兰州大学马建泰团队报道了Zr(OH)₄催化苯胺的可控选择性氧化制偶氮苯、偶氮苯和亚硝基苯。相关研究成果于2021年10月13日发表于国际顶尖学术期刊《德国应用化学》。

苯胺选择性氧化制备亚稳态、高价值的偶氮苯、偶氮苯或硝基苯在有机合成中具有重要的现实意义。然而，不可控的选择性和昂贵催化剂的费力合成严重阻碍了该反应在工业环境中的应用。

该文中，研究人员率先发现Zr(OH)₄作为一种高效的多相催化剂，能够使用过氧化物或O₂作为氧化剂选择性氧化苯胺，简单地通过调节反应溶剂，选择性地获得各种偶氮苯、对称/不对称偶氮苯以及亚硝基苯，且不需要添加剂。机理实验和密度泛函理论计算表明，H₂O₂和O₂的活化主要是通过Zr（OH）₄的桥连羟基和端羟基实现的。

该研究为苯胺的选择氧化提供了一种经济、环保的工业应用策略。

附：英文原文

Title: Zr(OH)4 Catalyzed Controllable Selective Oxidation of Anilines to Azoxybenzenes, Azobenzenes and Nitrosobenzenes

Author: Jiaheng Qin, Yu Long, Fangkun Sun, Pan-Pan Zhou, Wei David Wang, Nan Luo, Jiantai Ma

Issue&Volume: 2021-10-13

Abstract: The selective oxidation of aniline to metastable and valuable azoxybenzene, azobenzene or nitrosobenzene has important practical significance in organic synthesis. However, uncontrollable selectivity and laborious synthesis of the expensive required catalysts severely hinder the uptake of these reactions in industrial settings. Herein, we have pioneered the discovery of Zr(OH)  4  as an efficient heterogeneous catalyst capable of the selective oxidation of aniline, using either peroxide or O  2  as oxidant, to selectively obtain various azoxybenzenes, symmetric/unsymmetric azobenzenes, as well as nitrosobenzenes, by simply regulating the reaction solvent, without the need for additives. Mechanistic experiments and DFT calculations demonstrate that the activation of H  2  O  2  and O  2  is primarily achieved by the bridging hydroxyl and terminal hydroxyl groups of Zr(OH)  4  respectively. The present work provides an economical and environmentally friendly strategy for the selective oxidation of aniline in industrial applications.

DOI: 10.1002/anie.202112907

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202112907