- Nonlinear Hammett relationships in the reaction of peroxomonosulfate anion (HOOSO-3) with meta-and para-substituted anilines in alkaline medium
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The HOOSO-3 oxidation of eleven meta-and para-substituted anilines to the corresponding nitrosobenzenes at pH ≈ 11 was characterized by the rate equation v = kK[OX][An]/(1 + K[An]). Formation constant of the reactive intermediate and its rate of decomposition were evaluated separately for ascertaining the structure-reactivity relationships. Under the experimental conditions the dianion, -O-O-SO-3 is probably the effective electrophile. Kinetic data can be rationalized by a bimolecular process which involves the attack of nucleophilic nitrogen atom on the peroxidic oxygen. The highlight of the study is the opposite curvatures observed in the nonlinear Hammett plots of first-order rate constant k and the "equilibrium" constant K, being concave downward and upward, respectively.
- Meenakshisundaram, Subbiah,Sockalingam, Ramanathan
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Read Online
- Photochromic Evaluation of 3(5)-Arylazo-1 H-pyrazoles
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The desire to photocontrol molecular properties ranging from materials to pharmacology using light as an external trigger with high spatiotemporal resolution led to the development of a broad range of photochromic scaffolds. Among them, azobenzenes are synthetically well accessible and show excellent fatigue resistance. Their photochromic properties vary with the substitution pattern and for different heteroarenes. However, the photochromism of 3(5)-substituted-1H-pryazoles has not yet been investigated, although this compound class offers interesting possibilities of metal ion coordination and hydrogen bond formation via its NH moiety. Herein, we present the results of an experimental and computational investigation of arylazo-3(5)-arylazo-1H-pyrazoles. To elucidate their properties, solvent and substitution effects on their light absorption, thermal half-lives, photostationary states, fatigue, and quantum yields were determined.
- Rustler, Karin,Nitschke, Philipp,Zahnbrecher, Sophie,Zach, Julia,Crespi, Stefano,K?nig, Burkhard
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Read Online
- Zr(OH)4-Catalyzed Controllable Selective Oxidation of Anilines to Azoxybenzenes, Azobenzenes and Nitrosobenzenes
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The selective oxidation of aniline to metastable and valuable azoxybenzene, azobenzene or nitrosobenzene has important practical significance in organic synthesis. However, uncontrollable selectivity and laborious synthesis of the expensive required catalysts severely hinders the uptake of these reactions in industrial settings. Herein, we have pioneered the discovery of Zr(OH)4 as an efficient heterogeneous catalyst capable of the selective oxidation of aniline, using either peroxide or O2 as oxidant, to selectively obtain various azoxybenzenes, symmetric/unsymmetric azobenzenes, as well as nitrosobenzenes, by simply regulating the reaction solvent, without the need for additives. Mechanistic experiments and DFT calculations demonstrate that the activation of H2O2 and O2 is primarily achieved by the bridging hydroxyl and terminal hydroxyl groups of Zr(OH)4, respectively. The present work provides an economical and environmentally friendly strategy for the selective oxidation of aniline in industrial applications.
- Long, Yu,Luo, Nan,Ma, Jiantai,Qin, Jiaheng,Sun, Fangkun,Wang, Wei David,Zhou, Pan-Pan
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supporting information
(2021/12/09)
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- Rhodium(III)-catalyzed regioselective C–H nitrosation/annulation of unsymmetrical azobenzenes to synthesize benzotriazole N-oxides via a RhIII/RhIII redox-neutral pathway
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A Rh(III)-catalyzed regioselective C–H nitrosation/annulation reaction of unsymmetrical azobenzenes with [NO][BF4] has been developed to achieve high-yielding syntheses of benzotriazole N-oxides with excellent functional group tolerance. Computational studies have revealed that this oxidative C–H functionalization reaction involves an interesting redox-neutral Rh(III)/Rh(III) pathway without the change of Rh oxidation state.
- Zhang, Yuanfei,Chen, Zhe-Ning,Su, Weiping
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supporting information
(2021/05/19)
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- Phenylimino Indolinone: A Green-Light-Responsive T-Type Photoswitch Exhibiting Negative Photochromism
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Imines are photoaddressable motifs useful in the development of new generations of molecular switches, but their operation with low-energy photons and control over isomer stability remain challenging. Based on a computational design, we developed phenylimino indolinone (PIO), a green-light-addressable T-type photoswitch showing negative photochromism. The isomerization behavior of this photoactuator of the iminothioindoxyl (ITI) class was studied using time-resolved spectroscopies on time scales from femtoseconds to the steady state and by quantum-chemical analyses. The understanding of the isomerization properties and substituent effects governing these photoswitches opens new avenues for the development of novel T-type visible-light-addressable photoactuators based on C=N bonds.
