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Showing papers on "Nitrobenzene published in 2001"


Journal ArticleDOI
TL;DR: Fenton reagent has been used to test the degradation of different organic compounds in aqueous solution and eliminates the toxic substances and increases the biodegradability of the treated water (measured as the ratio BOD5/COD).

588 citations


Journal ArticleDOI
TL;DR: It is concluded that the adsorption trends of SNBs on K-SAz-1 can be explained without recourse to hypothetical electron donor-acceptor complexes.
Abstract: To more fully understand the potential for transport of nitroaromatic compounds in soils and subsoils, the adsorption of a series of para- and meta-substituted nitrobenzenes (SNBs) by K-smectite clay was measured. Adsorption isotherms were fit to the Freundlich equation, and the resultant Freundlich adsorption coefficients (log(Kf)) were positively correlated with the Hammett substituent constant (r2 = 0.80). This relationship and a positive reaction constant (ρ = 1.15) indicate that the adsorption reaction is favored by electron-withdrawing substituents. These results are consistent with an electron donor (smectite)−acceptor (substituted nitrobenzene) mechanism offered previously. However, quantum calculations did not reveal any systematic relationship between the Hammett constant and the electron density on the aromatic ring, which would explain a donor−acceptor relationship. Rather, electron density donated by a second substituent on nitrobenzene appears to be appropriated by the nitro group leaving ri...

277 citations


Journal ArticleDOI
TL;DR: In this article, a general reaction pathway for the degradation of each pollutant is proposed, where the initial mineralization rate increases as more oxidizing hydroxyl radical is produced in the medium by the catalyzed ozonations.
Abstract: Solutions with 1.07 mmol dm−3 aniline or with 1.38 mmol dm−3 4-chlorophenol at pH ca. 3 have been treated with ozone and ozonation catalyzed with Fe2+ and/or UVA. The initial mineralization rate increases as more oxidizing hydroxyl radical is produced in the medium by the catalyzed ozonations. Direct ozone treatment leads to stable oxidation products, which are quickly destroyed under UVA illumination. In the presence of Fe2+ as catalyst, the degradation process is inhibited by the formation of Fe3+ complexes with short organic diacids, being photodecomposed by UVA light. Each initial pollutant is destroyed at similar rate in all processes. p-Benzoquinone and nitrobenzene are identified as intermediates of aniline oxidation. The former product is only detected when high amounts of hydroxyl radical are produced by the action of Fe2+. Ammonium ion released during p-benzoquinone formation is also generated in larger extension under the same conditions. Nitrate ion reaches maximum production under UVA irradiation, indicating that generation of nitrobenzene from selective attack of O3 on the amino group of aniline is photocatalyzed. Reaction of 4-chlorophenol with ozone leads to 4-chloro-1,3-dihydroxybenzene and 4-chloro-1,2-dihydroxybenzene. The last product is produced in larger extension when high amounts of hydroxyl radical can selectively attack the initial pollutant. Chloride ion is completely lost during the further degradation of both dihydroxylated derivatives. Oxidation of all aromatic intermediates detected during aniline and 4-chlorophenol degradation gives maleic acid, which is further mineralized via oxalic acid. A general reaction pathway for the degradation of each pollutant is proposed.

187 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated the kinetics of catalytic hydrogenation of nitrobenzene in acid medium to p-aminophenol in a batch slurry reactor in a temperature range of 323-353 K.

