Microdetermination of aromatic nitro compounds

Conclusion A method was proposed for the microdetermination of nitro compounds, which is based on their reduction to amines by heating with potassium iodide and orthophosphoric acid.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 658–659, March, 1971.     

The reduction of aromatic nitro compounds by oxiranes

Aromatic nitro compounds are reduced to the corresponding amines by epoxides at elevated temperatures (>170 °C).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1491–1494, August, 1994.The authors are grateful to Prof. Yu. N. Belokon' for his participation in the discussion of the results of the work.This work was financially supported by the Russian Foundation for Basic Research (code No. 93-03-18044).     

Microdetermination of nitro compounds. I

Summary A specific colorimetric method is described for the determination of nitroanthraquinones. It is dependent on the red color produced on treatment of the sample with tetraethylene pentamine or imino bis-propylamine. The color is stable and is not affected by the presence of water in the system.

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Zusammenfassung Eine spezifische kolorimetrische Methode zur Bestimmung von Nitro-anthrachinonen wurde beschrieben. Sie beruht auf der bei Behandlung der Probe mit Tetraäthylenpentamin oder mit Iminobispropylamin auftretenden Rotfärbung. Diese ist beständig und wird von anwesendem Wasser nicht beeinflußt.

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Résumé On décrit une méthode colorimétrique spécifique pour doser les nitro-anthraquinones. Elle met en jeu la couleur rouge produite en traitant l'échantillon par la tétra-èthylénepentamine ou par l'imino bis-propylamine. La coloration est stable et n'est pas affectée par la présence d'eau dans le système.

     

Bromination of deactivated polycyclic aromatic nitro compounds

Bromination of 2,7-dinitro-9,10-phenanthrenequinone, 2,5-dinitro-9,10-phenanthrenequinone, and 2,4,7-trinitrofluorenone with bromine in concentrated sulfuric acid in the presence of acetic acid gave, respectively, 4-bromo-2,7-dinitro-9,10-phenanthrenequinone, 2-bromo-4,7-dinitro-9,10-phenanthrenequinone, and 5-bromo-2,4,7-trinitrofluorenone. No bromination occurred in the absence of nitric acid. The same brominated polynitro compounds can be obtained under analogous conditions directly from unsubstituted 9,10-phenanthrenequinone and fluorenone.     

Reduction of aromatic nitro compounds with phosphine

The reduction of 1- and 2-nitronaphthalene and of some mono- and dinitro-biphenyls with phosphine was carried out under the conditions described by Buckler.¹ Reduction of 1-nitro-naphthalene did not yield any crystalline product while reduction of 2-nitronaphthalene yielded benzo[f]naphtho[2,1-c]cinnoline-N-oxide together with 2,2′-azoxynaphthalene. The mononitro-biphenyls and 4,4′-dinitrobiphenyl were readily reduced to azoxy compounds, while reduction of 2,2′-dinitrobiphenyl gave benzo[c]cinnoline-N,N′-dioxide.     

Synthesis of azo compounds by nanosized iron-promoted reductive coupling of aromatic nitro compounds

Treatment of a variety of aromatic nitro compounds with the active-iron based reducing system composed of FeCl₂·4H₂O, an excess of lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB, 5 mol %) in THF at room temperature, led to the formation of the corresponding symmetrically substituted azo compounds in good yield, resulting from a reductive coupling process. Some other functionalities including carbonyl, halogen, amino and hydroxyl groups, demonstrated to be compatible with the reaction conditions, giving none reduced or coupled by-products. In all cases, the azo compounds formed have not experienced over-reduction to the corresponding hydrazo or amino derivatives even upon prolonged heating or using an excess of the reducing system.     

Determination of nanogram amounts of primary aromatic amines and nitro compounds in blood and plasma.

A rapid and highly sensitive method, based on the direct fluorimetric scanning of thin-layer chromatograms, is described for the quantitative determination of flunitrazepam and its main metabolites in human blood or plasma. This method is generally applicable to aromatic nitro compounds that are reducible with tin(II) chloride. In particular, it is possible to determine primary amines in nanogram amounts. Fluorescamine is used as a regent to produce fluorescent derivatives. The method is suitable for pharmacokinetic studies of flunitrazepam and its main metabolites in human blood and plasma.     