- Buma, Wybren Jan,Crespi, Stefano,Di Donato, Mariangela,Doria, Sandra,Feringa, Ben L.,Hilbers, Michiel F.,Kiss, Ferdinand L.,Simeth, Nadja A.,Stindt, Charlotte N.,Szymański, Wiktor,Toyoda, Ryojun,Wesseling, Sammo
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supporting information
p. 25290 - 25295
(2021/10/25)
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- Light-Promoted C–N Coupling of Aryl Halides with Nitroarenes
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A photochemical C–N coupling of aryl halides with nitroarenes is demonstrated for the first time. Catalyzed by a NiII complex in the absence of any external photosensitizer, readily available nitroarenes undergo coupling with a variety of aryl halides, providing a step-economic extension to the widely used Buchwald–Hartwig C–N coupling reaction. The method tolerates coupling partners with steric-congestion and functional groups sensitive to bases and nucleophiles. Mechanistic studies suggest that the reaction proceeds via the addition of an aryl radical, generated from a NiI/NiIII cycle, to a nitrosoarene intermediate.
- Li, Gang,Yang, Liu,Liu, Jian-Jun,Zhang, Wei,Cao, Rui,Wang, Chao,Zhang, Zunting,Xiao, Jianliang,Xue, Dong
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supporting information
p. 5230 - 5234
(2021/02/05)
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- Tungstate-supported silica-coated magnetite nanoparticles: a novel magnetically recoverable nanocatalyst for green synthesis of nitroso arenes
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Tungstate ion was heterogenized on the silica-coated magnetite nanoparticles and applied for the selective oxidation of anilines to nitroso arenes—with hydrogen peroxide/urea as oxidant in dimethyl carbonate as solvent—in moderate–good yields (40–96%). The catalyst was characterized using different techniques including Fourier-transform infrared spectroscopy, X-ray powder diffraction, vibrating sample magnetometry, scanning electron microscopy, energy dispersive X-ray and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The catalyst was easily recovered using an external magnet and reused for six times.
- Jadidi Nejad, Masoume,Yazdani, Elahe,Kazemi Miraki, Maryam,Heydari, Akbar
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p. 1575 - 1583
(2019/09/09)
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- Generation of alkyl radicals from alkylsilyl peroxides and their applications to C-N or C-O bond formations
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This article describes a novel method for the generation of alkyl radicals from alkylsilyl peroxides and their applications to the Cu-catalyzed mono-N-alkylation of amides or arylamines, and to the O-alkylation of carboxylic acids. The use of alkylsilyl peroxides as alkyl radical sources includes the following synthetic advantages: i) various alkylsilyl peroxides can be readily synthesized from the corresponding alcohols and be stored at bench, and ii) a variety of alkyl radicals can be generated efficiently under mild conditions.
- Sakurai, Shunya,Kato, Terumasa,Sakamoto, Ryu,Maruoka, Keiji
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p. 172 - 179
(2018/12/11)
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- A novel synthesis of N-hydroxy-3-aroylindoles and 3-aroylindoles
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A straightforward indole synthesis via annulation of C-nitrosoaromatics with conjugated terminal alkynones was realised achieving a simple, highly regioselective, atom- and step economical access to 3-aroylindoles in moderate to good yields. Further functionalizations of indole scaffolds were investigated and an easy way to JWH-018, a synthetic cannabinoid, was achieved.
- Ieronimo, Gabriella,Palmisano, Giovanni,Maspero, Angelo,Marzorati, Alessandro,Scapinello, Luca,Masciocchi, Norberto,Cravotto, Giancarlo,Barge, Alessandro,Simonetti, Marco,Ameta, Keshav Lalit,Nicholas, Kenneth M.,Penoni, Andrea
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supporting information
p. 6853 - 6859
(2018/10/20)
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- Synthesis of Nitrosobenzene Derivatives via Nitrosodesilylation Reaction
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The electrophilic ipso-substitution of trimethylsilyl-substituted benzene derivatives into nitrosobenzene derivatives is reported. The optimization of the reaction conditions was performed for moderately electron-deficient, electron-rich, and sterically hindered starting materials by varying reaction time, temperature, and equivalents of NOBF4. Also, a stable intermediate of the nitrosation reaction could be characterized by 19F NMR which can be assigned to a NO+ adduct with the nitrosobenzene derivative. This complex decomposes upon aqueous workup and liberates the desired nitrosobenzene derivative.
- Kohlmeyer, Corinna,Klüppel, Maike,Hilt, Gerhard
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p. 3915 - 3920
(2018/04/14)
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- Synthesis of Di(hetero)arylamines from Nitrosoarenes and Boronic Acids: A General, Mild, and Transition-Metal-Free Coupling
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The synthesis of di(hetero)arylamines by a transition-metal-free cross-coupling between nitrosoarenes and boronic acids is reported. The procedure is experimentally simple, fast, mild, and scalable and has a wide functional group tolerance, including carbonyls, nitro, halogens, free OH and NH groups. It also permits the synthesis of sterically hindered compounds.
- Roscales, Silvia,Csák?, Aurelio G.
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supporting information
p. 1667 - 1671
(2018/03/23)
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- Rh(III)-Catalyzed bilateral cyclization of aldehydes with nitrosos toward unsymmetrical acridines proceeding with C-H functionalization enabled by a transient directing group
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A Rh(iii)-catalyzed bilateral cyclization was developed for the efficient construction of acridines proceeding with C-H functionalization whereby in situ formation and removal of an imino transient directing group in the presence of catalytic amount of BnNH2 are achieved. In this transformation, a sequential Rh(iii)-catalyzed C-H amination, cyclization, and aromatization process was involved.