161 citations


Journal ArticleDOI
TL;DR: Zerovalent iron (Fe0) has been successfully employed to reduce nitrobenzene to aniline in synthetic wastewater in both batch and continuous flow reactors, a concentration range considerably higher than those studied previously with groundwater by other researchers.
Abstract: Nitrobenzene is a major environmental pollutant, and its degradation is difficultto achieve. Hence, a chemical reduction pretreatment is sought in this research, before the resulting aniline can be treated by enzyme-mediated oxidative polymerization. Zerovalent iron (Fe0) has been successfully employed to reduce nitrobenzene to aniline in synthetic wastewater in both batch and continuous flow reactors. The concentration of nitrobenzene studied was thatwhich would be present in industrial wastewater streams (millimolar, 123 ppm), a concentration range considerably higher than those studied previously with groundwater by other researchers. Anaerobic conditions were maintained in the reactors by including Na2SO3 as an oxygen scavenger in the presence of CoCl2.6H2O, which acted as a catalyst. Batch reactors exhibited adsorption of aniline on the Fe0, which could be described by a langmuir isotherm. A 200 g Fe0 (particle size: 1-2 mm) bed completely converted 1 mM of nitrobenzene flowing upward for about 600 pore-volumes before experiencing flow reduction due to clogging due to corrosion products. Green-black precipitates (Fe0 corrosion products) were formed at the influent end of the column which were identified as maghemite.

152 citations


Journal ArticleDOI
TL;DR: In this paper, the reduction of nitrobenzene using zero valent iron was investigated using differential pulse polarography (DPP) and the presence of a pH dependent induction period in the reduction was observed.

97 citations


Journal ArticleDOI
TL;DR: In this article, the degradation of nitrobenzene, a recalcitrant compound, using the combination of ozone with UV radiation and UV+Fe(III) has been carried out in a 21L reactor and compared with results obtained from single ozonation.
Abstract: The degradation of nitrobenzene, a recalcitrant compound, using the combination of ozone with UV radiation and UV+Fe(III) has been carried out in a 21 L reactor and compared with results obtained from single ozonation. Whereas TOC elimination was not improved by using UV radiation, the addition of Fe(III) (O3/UV/Fe(III)) enhanced the mineralization rate. The principal effect of Fe(III) on the photolytic ozonation is attributed to the photodecarboxilation of ferric ion complexes.

81 citations


Journal ArticleDOI
TL;DR: In this paper, the performance of vanadium polyoxometalates (POMs) was examined with GC and GC/MS measurements in order to clarify the mechanism of benzene oxidation catalyzed by them.
Abstract: Product distribution in the oxidation of toluene, as well as nitrobenzene, with 30% aqueous hydrogen peroxide catalyzed by Keggin- and Dawson-type selectively site-substituted vanadium(V) polyoxometalates (POMs) was carefully examined with GC and GC/MS measurements in order to clarify the mechanism of benzene oxidation catalyzed by them. The POMs used here as catalyst precursors were Y4[PMo11VO40] (Y=Bu4N, 1a; K, 1b; Na, 1c), Y4K[PW10V2O40] (Y=Bu4N, 2a; K, 2b) and K7[P2W15Mo2VO62] 3b. 1 As control experiments, radical reactions with [VO(O2)(pic)(H2O)2]·2H2O 4 (pic, picolinate) and Fenton reagent 5 (FeIISO4/30% aqueous H2O2 plus 0.05 ml of 60% aqueous HClO4) for the toluene and nitrobenzene oxidations were also examined under our conditions; the hydroxylation of benzene by 4 has been proposed to be promoted by the radical species formed on the vanadium complexes, while that by 5 has been considered to be promoted by the hydroxy radical species OH. The GC/MS spectral patterns of toluene oxidation catalyzed by the POMs have suggested that there are four different reactions by the POM groups and at least three of them, i.e. (1), (3) and (4), proceed via different radical mechanisms: (1) the reaction by 2a resembled that by Fenton reagent 5 closely in the preferential side-chain oxidation; (2) the reactions by 2b and 3b showed preferential ring-oxidation, in particular, the selective production of o-cresol, which were quite different from the radical reactions by 4 and 5; (3) the reactions by 1b and 1c were very similar to the radical reaction by 4 showing comparably both the side-chain oxidation and the ring-oxidation; and (4) the reaction by 1a showed low selectivity in side-chain oxidation, although the ring-oxidation was very similar to that by 1b and 1c. These facts will be also the case for benzene oxidation. The unique catalytic behavior of 2b and 3b has been also observed in nitrobenzene oxidation.

