Showing papers on "Nitrobenzene published in 2017"

High performance of a cobalt–nitrogen complex for the reduction and reductive coupling of nitro compounds into amines and their derivatives

Abstract: Replacement of precious noble metal catalysts with low-cost, non-noble heterogeneous catalysts for chemoselective reduction and reductive coupling of nitro compounds holds tremendous promise for the clean synthesis of nitrogen-containing chemicals. We report a robust cobalt–nitrogen/carbon (Co–Nx/C-800-AT) catalyst for the reduction and reductive coupling of nitro compounds into amines and their derivates. The Co–Nx/C-800-AT catalyst was prepared by the pyrolysis of cobalt phthalocyanine–silica colloid composites and the subsequent removal of silica template and cobalt nanoparticles. The Co–Nx/C-800-AT catalyst showed extremely high activity, chemoselectivity, and stability toward the reduction of nitro compounds with H2, affording full conversion and >97% selectivity in water after 1.5 hours at 110°C and under a H2 pressure of 3.5 bar for all cases. The hydrogenation of nitrobenzene over the Co–Nx/C-800-AT catalyst can even be smoothly performed under very mild conditions (40°C and a H2 pressure of 1 bar) with an aniline yield of 98.7%. Moreover, the Co–Nx/C-800-AT catalyst has high activity toward the transfer hydrogenation of nitrobenzene into aniline and the reductive coupling of nitrobenzene into other derivates with high yields. These processes were carried out in an environmentally friendly manner without base and ligands.

A nitrogen-rich fluorescent conjugated microporous polymer with triazine and triphenylamine units for high iodine capture and nitro aromatic compound detection

Abstract: A new kind of nitrogen-rich fluorescent conjugated microporous polymer TTPB was synthesized via a Friedel–Crafts reaction of 2,4,6-trichloro-1,3,5-triazine (TCT) and N,N,N′,N′-tetraphenylbenzidine (TPB) catalyzed by methanesulfonic acid. Having structural features of an expanded conjugated area, N-rich, twisted structure, and microporosity in polymer networks, TTPB showed excellent, efficient, reversible ultrahigh absorption performance for iodine vapour with an uptake of up to 4.43 g g−1, which is the highest value reported to date for CMPs. Furthermore, fluorescence study indicated that TTPB exhibits high sensitivity to electron-deficient nitrobenzene explosives via fluorescence quenching.

Highly Selective Bifunctional Luminescent Sensor toward Nitrobenzene and Cu2+ Ion Based on Microporous Metal–Organic Frameworks: Synthesis, Structures, and Properties

Abstract: Two metal–organic frameworks (MOFs), namely, [Ni(DTP)(H2O)]n (I) and [Cd2(DTP)2(bibp)1.5]n (II) (H2DPT = 4′-(4-(3,5-dicarboxylphenoxy) phenyl)-4,2′:6′,4″-terpyridine; bibp = 1,3-di(1H-imidazol-1-yl)propane), that present structural diversity were solvothermally prepared. Single-crystal X-ray diffraction analysis indicates that they consist of {NiN2O4} building units (for I) and {CdO4N2} and {CdO3N3} building units (for II), which are further linked by multicarboxylate H2DPT to construct microporous three-dimensional frameworks. The remarkable character of these frameworks is that coordination polymer II demonstrates highly selective and sensitive bifunctional luminescent sensor toward nitrobenzene and Cu2+ ion. The fluorescence quenching mechanism of II caused by nitrobenzene is ascribed to electron transfer from electron-rich (II) to electron-deficient nitrobenzene. The result was also evidenced by the density functional theory. Furthermore, anti-ferromagnetic as well as electrochemical characters of Ni-...

Amino-functionalized MIL-101(Fe) metal-organic framework as a viable fluorescent probe for nitroaromatic compounds

Abstract: A highly luminescent iron(III)-based amino-functionalized metal-organic framework (MOF) of type NH2-MIL-101(Fe) was synthesized by a solvothermal method. Its structure and morphology were studied by X-ray diffraction, scanning electron microscopy, and FTIR. The strong fluorescence of the electron-rich MOF is shown to be quenched by electron-deficient nitroaromatic compounds. Compared to solvents such as water and other organic solvents, quenching by the nitroaromatic compounds nitrobenzene (NB), 4-nitrophenol (4-NP), 4-nitrotoluene (4-NT) and 1,3-dinitrobenzene (1,3-DNB) is particularly strong. The detection limits for NB, 4-NP, 4-NT and 1,3-DNB are 32 ppm, 17 ppm, 9.8 ppm and 11.5 ppm.

Biosynthesis of silver nanoparticles by using Camellia japonica leaf extract for the electrocatalytic reduction of nitrobenzene and photocatalytic degradation of Eosin-Y.

