Showing papers on "Nitrobenzene published in 1987"
TL;DR: The oxidation kinetics of butyl chloride, nitrobenzene, anisole, and methylmercury in the presence of hydroxyl radical (OH) scavengers were used to determine the rate and quantum efficiency for production of OH from irradiated nitrate ions in water.
Abstract: The oxidation kinetics of butyl chloride, nitrobenzene, anisole, and methylmercury in the presence of hydroxyl radical (OH) scavengers were used to determine the rate and quantum efficiency for production of OH from irradiated nitrate ions in water. The experiments were conducted under steady-state irradiations with monochromatic radiation (313 nm) and with sunlight. The mean quantum efficiency for OH production at 313 nm rises from 0.013 +/- 0.002 at 20 /sup 0/C to 0.017 +/- 0.003 at 30 /sup 0/C in the pH range 6.2-8.2. Results of this study are used to estimate nitrate-induced photooxidation rates of trace organic chemicals under a variety of environmental conditions. 27 references, 6 figures, 2 tables.
530 citations
TL;DR: In this paper, an ab initio SCF approach was used to compute the optimized structures and molecular electrostatic potentials of these two forms of nitrobenzene and a comparison of the calculated structures indicated that there is only a very small degree of conjugation between the nitro group and the aromatic ring in the equilibrium form of the molecule.
Abstract: A computational analysis has been made of some of the effects of rotating the NO/sub 2/ group of nitrobenzene by 90/sup 0/ from its equilibrium position in the plane of the aromatic ring. An ab initio SCF approach was used to compute the optimized structures and molecular electrostatic potentials of these two forms of nitrobenzene. A comparison of the calculated structures indicates that there is only a very small degree of conjugation between the nitro group and the aromatic ring in the equilibrium form of the molecule. Chemical consequences of NO/sub 2/ rotation are expected to include a decreased reactivity toward nucleophiles, but a slightly greater susceptibility to electrophilic attack.
57 citations
TL;DR: The dependence of the rate of CO2 formation follows the simple Langmuir expression:R(CO2)=k1k2[s]/(1+k1[s]) as mentioned in this paper.
Abstract: The oxidation of a number of aromatic compounds to carbon dioxide by exposure to near U.V. light in aqueous titanium dioxide suspensions has been studied as a function of the solute concentration. In most, the dependence of the rate of CO2 formation follows the simple Langmuir expression:R(CO2)=k1k2[s]/(1+k1[s])The rate is essentially independent of concentration above 200 µM and becomes progressively more dependent on the concentration as it decreases. Changes in the mineralization rate are most clearly reflected in k2, the parameter determined by the limiting rate at high concentrations. A consequence of the dependence is that total mineralization is strictly never achieved but is approached asymptotically at extended illumination times. The expression and parameters are given which enable the prediction of the extent of mineralization over a wide range of concentrations. The solutes studied were benzene, benzoic acid, benzoate ion, salicylate ion, phenol, chlorobenzene , aniline, anilinium ion, nitrobenzene, chloroform and formic acid. It was confirmed that pH and oxygen concentration affect the rate of carbon dioxide formation but, in the photochemical reactor used, the rate was not significantly affected by the amount of TiO2 suspended for loadings from 0.05 to 0.40 g per 400 ml.
44 citations
TL;DR: In this article, it is suggested that at low concentration tin ions act as promoters by activating the oxygen-containing group, and at higher tin content, platinum is poisoned and availability of activated hydrogen becomes rate-determining.
41 citations
32 citations
27 citations
27 citations
TL;DR: In this paper, a nitrobenzene yield on benzene basis and on nitrogen dioxide basis attained to 93% and 70%, respectively, at 443 K under partial pressures of benzene and nitrogen dioxide of 9.3 kPa and 19 kPa, respectively.
Abstract: Silica-supported benzenesulfonic acid has a high catalyst activity for the title reaction. A nitrobenzene yield on benzene basis and on nitrogen dioxide basis attained to 93% and 70%, respectively, at 443 K under partial pressures of benzene and nitrogen dioxide of 9.3 kPa and 19 kPa, respectively.
