- A new and efficient pyridine-2,6-dicarboxamide-based fluorescent and colorimetric chemosensor for sensitive and selective recognition of Pb2+ and Cu2+
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A new fluorene-bearing pyridine-2,6-dicarboxamide (3) as an effectint fluorescent and colorimetric cation sensor was successfully synthesized and well-characterized using FT-IR, NMR, ESI+-MS and elemental analysis. The metal ion binding ability of the chemosensor 3 in the presence of different metal ions was investigated using UV–vis, fluorescence experiments and results exhibited a desirable selectivity and significant sensitivity of the chemosensor 3 for the detection of Cu2+ and Pb2+ ions. The association constant (Ka) of 3-Cu2+ and 3-Pb2+ complexes were determined to be 8.89 × 103 M?1 and 5.65 × 108 M-2, respectively. The obtained limit of detection (LOD) values (1.49 × 10?6 M for Cu2+ and 2.31 × 10?6 M for Pb2+) clearly revealed the considerable sensitivity of the chemosensor 3.
- Hosseinzadeh, Rahman,Rahimi, Hannaneh,Tajbakhsh, Mahmood
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- A new fluorene-based Schiff-base as fluorescent chemosensor for selective detection of Cr3?+ and Al3?+
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2-((9H-fluoren-2-ylimino) methyl)phenol (F3) was synthesized by condensation reaction of 9H-fluoren-2-amine and 2-hydroxybenzaldehyde in EtOH and characterized by its melting point, 1H-,13C NMR and molecular mass. F3 exhibits a high selectivity for detection of Cr3?+ and Al3?+ ions as a fluorescent chemosensor and showed a single emission band at 536?nm upon excitation at 333?nm according to fluorescence emission studies. The addition of Cr3?+ and Al3?+ make a significant increase in fluorescent intensity at 536?nm in CH3CN, while other metal ions have almost no influence on the fluorescence. The fluorescence enhancement was attributed to the inhibited C[dbnd]N isomerization and the obstructed excited state intra-molecular proton transfer (ESIPT) of compound F3. Job's plot and DFT calculations data showed that the binding stoichiometries of F3 with Cr3?+ and Al3?+ are 2:1. The association constants (Ka) for Cr3?+ and Al3?+ were calculated and found to be 8.33?×?104?M??1 and 5.44?×?104?M??1, respectively. The detection limits were also calculated for Cr3?+ and Al3?+ and found to be 2.5?×?10??7?mol/L and 3.1?×?10??7?mol/L, respectively.
- Tajbakhsh, Mahmood,Chalmardi, Gholam Babaei,Bekhradnia, Ahmadreza,Hosseinzadeh, Rahman,Hasani, Nahid,Amiri, Mohammadreza Azizi
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- Ultrasound-promoted highly efficient reduction of aromatic nitro compounds to the aromatic amines by samarium/ammonium chloride
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Ultrasound-promoted, highly efficient reduction of several aromatic nitro compounds to the aromatic amines was achieved by samarium/ammonium chloride mediated reaction. (C) 2000 Elsevier Science Ltd.
- Basu, Manas K.,Becker, Frederick F.,Banik, Bimal K.
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- Transfer hydrogenation of nitroarenes into anilines by palladium nanoparticles via dehydrogenation of dimethylamine borane complex
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This work reports a simple and highly efficient protocol for reduction of nitroarenes to corresponding amines via dehydrogenation of dimethylamine borane using palladium nanoparticle (Pd NPs) as a versatile heterogeneous catalyst. The facile approach for the synthesis of Pd NPs within 15 min in aqueous medium has been reported. The Pd NPs were well characterized using various analytical techniques such as XRD, FEG-SEM, TEM, EDAX and XPS. The developed catalytic system uses environmentally benign dimethylamine borane as a reducing agent which is highly stable, water soluble and nontoxic. The various amines were synthesized from nitroarenes in excellent yields within 10-60 min at room temperature. The catalyst was reused up to four successive cycles without significant loss in its catalytic activity.
- Patil, Nilesh M.,Bhosale, Manohar A.,Bhanage, Bhalchandra M.
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- Comparative analysis to explore the suitability of a short chain dyad in its pristine and nanocomposite forms for designing artificial light energy conversion device
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From the UV-vis, steady state and time resolved spectroscopic investigations on the pristine dyad, dyad-spherical gold nanoparticles (GNP) and dyad-star shaped gold nanoparticles (GNS), it was observed that though in the ground state the dyad in its pristine form possesses trans-type (elongated and planar) isomer but on photoexcitation trans-form converts into cis-structure (folded). Interestingly, the dyad exhibits different behavior when it combines with GNP or GNS. In nanocomposite form, even on photoexcitation some ground state trans-structure still retains its identity in the excited state. The 60% of the trans-species remains unchanged in the excited state due to excitation of dyad-GNS system and possibly this configuration facilitates the hindrance of energy destructive charge recombination processes as in this conformer the donor and acceptor moieties tend to move far away from each other causing lack of overlapping of charge clouds within the two redox components. The dyad-GNS nanocomposite appears to be the best possible light energy conversion or storage device within the three system studied in the present investigation. Investigations are underway to examine how the degree of surface coverage of the dyad on the surface of gold nanoparticles affect its geometry or conformational changes on photoexcitation.
- Paul, Somnath,Mitra, Ishani,Dutta, Rituparna,Bardhan, Munmun,Bose, Mridul,Das, Subrata,Saha, Mithu,Ganguly, Tapan
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- Non-specific tritiation of some carcinogenic aromatic amines
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2-Aminofluorene, 4-amino-3-methylbiphenyl, 4-amino-biphenyl and 4-amino-4'-fluorobiphenyl were tritiated by acid catalyzed exchange of the corresponding nitro compounds followed by catalytic reduction. The exchange reactions were carried out by heating the nitro compounds in [3H]-trifluoroacetic acid with a catalytic amount of trifluoromethanesulphonic acid (TFMS). No loss of tritium could be detected during the conversion of the tritiated nitro compounds into the corresponding amines by catalytic hydrogenation. Incorporation into the ortho position is very low (4%). During the metabolic activation and binding of the tritiated N-acetyl-2-aminofluorene to rat liver DNA in vivo, no tritium exchange occurred.
- Breeman,Kaspersen,Westra
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p. 741 - 750,748,749
(1978)
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- Rabbit liver enzymes responsible for reduction of nitropolycyclic aromatic hydrocarbons
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The present paper is the first description of mammalian nitroreductases acting upon nitropolycyclic aromatic hydrocarbons. Rabbit liver microsomal and cytosolic fractions have ability to reduce 1-nitropyrene or 2-nitrofluorene to the corresponding amine under anaerobic conditions. The nitroreductase activity in the former fraction is mainly due to a cytochrome P-450 system and that in the latter fraction is due to aldehyde oxidase.
