Showing papers on "Nitrobenzene published in 1976"

Toxicity of and biological monitoring for 1,3-diamino-2, 4, 6-trinitrobenzene and other nitro-amino derivatives of benzene and chlorobenzene.

Abstract: Methaemoglobin-forming capacity of 1,3-diamino-2,4,6-trinitrobenzene (DATNB) was studied in vivo as well as in vitro and compared with those of aniline, phenylenediamine (o- and p-), nitroaniline (o-, m- and p-), nitrobenzene, dinitrobenzene (o-, m- and p-), 1,3,5-trinitrobenzene, chloroaniline (o-, m- and p-), chloronitrobenzene (o-, m- and p-), and 1-chloro-2,4-dinitrobenzene. m-Chloronitrobenzene and two isomers (m- and p-) of dinitrobenzene were the most potent methaemoglobin formers in vivo and it was p-dinitrobenzene when studied in vitro, while the capacity of DATNB was much lower both in vivo and in vitro, being comparable to those of aniline and nitrobenzene. The exposure monitoring by means of the urinalysis for diazo-positive metabolite(s) is applicable to all the compounds studied except DATNB and o-phenylenediamine; conversion of DATNB to the diazo-positive metabolite(s) in urine was very limited, indicating poor metabolism in vivo. Cumulative effects of DATNB was also discussed.

Electron donor sites and acid-base properties of oxide surfaces, as studied by electron spin resonance spectroscopy

Abstract: The electron donor properties of several oxide powders (CaO, MgO, ZnO, Al2O3, SiO2–Al2O3), activated in vacuo at temperatures up to 1200 K, have been investigated using the e.s.r. of adsorbed nitrobenzene radicals as a probe.The results show the existence of a correlation between the electron donor activity of oxides and their Lewis base strength, indicating a direct connection between basic centres and donor surface states.The variations of the AN| parameter of adsorbed nitrobenzene radicals with the nature of the surface are attributed to the extent of interaction of radicals with surface protons, and are therefore related to the Bronsted acidity of the surface. The dual nature of the active site is discussed.

Solvation of the nitrobenzene radical anion

Abstract: An electrostatic solvation model within the INDO approximation, representing the interaction with the solvent by means of an effective solvent field, is applied to the nitrobenzene radical anion. The available solvent sensitivity data for the 1H, 13C, 14N and 17O hyperfine coupling constants are satisfactorily reproduced. The results are consistent with the assumption of a planar structure of the radical, in contrast with the results of a recent theoretical study.

Stabilized anaerobic adhesives

Abstract: A curable anaerobic adhesive composition is provided in which a nitrobenzene, particularly a chlorinated nitrobenzene, is incorporated as a stabilizer. The nitrobenzene stabilizer is particularly useful in anaerobic compositions having polyethylene glycol dimethacrylate as a basic polymerizable monomer.

The coextraction of water into nitrobenzene with alkali metal salts of hexanitrodiphenylamine in the presence of dibenzo-18-crown-6.

Abstract: The hydration numbers of alkali metal cations and their complex cations with dibenzo-18-crown-6 in water-saturated nitrobenzene were determined. The complexation causes a clear decrease in hydration number, indicating that the water molecules hydrated have partly been replaced by the six oxygen atoms of dibenzo-18-crown-6.

Method of stabilizing pyrophorous iron powder

Abstract: The stabilization of pyrophorous iron powder in a liquid medium can be carried out in a very short time and particularly carefully when the powders are contacted with organic compounds which contain nitrogen bound to oxygen, for example, nitromethane, nitrobenzene or nitrosobenzene.

Positron and positronium annihilation in benzene solutions

Abstract: Positron annihilation in nitrobenzene and manganese oleate solutions in benzene was studied in the liquid and solid states using both lifetime and angular correlation methods. It was found that a long lifetime component (τ2~1.3 ns) appeared in the lifetime spectrum for the solid state of a nitrobenzene solution in benzene but not in the liquid state. The results are briefly discussed.