26 citations
Patent•
08 Jun 1987TL;DR: In this paper, a process for the reduction of nitrobenzene is described, which is performed catalytically in an aqueous acid medium in the presence of a small amount of organic acid, such as a lower carboxylic acid, oxalic acid, methanesulfonic acid or trichloroacetic acid.
Abstract: A process for the reduction of nitrobenzene is described. The reaction is performed catalytically in an aqueous acid medium in the presence of a small amount of organic acid, such as a lower carboxylic acid, oxalic acid, methanesulfonic acid or trichloroacetic acid.
24 citations
TL;DR: The ion pair formed from aqueous rhodium trichloride and Aliquat 336 catalyzes the selective hydrogenation of olefinic CC bonds of a variety of unsaturated nitro compounds in a two liquid phase system at 30°C as mentioned in this paper.
21 citations
TL;DR: In this article, the ion transfer of the bromophenol blue (BPB) at the interfaces of water/nitrobenzene (W/NB), water/1,2-dichloroethane (W /1, 2-DCE) and water/(nitrophenzene+chlorobenzene) (W/(NB + CB)) was studied in detail by cyclic voltammetry (CV), chronopotentiometry with linear current scanning (CLC), controlled potential electrolysis and UV spectroscopic methods.
TL;DR: In this paper, the reduction of aromatic nitro compounds bearing different substituents with gaseous hydrogen, over a Pt catalyst (3% by weight) supported on a SiO2-AlPO4 system was carried out.
Abstract: In this work we have carried out the reduction of aromatic nitro compounds bearing different substituents with gaseous hydrogen, over a Pt catalyst (3% by weight) supported on a SiO2–AlPO4 system The catalyst was obtained by impregnation, the impregnating metal salt being reduced with α-phellandrene The kinetic data found allow us to describe the reduction of nitrobenzene as a Langmuir–Hinslwood kinetic The sequence of reaction rates for the different nitro compounds assayed conforms to the Hammett–Taft equation, which allows relating the electron density of the aromatic ring to the reduction rate of the nitro group Finally, we propose mechanism for the process, characterized by the absence of intermediates with net charges
TL;DR: In this article, the polarizable potential range was determined by cyclic voltammetry for the interface between an aqueous solution of lithium chloride or magnesium sulfate and a nitrobenzene solution of various electrolytes.
Abstract: The polarizable potential range was determined by cyclic voltammetry for the interface between an aqueous solution of lithium chloride or magnesium sulfate and a nitrobenzene solution of various electrolytes: tetrabutylammonium salts of tetraphenylborate, tetrakis(4-fluorophenyl)borate, tetrakis(4-chlorophenyl)borate, and tetrakis[3, 5- bis(trifluoromethyl)phenyl]borate, and tetrapentyl- and tetrahexylammonium salts of tetraphenylborate. The anodic and cathodic limits of polarizable potential range were discussed with reference to the standard ion-transfer potentials of the supporting-electrolyte ions.
TL;DR: In this paper, the authors present evidence for the participation of cluster intermediates in the carbonylation of nitrobenzene and show that they are useful in this process.
TL;DR: In this paper, the distribution equilibrium of Cr(VI) between an aqueous sulfuric acid solution of potassium bichromate and a nitrobenzene solution of 3-(4-pyridyl)-l,5-diphenyl pentane (PDPP) has been studied.
Abstract: The distribution equilibrium of Cr(VI) between an aqueous sulfuric acid solution of potassium bichromate and a nitrobenzene solution of 3-(4-pyridyl)-l,5-diphenyl pentane (PDPP or B) has been studied. Hydrogen chromate ion among several ionic species of Cr(VI) in the aqueous solution is extractable in the present system. The chromium concentration in the organic phase is correlated with the concentrations of hydrogen chromate and hydrogen ion in the aqueous phase with PDPP in the organic phase. The interfacial reaction rate is also obtained and it gives the equilibrium relation by equating the extraction rate with the stripping rate. Results of the freezing point depression of the organic solution and the interfacial tension, obtained for the present system, indicate that the Cr(VT)-PDPP complex in the organic phase might be the aggregation of several molecules of chromate acid and PDPP, and that the complex is surface active. A Cr(VI)-PDPP complex adsorbed at the liquid-liquid interface reacts w...
