Showing papers on "Nitrobenzene published in 1996"
TL;DR: The properties of iron metal that make it useful in remediation of chlorinated solvents may also lead to reduction of other groundwater contaminants such as nitro aromatic compounds (NACs) as mentioned in this paper.
Abstract: The properties of iron metal that make it useful in remediation of chlorinated solvents may also lead to reduction of other groundwater contaminants such as nitro aromatic compounds (NACs). Nitrobenzene is reduced by iron under anaerobic conditions to aniline with nitrosobenzene as an intermediate product. Coupling products such as azobenzene and azoxybenzene were not detected. First-order reduction rates are similar for nitrobenzene and nitrosobenzene, but aniline appearance occurs more slowly (typical pseudo-first-order rate constants 3.5 × 10-2, 3.4 × 10-2, and 8.8 × 10-3 min-1, respectively, in the presence of 33 g/L acid-washed, 18−20 mesh Fluka iron turnings). The nitro reduction rate increased linearly with concentration of iron surface area, giving a specific reaction rate constant (3.9 ± 0.2 × 10-2 min-1 m-2 L). The minimal effects of solution pH or ring substitution on nitro reduction rates, and the linear correlation between nitrobenzene reduction rate constants and the square-root of mixing ra...
709 citations
TL;DR: In this paper, the characteristics of organoclays as sorbents for neutral organic contaminants (NOCs) in aqueous systems containing multiple solutes were evaluated by measuring the sorption of trichloroethylene on hexadecyltrimethylammonium (HDTMA) exchanged illite and smectite in the absence and presence of carbon tetrachloride, nitrobenzene and ethyl ether.
91 citations
TL;DR: In this paper, the effect of temperature and time on the recovery yield of the products of alkaline nitrobenzene oxidation of in situ lignins in wheat straw inter-nodes and corresponding leaves were studied.
Abstract: The effect of temperature and time on the recovery yield of the products of alkaline nitrobenzene oxidation of in situ lignins in wheat straw inter-nodes and corresponding leaves were studied. The results showed that significant variations in the yields of aromatic aldehydes (p-hydroxybenzaldehyde, vanillin and syringaldehyde) as well as hydroxycinnamic acids (p-coumaric and ferulic acids) arise from changes in the temperature and the reaction time. The conditions for maximum yield depend on the aldehyde concerned. For example, the yield of p-hydroxybenzaldehyde increases with increasing temperature and reaction time. This phenomenon could be attributed to the low relative reactivity related to the specific electronic structure of the non-methoxylated units and/or to the existence of specific condensation reactions involving the p-hydroxyphenyl aromatic ring. Finally, the results indicate a much higher complexity of Gramineae lignins compared to those derived from hardwoods and softwoods.
81 citations
TL;DR: Giant palladium-561 clusters were found to be effective in catalysis of the oxidative carbonylation of phenol to diphenyl carbonate, conjugated with the reductive reduction of nitrobenzene under CO pressure.
Abstract: Giant palladium-561 clusters were found to be effective in catalysis of the oxidative carbonylation of phenol to diphenyl carbonate, conjugated with the reductive carbonylation and reduction of nitrobenzene under CO pressure.
60 citations
TL;DR: In this article, the transfer process of ferrocene derivatives (FeCp−X) across a single-nitrobenzene-microdroplet/water interface was studied by laser-trapping and microelectrochemical techniques.
Abstract: Mass transfer processes of ferrocene derivatives (FeCp−X) across a single-nitrobenzene-microdroplet/water interface were studied by laser-trapping and microelectrochemical techniques. Substituent e...
58 citations
TL;DR: In this article, the extraction constants corresponding to the equilibrium Cs+(aq)+Cl−(aq)+L(nb)⇆CsL+(nb)+C−(nb)) in the two-phase water-nitrobenzene system (L=valinomycin; aq=aqueous phase, nb=nitrogen phase) were evaluated as log Kex(CsL+, Cl−)=2.2.