- Hu, Weiming,Zheng, Qingheng,Sun, Song,Cheng, Jiang
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supporting information
p. 6263 - 6266
(2017/07/07)
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- A versatile synthesis of triarylantimony difluorides by fluorination of triarylstibanes with nitrosyl tetrafluoroborate and their antitumor activity
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Triarylantimony difluorides were synthesized in moderate to excellent yields by oxidative fluorination of triarylstibanes with nitrosyl tetrafluoroborate (NOBF4) under aerobic conditions. This reaction is the first example of fluorination of trivalent organoantimony compounds using NOBF4 as a fluorinating agent. The triarylantimony difluorides exhibited good anti-proliferation activity against tumor cell lines. In particular, the IC50 of p-Tol3SbF2 (2c) was the lowest in each cell lines.
- Kitamura, Yuki,Matsumura, Mio,Murata, Yuki,Yamada, Mizuki,Kakusawa, Naoki,Tanaka, Motohiro,Okabe, Hiroyuki,Naka, Hiroshi,Obata, Tohru,Yasuike, Shuji
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- Titania-Supported Gold Nanoparticles Catalyze the Selective Oxidation of Amines into Nitroso Compounds in the Presence of Hydrogen Peroxide
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In this article, the catalytic activity of titania-supported gold nanoparticles (Au/TiO2) was studied for the selective oxidation of amines into nitroso compounds using hydrogen peroxide (H2O2). Gold nanoparticles deposited on Degussa P25 polymorphs of titania (TiO2) have been found to promote the selective formation of a variety of nitroso arenes in high yields and selectivities, even in a large-scale synthesis. In contrast, alkyl amines are oxidized to the corresponding oximes under the examined conditions. Kinetic studies indicated that aryl amines substituted with electron-donating groups are oxidized faster than the corresponding amines bearing an electron-withdrawing functionality. A Hammett-type kinetic analysis of a range of para-X-substituted aryl amines implicates an electron transfer (ET) mechanism (ρ=-1.15) for oxidation reactions with concomitant formation of the corresponding N-aryl hydroxylamine as possible intermediate. We also show that the oxidation protocol of aryl amines in the presence of 1,3-cyclohexadiene leads in excellent yields to the corresponding hetero Diels-Alder adducts between the diene and the in situ formed nitrosoarenes.
- Fountoulaki, Stella,Gkizis, Petros L.,Symeonidis, Theodoros S.,Kaminioti, Eleni,Karina, Athanasia,Tamiolakis, Ioannis,Armatas, Gerasimos S.,Lykakis, Ioannis N.
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supporting information
p. 1500 - 1508
(2016/05/19)
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- Direct synthesis of anilines and nitrosobenzenes from phenols
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A one-pot synthesis of anilines and nitrosobenzenes from phenols has been developed using an ipso-oxidative aromatic substitution (iSOAr) process. The products are obtained in good yields under mild and metal-free conditions. The leaving group effect on reactions that proceed through mixed quionone monoketals has also been investigated and a predictive model has been established.
- St Amant,Frazier,Newmeyer,Fruehauf,Read De Alaniz
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supporting information
p. 5520 - 5524
(2016/07/06)
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- Synthesis of polyfunctional secondary amines by the addition of functionalized zinc reagents to nitrosoarenes
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Addition of functionalized aryl, heteroaryl or adamantyl zinc reagents to various nitroso-arenes in the presence of magnesium salts and LiCl in THF produces after a reductive work-up with FeCl2 and NaBH4 in ethanol the corresponding polyfunctional secondary amines in high yields. This journal is
- Dhayalan, Vasudevan,S?mann, Christoph,Knochel, Paul
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supporting information
p. 3239 - 3242
(2015/06/01)
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- Molecular-Level Insight into the Differential Oxidase and Oxygenase Reactivities of de Novo Due Ferri Proteins
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Using the single-chain due ferri (DFsc) peptide scaffold, the differential oxidase and oxygenase reactivities of two 4A→4G variants, one with two histidines at the diiron center (G4DFsc) and the other with three histidines (3His-G4DFsc(Mut3)), are explore
- Snyder, Rae Ana,Butch, Susan E.,Reig, Amanda J.,DeGrado, William F.,Solomon, Edward I.
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p. 9302 - 9314
(2015/08/18)
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- An umpolung approach toward N-aryl nitrone construction: A phosphine-mediated addition of 1,2-dicarbonyls to nitroso electrophiles
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An umpolung approach toward nitrone construction utilizing a phosphine-mediated addition of 1,2-dicarbonyls to nitroso compounds is reported. The reaction exhibits a high degree of chemoselectivity and provides direct access to isoxazolidines, imines, and
- Chavannavar, Aditi P.,Oliver, Allen G.,Ashfeld, Brandon L.
