of positive order for the initial concentration less than 0.58 mol/L

Synthesis of aromatic carbamate via palladium catalyzed reductive carbonylation reaction of Nitro benzene: An alternative approach with different nucleophiles other than MeOH

The reactivity of palladium complex supported by phenanthroline ligand has been studied in the reductive carbonylation of PhNO2 using different solvents. Nucleophiles like, 2,4,6- trimethyl phenol (TMP) and 2,2,2-trifluoro ethanol (TFE) were employed to obtain a carbamate that is more readily pyrolyzed, these nucleophiles were selected based on their larger size. TMP as the nucleophilic reagent and toluene as solvent resulted optimum conversion of nitrobenzene with excellent selectivity for carbamate. On the other hand, the use of p-toluene sulfonic acid was confirmed to be effective for the Pd/phenanthroline catalyzed nitrobenzene carbonylation reactions, even when co-solvents are present or other nucleophiles other than MeOH are employed, producing the corresponding carbamate in high selectivity.

Defect engineering mediated molecules coordination activation for one-pot synthesis of secondary amine over Bi2MoO6 hierarchical microspheres

Bi2MoO6 hierarchical microspheres (BMO-SP) consisting of monolayer nanosheets with abundant surface oxygen defects and unsaturated Mo sites are constructed for the one-pot synthesis of secondary amine via a photocatalytic coupling reaction of nitrobenzene (NB) and benzyl alcohol (BA). The performance of this photocatalyst is 12 times higher than that of bulk Bi2MoO6 (BMO-bulk). Experiment results and density functional theory calculations reveal that surface oxygen defects induce more unsaturated Mo atoms facilitating the coordination activation of NB and BA molecules through the formation of –N–O···Mo and –C–O···Mo coordination, respectively. The surface oxygen defects also promote the separation of photogenerated carriers. More photogenerated holes transfer to the surface for oxidizing the activated BA while the photogenerated electrons are trapped by oxygen defects for reducing NB. Thus, the photocatalytic performance is markedly improved. This work successfully designs an efficient photocatalyst for the tandem reaction via surface defect engineering.

Modeling of the Reaction of Nitrobenzene with Olefins: Influence of Electron-Donating and Electron-Withdrawing Substituents

Modeling of the Reaction of Nitrobenzene with Olefins: Influence of Electron-Donating and Electron-Withdrawing Substituents

Zn-Ce-Ga trimetal oxysulfide as a dual-functional catalyst: Hydrogen evolution and hydrogenation reactions in a mild condition

The works on photocatalytic hydrogen production and green chemical conversion have received significant attention due to the current need for clean energy and a secure environment. Herein, Ce and Ga codoped Zn(O,S) has been synthesized with different amounts of Ce using facile precipitation method at a low temperature of 95 °C and characterized by XRD, SEM, HRTEM, XPS, EPR, Raman, DRS, PL, EIS, UV–vis, GC–MS, and photocurrent response measurements. The as-prepared photocatalysts were utilized for hydrogen production and hydrogenation of toxic organic compounds, viz. nitrobenzene (NB) and azobenzene (AB) into a valuable product of aniline. The incorporation of Ce and Ga into Zn(O,S) enhanced the hydrogen evolution and hydrogenation reactions of NB and AB. This notable enhancement was ascribed to the synergistic effects of Ce and Ga dopants to form positively charged defects that trap the photogenerated electron. The trapping mechanism improves the photogenerated charge separation and transfer as confirmed with impedance spectroscopy (EIS), transient photocurrent response, and PL measurements. The highest hydrogen production was attained by 15Ce-5Ga-Zn(O,S) with a rate of 7130 μmol∙g−1∙h−1 in 10% ethanol solution. In addition, NB and AB were effectively converted to aniline in 15 min and 30 min, respectively. A plausible photocatalytic hydrogenation mechanism for both hydrogenation of NB and AB is proposed with the steps of surface adsorption, molecular diffusion, pinning at oxygen vacancy sites, and hydrogenation reaction with the help of in situ generated H+ coupled with electrons.

Abiotic Transformation of Nitrobenzene by Zero Valent Iron under Aerobic Conditions: Relative Contributions of Reduction and Oxidation in the Presence of Ethylene Diamine Tetraacetic Acid.

