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用第三代格鲁布斯催化剂进行活环开放转化聚合的动态研究

Dylan J Walsh¹, Sii Hong Lau¹, Michael G Hyatt²

¹Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.

Journal of the American Chemical Society

|September 26, 2017

概括

活环开放转化聚合 (ROMP) 速率独立于催化剂度. 一个新的税率法揭示了胺

科学领域:

聚合物化学
有机金属化学
催化剂

背景情况:

活环开放转化聚合 (ROMP) 对于合成明确的聚合物至关重要.
格鲁布斯第三代催化剂广泛用于ROMP,但它们的精确运动行为需要进一步阐明.
了解催化剂的行为是控制聚合结果的关键.

研究的目的:

通过Grubbs第三代催化剂启动的活体ROMP的动力依赖性.
为这种聚合系统制定一个全面的速率定律.
阐明在催化循环中素配体的作用.

主要方法:

使用两种不同的Grubbs第三代催化剂的N-hexyl-exo-norbornene-5,6-dicarboximideROMP的动力学研究.
开发一种包含观察到的动力依赖性的速率定律.
使用质子扩散顺序的NMR光谱 (1H DOSY) 进行溶液状态的表征.
通过范特霍夫图表进行热力学分析以确定平衡常数.

主要成果:

发现聚合率与催化剂度无关.
建立了一种速率定律,显示出对胺度的反向第一阶段依赖.
证据证实了一种胺配体与溶液中的催化剂分离.
均衡研究表明单双胺和双胺添加物之间的特定比率.

结论:

在这个ROMP的速率决定步骤中活跃的催化物可能不是皮里丁协调的.
胺配体的解离在聚合动力学中起着重要作用.
催化剂前体性能的差异与胺联体协调强度相关.

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