Abstract: In the present study, sphere-like silver nanoparticles (Ag-NPs) were synthesized by using Camellia japonica leaf extract and its remediation industrial pollutants such as nitrobenzene and Eosin-Y (EY). As-prepared sphere-like Ag-NPs were characterized by various analytical and spectroscopic methods such as UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), High-resolution transmission electron microscopy (HR-TEM), Energy dispersive X-ray spectra (EDX), and the chemical constituents of the leaf extract were also analyzed by using Gas chromatography and Mass Spectroscopy (GC-MS). Fascinatingly, the as-prepared sphere-like Ag-NPs exhibits excellent electrocatalytic and photocatalytic activity for the reduction of nitrobenzene and photo-degradation of EY dye respectively. The Cyclic voltammetry (CV) and amperometric (i-t) studies realized that the electrochemical behavior of sphere-like Ag-NPs modified electrode on nitrobenzene reduction. The proposed nitrobenzene sensor exhibited appreciable wide linear response range and low detection limit of 0.05-21μM, 23-2593μM and 12nM, respectively. The Ag-NPs modified electrode showed excellent selectivity towards the nitrobenzene detection even in the presence of common metal ions and nitroaromatic containing substances. On the other hand, Ag-NPs have excellent photocatalytic activity with >97% degradation of EY dye after irradiated 60min. These results indicated that the growth of sphere-like Ag-NPs should be a proficient.

Luminescent metal-organic frameworks for the detection of nitrobenzene in aqueous media

Abstract: The feasibility of highly water stable Zr-based metal organic frameworks (MOFs: UiO-66-NH2) as a sensing probe material was explored for the detection of the electron deficient nitrobenzene (NB) molecule in an aqueous phase. The probe system was highly sensitive toward the NB molecule within the range of 10–100 ppm with a linear range of 0–30 ppm and a quenching efficiency of around 95% (at 100 ppm). The limit of detection (LOD) of the proposed probe was estimated to be 0.9 ppm. In contrast, this method was not affected sensitively by potential interferences such as other aromatic compounds. For instance, benzene (B), toluene (T), and chlorobenzene (CB) showed reduced quenching efficiencies (<40%). The specificity toward NB molecules for the proposed probe was appreciable in the presence of co-existing components (B, T, and CB). DFT calculations showed that the sensing mechanism was ascribable to electron transfer from the excited missed-linker induced sites of the ZrOH to the NB molecule. This interaction was confirmed by an FTIR analysis of the UiO-66-NH2-NB material. Therefore, the proposed UiO-66-NH2 probe can be used as a potent sensing material for the NB even at low concentrations in an aqueous medium.

Selective gas adsorption and fluorescence sensing response of a Zn(II) metal–organic framework constructed by a mixed-ligand strategy

Abstract: By means of a mixed-ligand strategy, a novel bi-functional metal–organic framework, [H2N(CH3)2]·Zn(NDC)(atz)·H2O (NDC = 2,6-naphthalenedicarboxylic acid, Hatz = 1H-tetrazol-5-amine), was synthesized, which displays a three-dimensional two-fold interpenetrated framework. Owing to the introduction of two different functional organic ligands, this complex exhibits bi-functional properties, i.e., selective gas adsorption of CO2 over CH4 and fluorescence sensing response for nitrobenzene.

Preparation and Characterization of Parent Phenylphosphinidene and Its Oxidation to Phenyldioxophosphorane: The Elusive Phosphorus Analogue of Nitrobenzene.

Abstract: Triplet phenylphosphinidene was prepared by light-induced elimination of ethylene from the corresponding phenylphosphirane and was characterized by IR and UV/vis spectroscopy together with matching of its spectral data with density functional theory computations. The photolysis of phenylphosphirane in 3P-O2 doped matrices enabled the spectroscopic identification of a hitherto unknown phenyldioxophosphorane, the long elusive phosphorus analogue of nitrobenzene.

High Performance and Active Sites of a Ceria‐Supported Palladium Catalyst for Solvent‐Free Chemoselective Hydrogenation of Nitroarenes

Abstract: Cerium oxide-supported palladium catalysts (Pd/CeO2) prepared by a simple impregnation method exhibit exciting catalytic activity and high chemoselectivity for the solvent-free hydrogenation of a variety of substituted nitroarenes including the reducible functional groups to the corresponding aromatic amines under mild reaction conditions. Taking nitrobenzene as an example, the Pd/CeO2 catalyst can afford aniline yields of >99 % with turnover frequencies as high as 11 411 h−1 and 69 824 h−1 at 40 °C and 100 °C, respectively. Pd2+ ion species exist as isolated single atoms with −Pd2+−O2−−Ce4+− linkages on the surface of PdxCe1−xO2−σ solid solution and are found to be active sites for the selective hydrogenation of nitroarenes in the absence of solvent. The superior catalytic performance can be attributed to the cooperative effect between Pd2+ ions and unique surface sites of CeO2. A possible mechanism is proposed for the hydrogenation of nitroarenes with H2 over the Pd/CeO2. The Pd/CeO2 catalyst can be recovered easily and reused for at least seven recycling reactions without loss of catalytic properties.