Zero valent iron (ZVI) applications to remediation of shallow groundwaters can be affected by dissolved oxygen (DO) and organic ligands. To explore the intersection between these complicating factors, this study thoroughly characterized the reactions of nitrobenzene (NB) with ZVI in the presence DO and the model ligand ethylene diamine tetraacetic acid (EDTA). The results showed that NB is degraded by both ZVI reduction and ZVI-induced advanced oxidation under oxygen-limited conditions. The contribution of ·OH to the degradation of NB increased with time so that nearly 39% of NB was oxidized by ·OH at 15 min (pH = 3), but reduction was still the main pathway of NB transformation throughout. NB reduction products, such as aniline (AN), were also oxidized by ·OH. The lower the pH, the greater the contribution of advanced oxidation, but DO was the limiting factor for ·OH generation. Only 4.7% NB was fully degraded by ring opening and/or mineralization because the production of •OH was limited by low DO. After the transformation of NB and AN, other benzene ring and nitrogen-containing intermediates were identified (e.g., p-nitrophenol, p-aminophenol, hydroquinone, and p-benzoquinone). The removal of total organic carbon and total organic nitrogen was minimal. The results suggested that the relative doses of ZVI, DO, and iron-complexing ligands can be balanced for the optimal (rapid and deep) removal of organic contaminants.

Изучение кинетических особенностей синтеза анилина на Ni-содержащем сверхсшитом полистироле

This paper presents a study of the kinetics of catalytic hydrogenation of nitrobenzene to aniline in the presence of Ni-containing catalysts based on super-crosslinked polystyrene. Aniline hydrogenation is a complex multi-stage process accompanied by the formation of a large number of both intermediate and by-products, including azobenzene, azoxybenzene, nitrosobenzene, phenylhydroxylamine and other substances. Therefor the study of the process kinetics is an important scientific and technical task necessary to increase the yield of the target product — aniline. The hydrogenation reaction of nitrobenzene was carried out in a six-cell high-pressure reactor Parr instruments, Series 5000. The products were analyzed by chromatography using a gas chromatograph Kristallux-4000M (Russia, Meta–Chrom). The effect of temperature, pressure, and concentration of the catalyst was studied; optimal reaction conditions were selected that ensure the maximum yield of aniline. Investigation of the effect of the nitrobenzene initial concentration on the rate of its transformation shows that increase of catalyst to nitrobenzene ratio from 0.2 to 0.6 kg (Cat)/kg (NB) leads to a linear increase in the rate of transformation of nitrobenzene from 0.0002 kg (NB) / (kg (Cat)*s ) to 0.0028 kg(NB)/(kg(Cat)*s), a further increase in the ratio of catalyst concentration to nitrobenzene concentration to 1.2 kg (Cat)/kg(NB) leads to stabilization of the nitrobenzene transformation rate at the level of 0.003 kg(NB)/(kg(Cat)*s). An increase in the temperature of the reaction from 90 to 160 °C contributes to a significant increase in the nitrobenzene transformation rate. The constructed dependences made it possible to calculate the apparent activation energy of the process, which amounted to be 50.4 kJ/mol and the preexponential factor, which amounted to be 15821.1 1/s. The applicability of the Langmuir–Henschelwood model to describe the basic kinetic laws of the reaction of catalytic nitrobenzene hydrogenation with the formation of aniline is studied. Numerical methods in the Matlab software allows to determine the values of preexponential factors and activation energies of the nitrobenzene hydrogenation processes, adsorption of nitrobenzene and adsorption of hydrogen, which made it possible to establish the optimal area of nitrobenzene hydrogenation process of hydrogenation of Pн2 = 15–18 atm, C(NB) = 1.2 kg(NB)/kg(Cat), t =115–120 °C providing maximum speed.

Superhydrophobic nickel/carbon core–shell nanocomposites for the hydrogen transfer reactions of nitrobenzene and N-heterocycles

In this work, catalytic hydrogen transfer as an effective, green, convenient and economical strategy is for the first time used to synthesize anilines and N-heterocyclic aromatic compounds from nitrobenzene and N-heterocycles in one step.

