487-10-5Relevant academic research and scientific papers
Tandem selective reduction of nitroarenes catalyzed by palladium nanoclusters
Yan, Ziqiang,Xie, Xiaoyu,Song, Qun,Ma, Fulei,Sui, Xinyu,Huo, Ziyu,Ma, Mingming
supporting information, p. 1301 - 1307 (2020/03/11)
We report a catalytic tandem reduction of nitroarenes by sodium borohydride (NaBH4) in aqueous solution under ambient conditions, which can selectively produce five categories of nitrogen-containing compounds: anilines, N-aryl hydroxylamines, azoxy-, azo- and hydrazo-compounds. The catalyst is in situ-generated ultrasmall palladium nanoclusters (Pd NCs, diameter of 1.3 ± 0.3 nm) from the reduction of Pd(OAc)2 by NaBH4. These highly active Pd NCs are stabilized by surface-coordinated nitroarenes, which inhibit the further growth and aggregation of Pd NCs. By controlling the concentration of Pd(OAc)2 (0.1-0.5 mol% of nitroarene) and NaBH4, the water/ethanol solvent ratio and the tandem reaction sequence, each of the five categories of N-containing compounds can be obtained with excellent yields (up to 98%) in less than 30 min at room temperature. This tunable catalytic tandem reaction works efficiently with a broad range of nitroarene substrates and offers a green and sustainable method for the rapid and large-scale production of valuable N-containing chemicals.
Immobilized antimony species on magnetite: A novel and highly efficient magnetically reusable nanocatalyst for direct and gram-scale reductive-coupling of nitroarenes to azoarenes
Zeynizadeh, Behzad,Faraji, Fariba
, p. 13112 - 13121 (2019/05/10)
In this study, magnetic nanoparticles of Fe3O4@SbFx from the immobilization of SbF3 on magnetite were synthesized. The prepared nanocomposite system was then characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, vibrating sample magnetometry and inductively coupled plasma optical emission spectroscopy. Next, the catalytic activity of Fe3O4@SbFx MNPs was highlighted by one-pot reductive-coupling of aromatic nitro compounds to the corresponding azoarene materials with NaBH4. The reactions were carried out in refluxing EtOH within 6-25 min to afford the products in high yields. The reusability of the Sb-magnetite system was also studied for 6 consecutive cycles without significant loss of catalytic activity. This synthetic protocol provided several advantages in terms of introducing a novel catalytic system based on antimony species for direct and gram-scale preparation of azoarenes from nitroarenes, low loading of the nanocatalyst, mild reaction conditions, using ethanol as a green and economic solvent and high yield of the products.
Aromatic amine oxidation process for preparing aromatic azobenzene method
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Paragraph 0013; 0017, (2017/10/11)
The invention relates to a method for preparing an aromatic azo compound by utilizing aromatic amine oxidation. In the method, air or oxygen serves as an oxygen source, and under the effect of a catalyst, aromatic amine is oxidized into the aromatic azo compound. The method is high in oxidization efficiency and product yield; the air or the oxygen serves as the oxygen source, and the method is economical and environmentally friendly. The product and the catalyst can be separated easily, and the aftertreatment is simple. The catalyst is easy to reuse, and the method has very good application prospect.
The palladium and copper contrast: A twist to products of different chemotypes and altered mechanistic pathways
Seth, Kapileswar,Roy, Sudipta Raha,Kumar, Asim,Chakraborti, Asit K.
, p. 2892 - 2896 (2016/05/24)
A novel contrast in palladium and copper catalysis is revealed to form products of different chemotypes resulting in a phenazine to azoarene twist through an altered mechanistic pathway (from non-radical C-H activation mode of C-N coupling to radical N-N coupling) during the oxidative self-coupling of anilines catalysed by Pd-Ag and Cu-Ag nanoclusters.