- Kitamura,Narai,Hayashi,Tatsumi
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- Amidofluorene-appended lower rim 1,3-diconjugate of calix[4]arene: Synthesis, characterization and highly selective sensor for Cu2+
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Functionalization of calix[4]arene with amidofluorene moieties at the lower rim led to formation of the 1,3-diconjugate of calix[4]arene L as a novel fluorescent chemosensor for Cu2+. The receptor molecule L exhibited a pronounced selectivity towards Cu2+ over other mono and divalent ions. The formation of the complex between L and Cu2+ was evaluated by absorption, fluorescence and 1H NMR spectroscopy. The sensor L showed a remarkable color change from colorless to purple and a fluorescence quenching only upon interaction with Cu2+. The 1:1 stoichiometry of the obtained complex has been determined by Job's plot. The association constant determined by fluorescence titration was found to be 1.8 × 106 M-1. The sensor showed a linear response toward Cu2+ in the concentration range from 1 to 10 μM with a detection limit of 9.6 × 10-8 M.
- Hosseinzadeh, Rahman,Nemati, Mohammad,Zadmard, Reza,Mohadjerani, Maryam
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- Ionothermal Synthesis of an Antimonomolybdate Cluster, [Sb8MoVI13MoV5O66]5-, and Its Catalytic Behavior to the Reduction of Nitrobenzene
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The largest antimonomolybdate monomer, [Sb8MoVI13MoV5O66]5- (1-Sb8Mo18), has been isolated and displays a new breakthrough of polyoxometalates (POMs) with an ionothermal synthesis strategy. 1-Sb8Mo18 features the first hexanuclear sandwich-Type polymolybdate (POMo) with an unexpected metal ring {Sb6O12} to make its debut in Sb clusters. Furthermore, 1-Sb8Mo18 exhibits a prominent catalytic activity for reducing nitrobenzene to aniline with excellent sustainability.
- Shi, Shu-Kui,Li, Xin,Guo, Hui-Li,Fan, Yan-Hua,Li, Hai-Yan,Dang, Dong-Bin,Bai, Yan
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- Half-Sandwich Ruthenium Complexes of Amide-Phosphine Based Ligands: H-Bonding Cavity Assisted Binding and Reduction of Nitro-substrates
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We present synthesis and characterization of two half-sandwich Ru(II) complexes supported with amide-phosphine based ligands. These complexes presented a pyridine-2,6-dicarboxamide based pincer cavity, decorated with hydrogen bonds, that participated in the binding of nitro-substrates closer to the Ru(II) centers, which is further supported with binding and docking studies. These ruthenium complexes functioned as the noteworthy catalysts for the borohydride mediated reduction of assorted nitro-substrates. Mechanistic studies not only confirmed the intermediacy of [Ru-H] in the reduction but also asserted the involvement of several organic intermediates during the course of the catalysis. A similar Ru(II) complex that lacked pyridine-2,6-dicarboxamide based pincer cavity substantiated its unique role both in the substrate binding and the subsequent catalysis.
- Pachisia, Sanya,Kishan, Ram,Yadav, Samanta,Gupta, Rajeev
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p. 2009 - 2022
(2021/02/06)
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- Utilization of a Hydrogen Source from Renewable Lignocellulosic Biomass for Hydrogenation of Nitroarenes
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Exploring of hydrogen source from renewable biomass, such as glucose in alkaline solution, for hydrogenation reactions had been studied since 1860s. According to proposed pathway, only small part of hydrogen source in glucose was utilized. Herein, the utilization of a hydrogen source from renewable lignocellulosic biomass, one of the most abundant renewable sources in nature, for a hydrogenation reaction is described. The hydrogenation is demonstrated by reduction of nitroarenes to arylamines in up to 95 % yields. Mechanism studies suggest that the hydrogenation occurs via a hydrogen transformation pathway.
- Tan, Fang-Fang,Tang, Kai-Li,Zhang, Ping,Guo, Yan-Jun,Qu, Mengnan,Li, Yang
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p. 4189 - 4195
(2019/03/07)
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- Hydrogenation of nitroarenes catalyzed by a dipalladium complex
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A dipalladium complex [Pd2(L)Cl2](PF6)2 (2), via the substitution of (PhCN)2PdCl2 with 5-phenyl-2,8-bis(6′-bipyridinyl)-1,9,10-anthyridine (L) followed by the anion exchange, was found to be a good pre-catalyst for the reduction of nitroarenes to yield the corresponding anilines under atmospheric pressure of hydrogen in methanol. This method provides a straightforward access to a diverse array of functionalized anilines, exhibiting a possible application in synthetic chemistry. The catalytic activity of this complex is enhanced by the di-metallic system via the synergistic effect.
- Hung, Ming-Uei,Yang, Shu-Ting,Ramanathan, Mani,Liu, Shiuh-Tzung
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- NITROGEN-CONTAINING BIOPOLYMER-BASED CATALYSTS, THEIR PREPARATION AND USES IN HYDROGENATION PROCESSES, REDUCTIVE DEHALOGENATION AND OXIDATION
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The present invention relates to a process for the preparation of a nitrogen containing biopolymer-based catalyst by pyrolysis of a metal complex with a nitrogen-containing biopolymer and to the nitrogen containing biopolymer-based catalysts obtainable by this process. In particular, the invention relates to a nitrogen containing biopolymer-based catalyst comprising metal particles and at least one nitrogen containing carbon layer. The invention also relates to the use of a nitrogen containing biopolymer-based catalyst in a hydrogenation process, preferably in a process for hydrogenation of nitroarenes, nitriles or imines; in a reductive dehalogenation process of C-X bonds, wherein X is CI, Br or I, preferably in a process for dehalogenation of organohalides or in a process for deuterium labelling of arenes via dehalogenation of organohalides; or in an oxidation process. Further, the invention relates to a metal complex with the nitrogen containing biopolymer, wherein the metal is a transition metal selected from the group consisting of manganese, ruthenium, cobalt, rhodium, nickel, palladium and platinum, preferably cobalt or nickel, and wherein the nitrogen containing biopolymer is selected from chitosan, chitin and a polyamino acid, preferably chitosan or chitin.
