电子科技大学董帆团队报道了原子分散Bi位点上亲电和亲核自由基偶联的光催化合成甲酰胺。相关研究成果发表在2024年7月5日出版的《德国应用化学》。

甲酰胺（HCONH₂）在各种化学品、肥料和药品的生产中发挥着关键作用。光催化由于其环境友好性和温和的氧化还原能力，在碳氮（C-N）化合物的绿色制造中具有很大的前景。然而，C-N键的选择性形成在C-N化合物的光催化合成中提出了重大挑战。

该文开发了一种由氨（NH₃）和甲醇（CH₃OH）共同氧化合成甲酰胺的光催化自由基偶联方法。在TiO₂上原子分散的Bi位点（BiSA）上获得了5.47±0.03mmol·gcat^-1·h^-1（911.87±0.05mmol·gBi^-1·h^-1）的优异甲酰胺产率。长期光照后，甲酰胺的积累量为45.0 mmol·gcat^-1（0.2 g·gcat.^-1），代表了光催化C-N化合物合成的最高水平。

甲酰胺形成的临界C-N偶联源于亲电的●CH₂OH与亲核的●NH₂自由基之间的“σ-σ”相互作用。BiSAs位点促进了反应物和光催化剂之间的电子转移，增强了●NH₂自由基对●CH₂OH自由基的亲核攻击，从而促进了选择性C-N键的形成。

该项工作加深了对C-N偶联机制的理解，并为高效和可持续地生产C-N化合物提供了一种替代的、有趣的光催化方法。

附：英文原文

Title: Photocatalytic Formamide Synthesis via Coupling of Electrophilic and Nucleophilic Radicals over Atomically Dispersed Bi Sites

Author: Weiping Yang, Lei Xiao, Haoran Wu, Xin Li, Qin Ren, Jieyuan Li, Ying Zhou, Fan Dong

Issue&Volume: 2024-07-05

Abstract: Formamide (HCONH2) plays a pivotal role in the manufacture of a diverse array of chemicals, fertilizers, and pharmaceuticals. Photocatalysis holds great promise for green fabrication of carbon-nitrogen (C-N) compounds owing to its environmental friendliness and mild redox capability. However, the selective formation of the C-N bond presents a significant challenge in the photocatalytic synthesis of C-N compounds. This work developed a photocatalytic radical coupling method for the formamide synthesis from co-oxidation of ammonia (NH3) and methanol (CH3OH). An exceptional formamide yield rate of 5.47 ± 0.03 mmol·gcat-1·h-1 (911.87 ± 0.05 mmol·gBi-1·h-1) was achieved over atomically dispersed Bi sites (BiSAs) on TiO2. An accumulation of 45.0 mmol·gcat-1 (0.2 g·gcat-1) of formamide was achieved after long-term illumination, representing the highest level of photocatalytic C-N compounds synthesis. The critical C-N coupling for formamide formation originated from the “σ-σ” interaction between electrophilic ●CH2OH with nucleophilic ●NH2 radical. The  BiSAs sites facilitated the electron transfer between reactants and photocatalysts and enhanced the nucleophilic attack of ●NH2 radical at the ●CH2OH radical, thereby advancing the selective C-N bond formation. This work deepens the understanding of the C-N coupling mechanism and offers an alternative and intriguing photocatalytic approach for the efficient and sustainable production of C-N compounds.

DOI: 10.1002/anie.202408379

Source: https://onlinelibrary.wiley.com/doi/10.1002/anie.202408379