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supporting information
p. 10853 - 10856
(2014/10/16)
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- Ipso-Nitrosation of arylboronic acids with chlorotrimethylsilane and sodium nitrite
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Nitroso compounds are versatile reagents in synthetic organic chemistry. Herein, we disclose a feasible protocol for the ipso-nitrosation of aryl boronic acids using chlorotrimethylsilane-sodium nitrite unison as nitrosation reagent system.
- Prakash, G.K. Surya,Gurung, Laxman,Schmid, Philipp Christoph,Wang, Fang,Thomas, Tisa Elizabeth,Panja, Chiradeep,Mathew, Thomas,Olah, George A.
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p. 1975 - 1978
(2014/04/03)
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- Planar chiral flavinium salts: Synthesis and evaluation of the effect of substituents on the catalytic efficiency in enantioselective sulfoxidation reactions
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A series of substituted planar chiral flavinium salts with a phenyl "cap" have been prepared as potential catalysts for enantioselective sulfoxidation reactions with hydrogen peroxide by using an approach based on the synthesis of (arylamino)uracils and their condensation with substituted nitrosobenzenes. The effect of substituents at various positions on the ability of the catalyst to promote enantioselective sulfoxidation recations was investigated. Introduction of the tyrosine group into the side-chain of the flavinium species or substitution of the nitrogen N-3 of the flavin unit by o-isopropylphenyl has a remarkably positive effect on the enantioselectivity of the sulfoxidation reactions of aromatic and aliphatic substrates, respectively. On the other hand, substitution of the phenyl "cap" led to a substantial decrease in the efficiency of the catalyst. In summary, optimisation of the structures of the planar chiral flavinium catalysts led to enantioselectivities of up to 61 % ee for aromatic sulfides and of up to 65 % ee for tert-butyl methyl sulfide. By making structural changes to the planar chiral flavinium catalysts, the enantioselectivities of the sulfoxidation of aryl methyl sulfides and tert-butyl methyl sulfide with hydrogen peroxide have been improved. Copyright
- Jurok, Radek,Hodacova, Jana,Eigner, Vaclav,Dvorakova, Hana,Setnicka, Vladimir,Cibulka, Radek
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supporting information
p. 7724 - 7738
(2013/12/04)
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- Nitrosation of aryl and heteroaryltrifluoroborates with nitrosonium tetrafluoroborate
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Organotrifluoroborates have emerged as an alternative to toxic and air- and moisture-sensitive organometallic species for the synthesis of functionalized aryl and heteroaryl compounds. It has been shown that the trifluoroborate moiety can be easily converted into a variety of different substituents in a late synthetic stage. In this paper, we disclose a mild, selective, and convenient method for the ipso-nitrosation of organotrifluoroborates using nitrosonium tetrafluoroborate (NOBF4). Aryl- and heteroaryltrifluoroborates were converted into the corresponding nitroso products in good to excellent yields. This method proved to be tolerant of a broad range of functional groups.
- Molander, Gary A.,Cavalcanti, Livia N.
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experimental part
p. 4402 - 4413
(2012/06/18)
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- New nitrite ionic liquid (IL-ONO) and nanoparticles of organosilane-based nitrite ionic liquid immobilized on silica as nitrosonium sources for electrophilic aromatic nitrosation
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An improved method for the synthesis of nitrosoarenes has been developed using a new nitrite ionic liquid (IL-ONO) and immobilized nitrite ionic liquid. These ionic liquids play as nitrosonium sources for electrophilic aromatic nitrosation of active aromatics at 0-5 °C. Their action was accomplished in water and the satisfactory results were obtained under the mild conditions in short reaction time.
- Valizadeh, Hassan,Amiri, Mohammad,Shomali, Ashkan
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experimental part
p. 1103 - 1108
(2012/03/10)
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- NO2/H3BO3 as an effective nitrosonium source for electrophilic aromatic nitrosation under MW-promoted solvent-free conditions
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[Bmim]NO2/H3BO3 was used as a nitrosonium source for the efficient synthesis of nitrosoarenes. The reaction was accomplished under MW irradiation at 60 W in a solventless system. Side processes such as oxidation or dealkylation were not observed during the nitrosation of alkyl phenyl ethers in the presence of this new reagent. The satisfactory results were obtained with very short reaction time, simplicity in the experimental procedure and good to excellent yields.
- Valizadeh, Hassan,Gholipour, Hamid
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experimental part
p. 963 - 966
(2012/04/23)
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- Nitrosobenzene cross-dimerization: Structural selectivity in solution and in solid state
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Possibility of nitrosobenzenes to form dimeric molecular structures (azodioxides) is used as a model for intermolecular selectivity investigations in solution as well as in solid state. Cross-dimerization of different combinations of p- and m-substituted nitrosobenzene pairs was studied by variable temperature 1H NMR, solid-state NMR (CP MAS), IR, and ab initio calculations. It is evident that p-nitronitrosobenzene behaves nonselectively because it forms dimers with all the studied nitrosobenzene partners. In contrast, p-methoxynitrosobenzene in most cases does not form dimers. The evidence that ability to form dimers is different in solution than in the solid state can be explained by influence of molecular arrangements in the crystal lattice.
