- 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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- Continuous-flow oxidative homocouplings without auxiliary substances: Exploiting a solid base catalyst
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The catalytic oxidative dimerization of aromatic amines and acetylenes is of outstanding synthetic importance among homocoupling reactions. Both transformations necessitate the use of extraneous bases and ligands, which contains significant disadvantages as concerns environmental impacts and process costs. We exploited the inherent basic character of a copper-containing layered double hydroxide to facilitate the catalytic homocouplings of alkynes and aniline derivatives without the need for any auxiliary substances. The reactions were studied in a continuous-flow system to achieve extended parameter spaces for chemical intensification, and also to avoid undesired reaction pathways by means of strategic control over the residence time. Valuable 1,4-disubstituted 1,3-diynes and diversely substituted aromatic azo compounds were achieved chemoselectively in excellent yields and in short process times even on preparative scales.
- ?tv?s, Sándor B.,Georgiádes, ádám,Mészáros, Rebeka,Kis, Koppány,Pálinkó, István,Fül?p, Ferenc
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- Palladium-catalyzed direct ortho-sulfonylation of azobenzenes with arylsulfonyl chlorides via C-H activation
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A highly efficient and practical procedure to direct ortho-sulfonylation of azobenzenes' C-H bond with arylsulfonyl chlorides has been developed. The method was applicable to both electron-rich and electron-deficient substrates and delivered good yields f
- Xia, Chengcai,Wei, Zhenjiang,Shen, Chao,Xu, Jun,Yang, Yong,Su, Weike,Zhang, Pengfei
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p. 52588 - 52594
(2015/06/25)
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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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- Unexpected reactivity between aromatic nitro compounds and PCl3/AlCl3. A new one-pot synthesis of phenazines
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The reaction between 4-nitroalkoxybenzenes 7 and PCl3/AlCl3, when carried out in appropriate molar ratio, gives a prevalent formation of diazenes 8 and 2,7-dialkoxyphenazines 9 with their new chlorinated derivatives 10-13. These compounds are obtained, in satisfactory yield, in a one-pot procedure, in mild conditions, from commercially available and safe starting materials. In this reaction both the reagents PCl3 and AlCl3 play a fundamental role in obtaining the products, and this method might be applicable to other 4-alkoxynitrobenzenes.
- Abdayem, Rodolphe,Baccolini, Graziano,Boga, Carla,Monari, Magda,Selva, Simona
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p. 2649 - 2653
(2007/10/03)
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- Lead-Catalyzed Synthesis of Azo Compounds by Ammonium Acetate Reduction of Aromatic Nitro Compounds
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Lead/ammonium acetate is a convenient reagent for the reduction of aromatic nitro compounds to the corresponding symmetrically substituted azo compounds. Various azo compounds containing additional reducible substituents such as halogen, nitrile, acid, phenol, ester, methoxy, etc., functions have been synthesized in a single step by the use of this reagent. The conversion is reasonably fast, clean, high yielding and occurs at room temperature in methanol.
- Srinivasa,Abiraj,Gowda, D. Channe
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p. 4221 - 4227
(2007/10/03)
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- Insecticide evaporator comprising a stabilizer
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Insecticide evaporator comprising at least one volatile phosphoric ester insecticide, an agent for stabilizing the said ester against decomposition by protonization and used in an amount of 0.2 to 20% based on the weight of phosphoric ester, characterized in that the stabilizing agent contains at least one compound selected from the compounds of the chemical class of 1,3-benzodioxoles and at least one diazene.
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- Evaporator system comprising a stabilized pesticidal phosphoric acid ester and method for stabilizing such ester enclosed in an evaporator
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An evaporator system adapted for emitting insect killing vapors of an insecticide therefrom and comprising a liquid or solid composition enclosed therein, said insecticide consisting in at least one volatile phosphoric acid ester which is stabilized by at least one diazene compound.
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