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Page/Page column 31-32
(2018/07/29)
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- Metal–Organic-Framework-Derived Co3S4 Hollow Nanoboxes for the Selective Reduction of Nitroarenes
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MOF-derived Co3S4/CN hollow nanoboxes (CN=nitrogen-doped carbon) was used to catalyze the chemoselective reduction of nitroarenes to anilines under mild reaction conditions with H2 as the reducing agent. The catalyst provides high conversion efficiencies and selectivities for a variety of nitroarene substrates that contain electron-donating or electron-withdrawing substituents under mild reaction conditions (in methanol at 60 °C). Further, the nanobox inhibits both dehalogenation and vinyl hydrogenation reactions, which are common limitations of state-of-the-art Pd-based catalysts. Because the reactions result in pure aniline products, the need for separation by column chromatography is eliminated. The resulting anilines are easily separated from the methanolic reaction solution in just three simple steps (centrifugation, decantation, and drying). If employed in industrial processes, catalysts of this kind would significantly reduce the amount of waste organic solvent generated and thus satisfy the need for sustainable chemical processes.
- Yang, Shuliang,Peng, Li,Sun, Daniel T.,Oveisi, Emad,Bulut, Safak,Queen, Wendy L.
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p. 3131 - 3138
(2018/09/06)
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- Unravelling 2-aminoquinazolin-4(3: H)-one as an organocatalyst for the chemoselective reduction of nitroarenes
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A novel, mild and transition metal-free, 2-aminoquinazolin-4(3H)-one-assisted reduction of nitroarenes employing hydrazine hydrate as reducing agent and potassium carbonate as a base is reported. For the first time, the activation of hydrazine hydrate with an organocatalyst has been explored for reduction reactions. Also for the first time, 2-aminoquinazolin-4(3H)-one and its derivatives have been investigated as hydrogen bonding organocatalysts for the reduction of nitroarenes to anilines. Sensitive functional groups such as sulfonamide, carboxyl, amide and halides were well tolerated in this green methodology with scalability and high chemoselectivity.
- Thakur, Maheshwar S.,Nayal, Onkar S.,Rana, Rohit,Kumar, Manoranjan,Sharma, Sushila,Kumar, Neeraj,Maurya, Sushil K.
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supporting information
p. 1373 - 1378
(2018/02/06)
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- N-doped graphitic carbon-improved Co-MoO3 catalysts on ordered mesoporous SBA-15 for chemoselective reduction of nitroarenes
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Metallic Co-MoO3 catalysts supported on ordered mesoporous SBA-15 were first prepared through in situ reaction of SBA-15-supported Co-Mo oxides with 1,10-phenanthroline. The resulting Co-MoO3/NC@SBA-15 catalysts with N-doped carbon (NC) exhibited high catalytic activity and chemoselectivity for selective reduction of various functionalized nitroarenes to the corresponding arylamines in ethanol with hydrazine hydrate at near room temperature (30 °C). For reduction of all tested substrates (28 examples), the catalyst could afford a conversion of >99% and arylamine selectivity of >99%. The excellent catalytic performance of the Co-MoO3/NC@SBA-15 was attributed to the Co-Nχ(C)-Mo active sites generated through the interaction between the surface Co-Nχ(C) and MoO3 species, promoting the dissociation of hydrazine molecule into the active H* species for the reduction of nitro groups. After the seventh cycle for reduction of 4-methoxylnitrobenzene, the 2%Co-MoO3/NC@SBA-15 showed little change in catalytic performance, textural properties, size and dispersion of metal species and valence states of elements, indicating high stability and recyclability.
- Huang, Haigen,Liang, Xiangcheng,Wang, Xueguang,Sheng, Yao,Chen, Chenju,Zou, Xiujing,Lu, Xionggang
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p. 127 - 137
(2018/05/04)
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- N-Heterocyclic Carbene-Modified Au–Pd Alloy Nanoparticles and Their Application as Biomimetic and Heterogeneous Catalysts
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The preparation of water-soluble, N-heterocyclic-carbene-stabilized Au–Pd alloy nanoparticles by a straightforward ligand exchange process is presented. Extensive analysis revealed excellent size retention and stability over years in water. The alloy nanoparticles were applied as biomimetic catalysts for aerobic oxidation of d-glucose, for which monometallic Au and Pd nanoparticles showed no or negligible activity. The alloy nanoparticles were further applied as titania-supported heterogeneous catalysts for the mild hydrogenation of nitroarenes and the semihydrogenation of 1,2-diphenylacetylene with a solvent-dependent selectivity switch between E- and Z-stilbene.
- Tegeder, Patricia,Freitag, Matthias,Chepiga, Kathryn M.,Muratsugu, Satoshi,M?ller, Nadja,Lamping, Sebastian,Tada, Mizuki,Glorius, Frank,Ravoo, Bart Jan
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supporting information
p. 18682 - 18688
(2018/11/23)
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- Biomass-Derived Catalysts for Selective Hydrogenation of Nitroarenes
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Development of catalytically active materials from biowaste represents an important aspect of sustainable chemical research. Three heterogeneous materials were synthesized from inexpensive biomass-based chitosan and abundant Co(OAc)2 using complexation followed by pyrolysis at various temperatures. These materials were applied in the catalytic hydrogenation of nitroarenes using molecular hydrogen. A variety of diversely functionalized nitroarenes including some pharmaceutically active compounds were converted into aromatic amines in high yields, with high selectivity, and with excellent functional group tolerance. This green protocol has also been implemented for the synthesis of a biologically important TRPC3 inhibitor.
- Sahoo, Basudev,Formenti, Dario,Topf, Christoph,Bachmann, Stephan,Scalone, Michelangelo,Junge, Kathrin,Beller, Matthias
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p. 3035 - 3039
(2017/08/18)
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- Catalytic application of 1,3,5-triazine-pentaethylenehexamine polymer-supported palladium nanoparticles in the convenient reduction of nitroarenes with sodium borohydride or hydrazine
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The catalytic activity of 1,3,5-triazine-pentaethylenehexamine (TAPEHA) polymer-supported Pd nanoparticles was investigated in the reduction of nitro arenes to the corresponding amines by NaBH4 or N2H4 .H2 O. Optimized reaction conditions for both systems were successfully tested on 20 nitroarenes with different characteristics. Considerably high yields (80%-98% in NaBH4 and 85%-98% in N2H4) were obtained in a short time and at ambient temperature. In addition to these methods being selective against other reducible functionalities such as -CN, -Br, -Cl, and -I, the catalyst can be recovered easily and reused more than ten times.