Abstract: From extraction experiments and γ-activity measurements, the extraction constants corresponding to the equilibrium Cs+(aq)+Cl−(aq)+L(nb)⇆CsL+(nb)+Cl−(nb) in the two-phase water-nitrobenzene system (L=valinomycin; aq=aqueous phase, nb=nitrobenzene phase) was evaluated as log Kex(CsL+, Cl−)=2.2. Further, the stability constant of the valinomycin-cesium complex in nitrobenzene saturated with water was calculated: log βnb(Csl+)=10.1.
55 citations
TL;DR: In this article, an experimental investigation was carried out to evaluate the efficiencies of different selective solvents used for the extraction of aromatic hydrocarbons from naphtha (boiling range IBP-200°C).
Abstract: An experimental investigation was carried out to evaluate the efficiencies of different selective solvents used for the extraction of aromatic hydrocarbons from naphtha (boiling range IBP-200°C) distilled from Saudi Arabian light crude oil. The solvents used were 3-methoxypropionitrile, ethylene glycol, dimethylsulfoxide, sulfolane, phenol, and nitrobenzene. The parameters studied were operating temperature (range 20°-125°C), solvent-to-oil ratio (range 1:1-3:1), selectivity, and solvent capacity. The results indicate that sulfolane exhibits excellent extraction properties in comparison with other solvents. In addition, sulfolane has the advantage of having good solvent properties such as high density, low heat capacity, and appropriate boiling point, which helps simplify separation of the solvent from extract. Sulfolane is also commercially feasible as a solvent for aromatic extraction.
52 citations
TL;DR: In this paper, aniline, nitrobenzene, and isomeric nitroanilines were derived from inner-shell electron energy loss spectroscopy recorded under low momentum transfer conditions.
Abstract: Oscillator strengths for C Is, N Is, and 0 1s excitation spectra of aniline, nitrobenzene, and the isomeric nitroanilines have been derived from inner-shell electron energy loss spectroscopy recorded under low momentum transfer conditions (>2.5 keV impact energy and small scattering angle, 0 52'). Extended Hiickel Molecular Orbital (EHMO) calculations carried out within the equivalent core analogy are used to aid spectral interpretation. These spectra are used to investigate the sensitivity of core excitation spectroscopy to charge transfer interactions in aromatic molecules that have both electron-donating and electron- withdrawing substituents. Strong multielectron excitation features were not found, although these had been anticipated from photoemission studies. The C 1s + T* and N 1s (NH,) + n* spectral features of the nitroanilines are found to be strongly dependent on the substitution pattern (ortho, meta, or para).
50 citations
TL;DR: In this paper, the authors showed that the catalytic activity of Co(SB) depended on the nature of the SB ligand: the formal potential E° and steric factors seem to affect the reaction rate.
Abstract: Cobalt Schiff base complexes [Co(SB)] catalyze the oxidation of anilines (1) with tert-butyl hydroperoxide to give nitrobenzenes 2 and 4-(tert-butylperoxy)-2,5-cyclohexadien-1-imine derivatives 3 in yield distributions depending on the substitution mode of the substrate. 4-Alkyl- and 4-aryl-2,6-di-tert-butylanilines gave mixtures of 2 and 3, where the higher the bulkiness of the 4-substituent, the higher the yield of 2. With 2,4,6-trimethylaniline, the ratio of oxidations of the nitrogen and C-4 atoms was almost the same; but a hydrolyzed product 5 of the imine was obtained. 2,4,6-Triphenylaniline gave only 2. Nitrobenzene derivatives were also obtained from 2,6-dialkylanilines and 4-substituted anilines. The catalytic activity of Co(SB) depended on the nature of the SB ligand: the formal potential E° and steric factors seem to affect the reaction rate. Kinetic studies showed that the key step may involve hydrogen abstraction from the aniline, presumably by t-BuO• generated from homolytic decomposition o...
48 citations
TL;DR: Viscosities of binary liquid mixtures of N,N-dimethylformamide with toluene, ethylbenzene, chlorobenzene, bromobenzenes, nitrobenzenes, and aniline at 303.15 and 313.15 K have been measured over the entire composition range as mentioned in this paper.
