Incorporation of Radicals during Ni(II)-Catalyzed Ethylene Insertion Polymerization
Incorporation of Radicals during Ni(II)-Catalyzed Ethylene Insertion Polymerization
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DOI：
10.1021/acscatal.8b04707
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发表时间：
2019-02
期刊：
影响因子：
12.9
通讯作者：
S. M. Stadler;Inigo Göttker-Schnetmann;S. Mecking
中科院分区：
文献类型：
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作者：
S. M. Stadler;Inigo Göttker-Schnetmann;S. Mecking
自由基可能参与催化插入链的增长仍然难以捉摸，尽管它可以解释到目前为止尚未得出结论的实验观察结果，并使尚未实现的合成反应方案成为可能。这项工作表明，为此目的而特意生成的存在的自由基在乙烯插入聚合中作为端基被结合。在加压反应器中加入偶氮引发剂(R-N=N-R‘，R=C(CH3)2COOMe，Ph，3，5-F2C6H3)后，Ni(II)催化的缩水杨醛乙烯聚合分别得到了引发剂衍生的芳基或烷基端基，对所形成的聚合物进行了深入的核磁共振研究。观察到额外的溶剂衍生的芳基端基，起源于自由基转移到甲苯，强调端基确实是由自由基形成的。讨论了作为链引发端基和端基终止结合的证据。
A possible involvement of radicals in catalytic insertion chain growth remains elusive, albeit it could account for thus far inconclusive experimental observations and enable yet unachieved synthetic reaction schemes. This work shows that radicals present, deliberately generated for this purpose, are incorporated as end groups in ethylene insertion polymerizations. Azo initiators (R-N = N-R′ with R = C(CH3)2COOMe, Ph, 3,5-F2C6H3) added to pressure reactor Ni(II)salicylaldiminato-catalyzed ethylene polymerizations afforded initiator-derived aryl or alkyl end groups, respectively, as revealed by in-depth NMR studies of the polymer formed. The observation of additional solvent- derived aryl end groups, originating from radical transfer to toluene, underlines that end groups are indeed formed from radicals. Evidence for incorporation as a chain-initiating as well as -terminating end group is discussed.