- Solid supported platinum(0) nanoparticles catalyzed chemo-selective reduction of nitroarenes to N-arylhydroxylamines
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Solid supported platinum(0) (SS-Pt) nanoparticles were developed as a heterogeneous catalyst following a reduction/deposition method and characterized by SEM, TEM, EDX and XRD analysis. The SS-Pt catalyst was applied in the chemo-selective reduction of nitroarenes to N-arylhydroxylamines using hydrazine hydrate as a hydrogen source. A wide variety of reducible functional groups such as halides, carboxylic acids, esters, amides, nitriles, keto, alkenes, alkynes and N-benzyl were well tolerated under the reaction conditions. This process was further successfully employed in 10 g scale reactions. N-Arylhydroxylamines were further applied for catalyst free synthesis of azoxybenzenes. Moreover, use of PEG-400 as cheap reaction medium, additive free methodology and the recyclability of SS-Pt catalyst up to ten times without significant loss of catalytic activity evidently follow the principles of green chemistry.
- Shil, Arun K.,Das, Pralay
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supporting information
p. 3421 - 3428
(2013/12/04)
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- Effect of water on product yields of 2-azidobenzoic acid photolysis in aprotic solvents
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The effect of water admixtures on the formation of 2-oxo-(3H)-azepine-3- carboxylic acid and 2,1-benzisoxazol-3(1H)-one in the photolysis of 2-azidobenzoic acid in aprotic solvents has been investigated. It has been shown that the addition of nucleophilic
- Sinjagina,Budruev
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p. 162 - 165
(2013/08/14)
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- Carbon supported Pt colloid as effective catalyst for selective hydrogenation of nitroarenes to arylhydroxylamines
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The Pt colloid supported on carbon is an active and selective catalyst for the partial hydrogenation of nitroaromatics with electron-withdrawing substituents to the corresponding N-arylhydroxylamine, indicating an additive-free green catalytic approach fo
- Rong, Zeming,Du, Wenqiang,Wang, Yue,Lu, Lianhai
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supporting information; experimental part
p. 1559 - 1561
(2010/06/12)
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- Effect of substituents on the rate of oxidation of anilines with peroxomonosulfate monoanion (HOOSO3-) in aqueous acetonitrile: A mechanistic study
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Mechanistic studies on the oxidation of 18 meta-, para-, and ortho-substituted anilines (Ans) by HOOSO3- in aqueous acetonitrile medium have been performed. The reaction can be characterized by the experimental rate equation, -d[HSO5-]/dt = k[An][HSO5-] The addition of p-toluenesulfonic acid (TsOH) retards the reaction. The increase in the reactivity of anilines as the medium is made more aqueous is interpreted. The reaction is enhanced by electron-donating groups on the amine in the series consistent with the rate-limiting nucleophilic attack of the amine on the persulfate oxygen. The proposed mechanism involves the conversion of phenylhydroxylamine to nitrosobenzene in a fast step. The ESR study reveals the absence of free radicals in the reaction. Various attempts have been made to analyze the experimental rate constants in terms of LFER plots. Improved correlations are obtained with σ- values and the σ- form of the Yukawa-Tsuno equation.
- Meenakshisundaram, Subbiah,Selvaraju,Made Gowda,Rangappa, Kanchugarakoppal S.
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p. 649 - 657
(2007/10/03)
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- Mechanism and reactivity in perborate oxidation of anilines in acetic acid
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Perborate but not percarbonate in acetic acid generates peracetic acid on standing and the peracetic acid oxidation of anilines is fast. The oxidation with a fresh solution of perborate in acetic acid is smooth and second order but the specific oxidation rate increases with increasing [perborate]0 or [boric acid]. Perborate on dissolution affords hydrogen peroxide and a borate; the latter assists the former in the oxidation. The oxidation rates of anilines under identical conditions do not conform to any of the linear free energy relationships but the reaction rates of molecular anilines do. Perborate oxidation proceeds via two reaction paths but the overall oxidation rates of molecular anilines conform to structure reactivity relationships; the transition states do not differ significantly. Analysis of the oxidation rates of perborate and percarbonate reveals that while perborate oxidation is faster than percarbonate it is at least as selective as the latter.
- Karunakaran, Chockalingam,Kamalam, Ramasamy
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p. 2011 - 2018
(2007/10/03)
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- Preparation and study of chemical transformations of N-formyl-N-phenylhydroxylamines
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Nitrosobenzenes with CO2H 1b, CO2CH3 3b and CON(CH3)C6H5 4b ortho-substituents were obtained in a "redox" cell from the corresponding nitro compounds.In order to prepare the 3-oxo-1,2-dihydro-2,1-benzisoxazole-1-carbaldehyde from o-substituted N-formyl-N-phenylhydroxylamines, nitroso derivatives were formylated by glyoxylic acid.The N-formylbenzisoxazolone is unstable in the reaction medium and cannot be isolated.In addition to our study, we showed the unstability of N-formyl-N-phenylhydroxylamines and N-formylanilines in the presence of methanol without acetic acid; in an aqueous methanolic medium, formylation of nitrosoderivatives is equivalent to a reduction of the nitroso group.The mechanism was demonstrated by formylation of the nitrosobenzene and the electrogenerated 2-nitrosobenzene acetic acid 2b.Key Words: flow cell electrosynthesis / nitrosobenzenes / glyoxylic acid / formylation / N-formyl-N-phenylhydroxylamines / N-formylanilines / benzisoxazolones
- Guilbaud-Criqui, A.,Moinet, C.
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p. 164 - 172
(2007/10/02)
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- Role of the carboxy proton in heterogeneous electron transfer to onitrobenzoic acid
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Heterogeneous electron transfer (ET) to o-nitrobenzoic acid has been investigated in NNdimethylformamide containing tetrabutylammonium perchlorate. Although primary anion radicals undergo fast homogeneous decay, voltammetric measurements allowed the ET ra
- Brillas,Farnia, Giuseppe,Severin, Maria G.,Vianello, Elio
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p. 1173 - 1178
(2007/10/02)
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- The Pyrolysis of 2-Azidobenzoates. A New Synthesis of Carbazoles and Other N-Heterocycles
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The spray pyrolysis of aryl 2-azidobenzoates yields carbazoles, involving a rearrangement whereby the nitrogen of the product is attached to the aryl 1-carbon, a process involving a spiro 6-membered intermediate.When the aryl ortho-positions were both alkyl substituted the product was ab acridan instead.With an ortho-carboxylate, acridone formation competed with that of carbazole.When the CO-O group of the substrate was replaced by O-CO, CO-S, CO-NPh, or SO2-O the pyrolysis was ineffective.Benzyl 2-azidobenzoates, however, pyrolysed to yield 1-benzyl-2,1-benzisoxazolones by an unprecedented C-O insertion reaction of the intermediate nitrene.
- Clancy, Michael G.,Hesabi, Massoud M.,Meth-Cohn, Otto
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p. 429 - 434
(2007/10/02)
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- Polarographic Behaviour of Some ortho-Substituted Nitrobenzenes: Evaluation of Polarographic ortho-Shift
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The polarographic characteristics of thirteen ortho-substituted nitrobenzenes have been studied at 35 deg C +/- 0.1 deg C in a well-buffered medium of 50percent (v/v) aqueous ethanol, having pH 5.8.Reduction process for all the compounds is found to be ir
- Ganapathy, K,Ramanujam, M
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p. 1087 - 1089
(2007/10/02)
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