Understanding the Mechanism of Nitrobenzene Nitration with Nitronium Ion: A Molecular Electron Density Theory Study

AbstractThe nitration reaction of nitrobenzene with nitronium ion yielding ortho‐, meta‐ and para‐dinitrobenzenes has been studied within the Molecular Electron Density Theory, using DFT computational methods at the B3LYP/6‐311G(d,p) level. This electrophilic aromatic substitution (EAS) reaction takes place through a two‐step mechanism involving the formation of a tetrahedric cation intermediate. The electrophilic attack of nitronium ion on nitrobenzene is the rate‐determining step of this EAS reaction, and consequently, responsible for the composition of the reaction mixture. The subsequent proton abstraction from the cation intermediate is barrierless. From the computed activation Gibbs free energies, a relationship 11.0 (ortho) : 87.3 (meta) : 1.7 (para) of the dinitrobenzenes is estimated, in clear agreement with the experimental outcome. The similar nucleophilic activation of the ortho and meta carbons of nitrobenzene makes it possible to question the hypothesis for the orientation in EAS reactions involving nucleophilically deactivated benzenes based on the relative stability of the tetrahedric cation intermediates.

Self-Assembly of CdS/CdIn2S4 Heterostructure with Enhanced Photocascade Synthesis of Schiff Base Compounds in an Aromatic Alcohols and Nitrobenzene System with Visible Light.

A series of novel CdS/CdIn2S4 composite materials were prepared via a one-pot solvothermal process. The as-obtained photocatalysts were characterized by several techniques and the photocatalytic properties of CdS/CdIn2S4 photocatalysts were studied by photocascade synthesis of Schiff base compounds in a photocatalytic reaction system of aromatic alcohols and nitrobenzene irradiated with visible light. The results reveal that the resulting CdS/CdIn2S4 heterostructure samples show outstanding photocatalytic activities toward the photocascade production of Schiff base compounds in an aromatic alcohols and nitrobenzene reaction system irradiated with visible light. An optimized 50.0% CdS/CdIn2S4 heterostructure sample shows the highest Schiff base yield of 42.0% irradiated with visible light for 4 h, which is approximately 19.1 and 1.54 times higher than those of sole CdS and CdIn2S4 samples, respectively. The fabrication of heterogeneous structure improves the spatial separation and migration of photoinduced electron-hole pairs, thus contributing to the enhancement of photocatalytic properties. We foresee that this finding can offer a strategy to develop heterostructure composites for efficient synthesis of organics by photocatalysis under mild conditions.

Pd stabilized on nanocomposite of halloysite and β-cyclodextrin derived carbon: An efficient catalyst for hydrogenation of nitroarene

Carbon nanospheres, CCDs, were fabricated using β-cyclodextrin as carbon precursor. The as prepared CCD was then hybridized with halloysite nanotubes (Hal) through hydrothermal treatment to furnish a nanocomposite, Hal-CCD that was subsequently applied as support to stabilize Pd nanoparticles. Investigation of the catalytic activity of palladated nanocomposite, Pd@Hal-CCD, for the hydrogenation reaction of nitrobenzenes confirmed that Pd@Hal-CCD could efficiently promote the hydrogenation reaction under mild reaction condition. Moreover, the catalyst was recyclable and showed slight Pd leaching upon reusing. The comparison of the catalytic activity of Pd@Hal-CCD with that of Pd@Hal and Pd@CCD indicated the superior catalytic activity of the former. The observed high catalytic activity of the catalyst was attributed to its higher Pd loading and water disperse ability. Additionally, the results confirmed that the ratio of Hal:CCD could affect the catalytic activity and the best result was obtained by using Hal:CCD ratio of 1:2.

Activated carbon supported bimetallic catalysts with combined catalytic effects for aromatic nitro compounds hydrogenation under mild conditions

Non-noble nickel catalysts have been widely studied and tried in hydrogenation, however the problem of nickel particle sintering is more and more common in high-loaded nickel catalysts. A series of highly dispersed bimetallic Ni-M/AC (M = Cu, Co, Fe or Zn) catalysts were prepared by incipient wetness impregnation methods and applied in 1-nitronaphthalene hydrogenation to 1-naphthylamine under mild reaction conditions. The prepared catalysts were characterized by XRD, BET, H2-TPR, TEM, HRTEM, HAADF-STEM, XPS, ICP, FT-IR and H2 chemisorption. The results show that the introduction of the metal promoter inhibits the sintering of the nickel and enhances the reducibility of the catalysts, leading to higher ratio of effective Ni° on the surface of the support, especially for Ni-Zn/AC sample. Moreover, the results of XPS indicate that the electron donating effect of Cu promoter increases surface electronic density of Ni, as a result, the electron-rich Ni might be produced because of the interfacial electronic effect, which favors the desorption and further impedes the hydrogenation of N-naphthylhydroxylamine. Ni-Zn/AC-350 with smaller nickel particles, better dispersion and larger content of effective Ni° presents the best catalytic performance in 1-nitronaphthalene hydrogenation to 1-naphthylamine under mild reaction conditions, it gives 100% conversion of 1-nitronaphthalene and 96.82% selectivity to 1-naphthylamine under 0.6 MPa and 90℃ for 5 h. Additionally, superior performances are also obtained in hydrogenation reactions of nitrobenzene, chloronitrobenzene, 1,5-dinitronaphthalene and 1,8-dinitronaphthalene over Ni-Zn/AC catalysts. With good hydrogenation activity the catalyst shows, the application prospect in industrial production of aromatic amine from aromatic nitro compounds has been becoming more and more extension.