- Gen?, Hayriye,Zengin, Mustafa,Kü?ükislamo?lu, Mustafa,Imamoglu, Mustafa,Toplan, Hüseyin ?zkan,Arslan, Mustafa
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p. 784 - 792
(2017/11/20)
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- Chemoselective Hydrogenation of Nitroarenes Catalyzed by Molybdenum Sulphide Clusters
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Herein, we describe an atom efficient and general protocol for the chemoselective hydrogenation of nitroarenes to anilines catalyzed by well-defined diimino and diamino cubane-type Mo3S4 clusters. The novel diimino [Mo3S4Cl3(dnbpy)3]+ ([5]+) (dnbpy=4,4′-dinonyl-2,2′-dipyridyl, L1) trinuclear complex was synthesized in high yields by simple ligand substitution reactions starting from the thiourea (tu) [Mo3S4(tu)8(H2O)]Cl4?4 H2O (3) precursor. This strategy has also been successfully adapted for the isolation of the diamino [Mo3S4Cl3(dmen)3](BF4) ([6](BF4)), (dmen=N,N′-dimethylethylenediamine) salt. Applying these catalysts, high selectivity in the hydrogenation of functionalized nitroarenes has been accomplished. Over thirty anilines bearing synthetically functional groups have been synthesized in 70 to 99 % yield. Notably, the integrity of the cluster core is preserved during catalysis. Based on kinetic studies on the hydrogenation of nitrobenzene and other potential reaction intermediates, the direct reduction to aniline is the preferential route.
- Pedrajas, Elena,Sorribes, Iván,Gushchin, Artem L.,Laricheva, Yuliya A.,Junge, Kathrin,Beller, Matthias,Llusar, Rosa
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p. 1128 - 1134
(2017/03/27)
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- Co-based heterogeneous catalysts from well-defined Α-diimine complexes: Discussing the role of nitrogen
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Ar-BIANs and related α-diimine Co complexes were wet impregnated onto Vulcan XC 72 R carbon black powder and used as precursors for the synthesis of heterogeneous supported nanoscale catalysts by pyrolysis under argon at 800?°C. The catalytic materials feature a core-shell structure composed of metallic Co and Co oxides decorated with nitrogen-doped graphitic layers (NGr). These catalysts display high activity in the liquid phase hydrogenation of aromatic nitro compounds (110?°C, 50 bar H2) to give chemoselectively substituted aryl amines. The catalytic activity is closely related to the amount and type of nitrogen atoms in the final catalytic material, which suggests a heterolytic activation of dihydrogen.
- Formenti, Dario,Ferretti, Francesco,Topf, Christoph,Surkus, Annette-Enrica,Pohl, Marga-Martina,Radnik, J?rg,Schneider, Matthias,Junge, Kathrin,Beller, Matthias,Ragaini, Fabio
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- Graphene-Supported NiPd Alloy Nanoparticles for Effective Catalysis of Tandem Dehydrogenation of Ammonia Borane and Hydrogenation of Nitro/Nitrile Compounds
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Monodisperse NiPd alloy nanoparticles (NPs) are synthesized and assembled on graphene (G) or other support to provide clean, efficient catalysis of tandem reactions—dehydrogenation of ammonia borane (AB) and hydrogenation of R—NO2 and/or R—CN to R—NH2. The tandem reactions proceed quickly and with high efficiency in aqueous methanol solutions at room temperature, and the supported catalyst is readily recovered for re-use, providing a simple, efficient and ‘green’ route to the preparation of many common pharmaceutical, dye or other chemical products. NiPd alloy NPs of 3.4 nanometer size were prepared by co-reduction of nickel(II) acetate and palladium(II) acetlyacetonate by borane-tert-butylamine in oleylamine and deposited on G via a solution phase self-assembly process. The G-NiPd showed composition-dependent catalysis on the tandem reaction with G-Ni30Pd70 being the most active. A variety of R—NO2 and/or R—CN derivatives (R alkyl or aryl) were reduced selectively into R—NH2 via G-Ni30Pd70 catalyzed tandem reaction in short (5-30 minute) reaction times with conversion yields reaching up to 100%, demonstrating a new approach to G-NiPd-catalyzed dehydrogenation of AB and hydrogenation of R—NO2 and R—CN. The G-NiPd NP catalyst is efficient and is reusable; thus the reaction can be performed in an environment-friendly process with short reaction times and high yields.
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Paragraph 0022
(2016/10/17)
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- B(C6F5)3-Catalyzed Reduction of Aromatic and Aliphatic Nitro Groups with Hydrosilanes
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A transition-metal-free method for the hydrosilane reduction of aromatic and aliphatic nitro compounds to the corresponding amines is reported. Et3SiH is found to be the optimal reductant in this B(C6F5)3-catalyzed deoxygenation. The functional-group tolerance is, however, moderate.
- Porwal, Digvijay,Oestreich, Martin
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supporting information
p. 3307 - 3309
(2016/07/23)
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- Synthesis and Photoisomerization of Substituted Dibenzofulvene Molecular Rotors
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The synthesis, spectral and structural characterization, and photoisomerization of a family of 2-substituted dibenzofulvene molecular actuators based on (2,2,2-triphenylethylidene)fluorene (TEF) are reported. The 2-substituted species investigated are nitro (NTEF), cyano (CTEF), and iodo (ITEF). X-ray structures of these three compounds and three intermediates were determined to assign alkene configuration and investigate the effects of the 2-substituents on steric gearing. The addition–elimination reaction of Z-9 with trityl anion to form Z-10 proceeded with complete retention of configuration. Rates of photoisomerization were measured at irradiation wavelengths between 266–355 nm in acetonitrile/dioxane solutions at room temperature. Photoisomerization quantum yields (φ) were calculated by means of a mathematical model that accounts for a certain degree of photodecomposition in the cases of CTEF and ITEF. Quantum yields vary significantly with substituent, having maximum values of φ=0.26 for NTEF, 0.39 for CTEF, and 0.50 for ITEF. NTEF is photochemically robust and has a large quantum yield for photoisomerization in the near-UV, making it a particularly promising drive rotor moiety for light-powered molecular devices.
- Everhart, Stephanie C.,Jayasundara, Udaya K.,Kim, HyunJong,Procúpez-Schtirbu, Rolando,Stanbery, Wayne A.,Mishler, Clay H.,Frost, Brian J.,Cline, Joseph I.,Bell, Thomas W.
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p. 11291 - 11302
(2016/08/03)
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- Fe2O3/NGr@C- and Co-Co3O4/NGr@C-catalysed hydrogenation of nitroarenes under mild conditions
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An improved hydrogenation of nitroarenes using nano-structured iron- and cobalt-based catalysts is presented. Modifications of the heterogeneous catalysts by N-doped graphene-flakes are crucial for the success of selective reductions. The use of polar solvents and basic additives has a significant positive influence on the rate of reduction of nitroarenes. This allows performing non-noble metal-catalysed hydrogenations under very mild reaction conditions (e.g. 70 °C and 20 bar). On the basis of the obtained catalytic results a heterolytic mechanism for the hydrogenation process is postulated, too.