Ammonia in the ion source. II. Clustering with aromatic nitro compounds

Under positive ion chemical ionization conditions with ammonla at relatively low pressure, aromatic nitro compounds do not form [M + H]⁺ ions but often form ionic clusters [M + NH₄]⁺ and [M + N₂H₇]⁺. Nitrobenzene forms a cluster [2M + NH₄]⁺ and aniline, formed by nucleophilic substitution, leads to a cluster [anilinium ion + nitrobenzene]⁺. The dinitrobenzenes form [M + NH₄]⁺ clusters and show evidence of nitroaniline formation and clustering. 1,3,5-Trinitrobenzene gives little indication of clustering or of substitution. The six isomers of trinitrotoluene appear to be stabilized by the methyl group and form clusters up to [M + N₃H₁₀]⁺. Nucleophilic substitution leads to dinitrotoluidines, which also form clusters with ammonium ions.     

The Raman spectra of some aromatic nitro compounds

The paper provides a re-appraisal of the analytical value of Raman spectroscopy in the investigation of aromatic nitro compounds. Correlations are found between the frequencies of the NO vibrations and the electron-donating and -withdrawing effects of substituents on the phenyl rings. Further, relations are discussed between the highest-frequency CH stretching mode and the electron density and number of nitro groups. The paper contains a large number of spectra of typical aromatic nitro compounds.     

High-pressure synthesis of carbamates by the carbonylation of aromatic nitro compounds in cyclohexanol

A study was carried out on the high-pressure carbonylation of nitrobenzene and 3-chloronitrobenzene by CO in cyclohexanol in the presence of PdCl₂-FeCl₃-pyridine with the formation of cyclohexyl-N-phenylcarbamate and cyclohexyl-N-3-chlorophenylcarbamate in 90–95% yield and nitro compound conversion of 95–99%. The feasibility of the repeated use of this catalyst was demonstrated.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1885–1887, August, 1991.     

Spectrophotometric determination of reducing sugars with aromatic nitro compounds

Summary It has been found that mononitro-aromatic compounds can be used as quite sensitive reagents for determination of reducing sugars, and use of 2-, 3- and 4-nitrobenzoic and 3-nitrobenzenesulphonic acids has been investigated. Reduction of these reagents with sugars gives a yellow product which can be determined spectrophotometrically. The sugar (0.5–7 mg) is heated with fixed concentrations of reagent, base and sodium potassium tartrate for a prescribed time, at 100° C. The method can also be used for determination of the number-average molecular weight of dextran fractions if the molecular weight is not too high.

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Spektrophotometrische Bestimmung reduzierender Zucker mit aromatischen Nitroverbindungen

Zusammenfassung Aromatische Mononitroverbindungen lassen sich als ziemlich empfindliche Reagenzien zur Bestimmung reduzierender Zucker verwenden. 2-, 3-und 4-Nitrobenzoesäure und 3-Nitrobenzolsulfonsäure wurden zu diesem Zweck verwendet. Die Reduktion dieser Reagenzien durch Zucker gibt eine Gelbfärbung, die spektrophotometrisch ausgewertet werden kann. Der Zucker (0,5-7 mg) wird mit einer bestimmten Menge Reagens sowie mit einer Base und Seignettesalz für eine bestimmte Zeit auf 100° C erhitzt. Das Verfahren kann auch für die Bestimmung des durchschnittlichen Molekulargewichtes von Dextranfraktionen verwendet werden, soferne diese nicht zu hochmolekular sind.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

Catalytic hydrogenation of aromatic nitro compounds by non-noble metal complexes of chitosan

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.     

Identificatini and determination of aromatic nitro compounds by electron spin resonance spectrometry

Aromatic nitro compounds are quantitatively converted to the corresponding anion-radical form by electron tranfer at the surface of thermally activated magnesium oxide. The radicals are stable in the absorbed state, and the reaction is useful for the identification and determination of the parent compound. The method is applied to detect and quantify various nitrobenzenes, nitrotoluenes and teryl by electron spin resonance spectrometry. For 2,4,6-trinitrotoluene (TNT), the detection limit was ca. 10 ng; the r.s.d. at the 2 μg level was ± 1.8%. The analysis of hand-swab extracts that contained TNT at the trace levels demonstrateds a potentially important application of the method.