10473-06-0Relevant academic research and scientific papers
Bifunctional Cs?Au/Co3O4 (Basic and Redox)-Catalyzed Oxidative Synthesis of Aromatic Azo Compounds from Anilines
Akinnawo, Christianah Aarinola,Alimi, Oyekunle Azeez,Fapojuwo, Dele Peter,Meijboom, Reinout,Mogudi, Batsile M.,Onisuru, Oluwatayo Racheal,Oseghale, Charles O.
, p. 5063 - 5073 (2021)
An eco-friendly alkali-promoted (Cs?Au/Co3O4) catalyst, with redox and basic properties for the oxidative dehydrogenative coupling of anilines to symmetrical and unsymmetrical aromatic azo compounds, was developed. We realized a base additive- and molecular O2 oxidant-free process (using air), with reasonable reusability of the catalyst achieved under milder reaction conditions. Notably, the enhanced catalytic activity was also linked to the increased basic site concentration, low reduction temperatures, and the effect of lattice oxygen on the nanomaterials. The increased basic strength of the cation-promoted catalyst improved the electron density of the active Au species, resulting in higher yields of the desired aromatic azo compounds.
A metal-catalyst-free oxidative coupling of anilines to aromatic azo compounds in water using bleach
de Souza, Gabriela F.P.,von Zuben, Theodora W.,Salles, Airton G.
, p. 3753 - 3755 (2018)
A simple route toward the synthesis of symmetrical and unsymmetrical aromatic azo compounds through oxidative coupling of anilines using widely available NaOCl is presented. This metal catalyst-free protocol is performed in water and affords the desired products in high yields.
Trichloroisocyanuric Acid Mediated Oxidative Dehydrogenation of Hydrazines: A Practical Chemical Oxidation to Access Azo Compounds
Cao, Guiyan,Hu, Yulai,Huang, Danfeng,Huo, Congde,Liu, Xuan,Su, Yingpeng,Wang, Ke-Hu,Yu, Jie,Zhang, Rong,Zhao, Yanan
, p. 1103 - 1112 (2020)
A highly efficient, metal-free, chemical oxidation of hydrazines has been implemented using environmentally friendly TCCA as oxidant. This benign protocol provides straightforward access to a wide range of azo compounds in THF in excellent yield. Altogether, 35 azo compounds were obtained in this way and scale-up preparations were performed. Additionally, a plausible mechanism was also proposed. Step-economical process, mild reaction conditions, operational simplicity, high reaction efficiency, and easy scale-up highlight the practicality of this methodology.
Dimerization of Anilines and Benzylamines with Mercury(II) Oxide-Iodine Reagent
Orito, Kazuhiko,Hatakeyama, Takahiro,Takeo, Mitsuhiro,Uchiito, Shiho,Tokuda, Masao,Suginome, Hiroshi
, p. 8403 - 8410 (1998)
By treatment with mercury(II) oxide-iodine reagent in dichloromethane at room temperature, substituted anilines were transformed to the corresponding azobenzenes. A similar treatment of benzylamines and benzhydrylamine gave N-benzylidenebenzylamines and N-benzhydrylidene-benzhydrylamine, respectively. α-Alkyl-substituted benzylamines gave diazenes and the corresponding phenyl ketones, competitively. An azine was obtained by interaction with the reagent of a benzylamine carrying an electron-withdrawing substituent at the α position, such as ethyl phenylglycinate.
Synthesis of functionalized azobiphenyls and azoterphenyls with improved solubilities for switching applications
K?hl, Isabel,Lüning, Ulrich
, p. 2376 - 2382 (2014)
Nine new azo compounds, in particular azobiphenyls and azoterphenyls, have been synthesized and their photochemical switching has been investigated. 4,4′-Dihalogenated azobenzenes were generated by oxidative copper-mediated coupling of respective anilines followed by Suzuki-Miyaura cross-coupling reaction. The elongated azobenzenes carry functional groups at the terminal 4-positions and additional methyl substituents at the central benzene rings. While the introduction of two methyl groups improved the solubility of the resulting azo compounds considerably, the introduction of four methyl groups was less successful with respect to solubility. Differences were also found in the photochemical behavior for the dimethyl and the tetramethyl derivatives. Georg Thieme Verlag Stuttgart. New York.
Palladium-catalyzed cascade oxidation/ sp 2 C-H acylation of azoarenes with aryl methanes
Xiong, Feng,Qian, Cheng,Lin, Dongen,Zeng, Wei,Lu, Xiaoxia
, p. 5444 - 5447 (2013)
A Pd-catalyzed cascade oxidation/sp2 C-H bond acylation of azoarenes was developed in which readily available aryl methanes were used as the in situ generated acyl sources. This reaction provides a convenient access to ortho-acyl azoarenes under mild conditions.
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
, p. 2689 - 2700 (2020)
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.).
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)
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.
Study of halogen-mediated weak interactions in a series of halogen-substituted azobenzenes
Karanam, Maheswararao,Choudhury, Angshuman Roy
, p. 4803 - 4814 (2013)
The azobenzenes, known for their various importance in the industry, have been chosen as model compounds to understand the role of weak interactions involving the C-X (X = F, Cl, and Br) bond using single-crystal X-ray diffraction technique, especially in the absence of other stronger intermolecular forces such as hydrogen bonds. The fluorinated compounds have been found to pack in the lattice by utilizing C-H···F hydrogen bonds, whereas the chlorinated and brominated analogues have been found to prefer C-X···X-C, C-X···π, and π···π interactions while packing in the lattice. The stabilization energy offered by the C-H···F hydrogen bonds and the C-X···X-C interactions have been estimated by computational methods using Gaussian 09, and the topological properties have been determined by using the AIM2000 package. The lattice energy decomposition has been done using semiclassical density sums (SCDS) PIXEL method. Our studies indicate that the stabilization energy offered by each C- H···F hydrogen bond lies in the range from -0.8 to -1.0 kcal/mol, while that for the C-X···X-C interaction has been found to be -0.35 kcal/mol for the X = Cl interaction and -0.73 kcal/mol for the X = Br interaction. Further, the analysis of these interaction by atoms in molecules (AIM) theory indicates that the electron densities (ρc) at the bond critical points (BCP) for C-H···F and C-X···X-C (X = Cl and Br), calculated using the AIM2000 package, are small (-3), and the values of Laplacian (?2ρc) are positive. This indicates that these interactions are of the hydrogen bond type. A detailed study of these interactions by experimental and computational methods has been described in the manuscript.
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.