- Biljan, Ivana,Cvjetojevic, Gorana,Smrecki, Vilko,Novak, Predrag,Mali, Gregor,Plavec, Janez,Babic, Darko,Mihalic, Zlatko,Vancik, Hrvoj
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body text
p. 22 - 26
(2010/09/16)
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- One-pot synthesis of meridianins and meridianin analogues via indolization of nitrosoarenes
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Meridianins, marine alkaloids known as kinase inhibitors with an indole skeleton, and meridianin analogues were produced regioselectively and in moderate to good yields by thermal annulation of nitrosoarenes with 2-amino-4-ethynylpyrimidine and 2-chloro-4-ethynylpyrimidine, respectively, through a novel and atom-economical indolization process.
- Tibiletti, Francesco,Simonetti, Marco,Nicholas, Kenneth M.,Palmisano, Giovanni,Parravicini, Matteo,Imbesi, Federico,Tollari, Stefano,Penoni, Andrea
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experimental part
p. 1280 - 1288
(2010/04/02)
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- Reduction of nitrosobenzenes to azoarenes with SmI2
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A novel method was developed to synthesise azoarenes from nitrosobenzenes under mild conditions. Samarium (II) iodine was used to achieve the N-N coupling. The method also provides evidence for the proposed mechanism involved in the reduction of nitro compounds to the amines with SmI2.
- Ye, Wei,Ding, Wenbo,Hu, Zhang,Yu, Yongping,Zou, Hongbin
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body text
p. 214 - 215
(2010/07/08)
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- N-Oxidation of arylamines to nitrosobenzenes using chloroperoxidase purified from Musa paradisiaca stem juice
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N-Oxidation of arylamines to their corresponding nitrosobenzenes using a new chloroperoxidase purified from Musa paradisiaca stem juice has been examined. The enzymatic characteristics of the stem chloroperoxidase using 4-chloroaniline as substrate were determined. The Km values for 4-chloroaniline and H2O2 were 770 μM and 154 μM respectively, while the pH and temperature optima were 4.4 and 30°C respectively. The substrate specificities of the enzyme for the arylamines 3,4-dichloroamine, p-aminobenzoic acid, p-toluidine, p-anisidine, m-anisidine, p-aminophenol, o-aminophenol and m-aminophenol have been characterized. The feasibility of using concentrated M. paradisiaca stem juice for the specific conversion of 4-chloroaniline to 4-chloronitrosobenzene has been demonstrated. This enzyme can be used for the N-oxidation of other arylamines.
- Yadav, Pratibha,Sharma, Jitendra K.,K. Singh, Vinod,Yadav, Kapil D. S.
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body text
p. 222 - 226
(2011/12/04)
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- Influence of 1,3-dichloroacetone on the regularities of decay of arylnitroso oxides
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The decay kinetics of isomeric forms of a series of arylnitroso oxides in the presence of 1,3-dichloroacetone in acetonitrile was studied by the flash photolysis technique. The regularities observed are explained by the complex formation between the molecules of nitroso oxide and additive.
- Chainikova,Safiullin
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p. 2437 - 2442
(2014/05/06)
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- Oxidation of anilines with hydrogen peroxide and selenium dioxide as catalyst
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A variety of substituted anilines are selectively oxidized to afford high yields of azoxyarenes by using 30% hydrogen peroxide and selenium dioxide as catalyst in methanol at room temperature. The oxidation of 4-alkoxyanilines under the same reaction conditions furnishes the corresponding 4-alkoxy-N-(4-nitrophenyl)anilines in reasonable yields, alongside other oxidation byproducts. The structure of 4-methoxy-N-(4-nitrophenyl)aniline is elucidated by X-ray crystal structure analysis. From these results, some general aspects of the reaction pathways of aniline oxidation are discussed.
- Gebhardt, Christin,Priewisch, Beate,Irran, Elisabeth,Rueck-Braun, Karola
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body text
p. 1889 - 1894
(2009/04/04)
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- Selective N-oxidation of aromatic amines to nitroso derivatives using a molybdenum acetylide oxo-peroxo complex as catalyst
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The molybdenum acetylide oxo-peroxo complex obtained in situ by the treatment of the corresponding molybdenum acetylide carbonyl complex, CpMo(CO)3(C{triple bond, long}CPh); Cp = η5-C5H5 with H2O2, has been used as an efficient catalyst for selective N-oxidation of primary amines to nitroso derivatives. Excellent amine conversion (up to 100%) and very high selectivity for nitroso compounds (99%) have been obtained using 30% hydrogen peroxide as an oxidant. The oxo peroxo Mo(VI) complex has also been found to be very active for the oxidation of various substituted primary aromatic amines with electron donating as well as electron withdrawing substituents on the aromatic ring.
- Biradar, Ankush V.,Kotbagi, Trupti V.,Dongare, Mohan K.,Umbarkar, Shubhangi B.
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p. 3616 - 3619
(2008/09/19)
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- Multiphase oxidation of aniline to nitrosobenzene with hydrogen peroxide catalyzed by heteropolyacids
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Keggin-type heteropolyacids have been used as catalyst for high-yielding oxidation reactions in multiphase conditions. This simple and efficient procedure promoted the conversion of anilines to the corresponding nitroso and nitro derivatives. In comparison with homogeneous system the oxidation from anilines to nitroso compounds and nitro compounds were more effective and the solvents used were not toxic. Georg Thieme Verlag Stuttgart.