73 citations


Journal ArticleDOI
TL;DR: In this paper, the gas phase reaction of OH radicals with benzene was studied under flow conditions in the temperature range 276-353 K and at pressures of 100 and 500 mbar using on-line FT-IR spectroscopy and GC-MS measurements.
Abstract: The gas-phase reaction of OH radicals with benzene was studied in O2/He mixtures under flow conditions in the temperature range 276–353 K and at pressures of 100 and 500 mbar using on-line FT-IR spectroscopy and GC-MS measurements. The reaction conditions were chosen so that the initially formed OH/benzene adduct predominantly reacted either with O2 or O3. Under conditions of a predominant reaction of the OH/benzene adduct with O2 the product formation was studied for variable NO concentrations. Identified products were the isomers of hexa-2,4-dienedial, phenol, nitrobenzene, p-benzoquinone and glyoxal. Furan was found in small amounts. For increasing NO concentrations there was a decrease of the phenol yield and the yields of trans,trans-hexa-2,4-dienedial and nitrobenzene increased, resulting in maximum values of 0.36 ± 0.02 and 0.11 ± 0.02, respectively (100 mbar, 295 K). The p-benzoquinone yield of 0.08 ± 0.02 was found to be independent of the NO concentration. The temperature dependence of the phenol yield was measured in the range of 276–353 K for initial ratios of [NO]/[O2] = 1–20 × 10−6 at 500 mbar. For a fixed [NO]/[O2] ratio, a distinct increase of the phenol yield with increasing temperature was observed; initial [NO]/[O2] = 1–1.2 × 10−6, phenol yield: 0.18 ± 0.04 (276 K) and 0.68 ± 0.05 (353 K). Generally, the total yield of carbonylic substances was found to be anti-correlated to the phenol yield. When the OH/benzene adduct reacted with O3, trans,trans-hexa-2,4-dienedial, phenol and formic acid were identified as main products with formation yields of 0.28 ± 0.02, 0.20 ± 0.05 and 0.12 ± 0.02, respectively (100 mbar, 295 K). Further products were p-benzoquinone, CO and unidentified carbonylic substances. For the different experimental conditions, reaction mechanisms are proposed explaining the formation of the observed products. A simple model describing the temperature and NOx-dependence of the phenol yield is presented.

47 citations


Journal ArticleDOI
TL;DR: In this article, the reduction of nitroarenes to anilines by CO/H2O was shown to be chemoselective for the nitro group with respect to olefins and keto groups.
Abstract: Chelating diimines of the kind bis(arylimino)acenaphtene (Ar-BIAN) and bis(phenylimino)phenanthrene (Ph-BIP) are very effective promoters for the Ru3(CO)12 catalysed reduction of nitroarenes to anilines by CO/H2O. Their promoting efficiency for this catalytic system is higher than the one of any previously reported ligand. The corresponding quinones are also promoters for the same reaction and a comparison between several ligands under the same experimental conditions is reported. The reaction can be performed without any other solvent except water, but yields are better if ethanol is also added. The reduction is chemoselective for the nitro group with respect to olefins and keto groups.

46 citations


Journal ArticleDOI
TL;DR: In this paper, the nitrobenzene oxidation mixture was directly extracted after acidification without preextraction of by-products, which made the extractive step easy and gave reproducible data.
Abstract: The nitrobenzene oxidation method was modified to obtain more reproducible data and more structural information about lignin, not only by gas chromatography (GC) but also by proton nuclear magnetic resonance (1H-NMR) spectroscopy for quantitative determination of the oxidation products and to simplify the procedures. The nitrobenzene oxidation mixture was directly extracted after acidification without preextraction of by-products. The direct extraction made the extractive step easy and gave reproducible data. 5-Iodovanillin was selected as a new internal standard. The reason for this selection was that 5-iodovanillin did not exist in the nitrobenzene oxidation products from any plant species and had an aldehyde group whose peak did not overlap with the other aldehyde peaks on an1H-NMR spectrum. Thus, the use of 5-iodovanillin enabled us to quantifyp-hydroxybenzaldehyde, vanillin, and syringaldehyde in oxidation products on the basis of1H-NMR analysis as well as GC. Furthermore, more information about the condensed structure of lignin was derived by comparing the1H-NMR and GC analyses.