- Formenti, Dario,Topf, Christoph,Junge, Kathrin,Ragaini, Fabio,Beller, Matthias
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p. 4473 - 4477
(2016/07/06)
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- USE OF THERMALLY-TREATED SUPPORTED COBALT CATALYSTS COMPRISING A POLYCYCLIC AROMATIC STRUCTURE CONSISTING OF NITROGEN LIGANDS FOR HYROGENATING AROMATIC NITRO COMPOUNDS
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The invention relates to the use of thermally-treated supported cobalt catalysts for hydrogenating aromatic nitro compounds, the cobalt catalysts having been prepared by in situ immobilization of a cobalt-amine complex on an inorganic porous support and subsequent pyrolysis, and, in the cobalt-amine complex used, cobalt being present bonded to an aromatic or heterocyclic nitrogen ligand L, the nitrogen ligand being selected so as to form a polyaromatic structure with the cobalt atom.
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Paragraph 0031; 0032
(2015/11/16)
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- Efficient reductions of various nitroarenes with scrap automobile catalyst and NaBH4
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The effect of scrap automobile catalyst (SAC), a waste material, was investigated as a catalyst for the reduction of nitroarenes to the corresponding amines with sodium borohydride in aqueous ethanol at 5-25 °C. Along with the observed high conversions, the SAC and NaBH4 combination also exhibits a selectively catalyzed reduction in compounds containing other reducible functionalities, such as CN, Br, Cl and I. Recycling automobile wastes into a catalyst for organic reactions will offer both environmental protection and economic advantages. As a result, an effective, easy to use, low-priced and reliable method has been developed.
- Genc, Hayriye
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- Reduction of nitroarenes using CO and H2O in the presence of a nanostructured cobalt oxide/Nitrogen-Doped Graphene (NGr) catalyst
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The most common route to anilines is based on the reduction of the corresponding nitroarenes. In general, hydrogen is preferred as reducing agent and numerous catalytic systems are known to achieve such transformations. Besides, the use of CO/H2O as hydrogen source offers interesting possibilities for reductions. Carbon monoxide is a cheap and abundant chemical used on industrial scale for a variety of transformations. Although the reduction of nitroarenes with CO/H2O is known in the presence of noble-metal catalysts, earth-abundant inexpensive catalysts showing high selectivity have not yet been developed. In this respect, herein we present the use of a heterogeneous cobalt oxide catalyst (Co3O4/NGr@C), which is modified by nitrogen-doped graphene layers. Using this non-noble metal catalyst nitroarenes are reduced in high yields and good chemoselectivities.
- Westerhaus, Felix A.,Sorribes, Ivn,Wienh?fer, Gerrit,Junge, Kathrin,Beller, Matthias
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supporting information
p. 313 - 317
(2015/03/05)
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- Nitrogen-doped graphene-activated iron-oxide-based nanocatalysts for selective transfer hydrogenation of nitroarenes
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Nanoscaled iron oxides on carbon were modified with nitrogen-doped graphene (NGr) and found to be excellent catalysts for the chemoselective transfer hydrogenation of nitroarenes to anilines. Under standard reaction conditions, a variety of functionalized and structurally diverse anilines, which serve as key building blocks and central intermediates for fine and bulk chemicals, were synthesized in good to excellent yields.
- Jagadeesh, Rajenahally V.,Natte, Kishore,Junge, Henrik,Beller, Matthias
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p. 1526 - 1529
(2015/03/14)
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- Efficient and highly selective boron-doped carbon materials-catalyzed reduction of nitroarenes
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Exploring the potential catalytic applications of boron-doped carbon materials is a fascinating challenge. Here we describe that boron-doped onion-like carbon and carbon nanotubes as metal-free catalysts exhibit excellent catalytic activity and stability in nitroarene reduction under a stoichiometric amount of reductant.
- Lin, Yangming,Wu, Shuchang,Shi, Wen,Zhang, Bingsen,Wang, Jia,Kim, Yoong Ahm,Endo, Morinobu,Su, Dang Sheng
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p. 13086 - 13089
(2015/08/18)
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- Solid supported rhodium(0) nanoparticles: An efficient catalyst for chemo- and regio-selective transfer hydrogenation of nitroarenes to anilines under microwave irradiation
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A Solid-supported rhodium(0) (SS-Rh) catalyst has been developed and applied for the chemo- and regio-selective reduction of nitroarenes functionalized with CC multiple bonds and dinitroarenes to their corresponding amines respectively using hydrazine hydrate (N2H4· H2O) as a reducing source under mild microwave irradiation (MWI) conditions. The present methodology also shows excellent compatibility with a broad range of structurally diverse reducible functional groups. The catalyst can be recovered by simple filtration and reused for 13 cycles with consistent activity hence reduces the cost of the catalyst assertively.
- Guha, Nitul Ranjan,Bhattacherjee, Dhananjay,Das, Pralay
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supporting information
p. 2912 - 2916
(2014/05/06)
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- Iron and palladium(II) phthalocyanines as recyclable catalysts for reduction of nitroarenes
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Iron(II) and palladium(II) phthalocyanines have been established as recyclable heterogeneous catalysts for the reduction of aromatic nitro compounds to corresponding amines using diphenylsilane/sodium borohydride as hydrogen sources in ethanol. Various reducible functional groups, such as acetyl, ester, cyano, amide, sulphonamide and carboxylic acid etc. were well tolerated, and the methods were applicable up to gram scale. Mechanistic studies showed that reduction of nitro group proceed through direct (nitroso) pathway and possibly iron or palladium phthalocyanines activates nitro group for reduction. FePc and PdPc also catalyzed the generation of hydrogen from the combination of diphenylsilane/sodium borohydride and ethanol.
- Verma, Praveen Kumar,Bala, Manju,Thakur, Kavita,Sharma, Upendra,Kumar, Neeraj,Singh, Bikram
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p. 1258 - 1267
(2014/07/21)
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- Surfactant-free hydrothermal synthesis of sub-10 nm γ-Fe 2O3-polymer porous composites with high catalytic activity for reduction of nitroarenes
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Porous γ-Fe2O3-polymer composites were synthesized by a novel one-pot surfactant-free hydrothermal approach. The γ-Fe2O3-polymer composites consisting of 3.5 nm γ-Fe2O3 nanoparticles and porous polymers exhibited high catalytic activity and recycling performance in the reduction of nitroarenes. The Royal Society of Chemistry 2013.