- Tundo,Romanelli,Vázquez,Loris,Aricò
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experimental part
p. 967 - 970
(2009/04/06)
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- Tungsten- and molybdenum-based coordination polymer-catalyzed N-oxidation of primary aromatic amines with aqueous hydrogen peroxide
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Recyclable tungsten- and molybdenum-based coordination polymers efficiently catalyzed the oxidation of primary aromatic amines to the corresponding nitroso derivatives with 30% aqueous hydrogen peroxide in high yields at room temperature.
- Bordoloi, Ankur,Halligudi
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p. 2085 - 2088
(2008/09/18)
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- In situ generation of nitroso compounds from catalytic hydrogen peroxide oxidation of primary aromatic amines and their one-pot use in hetero-Diels-Alder reactions
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A method for in situ generation of nitroso compounds from organoselenium-catalyzed oxidation of anilines by hydrogen peroxide was developed. The generated nitroso compounds were subsequently used in hetero-Diels-Alder reactions. A variety of oxazines were synthesized in reasonable to good yields by this one-pot procedure using primary aromatic amines with different substituents and various conjugated dienes. This strategy might facilitate the current methodologies for nitroso chemistry since no isolation or purification of the nitroso compounds is required. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Zhao, Dongbo,Johansson, Mikael,Baeckvall, Jan-E.
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p. 4431 - 4436
(2008/04/13)
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- Photoreduction of 4-substituted nitrobenzenes by amines
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The reduction of several nitrobenzenes bearing electron-donor and electron-withdrawing substituents in the 4-position by triethylamine in acetonitrile was studied by cyclic voltammetry, EPR spectroscopy, and steady-state photolysis. The electrochemical re
- Norambuena,Olea-Azar,Rufs,Encinas
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p. 1230 - 1235
(2007/10/03)
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- Simple preparation of nitroso benzenes and nitro benzenes by oxidation of anilines with H2O2 catalysed with molybdenum salts
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Nitroso arenes 2a-k are prepared in 53-80% yield from anilines 1a-k by oxidation with H2O2 catalysed with MoO3/KOH, ammonium molybdate or other molybdenum salts. Further oxidation to nitro arenes 3a,d j in 66-90% is also described.
- Defoin, Albert
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p. 706 - 710
(2007/10/03)
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- An exceptionally stable Ti superoxide radical ion: A novel heterogeneous catalyst for the direct conversion of aromatic primary amines to nitro compounds
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A matrix-bound superoxide radical anion, generated by treating Ti(OR)4 (R =iPr, nBu) with H2O2, is a selective heterogeneous catalyst for the oxidation of anilines to the corresponding nitroarenes with 50 % aqueous H2O2 [Eq. (1)]. Yields of 82-98 % are obtained, even with anilines bearing electron-withdrawing substituents (R = NO2, COOH).
- Dewkar, Gajanan K.,Nikalje, Milind D.,Ali, Iliyas Sayyed,Paraskar, Abhimanyu S.,Jagtap,Sudalai
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p. 405 - 408
(2007/10/03)
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- Alkylation of nitroarenes with Grignard reagents via oxidative nucleophilic substitution of hydrogen
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Alkylation of nitroarenes with Grignard reagents via oxidative nucleophilic substitution of hydrogen (ONSH) can be efficiently executed with potasium permanganate in liquid ammonia as an oxidative system for the σH adducts. The addition of RMgX to ArNO2 of stoichiometry 1:1 is accompanied with a redox process apparently of stoichiometry 2:1. Because of that, real stoichiometry of the reaction between nitroarenes and Grignard reagents is ca. 1:1.5.
- Ma?kosza, Mieczys?aw,Surowiec, Marek
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p. 167 - 171
(2007/10/03)
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- Nitrosation of anisole, stability constants of complexes of the nitrosonium ion with aromatic nitroso compounds, and NMR studies of restricted rotation in the complexes
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Anisole can be nitrosated in good yield under the acidic and anaerobic conditions previously reported for methylbenzenes. The product, 4-nitrosoanisole, is slowly converted into 4-nitrosophenol in acetic-sulfuric acid mixtures. The decrease in the rate constant for this reaction with increasing concentration of nitrosonium ion leads to an estimate of the stability constant of the complex between 4-nitrosoanisole and nitrosonium ion. Stability constants for the similar complexes formed by 4-nitrosotoluene and 1,3-dimethyl-4-nitrosobenzene with nitrosonium ion in trifluoroacetic acid have been determined by UV spectroscopy. Restricted rotation about the bond between nitrogen and aromatic carbon is evident from the 1H NMR spectra of the complexes; activation parameters for the rotation are reported and compared with similar data in the literature for restricted rotation in uncomplexed aromatic nitroso compounds.
- Atherton, John H.,Moodie, Roy B.,Noble, Darren R.