Abstract: Viscosities of binary liquid mixtures of N,N-dimethylformamide with toluene, ethylbenzene, chlorobenzene, bromobenzene, nitrobenzene, and aniline at 303.15 and 313.15 K have been measured over the entire composition range.
42 citations
TL;DR: In this article, the authors investigated the reaction kinetics and pathways for the decomposition of nitrobenzene in SCW, and the fate of nitrogen upon the decomposition.
TL;DR: In this paper, the half-wave potential of the facilitated transfer of Pb2+ ion was shifted to a more positive potential with increasing concentration of acetate ion in water phase, which is explained by the formation of complexes of pb2− ion with acetate ions.
Abstract: Facilitated transfer of Pb2+ ion by macrocyclic polythiaethers across the polarizable nitrobenzene/water and 1, 2-dichloroethane/water interfaces has been studied by means of ion-transfer voltammetry. Well-defined voltammetric waves due to facilitated transfer of Pb2+ ion by 1, 4, 7, 10, 13, 16-hexathiacyclooctadecane (HTCO) were observed. The voltammetric waves at the nitrobenzene/water interface are shown to be due to the reversible transfer, assisted by the formation of 1:1(metal:ionophore) complex (PbHTCO2+). The half-wave potential of the facilitated transfer of Pb2+ ion was shifted to more positive potential with increasing concentration of acetate ion in water phase. This is explained by the formation of complexes of Pb2+ ion with acetate ion, using the theoretical equations of the half-wave potential of reversible facilitated ion-transfer across the oil/water interface. Also, the negative shift in the half-wave potential observed with increasing concentration of supporting electrolyte in oil phase can be attributed to the ionic association of PbHTCO2+ with the supporting electrolyte anion. The results suggest a new electrochemical method for the determination of Pb(II).
TL;DR: In this paper, the effects of type of metal, reaction temperature and pressure, solvent, nitrogen/metal molar ratio in the complex catalysts on the yields from nitrobenzene to aniline have been examined.
Abstract: Silica-supported mono-metal (such as Ni, Cu) complexes and mixed metal (such as Cu/Zn, Cu/Cr) complexes of chitosan have been prepared. It is found that these non-noble metal complexes could be used as efficient catalysts for the hydrogenation of aromatic nitro compounds. The effects of type of metal, reaction temperature and pressure, solvent, nitrogen/metal molar ratio in the complex catalysts on the yields from nitrobenzene to aniline have been examined. It was also found that catalysts are active for the catalytic hydrogenation of other aromatic nitro compounds such as 2-nitroanisole, 2-nitroaniline, 2-nitrotoluene and 1-chloro-4-nitrobenzene.
TL;DR: In this paper, the four-electron reduction of nitrobenzene in alkaline (pH 13) aqueous media was studied as a model system, and the results showed that the homogeneous pathway was dominant under applied ultrasound conditions.
TL;DR: In this article, a number of binary acetonitrile-nitrobenzene mixtures were used to study the complexation reaction between lithium ion and 12 Crowns.
Abstract: Proton NMR spectroscopy was used to study the complexation reaction between lithium ion and 12-crown-4, 15-crown-5 and 18-crown-6 in a number of binary acetonitrile-nitrobenzene mixtures. In all cases the exchange between free and complexed crowns was fast on the NMR time scale and only a single population average1H signal was observed. 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. It was found that, in all solvent mixtures used, 15-crown-5 forms the most stable complex with Li+ ion in the series.
TL;DR: In this article, cycloaliphatic poly(ether urethane) has been used as a sensitive layer for the detection of organic solvent vapours such as ketones, alcohols, amines, alkanes, aromatic compounds and chlorinated hydrocarbons with quartz microbalances (QMB), interdigital capacitors (IDC) and calorimetric transducers.
Abstract: Cycloaliphatic poly(ether urethane) has been used as a sensitive layer for the detection of organic solvent vapours such as ketones, alcohols, amines, alkanes, aromatic compounds and chlorinated hydrocarbons with quartz microbalances (QMB), interdigital capacitors (IDC) and calorimetric transducers. The sensor signals are completely reversible and reproducible at room temperature. Using QMBs, even less than 10 ppm of nitrobenzene in air can be detected. The IDC measurements show particularly high sensitivities for alcohols. The different transducer parameters are discussed comparatively for the different organic volatiles.
