19672-25-4Relevant academic research and scientific papers
Visible-Light-Promoted Diboron-Mediated Transfer Hydrogenation of Azobenzenes to Hydrazobenzenes
Song, Menghui,Zhou, Hongyan,Wang, Ganggang,Ma, Ben,Jiang, Yajing,Yang, Jingya,Huo, Congde,Wang, Xi-Cun
, p. 4804 - 4811 (2021/04/06)
A visible-light-promoted transfer hydrogenation of azobenzenes has been developed. In the presence of B2pin2 and upon visible-light irradiation, the reactions proceeded smoothly in methanol at ambient temperature. The azobenzenes with diverse functional groups have been reduced to the corresponding hydrazobenzenes with a yield of up to 96%. Preliminary mechanistic studies indicated that the hydrogen atom comes from the solvent and the transformation is achieved through a radical pathway.
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.
Homolytic Cleavage of a B-B Bond by the Cooperative Catalysis of Two Lewis Bases: Computational Design and Experimental Verification
Wang, Guoqiang,Zhang, Honglin,Zhao, Jiyang,Li, Wei,Cao, Jia,Zhu, Chengjian,Li, Shuhua
, p. 5985 - 5989 (2016/05/19)
Density functional theory (DFT) investigations revealed that 4-cyanopyridine was capable of homolytically cleaving the B-B σ bond of diborane via the cooperative coordination to the two boron atoms of the diborane to generate pyridine boryl radicals. Our experimental verification provides supportive evidence for this new B-B activation mode. With this novel activation strategy, we have experimentally realized the catalytic reduction of azo-compounds to hydrazine derivatives, deoxygenation of sulfoxides to sulfides, and reduction of quinones with B2(pin)2 at mild conditions. Breaking good: The diborane B-B bond can be homolytically cleaved via the cooperative catalysis of two 4-cyanopyridine molecules. Using this combination of a diborane (B2(pin)2) and 4-cyanopyridine also allows the catalytic reduction of the N=N double bond of azo-compounds to hydrazine derivatives, deoxygenation of sulfoxides to sulfides, and reduction of quinones under mild conditions.
Activation method of bis(pinacolato)diborane and application thereof
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Paragraph 0065; 0066; 0067, (2016/10/31)
The invention discloses an activation method of bis(pinacolato)diborane. R substituted pyridine induces the homolysis of bis(pinacolato)diborane to obtain boron free radicals, and the process is shown by a formula I, wherein R refers to independent cyano and nitro. The invention also provides an application of the activation method of bis(pinacolato)diborane. Specifically, the activation method is applied to the synthesis of hydro-azobenzene derivatives.
Titania-Supported Gold Nanoparticles Catalyze the Selective Oxidation of Amines into Nitroso Compounds in the Presence of Hydrogen Peroxide
Fountoulaki, Stella,Gkizis, Petros L.,Symeonidis, Theodoros S.,Kaminioti, Eleni,Karina, Athanasia,Tamiolakis, Ioannis,Armatas, Gerasimos S.,Lykakis, Ioannis N.
supporting information, p. 1500 - 1508 (2016/05/19)
In this article, the catalytic activity of titania-supported gold nanoparticles (Au/TiO2) was studied for the selective oxidation of amines into nitroso compounds using hydrogen peroxide (H2O2). Gold nanoparticles deposited on Degussa P25 polymorphs of titania (TiO2) have been found to promote the selective formation of a variety of nitroso arenes in high yields and selectivities, even in a large-scale synthesis. In contrast, alkyl amines are oxidized to the corresponding oximes under the examined conditions. Kinetic studies indicated that aryl amines substituted with electron-donating groups are oxidized faster than the corresponding amines bearing an electron-withdrawing functionality. A Hammett-type kinetic analysis of a range of para-X-substituted aryl amines implicates an electron transfer (ET) mechanism (ρ=-1.15) for oxidation reactions with concomitant formation of the corresponding N-aryl hydroxylamine as possible intermediate. We also show that the oxidation protocol of aryl amines in the presence of 1,3-cyclohexadiene leads in excellent yields to the corresponding hetero Diels-Alder adducts between the diene and the in situ formed nitrosoarenes.
Photobenzidine Rearrangements. 6. Mechanism of the Photodecomposition of 1,4-Diaryl-1,4-dialkyl-2-tetrazenes
Bae, Dong-Hak,Shine, Henry J.
, p. 4448 - 4455 (2007/10/02)
The photodecomposition of the tetrazene p-XC6H4N(Me)N=N(Me)NC6H4Y-p (1e,X=Y=Me) in dimethoxyethane (DME) gave 47.4percent of p-XC6H4(Me)NN(Me)C6H4Y-p (2e,X=Y=Me) and 39.6 percent of N-methyl-p-toluidine. When irradiation was carried out in the presence of increasing initial concentrations of n-BuSH, the yield of 2e fell and levelled off at 6percent.Similar experiments in cyclohexane showed that the yield of 2e fell from 45.1percent and leveled off at 10percent.The data indicate that 1e decomposes by a radical pathway and that the 2e is formed partly within and partly outside of a solvent cage. Similar studies with 1d(X=Me, Y=CO2Et) in DME gave three hydrazines: 2d(X=Me,Y=CO2Et) in 13percent and 14.7percent yield, 2e in 7.3percent and 8.0percent yield,and 2f(X=Y=CO2Et) in 14.9percent and 21.2percent yield. The formation of three hydrazines again indicates the formation and intermolecular recombination of methylarylamino radicals. Irradiation of 1d in DME solutions containing n-BuSH caused a fall in the yield of 2e to zero and a leveling off in the yield of 2d to 6percent. The yield of 2f also fell but could not be monitored at high concentrations of n-BuSH because of overlapping high-pressure LC peaks. The results with 1d are also consistent with a cage-recombination process (for 2d) and an intermolecular recombination of radicals (for 2d-f). The methylarylamines p-XC6H4NHMe and p-YC6H4NHMe (X=Me; Y=CO2Et) were also formed from 1d. A sixth product was the bis(arylamino)methane p-YC6H4NHCH2NHC6H4Y-p(4f, Y=CO2Et) in 14-32percent yield (three runs). The origin of 4f is believed to be the disproportionation of radicals p-YC6H4NMe, giving p-YC6H4NHMe and p-YC6H4N=CH2(7f). Hydrolysis of 7f (by small amounts of water in the solvent) to p-YC6H4NH2 (6f) and HCHO followed by addition of 6f to 7f would give 4f. HCHO was found as a volatile product after irradiation. The formation of 4f is further evidence for the formation and intermolecular reaction of arylamino radicals in the photodecomposition of 1,4-dialkyl-1,4-diaryl-2-tetrazenes.