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p. 229 - 234
(2007/10/03)
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- Kinetic study of the catalytic oxidation of anilines with hydrogen peroxide
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Kinetic study of homogeneous catalytic oxidation of substituted anilines with hydrogen peroxide in the presence of H3PW12O40 showed that the reaction involves formation of intermediate substrate-oxidant complex whose decomposition determines the rate of the process. Donor substituents in the benzene ring favor the oxidation process, indicating its electrophilic nature.
- Belyaev,Mel'nikov,Zadov,Suboch
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p. 1003 - 1006
(2007/10/03)
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- Nitrosation of arenes with nitrosonium ethyl sulfate
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Nitrosonium ethyl sulfate reacts with O-alkylphenols and N,N-dialkylanilines to give the corresponding 4-nitrosoarenes. The reaction is not accompanied by side processes characteristic of common nitrosating agents. Diazotization of primary aromatic amines with nitrosonium ethyl sulfate yields stable diazonium salts, which are promising reagents for organic synthesis.
- Zyk,Nesterov,Khlobystov,Zefirov
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p. 506 - 509
(2007/10/03)
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- Photosubstitution-photoreduction mechanistic duality in the SET photoreactions of nitrophenyl ethers with amines. The role of the steps that follow the ET
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Nitrophenyl ethers are photoreduced by primary amines in water through a mechanism initiated by single electron transfer that is in direct competition with the single electron transfer photosubstitution mechanism (S(N)Ar*-SET). Our results indicate that the preferred pathway does not depend on the electron donor or proton donor ability of the amine. The key factor that determines the progress of the photoreaction is the structure of the carbon skeleton of the amine, particularly the type of hydrogens on the carbon α to the amino group. A mechanistic rationale that includes hydrogen atom transfer as a key step is discussed.
- Mir, Miquel,Marquet, Jordi,Massot, Oriol
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p. 12603 - 12614
(2007/10/03)
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- Structural investigations of C-nitrosobenzenes. Part 1. Solution state 1H NMR studies
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Ambient and low temperature 1H NMR spectra of a wide range of 3- and 4-monosubstituted, and some di- and tri-substituted C-nitrosobenzenes have enabled -N=O substituent constants for the static and rotating ring molecules to be calculated. This has provided information on the shielding anisotropy of the N=O group which in turn leads to the firm identification of the monomeric and dimeric solution species. In all cases lowering the solution temperature enhances the relative populations of dimers to monomers, with the (Z)-azodioxy dimer being preferred over the (E)-form, irrespective of the nature of the solid state dimeric structure.
- Fletcher, Daniel A.,Gowenlock, Brian G.,Orrell, Keith G.
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p. 2201 - 2205
(2007/10/03)
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- Nitrosation of m-xylene, anisole, 4-nitrophenyl phenyl ether and toluene in trifluoroacetic acid or in acetic-sulfuric acid mixtures under nitric oxide
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Nitrosation in trifluoroacetic acid or in acetic-sulfuric acid mixtures is regioselective and accompanying non-selective nitrous acid catalysed nitration can be avoided by purging with nitric oxide.
- Atherton, John H.,Moodie, Roy B.,Noble, Darren R.,O'Sullivan, Brian
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p. 663 - 664
(2007/10/03)
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- Zirconium-catalysed Oxidation of Primary Aromatic Amines to Nitro Compounds Using tert-Butylhydroperoxide
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A broad range of primary aromatic amines (1a-x) with electron donating and accepting substituents are oxidized in good to excellent yields to the nitro compounds 3a-x using tert-butylhydroperoxide as the oxidant and Zr(OtBu)4 as the catalyst. The corresponding nitroso compounds 2m,-2n, 2s and 2u can be isolated in the conversion of electron-rich anilines 1m, 1n, 1s and 1u. The aminopyridines 5a-d are also converted to the corresponding nitropyridines 6a-d, but in lower yields (41-47%).
- Krohn, Karsten,Kuepke, Jochen,Rieger, Hagen
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p. 335 - 339
(2007/10/03)
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- Reduction of nitro aromatic compounds by zero-valent iron metal
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The properties of iron metal that make it useful in remediation of chlorinated solvents may also lead to reduction of other groundwater contaminants such as nitro aromatic compounds (NACs). Nitrobenzene is reduced by iron under anaerobic conditions to aniline with nitrosobenzene as an intermediate product. Coupling products such as azobenzene and azoxybenzene were not detected. First-order reduction rates are similar for nitrobenzene and nitrosobenzene, but aniline appearance occurs more slowly (typical pseudo-first-order rate constants 3.5 x 10-2, 3.4 x 10-2, and 8.8 x 10- 3 min-1, respectively, in the presence of 33 g/L acid-washed, 18-20 mesh Fluka iron turnings). The nitro reduction rate increased linearly with concentration of iron surface area, giving a specific reaction rate constant (3.9 ± 0.2 x 10-2 min-1 m-2 L). The minimal effects of solution pH or ring substitution on nitro reduction rates, and the linear correlation between nitrobenzene reduction rate constants and the square-root of mixing rate (rpm), suggest that the observed reaction rates were controlled by mass transfer of the NAC to the metal surface. The decrease in reduction rate for nitrobenzene with increased concentration of dissolved carbonate and with extended exposure of the metal to a particular carbonate buffer indicate that the precipitation of siderite on the metal inhibits nitro reduction.