Journal ArticleDOI
TL;DR: In this article, the coke formation at the coated section close to the inlet allows a fast determination of the fundamental dependencies of coke forming on partial pressures of reactants and on temperature for the first coated section partial pressures correspond to the well defined inlet values and do not depend on time.

Journal ArticleDOI
TL;DR: The effect of the redox state of structural Fe on the surface reactivity of iron-bearing phyllosilicates in aqueous suspension was investigated using a molecular probe using Nitrobenzene as an electron acceptor probe to react with unaltered and chemically reduced smectites.

Journal ArticleDOI
TL;DR: Under the authors' conditions, the combination O3/UV did not improve the degradation rate obtained by ozonation and the best TOC decrease was obtained when the O 3/UV process was carried out at low ferric ion concentrations.

Journal ArticleDOI
TL;DR: In this article, the Gibbs free energies of formation of hydride anion in several solvents (and concomitant solvation energies) were derived from differing theoretical approaches of satisfactory mutual consistency.
Abstract: Fundamental to its chemical and electrochemical—especially electrochromic—reactions, energies of formation of the hydride anion in several solvents (and concomitant solvation energies) were re-evaluated ia a radius estimate derived from differing theoretical approaches of satisfactory mutual consistency. The values (Gibbs free energies—ions at the standard 1 mol dm−3, gases at 100 kPa; 25°C) with subscripted error-estimates were, in kJ mol−1, for water 1414, acetonitrile 2079, N,N-dimethylformamide 22814, dimethyl sulfoxide 21911, methanol 1569 (a first estimate), and nitrobenzene 18311 (a first estimate). The aqueous, acetonitrile and N,N-dimethylformamide values are substantial revisions.

Journal ArticleDOI
TL;DR: In this article, the first examples of parallel interpenetration between noncovalent and metal-organic structures were presented, and they represent the first example of parallel parallel interconnection between non-covalents and metalorganic structures.

Journal ArticleDOI
TL;DR: In this article, the complexation reactions of the electron rich, linear and bi-functional ligand, 9,10-bis(4-pyridyl)anthracene, with metal salts Cd(NO3)2, CdI2, CoI2 and CuI were studied.
Abstract: The complexation reactions of the electron rich, linear and bi-functional ligand, 9,10-bis(4-pyridyl)anthracene, with metal salts Cd(NO3)2, CdI2, CoI2 and CuI in the presence of guest molecules nitrobenzene, benzene and alkoxysilanes were studied. The single crystal analyses of the complexes reveal that an electron deficient guest molecule such as nitrobenzene consistently templated the open two-dimensional network with grid dimensions of ca. 15 × 15A. On the other hand the presence of benzene or alkoxysilane templated1D-zigzag chains and/or 2D-grid layers. The crystal structures revealthe importance of host–guest interactions in tailoring the network architectures ofcoordination polymers.

Journal ArticleDOI
TL;DR: In this paper, the self-sustained oscillation of the membrane potential was elucidated referring to voltammograms for ion transfer at two interfaces existing in the membrane system.

Journal ArticleDOI
TL;DR: Electron beam irradiations of aqueous solutions containing 15-30 mg/L of nitrobenzene at 60 kGy dose removed 78% of the contaminant and led to the conceptual design of a two-stage electron beam microbial process for degradation of nitrophenol.
Abstract: Electron beam irradiations of aqueous solutions containing 15–30 mg/L of nitrobenzene at 60 kGy dose removed 78% of the contaminant. Three mononitrophenols were detected as by-products of electron beam treatment of nitrobenzene. A mixed culture enriched on a mixture of 2-, 3-, and 4-nitrophenol degraded both the residual nitrobenzene and the nitrophenol products. Percentage removal of nitrobenzene increased with increasing electron beam dose. This observation led to the conceptual design of a two-stage electron beam microbial process for degradation of nitrobenzene. Three groups of pure isolates were characterized from the mixed culture based on their abilities to grow on cor- responding nitrophenol substrates: Group A, 2NP−3NP−4NP+; Group B, 2NP+3NP+4NP−; and Group C, 2NP−3NP+4NP−. Bacteria that grew on 3-NP transformed nitrobenzene into ammonia in the electron beam-treated nitrobenzene samples. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 73: 306–312, 2001.

