- Convenient and rapid diazotization and diazo coupling reaction via aryl diazonium nanomagnetic sulfate under solvent-free conditions at room temperature
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For the first time, nanomagnetic-supported sulfonic acid is used for conversion of several types of aromatic amine, containing electron-withdrawing groups as well as electron-donating groups to the corresponding azo dyes in excellent yield. The synthesis of these compounds is described by the sequential diazotization-diazo coupling of various aromatic amines with sodium nitrite, nanomagnetic supported sulfonic acid and coupling agents under solvent-free conditions at room temperature. This new method offers several advantages including short reaction time, mild reaction conditions, avoidance of harmful acids, and simple work-up procedure. More importantly, aryldiazonium salts supported on magnetic nanoparticles (aryl diazonium nanomagnetic sulfate) were sufficiently stable to be kept at room temperature in the dry state.
- Koukabi, Nadiya,Otokesh, Somayeh,Kolvari, Eskandar,Amoozadeh, Ali
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- Room temperature activation of oxygen by monodispersed metal nanoparticles: Oxidative dehydrogenative coupling of anilines for azobenzene syntheses
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It is highly challenging but desirable to develop efficient catalysts for the activation of oxygen under mild conditions. Here, we report that various monodispersed metal nanoparticles (Ag, Pt, Co, Cu, Ni, Pd, and Au) efficiently activated molecular oxygen under mild conditions, illustrated by the aerobic oxidation of anilines to form either symmetric or asymmetric aromatic azo compounds. This discovery indicates that exploiting the catalytic power of nanoparticles could enable sustainable chemistry suitable for important oxidation reactions.
- Cai, Shuangfei,Rong, Hongpan,Yu, Xiaofei,Liu, Xiangwen,Wang, Dingsheng,He, Wei,Li, Yadong
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p. 478 - 486
(2013/05/22)
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- Activation of the aryl hydrocarbon receptor by methyl yellow and related congeners: structure-activity relationships in halogenated derivatives.
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The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that mediates the biological action of many environmental compounds. Methyl yellow (4-dimethylaminoazobenzene; MY) is a principal azo-dye, and structurally related compounds were subjected to analysis of structure-activity relationships as AhR ligands by using a yeast AhR signaling assay. The effects of halogen-substitution among 23 halogenated MYs on the AhR ligand activity can be summarized as follows: enhancement by halogen-substitution at the ortho-position (2'- and 6'-position), and reduction by substitution at the para-position (4'-position). The greatest enhancement of the ligand activity was observed in 2',6'-dichlorinated MY (13.5-fold of MY), and its AhR ligand activity was very close to that of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the present assay system. In the study of compounds structurally related to MY, benzanilide (BA) showed almost the same AhR ligand activity as azobenzene and trans-stilbene. Furthermore, 4'-chlorobenzanilide, in which the length of the molecule is similar to that of MY, enhanced the AhR ligand activity by ortho(2')-chlorine-substitution, and the AhR ligand activity of 2',4'-dichlorobenzanilide was similar to that of 2'-chloro-MY. These results suggest that the amide bond is equivalent to the -N=N- or -CH=CH- double bond for recognition as the ligand by AhR in 1,2-diphenyl-1,2-ene derivatives.
- Kato, Taka-aki,Matsuda, Tomonari,Matsui, Saburo,Mizutani, Takaharu,Saeki, Ken-ichi
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p. 466 - 471
(2007/10/03)
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- Electrophilic ipso-Substitutions. Part 2. Reactions of 3-Substituted Indoles and 4-Substituted NN-Dimethylanilines with Arenediazonium Ions
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3-Substituted indoles and 4-substituted NN-dimethylanilines react with arenediazonium ions to form 3-arylazo-indoles and 4-arylazo-NN-dimethylanilines, respectively.The formation of the ?-complex intermediate was interpreted both as electrophilic ipso-attack and as coupling of two radicals deriving from an electron transfer process.Both mechanisms are discussed on the basis of the experimental evidence and on the substrate oxidation potentials.The leaving abilities of the substituents are discussed on the basis of the experimental results.
- Colonna, Martino,Greci, Lucedio,Poloni, Marino
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p. 455 - 460
(2007/10/02)
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