TL;DR: In this article, the electron transfer from the nitrobenzene anion radical to VN labeled nitrogen was investigated and it was found that the equilibrium constant is within experimental error of unity at 305 K. This was attributed to the shortening of the C-N bond and a counterbalancing lengthening of the N-O bonds upon electron attachment to nitrogen.
Abstract: Ion cyclotron resonance and electron spin resonance have been utilized to determine the equilibrium constant for the electron transfer from the nitrobenzene anion radical to VN labeled nitrobenzene (Ph UNO2 + Ph VNO2 in equilibrium Ph UNO2 + Ph VNO2Z. It was found that the equilibrium constant is within experimental error of unity at 305 K. Molecular orbital calculations indicate that this might be accounted for by the shortening of the C-N bond and a counterbalancing lengthening of the N-O bonds upon electron attachment to nitrobenzene. An equilibrium constant that is much larger than unity can be observed in liquid ammonia at 208 K when K serves as the gegenion (K/sub eq/ = 2.1). However, when Na serves as the gegenion, the solution electron affinity of Ph UNO2 is greater than that of Ph VNO2 (K/sub eq/ = 0.4). These results are explained in terms of ion association. When the hydrogen atoms are replaced with deuteriums, the gas phase electron affinity is decreased. A similar decrease is observed in liquid ammonia. In the gas phase this is attributed to the slight lengthening of all the C-H bonds upon electron attachment.
TL;DR: In this paper, the coexistence curves and critical parameters for solutions of nitrobenzene with a series of n-alkanes from n-pentane to n-eicosane were given.
Abstract: Coexistence curves and critical parameters are given for solutions of nitrobenzene with a series of n-alkanes from n-pentane to n-eicosane. By mixing suitable n-alkanes, a pseudosolvent was obtained and the critical properties of the nitrobenzene + pseudo-n-alkane solution were compared with those of the corresponding binary solution.
TL;DR: In this article, the diffusion coefficients of the free and protonated bipyridine in the organic and aqueous phase, text-decoration:overlineDL and DHL+, are (6.4 ± 0.3)× 10-6 cm2s−1 and (7.2 ± 0 3)× 6.3 cm2 s−1, respectively.
Abstract: 2,2′-Bipyridine can extract protons from the aqueous phase to nitrobenzene at pH 1.5–5.5. The extraction process has been investigated by chrono-potentiometry with cyclic linear current-scanning and cyclic voltammetry. The complex ion is formed in the aqueous phase by the reaction between hydrogen ion and 2,2′-bipyridine that has diffused from the organic phase. The transfer process is diffusion-controlled. The transfer species is a 1 : 1 proton–bipyridine complex. The formal transfer potential, Δwoϕ°tr, and the apparent Gibbs energy, ΔG°, w→otr, for the protonated bipyridine transfer at the water–nitrobenzene interface is found to be –0.005 V and –0.48 kJ mol–1, respectively. The distribution constant of free bipyridine between the two phases was calculated as log K= 1.3 ± 0.1. The diffusion coefficients of the free and protonated bipyridine in the organic and aqueous phase, text-decoration:overlineDL and DHL+, are (6.4 ± 0.3)× 10–6 cm2s–1 and (7.2 ± 0.3)× 10–6 cm2 s–1, respectively.
TL;DR: In this article, the results of the experimental results indicated that the stoichiometry of the chelate and the adduct extracted are Co(TTA)2and Co(TLF)2•Dbl8C6, under all the experimental conditions investigated.
Abstract: Cobalt (II) was extracted by thenoyltrifluoroacetone (HTTA) and its mixture with dibenzo-18-crown-6(Dbl8C6) at different temperatures in nitrobenzene (Nb); toluene (Tol) or their mixtures, from perchlorate aqueous media of constant ionic strength (o.l;H+,NaClO4) buffered with acetic acid-sodium acetate solutions. Slop analysis of the experimental results indicated that the stoichiometry of the chelate and the adduct extracted are Co(TTA)2and Co(TTA)2•Dbl8C6, under all the experimental conditions investigated. The extraction constants of the chelate (k2o)’ tne mixed species (k2land the formation constant of the adduct ( B2lwere evaluated for the different diluents used at the different temperatures. It was found that log k2oand log2lincrease by increasing the dielectric constant (€ ) of the diluent whereby log B2ldecreases by increasing €. These results were expressed in terms of linear free energy relationships. From the effect of the temperature on the different constants evaluated; the thermody...