Growth and chemical modification of silicon nanostructures templated in molecule corrals: Parallels with the surface chemistry of single crystalline silicon

Molecule corrals having diameters of 30–50 nm were created on highly oriented pyrolytic graphite (HOPG) using cesium ion bombardment. The molecule corrals were used as templates to grow silicon nanostructures by physical vapor deposition (PVD). The nanostructures could be grown with control over geometry (rings and mesas), and size distribution. In addition, transmission electron microscopy (TEM) results suggest that the silicon nanostructures are most likely polycrystalline.The chemical modification of these silicon nanostructures with nitrobenzene was compared to that of clean and hydrogen-terminated single crystalline silicon. X-ray photoelectron spectroscopy (XPS) of the modified nanostructures showed peaks located at 398.9 eV, 400.4 eV, and 402.1 eV for the N 1s region, which are consistent with those observed on a Si(100) single crystal. The chemical modification was further characterized by the presence of nitrogen-containing peaks in TOF-SIMS spectra. We conclude that the reaction of nitrobenzene on silicon nanostructures provides evidence that the reactivity of the nanostructures is similar to that of hydrogen-terminated Si(111) and Si(100).

Ab initio calculation for isomerization reaction kinetics of nitrobenzene isomers

The potential energy surface (PES) of nitrobenzene isomers has been built by CCSD(T)/CBS methods. The geometries of isomers and transition states (TSs) are optimized at BHANDHLYP/6-311++G (d, p) level. Sixteen isomers and fifteen isomerization reactions of nitrobenzene were found. The rate constants for the isomerization reactions are calculated and compared according to different types of isomerization. The rate constants and activation energies (Ea) of all reactions are fitted using a qusi-Arrhenius equation. Branching ratios of the nitrobenzene isomerization reactions and the previously reported decomposition reactions are compared and the isomerization to C6H5ONO followed by cleavage of ONO dominates the decomposition of nitrobenzene at low temperature.

Synthesis of Amides by Nucleophilic Substitution of Hydrogen in 3-Nitropyridine

3-Nitropyridine reacted with nitrogen-centered carboxylic acid amide anions in anhydrous DMSO in the presence of K3Fe(CN)6 via oxidative nucleophilic substitution of hydrogen to give previously unknown N-(5-nitropyridin-2-yl) carboxamides. The reaction of nitrobenzene with urea anion in DMSO enabled one-pot synthesis of bis(4-nitrophenyl)amine.

Mechanistic roles of catalyst surface coating in nitrobenzene selective reduction: A first-principles study

Adsorbed organic modifiers can alter selectivity of metal catalysts by modifying reactant, intermediate, or product adsorption affinities and configurations. Herein, we show how alkylamine self-assembled monolayers with varying surface densities can be used to tune selectivity to desired hydrogenation products of nitrobenzene (NB) reduction on a Pt (111) catalyst. Nitrobenzene is a toxic environmental pollutant with deleterious health effects, and its selective conversion to valuable chemicals can both convert this pollutant and improve catalytic process efficiency. Density functional theory (DFT) calculations demonstrate that the selectivity of NB reduction to phenylhydroxylamine (PHA) is achieved by controlling the surface crowding, with specific sites exposed for the selective reduction of NB on the Pt (111) surface through the selection of alkylamine modifier surface density. Surface crowding forces NB and subsequent reaction intermediates to bind with their long axis vertical to the Pt (111) surface, increasing the selectivity to the desired product, PHA. This surface crowding serves both to enhance selectivity and provide insight into the reaction mechanism of NB reduction.