Chemoselective electrochemical reduction of nitroarenes with gaseous ammonia
作者:Liu Chang、Jin Li、Na Wu、Xu Cheng
DOI:10.1039/d1ob00077b
日期:——
Valuable aromatic nitrogen compounds can be synthesized by reduction of nitroarenes. Herein, we report electrochemicalreduction 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
demonstrated a facile methodology to construct single Nb site catalysts with merely 0.63 wt% Nb by employing α-hydroxy carboxylic acid-functionalized cotton fiber as green and sustainable supporting material. The as-synthesized catalysts have been characterized thoroughly and exhibited a superior catalytic activity for selective oxidation of aniline into azoxybenzene with nearly 100% utilization efficiency
这项工作展示了一种简便的方法,通过使用 α-羟基羧酸功能化的棉纤维作为绿色和可持续的支撑材料,构建含铌量仅为 0.63 wt% 的单 Nb 位点催化剂。合成后的催化剂已被彻底表征,并在温和和绿色条件下表现出优异的苯胺选择性氧化成偶氮基苯的催化活性,H 2 O 2的利用效率接近 100% 。值得注意的是,它展示了最高的 TOF (4806 h -1) 在目前报道的多相催化剂中。此外,该催化剂在连续流动条件下稳定运行,与这些转化中报道的间歇工艺相比具有显着优势。活性测试和催化剂表征表明原子分散的Nb-peroxo配位中心实际上是催化位点。特别是,棉纤维上的 α-羟基羧酸基团在配位/稳定单个 Nb 位点方面发挥了重要作用。此外,1H MAS NMR谱证实芳基胺与共价接枝在棉纤维上的游离α-羟基羧酸基团之间存在酸碱相互作用,有利于底物的吸附和活化。机理研究表明偶氮衍生物是通过N-苯基羟胺与亚硝基苯
Catalytic selective oxidation of aromatic amines to azoxy derivatives with an ultralow loading of peroxoniobate salts
Moreover, the reaction can proceed smoothly with stoichiometric amounts of H2O2 without external heating and additives. The salts are also highly active in the conversion of various substituted aromatic amines with excellent selectivity towards azoxy products in simple operations. Mechanistic studies utilizing butylated hydroxytoluene (BHT) as a radical scavenger proved that the reaction proceeded through
这项工作表明,酒石酸配位的过氧化铌酸盐可用作在绿色和非常温和的条件下将苯胺氧化偶联成偶氮苯的高效催化剂。这些盐通过 FT-IR 光谱、元素分析、ICP-AES、TGA、ESI-MS、93 Nb NMR、UV-vis 光谱和 EXAFS 光谱进行了全面的合成和表征。值得注意的是,使用 ppm 级过氧化铌基催化剂实现了苯胺的完全转化和对偶氮苯的出色选择性(超过 95%)。此外,反应可以在化学计量的 H 2 O 2下顺利进行无需外部加热和添加剂。这些盐在各种取代芳香胺的转化中也具有很高的活性,在简单的操作中对偶氮氧基产物具有优异的选择性。使用丁基化羟基甲苯 (BHT) 作为自由基清除剂的机理研究证明,该反应是通过催化机制而不是自由基方法进行的。此外,HRMS 和 UV-vis 表征提供了明确的证据表明 Nb-(η 2 -O 2 ) 物质是参与苯胺选择性氧化的活性中间体。-NH 2基团与盐的Nb-(η
Synergy of Oxygen Vacancies and Base Sites for Transfer Hydrogenation of Nitroarenes on Ceria Nanorods
作者:Ziliang Yuan、Liang Huang、Yuanshuai Liu、Yong Sun、Guanghui Wang、Xun Li、Johannes A. Lercher、Zehui Zhang
DOI:10.1002/anie.202317339
日期:2024.2.26
additive-free synthesis of azoxy-aromatics by the transferhydrogenation of nitroarenes with ethanol as the hydrogen donor. Oxygen vacancies (Ov) and basic sites play a synergistic role, where Ov serve as the sites for adsorption and activation of ethanol as well as nitroarenes, which greatly decreases the activation energy of hydrogen atom transfer from α−Csp3−H in ethanol to nitro groups.
二氧化铈纳米棒可有效地通过以乙醇作为氢供体进行硝基芳烃的转移氢化来无添加剂地合成氧化偶氮芳香族化合物。氧空位(O v )和碱性位点发挥协同作用,其中O v作为乙醇和硝基芳烃的吸附和活化位点,大大降低了氢原子从α−C sp3 -H 转移的活化能。乙醇转化为硝基。