51437-67-3Relevant academic research and scientific papers
Selective Oxidation of Anilines to Azobenzenes and Azoxybenzenes by a Molecular Mo Oxide Catalyst
Han, Sheng,Cheng, Ying,Liu, Shanshan,Tao, Chaofu,Wang, Aiping,Wei, Wanguo,Yu, Han,Wei, Yongge
supporting information, p. 6382 - 6385 (2021/02/09)
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.
Oxidative dehydrogenation of hydrazines and diarylamines using a polyoxomolybdate-based iron catalyst
Huang, Lei,Qiu, Shiqin,Wei, Yongge,Xie, Jingyan,Yu, Han,Zeng, Xianghua,Zhao, Weizhe
supporting information, p. 7677 - 7680 (2021/08/09)
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.
Electrosynthesis of Azobenzenes Directly from Nitrobenzenes
Ma, Yanfeng,Wu, Shanghui,Jiang, Shuxin,Xiao, Fuhong,Deng, Guo-Jun
, p. 3334 - 3338 (2021/10/29)
The electrochemical reduction strategy of nitrobenzenes is developed. The chemistry occurs under ambient conditions. The protocol uses inert electrodes and the solvent, DMSO, plays a dual role as a reducing agent. Its synthetic value has been demonstrated by the highly efficient synthesis of symmetric, unsymmetric and cyclic azo compounds.
Tuneable Copper Catalysed Transfer Hydrogenation of Nitrobenzenes to Aniline or Azo Derivatives
Moran, Maria Jesus,Martina, Katia,Baricco, Francesca,Tagliapietra, Silvia,Manzoli, Maela,Cravotto, Giancarlo
supporting information, p. 2689 - 2700 (2020/05/18)
A highly versatile and flexible copper nanoparticle (Cu(0) NPs) catalytic system has been developed for the controlled and selective transfer hydrogenation of nitroarene. Interestingly, the final catalytic product is strongly dependent on the nature of the hydrogen donor source. The yield of nitrobenzene reduction to aniline increased from 20% to an almost quantitative yield over a range of alcohols, diols and aminoalcohols. In glycerol at 130 °C aniline was isolated in 93% yield. In ethanolamine, the reaction was conveniently performed at a lower temperature (55 °C) and gave selectively substituted azobenzene (92% yield). Experimental studies provide support for a reaction pathway in which the Cu(0) NPs catalysed transfer hydrogenation of nitrobenzene to aniline proceeds via the condensation route. The high chemoselectivity of both protocols has been proved in experiments on a panel of variously substituted nitroarenes. Enabling technologies, microwaves and ultrasound, used both separately and in combination, have successfully increased the reaction rate and reaction yield. (Figure presented.).
Rhodium-Catalyzed Reaction of Azobenzenes and Nitrosoarenes toward Phenazines
Xiao, Yan,Wu, Xiaopeng,Wang, Hepan,Sun, Song,Yu, Jin-Tao,Cheng, Jiang
supporting information, p. 2565 - 2568 (2019/04/30)
A rhodium-catalyzed annulative reaction between azobenzenes and nitrosoarenes has been developed, leading to a series of phenazines in moderate to good yields. This procedure proceeds with sequential chelation-assisted addition of aryl C-H to nitrosoarenes and ring closure by electrophilic attack of azo group to aryl. During this transformation, the azo group served as not only a traceless directing group but also a building block in the final products.
Cage Encapsulated Gold Nanoparticles as Heterogeneous Photocatalyst for Facile and Selective Reduction of Nitroarenes to Azo Compounds
Mondal, Bijnaneswar,Mukherjee, Partha Sarathi
, p. 12592 - 12601 (2018/10/05)
A discrete nanoscopic organic cage (OC1R) has been synthesized from a phenothiazine based trialdehyde treating with chiral 1,2-cyclohexanediamine building block via dynamic imine bond formation followed by reductive amination. The cage compound has been characterized by several spectroscopic methods, which advocate that OC1R has trigonal prismatic shape formed via [2 + 3] self-assembled imine condensation followed by imine reduction. This newly designed cage has aromatic walls and porous interior decorated with two cyclic thioether and three vicinal diamine moieties suitable for binding gold ions to engineer the controlled nucleation and stabilization of ultrafine gold nanoparticles (AuNPs). The functionalized confined pocket of the cage has been used for the controlled synthesis of AuNPs with narrow size distribution via encapsulation of Au(III) ions. Inductively coupled plasma mass spectrometric (ICP-MS) analysis revealed that the composite Au@OC1R has very high (?68 wt %) gold loading. In distinction, reduction of gold salts in absence of the cage yielded structureless agglomerates. The fine-dispersed cage anchored AuNPs (Au@OC1R) have been finally used as potential heterogeneous photocatalyst for very facile and selective conversion of nitroarenes to respective azo compounds at ambient temperature in just 2 h reaction time. Exceptional chemical stability and reusability without any agglomeration of AuNPs even after several cycles of use are the potential features of this material. The composite Au@OC1R represents the first example of organic cage supported gold nanoparticles as photocatalyst.
Continuous-flow oxidative homocouplings without auxiliary substances: Exploiting a solid base catalyst
?tv?s, Sándor B.,Georgiádes, ádám,Mészáros, Rebeka,Kis, Koppány,Pálinkó, István,Fül?p, Ferenc
, p. 90 - 99 (2017/03/15)
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.
First use of p-tert-butylcalix[4]arene-tetra-O-acetate as a nanoreactor having tunable selectivity towards cross azo-compounds by trapping silver ions
Sarkar, Piyali,Mukhopadhyay, Chhanda
supporting information, p. 442 - 451 (2016/01/30)
p-tert-Butylcalix[4]arene-tetra-O-acetate was established for the first time as a member of the nanoreactor series, even without having any -OH group. The nano range distribution of this nanoreactor was ascertained by DLS, SEM and TEM studies. The capability of this cavitand towards hosting amines in a competitive manner generates a new green pathway for cross coupling of aromatic amines to give the corresponding azo-compounds. In this context, using p-tert-butylcalix[4]arene-tetra-O-acetate as a nanoreactor and silver nitrate as a catalyst, we got the cross azo-compound in good to excellent yields in the eco-friendly solvent water. This green methodology is also applicable for the synthesis of respective homo-compounds.
Synchronous double C-N bond formation via C-H activation for a novel synthetic route to phenazine
Seth, Kapileswar,Raha Roy, Sudipta,Chakraborti, Asit K.
supporting information, p. 922 - 925 (2016/01/16)
A novel synthetic strategy for phenazine formation is reported following self-coupling of anilines by Pd-Ag binary nanocluster-catalysed synchronous double C-N bond formation via non-radical mode of ortho-aryl C-H activation.
Rhenium-Catalyzed [4 + 1] Annulation of Azobenzenes and Aldehydes via Isolable Cyclic Rhenium(I) Complexes
Geng, Xiaoyu,Wang, Congyang
supporting information, p. 2434 - 2437 (2015/05/27)
The first Re-catalyzed [4 + 1] annulation of azobenzenes with aldehydes was developed to furnish 2H-indazoles via isolable and characterized cyclic ReI-complexes. For the first time, the acetate-acceleration effect is showcased in Re-catalyzed C-H activation reactions. Remarkably, mechanistic studies revealed an irreversible aldehyde-insertion step, which is in sharp contrast to those of previous Rh- and Co-systems. (Chemical Presented).