- Gu, Xianmo,Sun, Zhenhua,Wu, Shuchang,Qi, Wei,Wang, Haihua,Xu, Xianzhu,Su, Dangsheng
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supporting information
p. 10088 - 10090
(2013/10/22)
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- Hydrogenation of nitroarenes using defined iron-phosphine catalysts
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A novel iron-catalyzed hydrogenation of nitroarenes to the corresponding amines is reported. An in situ combination of Fe(BF4) 2·6H2O and phosphine allows for highly selective hydrogenation of a broad range of aromatic and nitroarenes tolerating different functional groups.
- Wienhoefer, Gerrit,Baseda-Krueger, Mario,Ziebart, Carolin,Westerhaus, Felix A.,Baumann, Wolfgang,Jackstell, Ralf,Junge, Kathrin,Beller, Matthias
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supporting information
p. 9089 - 9091
(2013/09/24)
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- Solid supported Pd(0): An efficient recyclable heterogeneous catalyst for chemoselective reduction of nitroarenes
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Solid supported palladium(0) (SS-Pd) catalyzed highly chemoselective reduction of nitroarenes to the corresponding anilines was accomplished under a milder reaction condition. This catalyst showed high compatibility with various reducing agents (NaBH4, Et3SiH, and NH2NH 2·H2O) and a large number of reducible functional groups such as sulfonamide, amides, carboxylic acid, ester, alcohol, halide, hetero cycle, nitrile, alkene, carbonyl, O-benzyl, and N-benzyl were tolerated. Most of the reactions were clean and high yielding. The SS-Pd catalyst could be recycled up to seven runs without significant loss of activity.
- Shil, Arun K.,Sharma, Dharminder,Guha, Nitul Ranjan,Das, Pralay
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supporting information; experimental part
p. 4858 - 4861
(2012/09/08)
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- Pinacol as a new green reducing agent: Molybdenum-catalyzed chemoselective reduction of sulfoxides and nitroaromatics
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Pinacol is disclosed as a new chemoselective and environmentally benign reducing agent for sulfoxides and nitroaromatics assisted by readily available dichlorodioxomolybdenum(VI) complexes as catalysts. A wide range of substrates including those bearing challenging functional groups has been efficiently and selectively reduced with acetone and water being the only by-products of these reactions. Copyright
- Garcia, Nuria,Garcia-Garcia, Patricia,Fernandez-Rodriguez, Manuel A.,Rubio, Ruben,Pedrosa, Maria R.,Arnaiz, Francisco J.,Sanz, Roberto
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supporting information; experimental part
p. 321 - 327
(2012/04/11)
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- LIGHT-DRIVEN ROTARY MOLECULAR MOTORS
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Compounds of Formula (1) are disclosed. Cb is a carbocyclic or heterocyclic group having an atom within the cyclic structure selected from C, N, Si, and Cr and singly bound to A. A is CR, COR, CSR, CNR2, CCN, CCONR2, CNO2, CNNAr, CX′, or N. Cr is a chromophore having a substantially planar cyclic structure. The compounds function as nanometer-scale rotary molecular motors powered and controlled by light energy. The design of the molecular motor devices is flexible so that the rotary direction, drive light wavelength, and other physical characteristics can be varied. The compounds can be chemically functionalized to allow it to be integrated into or attached to a variety of structures. The device can be used in applications where mechanical power, positional control, and information encoding are to be generated at the size scale of individual molecules.
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Page/Page column 15
(2011/04/19)
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- Scope and selectivity of heterogeneous Rh0-catalyzed tandem dehydrocoupling/hydrogenation using Me2NHA·BH 3 as a stoichiometric H2 source
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The catalytic dehydrocoupling of Me2NHA·BH 3 (1) by Rh/Al2O3 (2) has been shown to act as an efficient hydrogenation and reduction system for a variety of organic substrates. A range of functional groups have been reduced, but chloro, bromo and iodo substituents, epoxide and nitrile groups were found to be stable under the reaction conditions, allowing chemoselective hydrogenation reactions to be performed. This reduction has also been shown to proceed cleanly under atmospheric air for a few representative examples of alkene and nitro functional groups. The use of dimethylamine-borane in a the presence of Rh0 has been shown to function as an efficient hydrogenation/reduction system for a variety of organic substrates. This system has been shown to be mild by comparison to other reduction systems with epoxide, halide and nitrile groups unaffected under the reaction conditions used.
- Sloan, Matthew E.,Staubitz, Anne,Lee, Kajin,Manners, Ian
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supporting information; experimental part
p. 672 - 675
(2011/03/22)
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- A new class of heterogeneous platinum catalysts for the chemoselective hydrogenation of nitroarenes
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A new series of nanostructured platinum catalysts able to catalyze the selective reduction of nitroarenes has been developed. The materials, made of organosilica physically doped with nanostructured platinum(0), are stable and efficient. Reactions in general proceed with high yield and often go to completion, while the catalysts can be reused in further reaction runs. This establishes a new class of relevant solid catalysts for synthetic organic chemistry named SiliaCat Platinum-Hydrogel.
- Pandarus, Valerica,Ciriminna, Rosaria,Beland, Francois,Pagliaro, Mario
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scheme or table
p. 1306 - 1316
(2011/06/25)
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- Phosphane-free green protocol for selective nitro reduction with an iron-based catalyst
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Iron phthalocyanine with iron sulfate has been successfully applied for high chemo- and regioselective reduction of aromatic nitro compounds to give the corresponding amines in a green solvent system without using any toxic ligand. The catalytic systems were also compatible with a large range of other reducible functional groups, such as keto, acid, amide, ester, halogen, lactone, nitrile, N-benzyl, O-benzyl, hydroxy, and heterocycles. In the present study, dinitro compounds have been regioselectively reduced to the corresponding amines with high yield. In most of the cases the conversion and selectivity was greater than 99% as determined by GC-MS analysis. Copyright
- Sharma, Upendra,Verma, Praveen Kumar,Kumar, Neeraj,Kumar, Vishal,Bala, Manju,Singh, Bikram
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experimental part
p. 5903 - 5907
(2011/06/20)
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- Efficient and highly selective iron-catalyzed reduction of nitroarenes
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Pyrolysis of iron-phenanthroline complexes supported on carbon leads to highly selective catalysts for the reduction of structurally diverse nitroarenes to anilines in 90-99% yields. Excellent chemoselectivity for the nitro group reduction is demonstrated.
