Izadi Farhad, Arthur-Baidoo Eugene, Strover Lisa T, Yu Li-Juan, Coote Michelle L, Moad Graeme, Denifl Stephan
Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstrasse 25, A-6020, Innsbruck, Austria.
CSIRO Manufacturing, Clayton, VIC, 3168, Australia.
Angew Chem Int Ed Engl. 2021 Aug 23;60(35):19128-19132. doi: 10.1002/anie.202107480. Epub 2021 Jul 20.
Radical polymerization with reversible addition-fragmentation chain transfer (RAFT polymerization) has been successfully applied to generate polymers of well-defined architecture. For RAFT polymerization a source of radicals is required. Recent work has demonstrated that for minimal side-reactions and high spatio-temporal control these should be formed directly from the RAFT agent or macroRAFT agent (usually carbonothiosulfanyl compounds) thermally, photochemically or by electrochemical reduction. In this work, we investigated low-energy electron attachment to a common RAFT agent (cyanomethyl benzodithioate), and, for comparison, a simple carbonothioylsulfanyl compound (dimethyl trithiocarbonate, DMTTC) in the gas phase by means of mass spectrometry as well as quantum chemical calculations. We observe for both compounds that specific cleavage of the C-S bond is induced upon low-energy electron attachment at electron energies close to zero eV. This applies even in the case of a poor homolytic leaving group ( CH in DMTTC). All other dissociation reactions found at higher electron energies are much less abundant. The present results show a high control of the chemical reactions induced by electron attachment.
采用可逆加成-断裂链转移的自由基聚合反应（RAFT聚合）已成功应用于生成具有明确结构的聚合物。对于RAFT聚合反应，需要自由基源。最近的研究表明，为了使副反应最少并实现高时空控制，这些自由基应通过热、光化学或电化学还原直接由RAFT试剂或大分子RAFT试剂（通常是碳硫代硫烷基化合物）形成。在这项工作中，我们通过质谱以及量子化学计算研究了低能电子与一种常见的RAFT试剂（氰基甲基二硫代苯甲酸酯）的结合，并作为对比，研究了气相中的一种简单碳硫代硫酰基硫烷基化合物（二甲基三硫代碳酸酯，DMTTC）。我们观察到，对于这两种化合物，在电子能量接近零电子伏特时，低能电子附着会诱导C-S键的特定裂解。即使在均裂离去基团较差（DMTTC中的CH）的情况下也是如此。在较高电子能量下发现的所有其他解离反应都要少得多。目前的结果表明，电子附着引发的化学反应具有高度可控性。
