- Selective Oxidation of Anilines to Azobenzenes and Azoxybenzenes by a Molecular Mo Oxide Catalyst
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Aromatic azo compounds, which play an important role in pharmaceutical and industrial applications, still face great challenges in synthesis. Herein, we report a molybdenum oxide compound, [N(C4H9)4]2[Mo6O19] (1), catalyzed selective oxidation of anilines with hydrogen peroxide as green oxidant. The oxidation of anilines can be realized in a fully selectively fashion to afford various symmetric/asymmetric azobenzene and azoxybenzene compounds, respectively, by changing additive and solvent, avoiding the use of stoichiometric metal oxidants. Preliminary mechanistic investigations suggest the intermediacy of highly active reactive and elusive Mo imido complexes.
- Han, Sheng,Cheng, Ying,Liu, Shanshan,Tao, Chaofu,Wang, Aiping,Wei, Wanguo,Yu, Han,Wei, Yongge
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supporting information
p. 6382 - 6385
(2021/02/09)
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- Method for synthesizing oxidized azo compound through selective oxidation of aromatic amine
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The invention discloses a method for synthesizing an oxidized azo compound through selective oxidation of an aromatic amine, wherein an aromatic amine is used as a raw material, hydrogen peroxide is used as an oxidizing agent, a titanium-silicon molecular sieve or a metal modified titanium-silicon molecular sieve is used as a catalyst, and the aromatic amine is subjected to selective catalytic oxidation to prepare the corresponding oxidized azobenzene compound. According to the present invention, the method has advantages of environmental protection, good selectivity, high product yield, easyseparation and recycling of the catalyst, simple instrument required by the reaction, and easy operation.
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Paragraph 0027-0051; 0052-0054; 0056
(2019/02/13)
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- Organocatalytic oxidation of substituted anilines to azoxybenzenes and nitro compounds: Mechanistic studies excluding the involvement of a dioxirane intermediate
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An organocatalytic and environmentally friendly approach for the selective oxidation of substituted anilines was developed. Utilizing a 2,2,2-trifluoroacetophenone-mediated oxidation process, substituted anilines can be transformed into azoxybenzenes, while a simple treatment with MeCN and H2O2 leads to the corresponding nitro compounds, providing user-friendly protocols that can be easily scaled up. Various substitution patterns and functional groups were tolerated leading to products in high to excellent yields. Mechanistic studies utilizing HRMS provide clear evidence for the distinct mechanistic intermediates that are involved. This study constitutes an indirect proof excluding the involvement of a dioxirane intermediate in the green organocatalytic oxidation, utilizing 2,2,2-trifluoroacetophenone as the catalyst.
- Voutyritsa, Errika,Theodorou, Alexis,Kokotou, Maroula G.,Kokotos, Christoforos G.
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supporting information
p. 1291 - 1298
(2017/06/06)
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- Reduction of nitroarenes to azoxybenzenes by NaOH-PEG 400
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The reduction of nitroarenes to azoxybenzenes by NaOH-PEG 400 in benzene is described. The protocol is facile, economical, and effective.
- Liu, Yufang,Liu, Bo,Guo, Ailing,Dong, Zhenming,Jin, Shuo,Lu, Yun
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experimental part
p. 2201 - 2206
(2012/06/16)
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- 1,2-Eliminations in a novel reductive coupling of nitroarenes to give azoxy arenes by sodium bis(trimethylsilyl)amide
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(Chemical Equation Presented) Symmetric azoxy arenes were successfully prepared in one step from 2 equiv of the corresponding nitroarenes by use of sodium bis-(trimethylsilyl)amide as the deoxygenating agents in THF at 150°C in a sealed tube.
- Jih, Ru Hwu,Das, Asish R.,Chia, Wei Yang,Huang, Jiann-Jyh,Hsu, Ming-Hua
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p. 3211 - 3214
(2007/10/03)
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- Aqueous biphasic oxidation: A water-soluble polyoxometalate catalyst for selective oxidation of various functional groups with hydrogen peroxide
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A "sandwich" type polyoxometalate, Na12[(WZn 3(H2O)2][(ZnW9O34) 2], was used as an oxidation catalyst in aqueous biphasic reaction media to effect oxidation of alcohols, diols, pyridine derivatives, amines and aniline derivatives with hydrogen peroxide. The catalyst was shown by 183W NMR to be stable in aqueous solutions in the presence of H 2O2 and showed only minimal non-productive decomposition of the oxidant. Secondary alcohols were selectively oxidized to ketones, while primary alcohols tended to be oxidized to the corresponding carboxylic acids, although secondary alcohols were selectively oxidized in the presence of primary alcohols. Vicinal diols yielded carbon-carbon bond cleavage products in very high yields. Pyridine derivatives were oxidized to the respective TV-oxides, but strongly electron-withdrawing moieties inhibited the oxidation reaction. Primary amines were oxidized to the oximes, but significantly hydrolyzed in situ. Aniline derivatives were oxidized to the corresponding azoxy or nitro products depending on the substitution pattern in the aromatic ring. Catalyst recovery and recycle was demonstrated.
- Sloboda-Rozner, Dorit,Witte, Peter,Alsters, Paul L.,Neumann, Ronny
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p. 339 - 345
(2007/10/03)
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- Selective reduction of aromatic nitro compounds to azoxy compounds with zinc/aluminium chloride reagent
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Aromatic azoxy compounds have been prepared in good yields by the selective reduction of aromatic nitro compounds with Zn/AlCl3 reagent.
- Dutta, Dilip Kumar
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p. 672 - 673
(2007/10/03)
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- The newborn surface of dull metals in organic synthesis. Bismuth-mediated solvent-free one-step conversion of nitroarenes to azoxy- and azoarenes
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When milled together with bismuth shots, nitroarenes are readily converted to azoxy- and/or azoarenes depending on substrates and conditions employed. Simple extraction with organic solvent followed by evaporation of the resulting dark pasty solid gave the product in good yield.
- Wada, Shinobu,Urano, Mika,Suzuki, Hitomi
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p. 8254 - 8257
(2007/10/03)
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- Synthesis of N-arylhydroxylamines by antimony-catalyzed reduction of nitroarenes
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Metallic antimony catalyzes the reduction of aromatic nitro compounds to the corresponding N-arylhydroxylamines in good yields with NaBH4 under mild conditions. The azoxybenzenes from autoxidation of N-arylhydroxylamines were also obtained in basic conditions.
- Ren, Pingda,Dong, Tingwei,Wu, Shihui
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p. 1547 - 1552
(2007/10/03)
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- Reduction of nitroarenes to N-arylhydroxylamines with KBH4/BiCl3 system
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Aromatic nitro compounds could be selectively and rapidly reduced to the corresponding N-arylhydroxylamines in good yields with KBH4/BiCl3 system under mild conditions.
- Ren, Ping-Da,Pan, Xin-Wei,Jin, Qi-Hui,Yao, Zi-Peng
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p. 3497 - 3503
(2007/10/03)
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- Catalytic reduction of nitroarenes to azoxybenzenes with sodium borohydride in the presence of bismuth
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Aromatic nitro compounds have been found to be selectively reduced to axoxy compounds in good yields by NaBH4 in the presence of bismuth powder.
- Ren, Pingda,Pan, Shifeng,Dong, Tingwei,Wu, Shihui
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p. 3903 - 3908
(2007/10/03)
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