ESR Studies of Nitrobenzene Ion-Pair Equilibria in N,N-Dimethylformamide

Abstract: The hyperfine splitting constants of the nitrobenzene radical anion in DMF vary with the type of the counter cations and the concentrations. The tendency of these variations is related to the shift of the half-wave reduction potential of nitrobenzene. The variation of the nitrogen 14N hyperfine splitting constant is attributable to the formation of ion pairs involving the nitrobenzene radical anion and its counter cation. The ion-pair formation constants were evaluated from the changes in the hyperfine splitting and are completely consistent with those obtained from polarographic studies.

Studies in the formation of heterocyclic rings containing nitrogen: Part XXIII. Condensation ofo-aminobenzamide with aldehydes and schiff bases

Abstract: N-Arylidene orthanilamides undergo isomeric cyclisation in acetic acid to the corresponding 2-aryl-1, 2, 3, 4-tetrahydro-4-oxoquinazolines. The u.v. and n.m.r. spectra of some of the arylidene derivatives and their isomeric tetrahydroquinazolines have neeb studied. Condensation ofo-aminobenzamide either with aromatic aldehydes in nitrobenzene or Schiff bases in acetic acid has yielded 2-aryl-4 (3H)-quinazolinones.

Die Rolle der Wasserstoffbrückenbindung bei der ionenassoziation von Ammoniumsalzen

Abstract: The dissociation constants of quinuclidinium chloride have been determined in dimethylsulfoxide (DMSO), dimethylacetamide (DMA), dimethylformamide (DMF), propanediol-1,2-carbonate (PDC), acetonitrile (AN), nitromethane (NM) and nitrobenzene (NB). The data suggest that the H-atom bonded to the N-atom is sufficiently acidic in order to form H-bridges either with the chloride ion or with solvent molecules. In contrast to the failure of elementary electrostatic models the results have been successfully interpreted by the coordination chemical approach which takes into account the different nucleophilic and electrophilic properties of the solvents.

Cathodic reduction of nitrobenzene on the packed-bed copper electrode.

Abstract: An application of a packed-bed copper electrode to the formation of aniline by the cathodic reduction of nitrobenzene was investigated. As the particles for the packed-bed, spherical particles of an anion exchange resin chemically plated with copper were successfully used. Though the current efficiency for the aniline formation on the packed-bed electrode in a batch cell decreased with continuing electrolysis, the efficiency was improved by the electrolysis under a flowing electrolyte and became very high, i.e., near 100%. This is due to the removal of the accumulated products on the electrode surface by the flowing electrolyte. The effective depth of the bed electrode on which the nitrobenzene reacted cathodically was also determined from the measurement of the potential profile in a packed-bed electrode: the result was about 3 mm. This low value of the effective depth is ascribed to the low conductivity of the electrolyte and to the high electronic conductivity of the packed-bed. This may be improved by...

Process of semicontinuously producing aniline condensed dyes

Abstract: An aniline condensed dye is semicontinuously prepared from aniline and nitrobenzene (and/or alkylanilines, alkylnitrobenzenes, diazoaminobenzene and the like) in the presence of a catalyst such as hydrochloric acid and iron chloride by dividing a reaction system into two or more sections and maintaining each section at a different reaction temperature.

Studies of Sulfonyl Radicals. III. Solvent Effects on the Thermal Decomposition of Benzyl Phenylazo Sulfone

Abstract: The first-order rate constants for thermal decomposition of benzyl phenylazo sulfone (BPA, 1) have been determined spectrophotometrically in six solvents using the free radical scavenging technique with a stable Koelsch free radical. Activation parameters in the non-polar solvents such as benzene, toluene, anisole and chlorobenzene were almost the same, but in the two polar solvents, pyridine and nitrobenzene, activation entropies decreased significantly as compared with those in the non-polar solvents. This can be explained by the solvation of the polar solvent in the transition state leading to a phenyldiazenyl and α-toluenesulfonyl radical pair.

