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).     

Catalytic oxidation of 1-hexene with molecular oxygen by iridium nitro complexes

The oxidation of 1-hexene by molecular oxygen catalyzed by iridium(III) complexes, [Ir(CH₃CN)_5−xCl_x(NO₂)]^2−x (x=0, 1, or 2) has been studied in acetonitrile under P(O₂)=1.5 atm and T=100°C. [Ir(CH₃CN)₅(NO₂)](PF₆)₂ oxidizes 1-hexene to 1,2-epoxyhexane. Complex [Ir(CH₃CN)₄Cl(NO₂)]PF₆ oxidizes 1-hexene to 2,3-epoxyhexane only in the presence of [Pd(PhCN)₂(Cl)₂] (an olefin activator). In contrast to the cationic complexes, the neutral complex [Ir(CH₃CN)₄Cl₂(NO₂)] oxidizes 1-hexene to 2-hexanone only in the presence of [Pd(PhCN)₂(Cl)₂].     

活性炭负载氢氧化氧铋催化水合肼还原芳香族硝基化合物

采用浸渍法制备了BiO(OH)/C催化剂。催化剂的XRD谱表明,当催化剂中BiO(OH)的质量分数小于10%时,BiO(OH)在活性炭中高度分散。反应温度为75 ℃时,催化剂重复使用7次仍保持较高活性。在5 mL乙醇中以0.05 g 10%（质量分数）BiO(OH)/C,1 mmol芳香族硝基化合物和2 mmol水合肼于75 ℃反应一定的时间,所得芳胺的收率为88%～99%。     

The synthesis of azo compounds from nitro compounds using lead and triethylammonium formate

Aromatic nitro compounds were reduced to the corresponding symmetrically substituted azo compounds using lead as catalyst and triethylammonium formate as hydrogen donor. Various azo compounds containing additional reducible substituents including halogens, nitrile, acid, phenol, ester, methoxy functions, etc, have been synthesized in a single step by the use of this reagent. The conversion is reasonably fast, clean, high yielding and occurs at room temperature in methanol.     

Highly efficient reduction of nitro compounds: Recyclable Pd/C-catalyzed transfer hydrogenation with ammonium formate or hydrazine hydrate as hydrogen source

Herein, we described a highly efficient heterogeneous Pd/C-catalyzed transfer hydrogenation of nitro compounds for the synthesis of primary amines, using ammonium formate and hydrazine hydrate as hydrogen source independently. The products were obtained with up to >99% yield. Furthermore, gram scale and recycling of catalyst had been tested with well results.     

新型多孔芳香骨架材料用于硝基爆炸物的检测

采用付玫瑰苯胺与对苯二甲醛通过希夫碱偶联反应制备了新型的多孔芳香骨架材料.经过FTIR,TGA,PXRD,SEM,TEM和Ar吸附等分析方法对多孔芳香骨架材料的成键方式和骨架结构进行了表征.分析结果显示,该多孔芳香骨架材料具有优异的热稳定性(350℃仅失重5%)和溶剂稳定性,其Langmuir比表面积约为472m~2/g.紫外光谱和荧光光谱测试分析表明,该材料在苯、甲苯和氯苯等芳香化合物环境中无明显的荧光强度变化.然而在硝基爆炸物环境中会发生灵敏的、专一的荧光淬灭现象.该多孔材料可应用于硝基爆炸物的检测.     

Some peculiarities of the effect of molecular structure on the activation energy of radical gas-phase decay of aromatic nitro compounds

The relation of parameters of geometric and electronic structures to the activation energies of the radical gas-phase decomposition of nitro compounds is shown. A sufficiently simple and precise method for calculation of the activation energy is suggested.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2118–2122, December, 1994.     

Palladium-catalysed transfer hydrogenation of aromatic nitro compounds — an unusual chain elongation

Aromatic nitro compounds are reduced via transfer hydrogenation in the presence of palladium on magnesium-lanthanum mixed oxide support in ethanol yielding the corresponding amines. With several acetophenone derivatives, the reduction was accompanied by chain elongation whilst the carbonyl group remained intact.     

Selective hydrogenation of aromatic compounds using modified iridium nanoparticles

Till now, Ionic liquid‐stabilized metal nanoparticles were investigated as catalytic materials, mostly in the hydrogenation of simple substrates like olefins or arenes. The adjustable hydrogenation products of aromatic compounds, including quinoline and relevant compounds, aromatic nitro compounds, aromatic ketones as well as aromatic aldehydes, are always of special interest, since they provide more choices for additional derivatization. Iridium nanoparticles (Ir NPs) were synthesized by the H₂ reduction in imidazolium ionic liquid. TEM indicated that the Ir NPs is worm‐like shape with the diameter around 12.2 nm and IR confirmed the modification of phosphine‐functionalized ionic liquids (PFILs) to the Ir NPs. With the variation of the modifier, solvent and reaction temperature, substrate like quinoline and relevant compounds, aromatic nitro compounds, aromatic ketones as well as aromatic aldehydes could be hydrogenated by Ir NPs with interesting adjustable catalytic activity and chemoselectivity. Ir NPs modified by PFILs are simple and efficient catalysts in challenging chemoselective hydrogenation of quinoline and relevant compounds, aromatic nitro compounds, aromatic ketones as well as aromatic aldehydes. The activity and chemoselectivity of the Ir NPs could be obviously impacted or adjusted by altering the modifier, solvent and reaction temperature.     

Catalytic transfer hydrogenation of aromatic nitro compounds in the presence of nickel thiolato-complexes

Summary Transfer hydrogenation of aromatic nitro compounds by hydrazine to the corresponding anilines is catalyzed by (Bu₄N)[Ni(tdt)₂] (tdt=toluene-3,4-dithiolate) and analogous Ni^III complexes in refluxing THF; hydroxylamine derivatives are formed as intermediates.     