- Jagadeesh, Rajenahally V.,Wienhoefer, Gerrit,Westerhaus, Felix A.,Surkus, Annette-Enrica,Pohl, Marga-Martina,Junge, Henrik,Junge, Kathrin,Beller, Matthias
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supporting information; experimental part
p. 10972 - 10974
(2011/10/31)
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- Synthesis and structure of benzotriazolyl fluorenes
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1-(Fluoren-2-yl)-benzo[d][1,2,3]triazoles 5a-b were synthesized starting from 2-nitrofluorene. 2-Nitrofluorenes 1a-b were reduced by catalytic hydrogenation, reacted with 2,4-dinitrofluorobenzene followed by catalytic hydrogenation to afford 2-(N-2,4-diaminophenyl)aminofluorenes 4a-b. Diazotization of 4a-b with NaNO2/H2SO4 followed by treatment with H3PO2 gave 5a-b. Sulfonation of 5a-b yielded 7-benzotriazol-1-yl-fluorene-2-sulfonic acids 6a-b. The structures of 5b and 6b were firmly identified by X-ray crystal analysis in addition to 1H NMR, 13C NMR, and elemental analysis.
- Park, Kwanghee Koh,Jung, Hyemi,Lee, Taewoo,Kang, Sung Kwon
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experimental part
p. 984 - 988
(2010/10/18)
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- Iron-catalyzed selective reduction of nitroarenes to anilines using organosilanes
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The iron-catalyzed reduction of aromatic nitro compounds to the corresponding anilines applying organosilanes is reported. In the presence of FeX2-R3P catalysts a series of nitroarenes is selectively reduced tolerating a wide range of functional groups.
- Junge, Kathrin,Wendt, Bianca,Shaikh, Nadim,Beller, Matthias
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experimental part
p. 1769 - 1771
(2010/07/06)
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- Facile Transfer Hydrogenation of Azo Compounds to Hydrazo Compounds and Anilines by Using Raney Nickel and Hydrazinium Monoformate
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Azo compounds are conveniently reduced to either partially reduced hydrazo compounds or completely reduced anilines by employing Raney nickel in presence of hydrazinium monoformate depending upon reaction conditions. The other reducible moieties like -COOH and halogens are tolerated. The reduction process is selective, rapid and high yielding.
- Prasad,Gowda, Shankare,Gowda, D. Channe
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- Facile synthesis of biologically active heterocycles by indium-induced reactions of aromatic nitro compounds in aqueous ethanol
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Indium/ammonium chloride-induced reduction of aromatic nitro compounds to aromatic amines in aqueous ethanol was developed. Useful chemoselectivity was observed in the reduction reaction. This method was extended to reductive cyclization and rearrangement toward the synthesis of various biologically active heterocycles, including quinoline, oxazines, quinalonones, and phenanthridine in excellent yield. The oxophilicity of indium metal influenced the reaction in aqueous ethanol. Metals like zinc and tin were not effective in promoting this kind of reactions under the present environmentally friendly conditions.
- Banik, Bimal K.,Banik, Indrani,Samajdar, Susanta,Wilson, Mary
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p. 283 - 296
(2007/10/03)
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- Rapid cleavage of azo compounds to amine/s using Raney nickel and ammonium formate or formic acid
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Azo compounds, both symmetrical and unsymmetrical are cleaved to amine/s by using Raney nickel and ammonium formate or formic acid in methanol at room temperature. The reductive cleavage is very fast, clean, cost effective and high yielding as compared to earlier methods and many other functionality such as -OH, -CH3 -OCH3, -COOH, -COCH3 and halogen remained unaffected.
- Gowda, D. Channe,Gowda, Shankare,Abiraj
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p. 1774 - 1776
(2007/10/03)
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- DNA adducts from nitroreduction of 2,7-dinitrofluorene, a mammary gland carcinogen, catalyzed by rat liver or mammary gland cytosol
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Nitrofluorenes are mutagenic and carcinogenic environmental pollutants arising chiefly from combustion of fossil fuels. Nitro aromatic compounds undergo nitroreduction to N-hydroxy arylamines that bind to DNA directly or after O-esterification. This study analyzes the DNA binding and adducts from the in vitro nitroreduction of 2,7-dinitrofluorene (2,7-diNF), a potent mammary carcinogen in the rat. Potential adduct(s) of 2,7-diNF was (were) generated by reduction of 2-nitroso-7-NF with ascorbate/H+ in the presence of calf thymus DNA. The major adduct was characterized by HPLC/ESI/MS and 1H NMR spectrometry as N-(deoxyguanosin-8-yl)-2-amino-7-NF, and a minor one was determined by HPLC/ESI/MS to be a deoxyadenosine adduct of 2-amino-7-NF. Products from enzymatic nitroreduction were monitored by HPLC and DNA adduct formation by 32P-postlabeling. Xanthine oxidase/hypoxanthine-catalyzed nitroreduction of 2,7-diNF, 2-nitrofluorene (2-NF), and 1-nitropyrene (1-NP) yielded the respective amines to similar extents (30-50%). However, the level of the major adducts (～0.15/106 nucleotides) from 2-NF [N-(deoxyguanosin-8-yl)-2-aminofluorene] and 2,7-diNF [N-(deoxyguanosin-8-yl)-2-amino-7-NF] was ≤2% that from 1-NP. In the presence of acetyl CoA, nitroreduction of 2-NF catalyzed by rat liver cytosol/NADH yielded the same adduct at a level of 2.2/106 nucleotides. Liver or mammary gland cytosol with acetyl CoA yielded mainly N-(deoxyguanosin-8-yl)-2-amino-7-NF from 2,7-diNF at >30 adducts/106 nucleotides, levels comparable to those from 1,6-dinitropyrene and 4- or 49-fold greater than the respective levels without acetyl CoA. Recovery of 2-nitroso-7-NF and 2-amino-7-NF from cytosol-catalyzed reduction of 2,7-diNF indicated nitroreduction and an N-hydroxy arylamine intermediate. Likewise, the presence of 2-acetylamino-7-NF indicated that reactivity with acyltransferase(s) was not prevented by the nitro group at C7. These data are consistent with activation of 2,7-diNF via nitroreduction to the N-hydroxy arylamine and acetyl CoA-dependent O-acetylation of the latter to bind to DNA. Enzymatic nitroreduction of 2,7-diNF was greatly enhanced by 9-oxidation. The nitroreduction of either 9-oxo-2,7-diNF or 9-hydroxy-2,7-diNF catalyzed by liver cytosol with acetyl CoA yielded two adducts (>2/106 nucleotides). Differences in the TLC migration of these adducts, compared to those from 2,7-diNF, and the lack of 2,7-diNF formation in the incubations suggested retention of the C9-oxidized groups. The relative ratios of the amine to amide from nitroreductions of 9-oxo-2,7-diNF and 2,7-diNF catalyzed by liver cytosol suggested that the 9-oxo group decreased reactivity with acyltransferase and, thus, the amount of N-acetoxy arylamine that binds to DNA. The mammary gland tumorigenicity of 2,7-diNF and the extent of its activation by the tumor target tissue shown herein suggest relevance of this environmental pollutant for breast cancer.