Patent
20 Jun 2001
TL;DR: In this paper, aniline is reacted with nitrobenzene to obtain intermediates of 4-amino-diphenylamine comprising a solide support having interior channels with base material employed in the reaction loaded into the channels.
Abstract: This invention provides a composition suitable for use in a reaction zone where aniline is reacted with nitrobenzene to obtain intermediates of 4-amino-diphenylamine comprising a solide support having interior channels with base material employed in the reaction loaded into the channels. The cross-sectional dimensions of the channels are such as to provide a restricted transition state with regard to the reaction and to improve the selectivity of the reaction in favor of the intermediates The invention also provides a method for loading the base material in the solid support. The invention further provides a process for carrying out the above reaction using the above composition.

Journal ArticleDOI
TL;DR: In this article, the reaction of 1-chloro-2-nitrobenzene with dinitrogen pentoxide in dichloromethane catalysed by H-faujasite zeolites was shown to be a kinetically first-order process.
Abstract: The reaction of 1-chloro-2-nitrobenzene with dinitrogen pentoxide in dichloromethane catalysed by H-faujasite zeolites F-712, F-720, F-780 and F-901, giving 1-chloro-2,4-dinitro- and 1-chloro-2,6-dinitrobenzene in approximately 30∶1 ratio, is a kinetically first-order process. First-order rate constants are independent of the concentration of N2O5 and proportional to the mass of catalyst used. Specific rate constants, obtained by dividing the first-order rate constant by the mass of faujasite, are constant for a given faujasite. Amongst the faujasites, they increase in approximate proportion to the aluminium content. A mechanism is proposed in which the protons in the faujasite, near aluminium in the faujasite framework, are replaced by nitronium ions derived from N2O5 in a fast pre-equilibrium process. This produces active sites for transfer of nitronium ion from faujasite to aromatic in the rate-determining step. The similar reactions of 2-nitrotoluene, too fast for kinetic study, reveal that the ratio of 2,4- to 2,6-dinitrotoluene in the product increases with the aluminium content of the faujasite.Nitration of nitrobenzene is also catalysed by faujasite. Relative reactivities of nitrobenzene, 1-chloro-2-nitro- and 1-chloro-4-nitrobenzene are compared to those found in mixed-acid nitration.Pyrazole can be nitrated readily with N2O5 over faujasites, yielding 1,4-dinitropyrazole in 80% yield under mild conditions. p

Journal ArticleDOI
TL;DR: Kuzyk as mentioned in this paper reported the results of pump-probe optical Kerr effect (OKE) experiments performed on neat solutions of carbon tetrachloride, nitrobenzene, methyl methacrylate monomer.
Abstract: We report the results of pump–probe optical Kerr effect (OKE) experiments performed on neat solutions of carbon tetrachloride, nitrobenzene, methyl methacrylate monomer, binary solutions of the squaraine dye indole squarylium, and the phthalocyanine dye silicon phthalocyanine-monomethacrylate, respectively, in carbon tetrachloride, and solid solutions of indole squarylium and phthalocyanine-monomethacrylate in poly(methyl methacrylate). Dispersion measurements of the dye solutions were performed in the visible one-photon resonant region of the dyes defined by their linear-absorption spectra. The dyes’ third-order molecular susceptibility response γxxxx(-ω2;ω1,-ω1, ω2) in this spectral region is markedly different, with R{γISQ}>0 and R{γSiPc}<0. Analysis of the dyes’ OKE response requires the inclusion of high-lying two-photon states and suggests that a purely electronic mechanism dominates their OKE response. The results are used to calculate the dyes’ off-resonant third-order molecular susceptibilities, which are well within the limits predicted by the Thomas–Reiche–Kuhn sum rule [ M. G. Kuzyk , Opt. Lett.25, 1183–1185 (2000)].