TL;DR: A series of ionic complexes of 1,8-bis(dimethylamino)naphthalene (DMAN) with organic and inorganic acids such as HF, HCl, HBr, HI, HclO4, HBF4, HNCS, CCl3COOH, 4-nitrosophenol, 4-(dicyanomethyl)nitrobenzene, and 1,2-dichloromaleic acid have been studied by electron spectroscopy (ESCA) and 13C and 1H MAS
Abstract: A series of ionic complexes of 1,8-bis(dimethylamino)naphthalene (DMAN) with organic and inorganic acids such as HF, HCl, HBr, HI, HClO4, HBF4, HNCS, CCl3COOH, 4-nitrosophenol, 4-(dicyanomethyl)nitrobenzene, and 1,2-dichloromaleic acid have been studied by electron spectroscopy (ESCA) and 13C and 1H MAS NMR. Structural and spectroscopic features of this series of compounds are discussed and correlated. We demonstrate the influence of strong ionic [N−H···N]+ hydrogen bonds in proton sponges on the binding energies of core electrons of donor and acceptor atoms in the ionic complexes and give the detailed X-ray structure of the complex of DMAN with 4-(dicyanomethyl)nitrobenzene.
TL;DR: In this article, the barrier heights to the internal rotation of the nitro group in 2-nitroresorcinol, 4-6-dinitro-resorcinol, and nitrobenzene have been determined by the application of a dynamic model to the electron diffraction data.
TL;DR: In this article, it was shown that [Rh(CO) 4 ] − (either as a K +, Cs + or PPN + salt, PPN+ = (PPh 3 ) 2 N + ) is a very active catalyst for the reduction of nitrobenzene to aniline by CO/H 2 O in water as solvent.
Abstract: We report here that [Rh(CO) 4 ] − (either as a K + , Cs + or PPN + salt, PPN + = (PPh 3 ) 2 N + ) is a very active catalyst for the reduction of nitrobenzene to aniline by CO/H 2 O in water as solvent. No other ligand, except for CO itself, has to be added. The addition of bases, both inorganic or organic, has a negative effect on the reaction. The experimental conditions have been partly optimised. The reaction is selective for the nitro group.
TL;DR: In this article, the sorption of nitrobenzene and n-pentanol from dilute aqueous solution on swelling clay minerals and their organophilized derivatives (organo clays) was studied.
Abstract: The sorption of nitrobenzene andn-pentanol from dilute aqueous solution on swelling clay minerals and their organophilized derivatives (organo clays) was studied. Adsorption excess isotherms were obtained by the immersion method. The basal spacings of the clay minerals were determined by X-ray diffraction measurements. By combining these two independent methods, composition and structure of the interlamellar space could be calculated. On the hydrophilic surface of montmorillonite negative adsorption of the organic component was observed at low molar fractions of nitrobenzene or pentanol, i.e., water was preferentially adsorbed. On organophilized montmorillonite and vermiculite adsorption of nitrobenzene and pentanol was positive over the whole range of liquid composition. The amount of interlamellar alkyl chains which is determined by the surface charge of clay mineral inversely affected the adsorption of both solutes.
TL;DR: In this article, the phase-transfer-catalyzed reaction of Fe3(CO)12 with OH- affords the radical anion cluster [Fe3[CO]•- and not [HFe3•CO]−.
TL;DR: In this article, 2,6-1utidine and 3-picoline with pd(CH3COO)2 in dry benzene gave diacetato bis-bis-2, 6-1-utidine palladium(l I) (1) and bis-3picoline palladium (I I)(2) respectively.
TL;DR: In this paper, the effect of zinc on nitrobenzene degradation in methanogenic systems was investigated using an autoclaved culture of methanogens, and it was shown that zinc alone could remove 60% of spiked NB in 36 days, indicating toxicity of zinc to methanogenesis.