TL;DR: The Fe4S4(SPh)42-42 cluster, in MeCN or MeCN-MeOH (1:1) containing t-butyl thiol and Et3N, catalyses the reduction of nitrobenzene and m-dinitrobenzinene to aniline and n-nitroaniline, respectively, with concomitant oxidation of the terminal ligand of the Fe 4S4 cluster to t -butyl phenyl disulphide, and then di-t-Butyl disULphide
Abstract: The Fe4S4(SPh)42– cluster, in MeCN or MeCN–MeOH (1:1) containing t-butyl thiol and Et3N, catalyses the reduction of nitrobenzene and m-dinitrobenzene to aniline and m-nitroaniline, respectively, with concomitant oxidation of the terminal ligand of the Fe4S4 cluster to t-butyl phenyl disulphide, and then di-t-butyl disulphide.
Patent•
30 Nov 1987
TL;DR: In this paper, a fluorine-containing aromatic diamine was shown to have excellent heat resistance, can improve water vapor resistance and reduce permittivity and was used as a basic component of polyimide, polyamide, etc.
Abstract: NEW MATERIAL:A fluorine-containing aromatic diamine shown by formula I (R l and R 2 are 1-10C perfluoroalkyl or H and a case wherein R 1 =R 2 =H is omitted). EXAMPLE: 2,2-Bis[(4-amino-2 trifluoromethylphenoxy)phenyl]hexafluoropropane. USE: Useful as a basic component of polyimide, polyamide, etc. A polymer obtained from the diamine has excellent heat resistance, can improve water vapor resistance and reduce permittivity and is extremely useful. PREPARATION: 2,2-Bis(4-hydroxyphenyl)hexafluoropropane is condensed with a nitrobenzene shown by formula II (X is halogen) in an aprotic solvent in the presence of a base to give a dinitro compound shown by formula III. Then the compound shown by formula III is reduced to give a compound shown by formula I. COPYRIGHT: (C)1989,JPO&Japio
TL;DR: In this article, the transfer behavior of acridine across the water/nitrobenzene interface at various pHs has been investigated by chronopotentiometry with linear current scanning and cyclic voltammetry.
TL;DR: In this paper, the titration curves of symmetric symmetric diamines (1,2-diaminoethane, 1,3diaminopropane, and 1,4-Diaminobutane) plus their Schiff bases with salicylaldehyde were titrated with perchloric acid in acetonitrile, nitrobenzene and acetic acid solvents.
Abstract: Four aliphatic symmetrical diamines (1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane and 1,6-diaminohexane) plus hydrazine and their Schiff bases with salicylaldehyde were titrated potentiometrically with perchloric acid in acetonitrile, nitrobenzene and acetic acid solvents. 1,2-Diaminoethane and 1,3-diaminopropane were titrated stepwise in acetonitrile, but not in nitrobenzene and acetic acid solvents. An increase in the number of methylene groups between the two amino groups increased the basicity. The basicity order of these diamines, extracted from the second half of the titration curves in all solvents, and also for their Schiff bases, was 1,6-diaminohexane > 1,4-diaminobutane > 1,3-diaminopropane > 1,2-diaminoethane > hydrazine. Among the Schiff bases, only N,N′-bis(salicylidene)-1,2-diaminoethane could be titrated differentially in acetonitrile and nitrobenzene solvents. N,N′-Bis(salicylidene)hydrazine could not be titrated even in acetic acid. However, the same compounds could be titrated in acetonitrile and nitrobenzene. Acetic acid had a very strong levelling effect on the basicity on both sides of the potential range.
Patent•
19 Oct 1987TL;DR: In this paper, high purity amino-1,3-benzenediols are prepared by contacting a 1, 3-bis(alkyl carbonato)benzene with a nitrating agent under rection conditions such that a 1 3-bis (alkylcarbonato)nitrobenzenes is formed.
