Ocaña Ivan, Williams Peter J H, Donald James, Griffin Neil, Hodges George, Rickard Andrew R, Chechik Victor
Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
Jealott's Hill International Research Centre, Syngenta, Bracknell, Berkshire RG42 6EY, UK.
Chimia (Aarau). 2024 Mar 27;78(3):123-128. doi: 10.2533/chimia.2024.123.
Two applications of a radical trap based on a homolytic substitution reaction (SH2') are presented for the trapping of short-lived radical intermediates in organic reactions. The first example is a photochemical cyanomethylation catalyzed by a Ru complex. Two intermediate radicals in the radical chain propagation have been trapped and detected using mass spectrometry (MS), along with the starting materials, products and catalyst degradation fragments. Although qualitative, these results helped to elucidate the reaction mechanism. In the second example, the trapping method was applied to study the radical initiation catalyzed by a triethylboronoxygen mixture. In this case, the concentration of trapped radicals was sufficiently high to enable their detection by nuclear magnetic resonance (NMR). Quantitative measurements made it possible to characterize the radical flux in the system under different reaction conditions (including variations of solvent, temperature and concentration) where modelling was complicated by chain reactions and heterogeneous mass transfer.
本文介绍了基于均裂取代反应（SH2'）的自由基捕获剂在有机反应中捕获短寿命自由基中间体的两种应用。第一个例子是钌配合物催化的光化学氰甲基化反应。利用质谱（MS）捕获并检测了自由基链增长过程中的两个中间体自由基，以及起始原料、产物和催化剂降解片段。尽管这些结果是定性的，但有助于阐明反应机理。在第二个例子中，该捕获方法用于研究三乙基硼-氧气混合物催化的自由基引发反应。在这种情况下，捕获自由基的浓度足够高，能够通过核磁共振（NMR）进行检测。定量测量使得在不同反应条件（包括溶剂、温度和浓度的变化）下对体系中的自由基通量进行表征成为可能，而在这些条件下，链反应和非均相传质使建模变得复杂。