Hydrogen-1 nuclear magnetic resonance studies of the ion association of some unsymmetrically substituted tetra-alkylammonium tribromo(triphenylphosphine)cobaltate(II) complexes in various solvents

Abstract: The concentration association constant of [NMe(n-C8H17)3][CoBr3(PPh3)] in nitrobenzene at 34 °C has been determined by n.m.r. spectrometry. On comparing this result with those obtained earlier for [NRBun3][CoBr3(PPh3)](R = Me and Bun), it is concluded that the symmetry of the cation plays a very important role in determining the extent of ion association for this type of ion-pair complex. There is a linear correlation between the observed difference in isotropic shift of the N-methyl and N-methylene protons and the dielectric constant (Iµ) of the solvents for Iµ⩽ 10, but not at higher values of Iµ. This is interpreted in terms of the preferred orientation of the N-methyl group towards the anion, the decrease in interionic distance with decreasing Iµ, the formation of micelles in solvents of low dielectric constant, and the 1:1 ion-pair formation in solvents of higher dielectric constant. The problem of analyzing the concentration dependence of observed isotropic shifts in solvents of low dielectric constant is discussed.

Excess volume of mixing of some polar and nonpolar liquids with propylene carbonate

Abstract: The excess volume of mixing as a function of composition has been measured at 30°C and 40°C for mixtures of propylene carbonate with nitrobenzene, chlorobenzene, benzene, toluene, cyclohexane, dioxane, carbon tetrachloride, and chloroform. The highly polar nitrobenzene forms an ideal mixture with propylene carbonate. Chloroform, carbon tetrachloride, dioxane, chlorobenzene, benzene, and toluene give negative volume changes on mixing. In mixtures with cyclohexane,VmE is positive at lower mole fractions of cyclohexane but becomes negative as the mole fraction of cyclohexane increases.

Cationic polymerization of vinyl monomers initiated by phosphorus compounds containing halogens

Abstract: Polymerization of vinyl monomers having large negative e values in the presence of phosphorus compounds containing halogens was studied in order to examine the cationic initiation ability of phosphorus compounds. N-Vinylcarbazole was effectively polymerized by phosphorus compounds such as PCI3, PBr3, PCI2C6H5, PCI(C6H5)2, POCI3, and POCI2C6H5 even in benzene. The initiation ability of phosphorus compounds decreased in the order; PCI2 ≃ PBr3 > PCI2C6H5 > PCI(C6H5)2, and also POCI3 > POCI265. On the other hand, PCI3 and PBr3, which were less effective than POCI3, showed initiation ability for the polymerizations of styrene and α-methylstyrene in nitrobenzene as a solvent. The results of the copolymerization of styrene with methyl methacrylate by PCI3 in nitrobenzene, the result of solvent dielectric constant effect, and the effect of additives such as water, tert-butyl chloride, triethylamine, and hydroquinone, indicate the polymerization of styrene by PCI3 to proceed by a cationic mechanism.

Alkoxy-aminobenzene electrolytic prodn. - by nitrobenzene redn. in acidic methanol soln., useful as dye intermediates

Abstract: Prepn. of amino- methoxybenzene (I) comprises electrolytic reduction of nitrobenzene (II), having one ortho or the para posn. unsubstd., in a soln. comprising CH3OH and an acid. (II) is esp. nitrobenzene opt. with additionally 1-4 alkyl substits., 1-2 halo, OH, NH2, alkylamino, CN, alkoxy, COOH, SO3H, HCO and/or alkylester substits., and/or one more NO2 gp. Pref. the methanolic soln. contains up to 30 wt. % H2SO4 and reaction is at up to l5 degrees C. They are prepd. simply in a single-stage process which can be operated at low temp. and does not demand precise pH control.

Para-nitro-phenetole prepn. - from para-chloro-nitrobenzene and ethanol in di:methyl sulphoxide

Abstract: Pren. of p-nitrophenetole (I) comprises reacting p-chloronitrobenzene (II) with EtOH in DMSO in the presence of an alkali metal hydroxide. (I) can be reduced to p-phenetidine, a dyestuffs intermediate. Carrying out the reaction in DMSO ensures high yields (e.g. 93-97%) and gives a high-purity product free of traces of (II).

Cleaning and protecting light metal surfaces - with mixt. of paraffin oil and solvents for synthetic resins

Abstract: A cleaning compsn. contains nitrobenzene and paraffin oil for cleaning, care and formation of a layer protecting anodised light meals, esp. Al, against corrosion, discolouration and soiling. In this addn., nitrobenzene is replaced by a solvent for synthetic resins, e.g. benzene, toluene or xylene, or by C2HCl3. Cleaning is intensified. Protective layer has no great affinity towards dirt particles.