- Oxidative dehydrogenation of hydrazines and diarylamines using a polyoxomolybdate-based iron catalyst
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We report an efficient method for the oxidative dehydrogenation of hydrazines and diarylamines in aqueous ethanol using Anderson-type polyoxomolybdate-based iron(iii) as a catalyst and hydrogen peroxide as an oxidant. A series of azo compounds and tetraarylhydrazines were obtained in moderate to excellent yields. The reaction conditions and substrate scopes are complementary or superior to those of more established protocols. In addition, the catalyst shows good stability and reusability in water. The preliminary mechanistic studies suggest that a radical process is involved in the reaction.
- Huang, Lei,Qiu, Shiqin,Wei, Yongge,Xie, Jingyan,Yu, Han,Zeng, Xianghua,Zhao, Weizhe
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supporting information
p. 7677 - 7680
(2021/08/09)
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- 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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- Azo synthesis meets molecular iodine catalysis
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A metal-free synthetic protocol for azo compound formation by the direct oxidation of hydrazine HN-NH bonds to azo group functionality catalyzed by molecular iodine is disclosed. The strengths of this reactivity include rapid reaction times, low catalyst loadings, use of ambient dioxygen as a stoichiometric oxidant, and ease of experimental set-up and azo product isolation. Mechanistic studies and density functional theory computations offering insight into this reactivity, as well as the events leading to azo group formation are presented. Collectively, this study expands the potential of main-group element iodine as an inexpensive catalyst, while delivering a useful transformation for forming azo compounds.
- Rowshanpour, Rozhin,Dudding, Travis
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p. 7251 - 7256
(2021/02/26)
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- AgNO3 as nitrogen source for rhodium(III)-catalyzed synthesis of 2-aryl-2H -benzotriazoles from azobenzenes
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A new approach has been established for Rh(iii)-catalyzed direct aza oxidative cyclization of non-prefunctionalized azobenzenes to provide 2-aryl-2H-benzotriazoles in good yields, in which AgNO3 instead of conventional azide reagents for the first time functions as the nitrogen source for the nitrogenation reaction. Preliminary mechanistic studies suggest that the Rh(iii)-catalyst could account for the nitration reaction, and subsequently cationic silver species might both play a vital role in the fission of the nitrogen-oxygen bonds in nitro groups and promote aza oxidative cyclization.
- Li, Jixing,Zhou, Hui,Zhang, Jinlong,Yang, Huameng,Jiang, Gaoxi
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supporting information
p. 9589 - 9592
(2016/08/01)
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- Bismuth nanoparticles: an efficient catalyst for reductive coupling of nitroarenes to azo-compounds
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The synthesis of azoarenes from corresponding nitroarenes was developed by virtue of in situ bismuth nanoparticles. A series of aromatic azo compounds can be obtained under mild reaction conditions with excellent yields.
- Pothula, Kishore,Tang, Lin,Zha, Zhenggen,Wang, Zhiyong
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p. 83144 - 83148
(2015/10/19)
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- A novel method. The synthesis of ketones and azobenzenes using supported permanganate
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The heterogeneous use of potassium permanganate, supported on copper(II) sulfate pentahydrate, provides a simple and effective means for oxidizing amines. Primary aliphatic amines, such as sec-butylamine, are oxidized to the corresponding carbonyl compounds in good to excellent yields. Primary aromatic amines, such as 4-chloroaniline, are converted quantitatively into the corresponding azo compounds. Carbon-carbon bond cleavage, which usually occurs when alkylbenzene side chains are oxidized by permanganate under homogeneous conditions, does not occur. Under appropriate reaction conditions carbon-hydrogen bond cleavage at the benzylic position, known to occur under heterogeneous permanganate conditions, is also eliminated. For example, a quantitative yield of bis(2,4,6-trimethylphenyl)diazene is obtained from the oxidation of 2,4,6-trimethylaniline using small amounts of permanganate and copper(II) sulfate pentahydrate.
- Noureldin, Nazih A.,Bellegarde, Jody W.
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p. 939 - 942
(2007/10/03)
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- The use of thermotropic liquid crystals in organometallic chemistry. Synthesis of new mercury, silver and gold complexes with 4,4'-disubstituted azobenzenes
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Liquid crystalline 4-XC6H4N=NC6H4X-4' can be easily prepared in high yields from the corresponding anilines.In order to study the influence of metals on the thermal properties of these materials, we have obtained adducts (2) and .The silver adducts show thermotropic behaviour.Mercuriation of dialkylazobenzenes 1a-b takes place with and LiCl to give while dialkoxyazobenzenes 1c-d require to obtain . 4a-c react with NaI to give .Both chloroaryl-, 4a and 4c, and diaryl-mercurials, 5a and 5c, act readily as transmetallating agents towards in the presence of Cl to give 2-R)Cl2> .After reaction of (tht = tetrahydrothiophene) with Cl and 4b (1:2:1), (7) can be isolated.C-H activation of acetone by 6a-b leads to 2-R)Cl> .None of the complexes 4-8 shows mesomorphic behaviour. Key words: Gold; Silver; Mercury; Aryl; Transmetallation; Orthometallated complexes
- Vicente, Jose,Bermudez, Maria Dolores,Carrion, Francisco J.,Martinez-Nicolas, Gines
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p. 103 - 110
(2007/10/02)
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