331-21-5Relevant 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.
Nitrate promoted mild and versatile Pd-catalysed C(sp2)-H oxidation with carboxylic acids
Hao, Hong-Yan,He, Yu-Ting,Lou, Shao-Jie,Luo, Gen,Mao, Yang-Jie,Xiong, Xue,Xu, Dan-Qian,Xu, Zhen-Yuan
supporting information, p. 6732 - 6737 (2020/09/21)
A nitrate-promoted Pd-catalysed mild cross-dehydrogenative C(sp2)-H bond oxidation of oximes or azobenzenes with diverse carboxylic acids has been developed. In contrast to the previous catalytic systems, this protocol features mild conditions (close to room temperature for most cases) and a broad substrate scope (up to 64 examples), thus constituting a versatile method to directly prepare diverse O-aryl esters. Moreover, the superiority of the nitrate additive in this mild transformation was further determined by experimental and computational evidence.
Transition Metal-Free Oxidative Coupling of Primary Amines in Polyethylene Glycol at Room Temperature: Synthesis of Imines, Azobenzenes, Benzothiazoles, and Disulfides
Hudwekar, Abhinandan D.,Verma, Praveen K.,Kour, Jaspreet,Balgotra, Shilpi,Sawant, Sanghapal D.
, p. 1242 - 1250 (2019/01/09)
A transition metal-free protocol has been developed for the oxidative coupling of primary amines to imines and azobenzenes, thiols to disulfides, and 2-aminothiophenols to benzothiazoles, offering excellent yields. The advantageous features of the present environmentally benign methodology include the usage of biocompatible and green reaction conditions such as, solvent, room temperature reactions and transition metal-free approach. Moreover, it offers a broader substrate scope.
Modulating the catalytic behavior of non-noble metal nanoparticles by inter-particle interaction for chemoselective hydrogenation of nitroarenes into corresponding azoxy or azo compounds
Liu, Lichen,Concepción, Patricia,Corma, Avelino
, p. 312 - 323 (2018/12/11)
Aromatic azoxy compounds have wide applications and they can be prepared by stoichiometric or catalytic reactions with H2O2 or N2H4 starting from anilines or nitroarenes. In this work, we will present the direct chemoselective hydrogenation of nitroarenes with H2 to give aromatic azoxy compounds under base-free mild conditions, with a bifunctional catalytic system formed by Ni nanoparticles covered by a few layers of carbon (Ni@C NPs) and CeO2 nanoparticles. The catalytic performance of Ni@C-CeO2 catalyst surpasses the state-of-art Au/CeO2 catalyst for the direct production of azoxybenzene from nitrobenzene. By means of kinetic and spectroscopic results, a bifunctional mechanism is proposed in which, the hydrogenation of nitrobenzene can be stopped at the formation of azoxybenzene with >95% conversion and >93% selectivity, or can be further driven to the formation of azobenzene with >85% selectivity. By making a bifunctional catalyst with a non-noble metal, one can achieve chemoselective hydrogenation of nitroarenes not only to anilines, but also to corresponding azoxy and azo compounds.
Visible-light triggered selective reduction of nitroarenes to azo compounds catalysed by Ag@organic molecular cages
Chen, Gong-Jun,Xin, Wen-Ling,Wang, Jing-Si,Cheng, Jun-Yan,Dong, Yu-Bin
supporting information, p. 3586 - 3589 (2019/03/26)
Herein, a new Ag nanoparticle (Ag NP) loaded organic molecular cage is reported. The obtained Ag@1 can act as a highly efficient heterogeneous catalyst for the selective reduction of nitroarenes to azo compounds under visible-light irradiation.
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.
Synthesis of Azobenzenes Using N-Chlorosuccinimide and 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU)
Antoine John, Alford,Lin, Qing
, p. 9873 - 9876 (2017/09/23)
A convenient method for the synthesis of symmetrical azobenzenes is reported. This one-step procedure involves treatment of anilines with N-chlorosuccinimide (NCS) and organic base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). A wide range of commercially available substituted anilines readily participate in this reaction to produce the corresponding azobenzenes in moderate-to-excellent yields in minutes.
Kinetics and thermodynamics of oxidation of some meta-substituted anilines by tetrabutylammonium bromochromate in aqueous acetic acid medium
Jabir, Shaik,Asghar, Basim H.,Mansoor, S. Sheik
, p. 288 - 295 (2017/03/17)
The tetrabutylammonium bromochromate (TBABC) oxidation of anilines, in an aqueous acetic acid medium in the presence of perchloric acid is described. The reaction is first order with respect to aniline, TBABC and acid. The reaction rate has been determined at different temperatures and activation parameters calculated. The TBABC oxidation of meta-substituted anilines obeys Hammett relationships.
Electrocatalytic Z → E Isomerization of Azobenzenes
Goulet-Hanssens, Alexis,Utecht, Manuel,Mutruc, Dragos,Titov, Evgenii,Schwarz, Jutta,Grubert, Lutz,Bléger, David,Saalfrank, Peter,Hecht, Stefan
supporting information, p. 335 - 341 (2017/05/16)
A variety of azobenzenes were synthesized to study the behavior of their E and Z isomers upon electrochemical reduction. Our results show that the radical anion of the Z isomer is able to rapidly isomerize to the corresponding E configured counterpart with a dramatically enhanced rate as compared to the neutral species. Due to a subsequent electron transfer from the formed E radical anion to the neutral Z starting material the overall transformation is catalytic in electrons; i.e., a substoichiometric amount of reduced species can isomerize the entire mixture. This pathway greatly increases the efficiency of (photo) switching while also allowing one to reach photostationary state compositions that are not restricted to the spectral separation of the individual azobenzene isomers and their quantum yields. In addition, activating this radical isomerization pathway with photoelectron transfer agents allows us to override the intrinsic properties of an azobenzene species by triggering the reverse isomerization direction (Z → E) by the same wavelength of light, which normally triggers E → Z isomerization. The behavior we report appears to be general, implying that the metastable isomer of a photoswitch can be isomerized to the more stable one catalytically upon reduction, permitting the optimization of azobenzene switching in new as well as indirect ways.
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.