Developments in transfer hydrogenations of aromatic ketones catalyzed by boron compounds

Boron complexes BL1 and BL2 were prepared from O-donor ligands, 2,2′-(1E,1′E)-(ethane-1,2-diylbis(azan-1-yl-1-ylidene))bis(methane-1-yl-1-ylidene)diphenol (L1) and 2,2′-(propane-1,3-diylbis(azan-1-yl-1-ylidene))bis(methane-1-yl-1-ylidene)diphenol (L2). The complexes were fully characterized by ¹H and ¹³C NMR, LC-MS/MS, TGA/DTA, UV-Vis, elemental analysis, SEM, and FTIR. The transfer hydrogenation of acetophenone derivatives was investigated by the boron complexes in the presence of isoPrOH, as the hydrogen source, under basic condition with NaOH. The results showed that the boron complexes were promising catalytic precursors for transfer hydrogenation of aromatic ketones in 0.1 M isoPrOH solution (up to 99%). Both steric and electronic factors of this class of molecules had a significant impact on the catalytic properties.     

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.     

Asymmetric hydrogenation ofN-acetyldehydrodipeptide complexes with Mg(II) and Ca(II) ions

N-Ac--Phe-AA form labile complexes with Mg(II) ions. Potentiometric titration data show that the carboxyl group of the dehydrodipeptide in them scarcely participates in complexation, unlike the complexes with Ca(II) ions. The hydrogenation of these complexes over Pd/C occurs asymmetrically, the diastereomeric excess being as high as 58%.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 601–602, March, 1993.     

Propylene oxidation by palladium nitro and nitrato complexes: in situ NMR and IR studies

The mechanism of the propylene oxidation by Pd(NO_n)Cl_2 − m(CH₃CN)₂ complexes (n = 2, 3; m = 0, 1, 2) in chloroform solutions has been studied by ¹H NMR and IR spectroscopy. The main reaction products are acetone and 2-nitropropylene, with their ratio depending on the equilibrium existing in the reaction solutions between palladium complexes containing NO_n ligands bonded to a palladium atom via either an oxygen or a nitrogen atom. Reactivities of the oxygen bonded nitrato and nitrito complexes are significantly higher than that of the nitrogen bonded nitro complex. Various new organopalladium intermediates have been observed and monitored in situ. A reversible insertion of the coordinated propylene into the Pd-O or Pd-N bonds results in nitrato-, nitrito- and nitropalladation intermediates, which then decompose via a β-hydrogen elimination. Two isomers of the nitritopalladation intermediate have been detected, i.e., a palladium metallacycle and an open ring complex, with the latter being much more reactive towards the β-hydrogen elimination than the former. The decomposition of the nitrato- and nitritopalladation intermediates results in the organometallic precursor of acetone, i.e., an acetonylpalladium complex, and then in acetone itself. On the other hand, the nitropalladation intermediate originates 2-nitropropylene. In the presence of dioxygen, which re-oxidizes the nitrosyl groups, the acetone formation becomes a catalytic reaction with respect to both palladium and nitrogen.     

The nitro aromatic compounds detection by triazole carboxylic acid and its complex with the fluorescent property

The 5-methyl-1-(4-nitrophenyl)-1H-1, 2, 3-triazole-4-carboxylic acid (1) was synthesized by an improved method. By using the compound 1 as ligand, a new complex [Cu(L)₂][Cu(L)₂(H₂O)₂] (2) was prepared firstly under hydrothermal condition. Both 1 and 2 were all used as exclusive fluorescence sensor for 2, 4, 6-trinitrophenol (TNP) for the first time. The fluorescence exploration demonstrated that they exhibit highly selective and sensitive (K_SV = 393685 M^?1 and K_SV = 213269 M^?1, respectively) sensing to TNP from other nitro aromatic compounds (NACs) with high quenching efficiency QP value of 96.76% and 93.37%, as well as low detection limit (0.68 μM and 0.37 μM, respectively). It means that complex 2 had higher selectivity due to the less interference by 4-NT and 2-NP compared with 1. Moreover, the fluorescence quenching phenomenon of sensor 1 with TNP was analyzed by density functional theory (DFT).     

氰基化合物非均相加氢制备有机胺的研究进展

介绍了不同结构的氰基化合物加氢还原制备有机胺的研究工作,重点对用非均相催化剂的氰基化合物加氢研究现状进行了综述,指出高性能催化剂的开发仍是今后研究的主要方向。     

Nucleophilic aromatic substitution of hydrogen through lithiated phosphine borane complexes and N-phosphorylphosphazenes

Organophosphorus compounds containing nitroaryl and cyanoaryl groups have been prepared in good yield through nucleophilic aromatic substitution of hydrogen using α-lithiated phosphazenes and phosphine borane complexes as nucleophiles. In all cases, nearly exclusive replacement of the hydrogen in the para position with respect to the activating group has been observed.     

Reduction of aromatic compounds with Al powder using noble metal catalysts in water under mild reaction conditions

In water, Al powder becomes a powerful reducing agent, transforming in cyclohexyl either one or both benzene rings of aromatic compounds such as biphenyl, fluorene and 9,10-dihydroanthracene under mild reaction conditions in the presence of noble metal catalysts, such as Pd/C, Rh/C, Pt/C, or Ru/C. The reaction is carried out in a sealed tube, without the use of any organic solvent, at low temperature. Partial aromatic ring reduction was observed when using Pd/C, the reaction conditions being 24 h and 60 °C. The complete reduction process of both aromatic rings required 12 h and 80 °C with Al powder in the presence of Pt/C.