- Agrawal, Abinash,Tratnyek, Paul G.
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p. 153 - 160
(2007/10/03)
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- Kinetics and Mechanism of Oxidation of Anilines by Hydrogen Peroxide As Catalyzed by Methylrhenium Trioxide
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The oxidation of anilines by hydrogen peroxide in methanol is catalyzed by methylrhenium trioxide, CH3ReO3.The major product of the oxidation of aniline at room temperature is nitrosobenzene.For 4-substituted N,N-dimethylanilines, the N-oxide is the only product.The rate constants for the oxidation of 4-substituted N,N-dimethylanilines follow a linear Hammett relationship with ρ = -1.19.The rate constants for the reaction between CH3Re(O)2(O2), referred to as A, and 4-XC6H4-NMe2 are as follows: 4-Me, 24.5; 4-H, 18.4; 4-F, 12.7; 4-Br, 8.7; and 4-NO2, 1.0 L mol-1 s-1.This shows that electron-withdrawing substituents inhibit the reaction.The corresponding rate constant for the oxidation of aniline is 2.04 +/- 0.11 L mol-1 s-1, whereas it is 178 +/- 11 L mol-1 s-1 for the oxidation of N-phenylhydroxylamine to nitrosobenzene.A mechanism has been assigned on the basis of the kinetics and product yields.The data are consistent with the attack of the nucleophilic nitrogen atom on one of the peroxidic oxygen atom of A.The kinetics of the reaction of CH3ReO3 and hydrogen peroxide in methanol were also investigated.The formation of the 1:1 peroxide compound A is characterized by an equilibrium constant K1 = 261 +/- 6 L mol-1.The equilibration occurs rapidly: k1 = 1150 +/- 60 L mol-1 s-1 and k-1 = 4.4 +/- 0.4 s-1 at 25.0 deg C.The bisperoxide compound, CH3Re(O)(O2)2(H2O), B, forms more slowly.The rate constant is k2 = 308 +/- 16 L mol-1 s-1, and the equilibrium constant is K2 = 814 +/- 14 L mol-1 at 25.0 deg C in methanol.B reacts with the anilines, but much more slowly than A.
- Zhu, Zuolin,Espenson, James H.
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p. 1326 - 1332
(2007/10/02)
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- Oxidation of Primary Aromatic Amines, Catalyzed by Tungsten Compounds
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Treatment of o-nitroanilines and o-aminobenzoic acids with 30 percent hydrogen peroxide in the presence of Na2WO4 and H3PO4 results in selective formation of corresponding nitroso derivatives.In other cases, the products are azoxy compounds.Oxidation of anilines containing alkyl or alkoxy groups in the ortho and para positions with hydrogen peroxide in the presence of Na2WO4 and tetrabutylammonium bromide quantitatively yields corresponding nitrosobenzenes.The H2O2-Na2WO4-H3PO4 system in the presence of tetrabutylammonium bromide is proposed for preparation of nitroso derivatives from anilines containing electron-acceptor meta and para substituents.
- Mel'nikov, E. B.,Suboch, G. A.,Belyaev, E. Yu.
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p. 1640 - 1642
(2007/10/03)
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- Direct Nitrosation of Aromatic Hydrocarbons and Ethers with the Electrophilic Nitrosonium Cation
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Various polymethylbenzenes and anisoles are selectively nitrosated with the electrophilic nitrosonium salt NO(1+)BF4(1-) in good conversions and yields under mild conditions in which the conventional procedure (based on nitrile neutralization with strong acid) is ineffective.The reactivity patterns in acetonitrile deduced from the various time/conversions in Tables 2 and 3 indicate that aromatic nitrosation is distinctly different from those previously established for electrophilic aromatic nitration.The contrasting behavior of NO(1+) in aromatic nitrosation is ascribed to a rate-limiting deprotonation of the reversibly formed Wheland intermediate, which in the case of aromatic nitration with NO2(1+) occurs with no deuterium kinetic isotope effect.Aromatic nitroso derivatives (unlike the nitro counterpart) are excellent electron donors that are subject to a reversible one-electron oxidation at positive potentials significantly less than that of the parent polymethylbenzene or anisole.As a result, the series of nitrosobenzenes are also much better Broensted bases than the corresponding nitro derivatives, and this marked distinction, therefore, accounts for the large differentiation in the deprotonation rates of their respective conjugate acids (i.e.Wheland intermediates).
- Bosch, Eric,Kochi, Jay K.
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p. 5573 - 5586
(2007/10/02)
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- Catalytic Oxidation of Primary Aromatic Amines to the Corresponding Nitroso Compounds by H2O2 and (hmpa = Hexamethylphosphoric Triamide)
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1 catalyses the oxidation of primary aromatic amines to the corresponding nitroso derivatives, in the presence of H2O2 as oxidant.
- Tollari, Stefano,Cuscela, Michaela,Porta, Francesca
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p. 1510 - 1511
(2007/10/02)
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