Department of Applied Chemistry, Tokyo Institute of Technology, Ookayama, Meguro, Japan.
ACS Comb Sci. 2012 Jan 9;14(1):17-24. doi: 10.1021/co200081j. Epub 2011 Nov 15.
Late-transition metal catalysts used for olefin polymerization, the so-called postmetallocenes, which includes α-iminocarboxamide-nickel(II) catalysts have attracted a great deal of attention because of many valuable features such as the copolymerization of α-olefins with polar monomers. In this paper, the combinatorial synthesis and evaluation of α-iminocarboxamide-nickel(II) catalysts are discussed for their roles in the discovery of a highly active catalyst and elucidation of its structure-activity relationship. The combinatorial optimization of each reaction condition was performed, then a combinatorial library of α-iminocarboxamides with systematically modified substituents was constructed by amidation of α-keto acid chlorides and subsequent imination of α-keto carboxamides in parallel fashion. As a result, 87 analytically pure α-iminocarboxamide ligands were successfully synthesized. α-Iminocarboxamide-nickel(II) catalysts were prepared from the synthesized α-iminocarboxamide ligands. The catalysts' activities for polymerization of ethylene and copolymerization of ethylene and 5-norbornen-2-ol were evaluated. Results of the present study revealed 9 novel active catalysts for ethylene polymerization and 7 novel active catalysts for copolymerization of ethylene and 5-norbornen-2-ol. It should be noted that the best catalysts for ethylene polymerization and for copolymerization in the present study showed higher activities compared to the known active catalyst. Polymerization activities of the catalysts varied dramatically according to the combination of substituents on the α-iminocarboxamides.
用于烯烃聚合的后过渡金属催化剂，即所谓的后茂金属催化剂，由于其许多有价值的特性，如α-烯烃与极性单体的共聚，引起了极大的关注。本文讨论了α-亚氨基甲酰胺镍(II)催化剂的组合合成和评价，其在发现高活性催化剂及其结构-活性关系的阐明中发挥了作用。对每个反应条件进行了组合优化，然后通过α-酮酸氯的酰胺化和随后的α-酮酰胺的亚胺化平行进行，构建了具有系统修饰取代基的α-亚氨基甲酰胺的组合文库。结果，成功合成了 87 个分析纯的α-亚氨基甲酰胺配体。由合成的α-亚氨基甲酰胺配体制备了α-亚氨基甲酰胺镍(II)催化剂。评估了催化剂对乙烯聚合和乙烯与 5-降冰片烯-2-醇共聚的活性。本研究的结果揭示了 9 种用于乙烯聚合的新型活性催化剂和 7 种用于乙烯与 5-降冰片烯-2-醇共聚的新型活性催化剂。值得注意的是，本研究中用于乙烯聚合和共聚的最佳催化剂的活性高于已知的活性催化剂。催化剂的聚合活性根据α-亚氨基甲酰胺上取代基的组合而有很大差异。