Mesoporous manganese oxide catalyzed aerobic oxidative coupling of anilines to aromatic azo compounds
Dutta, Biswanath,Biswas, Sourav,Sharma, Vinit,Savage, Nancy Ortins,Alpay, S. Pamir,Suib, Steven L.
supporting information, p. 2171 - 2175 (2016/02/18)
Herein we introduce an environmentally friendly approach to the synthesis of symmetrical and asymmetrical aromatic azo compounds by using air as the sole oxidant under mild reaction conditions in the presence of cost-effective and reusable mesoporous manganese oxide materials.
Photocatalytic reduction of nitroarenes to azo compounds over N-doped TiO2: Relationship between catalysts and chemical reactivity
Wang, Huqun,Yang, Xiaofeng,Xiong, Weifeng,Zhang, Zhimin
, p. 3981 - 3997 (2015/06/08)
This work deals with selective reduction of aromatic nitro compounds to corresponding symmetrical substituted azo compounds using nitrogen-doped TiO2 nanoparticles as photocatalyst in the presence of a catalytic amount of formic acid. Various azo compounds containing additional reducible substituents including halogens, and carboxyl and phenol functions have been synthesized in a single step by use of this catalyst. The conversion was reasonably fast, clean, and high yielding at room temperature. A mechanism of formation for the azo compounds is proposed. The behavior of the N/TiO2 catalyst is of particular interest because this is the first time, as far as we know, that formation of azo compounds has been catalyzed by an N-doped TiO2 photocatalyst. Nitrogen-doped TiO2 was prepared by a simple modified sol-gel process with urea as nitrogen source. The catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy, and transmission electron microscopy. The chemical nature of N was identified by XPS as N-Ti-O in the anatase TiO2 lattice.
A facile superoxide induced conversion of aromatic amines to azo compounds under microwave irradiation
Singh, Sundaram,Singh, Krishna Nand
experimental part, p. 841 - 843 (2012/04/04)
The present report demonstrates an efficient use of tetraethylammonium superoxide under non-aqueous conditions to bring about a mild and convenient transformation of aromatic amines to azo compounds in good yield under mono-mode microwave irradiation.
Synthesis of azo compounds by nanosized iron-promoted reductive coupling of aromatic nitro compounds
Moglie, Yanina,Vitale, Cristian,Radivoy, Gabriel
, p. 1828 - 1831 (2008/09/18)
Treatment of a variety of aromatic nitro compounds with the active-iron based reducing system composed of FeCl2·4H2O, an excess of lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB, 5 mol %) in THF at room temperature, led to the formation of the corresponding symmetrically substituted azo compounds in good yield, resulting from a reductive coupling process. Some other functionalities including carbonyl, halogen, amino and hydroxyl groups, demonstrated to be compatible with the reaction conditions, giving none reduced or coupled by-products. In all cases, the azo compounds formed have not experienced over-reduction to the corresponding hydrazo or amino derivatives even upon prolonged heating or using an excess of the reducing system.
An easy access to aromatic azo compounds under ultrasound/microwave irradiation
Cravotto, Giancarlo,Boffa, Luisa,Bia, Marco,Bonrath, Werner,Curini, Massimo,Heropoulos, Georgios A.
, p. 2605 - 2608 (2008/09/16)
Chemoselective reduction of nitroarenes to azo and azoxy compounds was easily achieved using zinc powder and ammonium chloride in DMF or DMF-water (95:5) under high intensity ultrasound (US) or microwave (MW) irradiation, separately or combined. When carried out under conventional heating the reaction required much higher temperatures and gave lower yields. The addition of a small amount of water caused a dramatic increase in the reactivity, permitting the reduction of hindered nitroarenes at the expense of selectivity. A novel reactor for combined US/MW irradiation was employed which demonstrated additional beneficial effects. Georg Thieme Verlag Stuttgart.
Facile synthesis of azo compounds from aromatic nitro compounds using magnesium and triethylammonium formate
Srinivasa,Abiraj,Gowda, D. Channe
, p. 609 - 610 (2007/10/03)
Magnesium/triethylammonium formate is a convenient reagent for the reduction of aromatic nitro compounds to corresponding symmetrically substituted azo compounds. Various azo compounds containing additional reducible substituents, including halogen, nitrile, acid, phenol, ester, and methoxy 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.