Tetraphenylethylene tetracylhydrazine macrocycle with capability for discrimination of n-propanol from i-propanol and highly sensitive/selective detection of nitrobenzene

Abstract: A novel tetraphenylethylene tetracylhydrazine macrocycle with an aggregation-induced emission effect was synthesized. Due to cyclization at the ortho position of the phenyl ring, the two TPE units that composed the macrocycle were almost folded and offered a deep V-like cavity. By grinding, the macrocycle powder could be made to emit yellow-green rather than blue-green fluorescence. Interestingly, the ground powder that emitted yellow-green fluorescence could be caused to emit blue light by methanol, ethanol or n-propanol while other conventional solvents including i-propanol did not cause this solvatochromism. Therefore, the macrocycle could discriminate between n-propanol and i-propanol. Moreover, the fluorescence of a suspension of the macrocycle in a mixed H2O/THF solvent was more easily quenched by nitrobenzene than by other nitroaromatic compounds, probably due to the smaller size of nitrobenzene instead of its greater electron-deficiency. The detection limit for the measurement of nitrobenzene was as low as 3.99 μg L−1, which has potential for usage in the analysis of nitrobenzene in potable water sources. Moreover, a solid film of the macrocycle showed a sensitive response to nitrobenzene vapour at a concentration as low as 1.01 femtograms per mL of air.

Gold Nanoparticles Supported on Alumina as a Catalyst for Surface Plasmon-Enhanced Selective Reductions of Nitrobenzene

Abstract: Au nanoparticles supported on alumina (Au/Al2O3) with average particle size of 3.9 ± 0.7 nm and surface plasmon band centerned at 516.5 nm were prepared by deposition–precipitation method, and their photocatalytic activities for the reduction of nitrobenzene using either formic acid in acetonitrile (method A) or KOH in 2-propanol (method B) were investigated. Even at room temperature, the Au/Al2O3 was found to be highly active and selective for conversion of nitrobenzene to aniline when used with formic acid in acetonitrile or to azobenzene when performed with KOH in 2-propanol under irradiation with green light-emitting diode (517 nm).

A novel Ag(I)-calix[4]arene coordination polymer for the sensitive detection and efficient photodegradation of nitrobenzene in aqueous solution

Abstract: Nitrobenzene (NB) is a widespread and highly toxic organic pollutant in water, and consequently its detection and removal have attracted considerable attention. In the present study, we designed and synthesized a novel coordination polymer, [AgL0.5(NO3)]n (1), {L = 25,26,27,28-tetra[(3-pyridylmethyl)oxy]calix[4]arene}, from AgNO3 and a tetra-pyridyl-functionalized calix[4]arene ligand, which possessed a 2D network based on [Ag4L(NO3)4] units. The 1-modified glassy carbon electrode (1/GCE) exhibited good electrocatalytic activity toward the reduction of NB, offering the selective detection of NB in a wide linear range (1-2450 μM) and a low detection limit (0.62 μM). Furthermore, it displayed excellent photocatalytic activity for the degradation of NB in aqueous solution under UV light. The kinetics of the catalytic degradation reaction and the stability of the catalyst were also studied. These results indicated that compound 1 is a favorable material for the effective determination and degradation of NB, which makes it a promising candidate in both monitoring water quality and treating wastewater.

Degradation of nitrobenzene by sodium persulfate activated with zero-valent zinc in the presence of low frequency ultrasound

Abstract: In the presence of low frequency ultrasound (US) generated from an ultrasonic cleaning bath, the degradation efficiency of nitrobenzene (C6H5NO2, NB) by Zn0-activated persulfate (PS) reached 96% within 2 h, which is much higher than that by PS or Zn0 alone in the presence of US or that by Zn0-activated PS in the absence of US. The synergistic effect in the US/Zn0/PS system and the optimum degradation conditions was investigated by batch experiments. The variations of pH and concentrations of Zn2+ and SO42− over time and the removal of chemical oxygen demand (COD) and total organic carbon (TOC) in different systems were analyzed, which agreed well with the degradation pattern of NB in different systems. The formation of free radicals was measured using electron paramagnetic resonance (EPR) spectroscopy to further investigate the possible mechanism of the enhanced degradation of NB by Zn0-activated PS in the presence of low frequency US.