122045-07-2Relevant articles and documents
A Molecular Hybrid of an Atomically Precise Silver Nanocluster and Polyoxometalates for H2 Cleavage into Protons and Electrons
Suzuki, Kosuke,Yamaguchi, Kazuya,Yamazoe, Seiji,Yokogawa, Daisuke,Yonesato, Kentaro
, p. 16994 - 16998 (2021)
Atomically precise silver (Ag) nanoclusters are promising materials as catalysts, photocatalysts, and sensors because of their unique structures and mixed-valence states (Ag+/Ag0). However, their low stability hinders the in-depth st
Concise preparation of azenes by oxidation of aromatic amines with molecular oxygen in subcritical water
Kus, Nermin Simsek
, p. 1089 - 1091 (2010)
Reaction of organic substrates with molecular oxygen, the most abundant and accessible oxidant, has always been an attractive method for preparation of target molecules. In terms of green chemistry, non-metal-catalyzed oxidation of organic substrates is very attractive. This paper describes a general procedure for synthesis of azenes by oxidation of primary aromatic amines with molecular oxygen (3O2) in subcritical water. The reactions afforded the corresponding azenes in moderate to good yield. Springer-Verlag 2010.
Chemoselective electrochemical reduction of nitroarenes with gaseous ammonia
Chang, Liu,Li, Jin,Wu, Na,Cheng, Xu
supporting information, p. 2468 - 2472 (2021/04/02)
Valuable aromatic nitrogen compounds can be synthesized by reduction of nitroarenes. Herein, we report electrochemical reduction of nitroarenes by a protocol that uses inert graphite felt as electrodes and ammonia as a reductant. Depending on the cell voltage and the solvent, the protocol can be used to obtain aromatic azoxy, azo, and hydrazo compounds, as well as aniline derivatives with high chemoselectivities. The protocol can be readily scaled up to >10 g with no decrease in yield, demonstrating its potential synthetic utility. A stepwise cathodic reduction pathway was proposed to account for the generations of products in turn.
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.
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.
Super electron donor-mediated reductive transformation of nitrobenzenes: A novel strategy to synthesize azobenzenes and phenazines
Nozawa-Kumada, Kanako,Abe, Erina,Ito, Shungo,Shigeno, Masanori,Kondo, Yoshinori
supporting information, p. 3095 - 3098 (2018/05/22)
The transformation of nitrobenzenes into azobenzenes by pyridine-derived super electron donor 2 is described. This method provides an efficient synthesis of azobenzenes because of not requiring the use of expensive transition-metals, toxic or flammable reagents, or harsh conditions. Moreover, when using 2-fluoronitrobenzenes as substrates, phenazines were found to be obtained. The process affords a novel synthesis of phenazines.
When Do Strongly Coupled Diradicals Show Strongly Coupled Reactivity? Thermodynamics and Kinetics of Hydrogen Atom Transfer Reactions of Palladium and Platinum Bis(iminosemiquinone) Complexes
Conner, Kyle M.,Arostegui, AnnaMaria C.,Swanson, Daniel D.,Brown, Seth N.
, p. 9696 - 9707 (2018/08/28)
The 2,2′-biphenylene-bridged bis(iminosemiquinone) complexes (tBuClip)M [tBuClipH4 = 4,4′-di-tert-butyl-N,N′-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-2,2′-diaminobiphenyl; M = Pd, Pt] can be reduced to the bis(aminophenoxide) complexes (tBuClipH2)M by reaction with hydrazobenzene (M = Pd) or by catalytic hydrogenation (M = Pt). The palladium complex with one aminophenoxide ligand and one iminosemiquinone ligand, (tBuClipH)Pd, is generated by comproportionation of (tBuClip)Pd with (tBuClipH2)Pd in a process that is both slow (0.06 M-1 s-1 in toluene at 23 °C) and only modestly favorable (Kcom = 1.9 in CDCl3), indicating that both N-H bonds have essentially the same bond strength. The mono(iminoquinone) complex (tBuClipH)Pt has not been observed, indicating that the platinum analogue shows no tendency to comproportionate (Kcom tBuClipH2)Pt to (tBuClip)Pd occurring with ?G° = ?8.9 kcal mol-1. The palladium complex (tBuClipH2)Pd reacts with nitroxyl radicals in two observable steps, with the first hydrogen transfer taking place slightly faster than the second. In the platinum analogue, the first hydrogen transfer is much slower than the second, presumably because the N-H bond in the monoradical complex (tBuClipH)Pt is unusually weak. Using driving force-rate correlations, it is estimated that this bond has a BDFE of 55.1 kcal mol-1, which is 7.1 kcal mol-1 weaker than that of the first N-H bond in (tBuClipH2)Pt. The two radical centers in the platinum, but not the palladium, complex thus act in concert with each other and display a strong thermodynamic bias toward two-electron reactivity. The greater thermodynamic and kinetic coupling in the platinum complex is attributed to the stronger metal-ligand ? interactions in this compound.
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.
Convenient Electrocatalytic Synthesis of Azobenzenes from Nitroaromatic Derivatives Using SmI2
Zhang, Yu-Feng,Mellah, Mohamed
, p. 8480 - 8486 (2017/12/08)
The synthesis of azobenzenes has been a long-standing challenge. Their current preparation at a preparative or industrial scale requires stoichiometric amounts of environmentally unfriendly reactants. Herein, we demonstrate that the catalytic use of electrogenerated samarium diiodide (SmI2) could promote, in one-step synthesis, the reduction of nitrobenzenes into azobenzenes in high yields under mild reaction conditions. This catalytic procedure contains many elements satisfying a sustainable chemical process for the preparation of one of the most widely wanted family of chemical compounds. The easy synthetic procedure, and the absence of precious metals, bases, and nonhazardous substances, already makes our catalytic procedure a serious alternative to currently available methods. This is a promising method for the efficient synthesis of both symmetrical and asymmetrical azo compounds with a high functional group tolerance.
Stabilisation of gold nanoparticles by N-heterocyclic thiones
Moraes, Leonardo C.,Lacroix, Bertrand,Figueiredo, Rute C.,Lara, Patricia,Rojo, Javier,Conejero, Salvador
supporting information, p. 8367 - 8371 (2017/07/12)
Gold nanoparticles (Au-NPs) have been prepared using N-heterocyclic thiones (NHTs) as ligand stabilisers. These Au-NPs have been shown to be very stable, even in air, and have been characterized by a combination of several techniques (TEM, HR-TEM, STEM-HAADF, EDX, DLS, elemental analysis and 1H NMR). These nanoparticles are active in the catalytic reduction of nitroarenes to anilines.
