Max Planck Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 2, 45470, Mülheim an der Ruhr, Germany.
Chem Asian J. 2019 Jan 4;14(1):105-115. doi: 10.1002/asia.201801636. Epub 2018 Dec 13.
An overview of methods for the initiation of radical chain reactions by specific initiator compounds, which generate radicals, is given. These can be utilized to initiate any kind of radical chain reaction by transforming substrates into the desired radical intermediates. Azo initiators, peroxides, nitroxides, trialkylboranes, dialkyl zinc compounds, and type I photoinitiators are discussed, as well as methods of redox- and sonochemical initiation. Methods of direct radical formation from the substrates, such as photoredox catalysis or high-energy irradiation, are not included. The focus of this review lies on rather "low" temperatures in the range of 50 °C down to -78 °C, which can be useful to achieve more selective reactions. Illustrative applications of such radical chain initiators in a variety of reactions are discussed, including stereoselective ones and polymerizations.
介绍了通过特定引发剂化合物引发自由基链式反应的方法，这些引发剂化合物可以产生自由基，将底物转化为所需的自由基中间体，从而引发任何类型的自由基链式反应。讨论了偶氮引发剂、过氧化物、氮氧自由基、三烷基硼、二烷基锌化合物和 I 型光引发剂，以及氧化还原和超声化学引发方法。不包括直接从底物形成自由基的方法，如光氧化还原催化或高能辐射。这篇综述的重点是在 50°C 到-78°C 的“较低”温度范围内，这对于实现更具选择性的反应可能很有用。讨论了这些自由基链式引发剂在各种反应中的应用实例，包括立体选择性反应和聚合反应。