Journal ArticleDOI
TL;DR: In this article, the interaction of nitrobenzene (C6H5NO2) with a Au(1 1 1) surface was investigated and the infrared reflection-absorption spectra (IRAS) was obtained at sub-monolayer, monolayer and multilayer coverages.


Journal ArticleDOI
TL;DR: In this paper, modified catalyst systems composed of palladium or its chloride and a co-catalyst such as metallic Fe-powder, iodine, and pyridine were used in the reduction of nitrobenzene to aniline with carbon monoxide and water at 180°C and 2.5-4 MPa pressure.
Abstract: A study of modified catalyst systems composed of palladium or its chloride and a co-catalyst such as metallic Fe-powder, iodine, and pyridine was used in the reduction of nitrobenzene to aniline with carbon monoxide and water at 180°C and 2.5-4 MPa pressure. The reaction is complete in 2 h with a nitrobenzene conversion of 98-100% and a 100% selectivity with respect to aniline.

Journal ArticleDOI
TL;DR: In this paper, a new synthetic process for oxidation of methyl ketones into their corresponding carboxylic acids using a modified alkaline nitrobenzene method is described, which proceeds smoothly in aqueous alkaline solution at 100 °C.

Journal ArticleDOI
TL;DR: In this article, a selectively ortho -deuterated nitroarenes of high isotopic purity are prepared via acid catalysed H→D exchange in para -substituted anilines followed by oxidation of the amino groups.

Journal ArticleDOI
TL;DR: In this article, the authors used NMR spectrometers to study the complexation reaction between lithium ions and several 12-, 15- and 18-membered crown ethers in a number of binary acetonitrile-nitrobenzene mixtures.
Abstract: Lithium-7 NMR spectrometry was used to study the complexation reaction between lithium ions and several 12-, 15- and 18-membered crown ethers in a number of binary acetonitrile-nitrobenzene mixtures. Formation constants of the resulting 1:1 complexes in different solvent mixtures were determined by computer fitting of the chemical shift-mole ratio data. There is an inverse relationship between the complex stability and the amount of acetonitrile in the mixed solvent. Among different sized crown ethers used, 15-crowns were found to form the most stable Li + complexes in the series. The influence of substitution on the macrocyclic rings on the stability of the resulting complexes is discussed.

Journal ArticleDOI
TL;DR: In this paper, Nitrobenzene, 4-nitrotoluene and 4-naphroxyl acetate are selectively adsorbed from aqueous 1% sodium dodecyl sulfate solutions onto aligned, randomly oriented and oxidised carbon nanotubes, as well as graphite and C60 fullerene.
Abstract: Nitrobenzene, 4-nitrotoluene and 4-nitrophenyl acetate are selectively adsorbed from aqueous 1% sodium dodecyl sulfate solutions onto aligned, randomly oriented and oxidised carbon nanotubes, as well as graphite and C60 fullerene. The rate of hydrolysis of 4-nitrophenyl acetate to 4-nitrophenolate is modestly accelerated through this process. Selective adsorption requires the presence of the surfactant and the hydrolysis of pNPA is accelerated only by a carbon surface that is graphitic in nature.

Patent
31 Jan 2001
TL;DR: In this article, a single step process for the preparation of p-aminophenol by hydrogenation of nitrobenzene in presence of an aqueous acid over a mono or bimetallic nickel catalyst at a temperature in the range of 80-120° C. for a period of 1 to 4 hrs.
Abstract: The present invention provides a single step process for the preparation of p-aminophenol by hydrogenation of nitrobenzene in presence of an aqueous acid over a mono or bimetallic nickel catalyst at a temperature in the range of 80-120° C. for a period of 1 to 4 hrs. The resulting reaction mixture is extracted with an organic solvent like ethyl acetate, cyclohexane or toluene to separate the aqueous layer containing PAP and neutralizing it with ammonia solution to recover the solid p-aminophenol.