TL;DR: In this paper, the excess molar enthalpies of binary solvent mixtures of N,N-diemthylformamide with toluene, ethylbenzene, chlorobenzene, bromobenzenes, nitrobenzenes and aniline have been measured with a new paar 1451 solution calorimeter at 29815 K over the entire range of composition.
TL;DR: In this paper, the NMR spectra of lithium-7 and sodium-23 were used to study the interactions of Li+ and Na+ ions with 1,10-phenanthroline, 2,2′-bipyridine and 8-hydroxyquinoline in nitromethane, nitrobenzene, acetonitrile and acetone solutions.
TL;DR: In this paper, a modified styrene-divinyl benzene copolymer with different types of crosslink was treated with glycine for the introduction of the ligand, and the polymer modified with ligand was kept in contact with RuCl 3 to form the metal complex on the surface of the polymer.
Abstract: Chloromethylated styrene-divinyl benzene copolymer with different types of cross-link was treated with glycine for the introduction of the ligand. The polymer modified with ligand was kept in contact with RuCl 3 to form the metal complex on the surface of the polymer. The catalysts thus prepared were characterised by techniques such as IR, UV-Vis reflectance spectroscopy and DTA-TG analysis. Other physico-chemical properties such as surface area, moisture content, bulk density and swelling were also studied. The morphology of the catalysts was observed by scanning electron microscope. The catalysts were tested for the hydrogenation of nitrobenzene as a model reaction. The influence of various parameters such as concentration of catalyst and substrate, temperature and different solvents on the rate of the reaction has been studied.
TL;DR: In this paper, porous copolymers with different functional groups were tested as sorbents for off-line preconcentration of nitrobenzenes together with their reduction products from water.
TL;DR: In this paper, the catalytic hydrogenation of aniline in aqueous media of different acidities was studied, and a platinum catalyst supported on graphite was used.
Abstract: The catalytic hydrogenation of aniline in aqueous media of different acidities was studied. A platinum catalyst supported on graphite was used. The composition of aniline solutions was determined by UV spectroscopy. The characterization of platinum surface and of adsorbed species was performed by cyclic voltammetry. Aniline can be hydrogenated in acid medium, whereas in neutral conditions it acts as a poison. During the hydrogenation of nitrobenzene, the hydrogenation of benzene nucleus is possible in acid medium after a complete conversion of nitrobenzene into aniline.
TL;DR: In this paper, the effect of hydrostatic pressure on the 1-e-reduction of acetophenone and nitrobenzene in the absence of an inert solvent is reported.
Abstract: The effect of hydrostatic pressure on the 1-e- reductions of acetophenone (AP) and nitrobenzene (NB) in the absence of an inert solvent is reported. Steady-state voltammetric responses for these re...
TL;DR: In this paper, the extraction of uranium(VI) from nitric acid solutions by bis(2-ethylhexyl) sulfoxide (BESO) has been examined using sixteen inert organic diluents in order to establish the correlation between its distribution coefficient and some physico-chemical properties of the dilusents.
Abstract: The extraction of uranium(VI) from nitric acid solutions by bis(2-ethylhexyl) sulfoxide (BESO) has been examined using sixteen inert organic diluents in order to establish the correlation between its distribution coefficient and some physico-chemical properties of the diluents. The extracted solvated species is shown to be UO2(NO3)2·2BESO, irrespective of their nature. The extraction rate is lower in halogen substituted hydrocarbons as compared to the other diluents used. Among benzene derivatives, extraction is found to decrease with number of substituted methyl groups. Extraction efficiency decreases as the organic solvent is varied in the order: benzene>nitromethane>toluene> >nitrobenzene>cyclohexane>p-xylene>monochlorobenzene>dodecane>o-dichlorobenzene> >hexane>decalin>1,2-dichloroethane>1,1,1-trichloroethane>carbon tetrachloride> >tetrachloroethane>chloroform. Among the properties showing good correlations with distribution coefficient are Hansen's three-dimensional solubility parameters and Dimroth's empirical solvent polarity parameters [ET(30)]. Polarizability indices are most satisfactorily applicable to a wide variety of solvents.