Abstract: High purity amino-1,3-benzenediols are prepared by (a) contacting a 1,3-bis(alkylcarbonato)benzene with a nitrating agent under rection conditions such that a 1,3-bis(alkylcarbonato)nitrobenzene is formed, (b) contacting the 1,3-bis(alkylcarbonato)nitrobenzene with a hydrolyzing agent under conditions such that a nitro-1,3-benzenediol is produced, and (c) contacting the nitro-1,3-benzenediol with a reducing agent under conditions such that an amino-1,3-benzenediol is produced. Of the amino-1,3-benzenediols, 4,6-diamino-1,3-benzenediol is particularly useful in the preparation of high molecular weight polybenzoxazoles.
Proceedings Article•
26 Apr 1987
TL;DR: In this article, the optical Kerr effect of liquid nitrobenzene and chlorobenzene was probed with 65 fs optical pulses at 633 nm, and three non-instantaneous relaxation components were observed in each liquid, including an ultrafast relaxation with an 80 fs lifetime and the previously observed orientational relaxations.
Abstract: Abstract The optical Kerr effect of liquid nitrobenzene and chlorobenzene is probed with 65 fs optical pulses at 633 nm. We observe an instantaneous signal contribution which is attributed to the incoherent (dephased) electronic component of the third-order nonlinear susceptibility χ (3) . Additionally, three non-instantaneous relaxation components are observed in each liquid, including an ultrafast relaxation with an 80 fs lifetime and the previously observed orientational relaxations. A third relaxation component is observed in both liquids with a lifetime on the order of 450 fs. The prevailing diffusional theory of the optical Kerr effect fails to describe the temporal profile of the measured response in both liquids.
01 Jan 1987
TL;DR: The dependence of the rate of C02 formation follows the simple Langmuir expression: the rate is essentially independent of concentration above 200 p~ and becomes progressively more dependent on the concentration as it decreases as discussed by the authors.
Abstract: The oxidation of a number of aromatic compounds to carbon dioxide by exposure to near U.V. light in aqueous titanium dioxide suspensions has been studied as a function of the solute concentration. In most, the dependence of the rate of C02 formation follows the simple Langmuir expression: The rate is essentially independent of concentration above 200 p~ and becomes progressively more dependent on the concentration as it decreases. Changes in the mineralization rate are most clearly reflected in k2, the parameter determined by the limiting rate at high concentrations. A consequence of the dependence is that total mineralization is strictly never achieved but is approached asymptotically at extended illumination times. The expression and parameters are given which enable the prediction of the extent of mineralization over a wide range of concentrations. The solutes studied were benzene, benzoic acid, benzoate ion, salicylate ion, phenol, chlorobenzene, aniline, anilinium ion, nitrobenzene, chloroform and formic acid. It was confirmed that pH and oxygen concentration affect the rate of carbon dioxide formation but, in the photochemical reactor used, the rate was not significantly affected by the amount of TiOz suspended for loadings from 0.05 to 0.40 g per 400 ml.
TL;DR: Several organic solvents, including benzene, xylene, toluene, nitrobenzene, chloroform, carbon tetrachloride, chlorobenzene and high molecular-weight pyridines have been investigated as components of systems for the extraction and preconcentration of selenium from nitric acid solutions containing iodide.
Patent•
02 Dec 1987
TL;DR: In this paper, a colorant for guest-host type liquid crystal display devices, near infrared absorption films or absorption plates or colorants for optical recording materials, polyester fibers or synthetic resins.
Abstract: NEW MATERIAL:A compound expressed by formula I [R1 is cyclohexyl(oxyethyl) or 1-18C alkyl which may be interrupted by 1-3 O atoms; R2 and R3 are H, F, Cl, methyl or ethyl; A, B and C are 1-12C alkyl, 1-12C alkoxy, nitro, 2-8C dialkylamino, carboxylic acid 1-4C alkyl ester, F, Cl, Br or H]. EXAMPLE:A compound expressed by formula II. USE:A coloring matter for guest-host type liquid crystal display devices, near infrared absorption films or absorption plates or colorant for optical recording materials, polyester fibers or synthetic resins. PREPARATION:For example, 1,5-dihydroxy-4,8-dinitroanthraquinone is reacted with a compound expressed by formula III in the presence of boric acid in sulfuric acid, preferably at 0-20 deg.C to give a compound expressed by formula IV, which is then reacted with a compound expressed by formula V in a solvent, e.g. nitrobenzene, etc., at 120-180 deg.C.