- Ritter, Clare L.,Culp, Sandra J.,Freeman, James P.,Marques, M. Matilde,Beland, Frederick A.,Malejka-Giganti, Danuta
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p. 536 - 544
(2007/10/03)
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- Antitumor dibenzofluorene derivatives
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Dibenzofluorene derivatives having a formula selected from the group consisting of and salts thereof have antitumor activity. At least one of R1-R13in formula (I) or R1-R12in formula (II) is —R14Z. R14is a substituted or unsubstituted amino or amido group having from 1-12 carbon atoms, and Z is a substituted or unsubstituted heterocyclic group having from 1-12 carbon atoms. The remainder of R1-R13in formula (I) or R1-R12in formula (II) are independently selected from the group consisting of hydrogen, hydroxyl, halogen, nitro, substituted or unsubstituted amino or amido groups having from 1-12 carbon atoms, and alkyl groups having 1-12 carbon atoms.
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- Indium/ammonium chloride mediated selective reduction of aromatic nitro compounds: Practical synthesis of 6-aminochrysene
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Reduction of aromatic and heteroaromatic nitro compounds to the corresponding amino compounds was achieved by indium/ammonium chloride induced reaction in aqueous ethanol. This method was extended for the preparation of large quantities of 6-aminochrysene in excellent yield.
- Banik,Suhendra,Banik,Becker
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p. 3745 - 3754
(2007/10/03)
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- Reductions of nitro and 9-oxo groups of environmental nitrofluorenes by the rat mammary gland in vitro
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Nitrofluorenes and C-9-oxidized nitrofluorenes are widespread environmental genotoxins which may be relevant for breast cancer on the basis of their carcinogenicities, particularly of 2,7-dinitrofluorene (2,7-diNF), for the rat mammary gland. Since their metabolism to active carcinogens may involve nitroreduction, this study examined the reduction of 2-nitrofluorene (2-NF) and 2,7-diNF and their 9-oxo- and 9-hydroxy (OH) derivatives by the rat mammary gland. Cytosolic fractions catalyze NADH- and NADPH-dependent reductions of the 2-nitro and 9-oxo to the respective 2-amino and 9-OH compounds at rates 4- and ≥10-fold greater than those with microsomes. Rates of amine formation catalyzed by cytosol from 2,7-diNF are greater than the rate from 2-NF and increase for C-9-oxidized derivatives: 9-oxo-2-NF >> 9-OH-2-NF > 2-NF and 9-OH-2,7-diNF 9-oxo-2,7-diNF >> 2,7-diNF. Nitroreduction is inhibited by O2 or allopurinol (20 μM), dicoumarol (100 μM), and rutin (50 μM). 9-Oxoreduction is inhibited by rutin, dicoumarol, and indomethacin (100 μM), but not by O2 or allopurinol. Pyrazole or menadione does not inhibit nitro or 9-oxoreduction. Xanthine, hypoxanthine, 2-hydroxypyrimidine, and N'-methylnicotinamide support cytosol-catalyzed nitro, but not 9-oxo, reduction. The data suggest that the nitroreduction is catalyzed largely by a xanthine oxidase and partially by a diaphorase and 9-oxoreduction by a carbonyl reductase. The extents of the nitro and carbonyl reductions of the nitrofluorenes may determine their reactivities with DNA, and thus genotoxicities for the mammary gland.
- Ritter,Decker,Malejka-Giganti
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p. 793 - 800
(2007/10/03)
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- Efficient method for the synthesis of N-cyclic maleamic acids and N-cyclic maleimides
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Provided are methods for the synthesis of N-cyclic maleamic acids and N-cyclic maleimide derivatives, as well as N-cyclic maleamic acids and N-cyclic maleimides synthesized thereby. The method for synthesis of an N-cyclic maleamic acid involves reacting an amino group-containing N-cyclic compound with maleic anhydride in acetic acid to obtain an N-cyclic maleamic acid. An N-cyclic maleimide can be formed by adding hexamethyldisilazane to an N-cyclic maleamic acid prepared according to the above-described method, thereby cyclizing a maleamic acid site of the N-cyclic maleamic acid. The described methods allow for the products to be obtained at high yields.
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- Nitroreduction of nitrated and C-9 oxidized fluorenes in vitro
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Widespread environmental pollution with mutagenic and carcinogenic nitrofluorenes contributes to human health risks. Since nitroreduction leads to activation of many nitro compounds, nitroreduction of the nitrofluorene (NF) derivatives by one- and two-electron reductants was examined. Rates of nitroreduction catalyzed by xanthine oxidase (XO)/hypoxanthine and measured via stimulation of acetylated cytochrome c reduction increased with the number of nitro groups and oxidation at C-9: 9-oxo-2,4,7-triNF > 9-oxo-2,7- diNF > 2,7-diNF > 9-oxo-2-NF = 2,5-diNF > 9-hydroxy-2-NF > 2-NF. Ascorbate catalyzed one-electron reduction to nitro anion radicals which reacted with molecular O2 to yield superoxide. Rates of O2 uptake with 9-oxo-2,4,7- triNF and 9-oxo-2,7-diNF were 63 and 0.17 times those, respectively, with equivalent concentrations of nitrofurazone, a classical substrate. Superoxide formation was indicated by the ~75% regeneration of O2 upon addition of superoxide dismutase and catalase. 9-Oxo-2,4,7-triNF stimulated O2 uptake in the presence of XO/NADH with typical Michaelis-Menten kinetics with an apparent K(m) of 0.476 ± 0.054 μM versus a K(m) of 6.18 ± 0.719 μM for nitrofurazone. HPLC analyses of products from reduction catalyzed by XO or diaphorase of Clostridium with NADH showed the following trends for the rates of amine formation from 9-oxo-2,7-diNF > 2,7-diNF; 9-oxo-2-NF > 9-hydroxy-2- NF > 2-NF; 2,7-diNF > 2-NF; and 9-oxo-2,7-diNF > 9-oxo-2-NF. Little or no amine was formed in 95% O2, suggesting O2-labile intermediates. The data herein suggest that oxidation at C-9 and multiple nitro groups increase the potential for nitroreduction of the nitrofluorenes in vivo which may lead to genotoxic effects.
- Ritter, Clare L.,Malejka-Giganti, Danuta
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p. 1361 - 1367
(2007/10/03)
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