乙烯基化物与4组金属烯酸聚合催化剂的反应
Robert A Stockland1, Stephen R Foley, Richard F Jordan
1Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Illinois 60637, USA.
Journal of the American Chemical Society
|January 16, 2003
概括
第4组金属催化剂通过基聚合或插入,然后通过β-Cl消除与乙烯基化物 (VC) 反应. 这种β-Cl消除机制终止了链的生长,阻碍了VC与的共聚合.
科学领域:
- 有机金属化学 有机金属化学
- 聚合物科学 聚合物科学
- 催化剂是一种催化剂.
背景情况:
- 第4组金属复合物被广泛研究为烯聚合物的催化剂.
- 乙烯基化物 (VC) 对插入聚合具有独特的挑战,因为它倾向于消除β-Cl.
研究的目的:
- 为了研究4组金属催化剂与乙烯化物 (VC) 和VC/混合物的反应途径.
- 阐明VC聚合和寡合的机制,并确定共聚合的局限性.
主要方法:
- 使用了三种类型的4组金属催化剂: (C(5) R(5)) ZrX(2) /激活器, (C(5) Me(5) TiX(3) /MAO,和 (C(5) Me(4) SiMe(2) N(t) BuMX(2) /激活器.
- 在不同的条件下 (例如,Al/Zr比率,O的存在) 研究了与乙烯 (VC) 和VC/烯混合物的反应.
- 分析反应产品,包括寡烯和聚乙烯 (PVC),使用终端组分析和聚合物缺陷的表征.
主要成果:
- 观察到两个主要的反应途径:VC的基性聚合和1,2-VC插入,随后是β-Cl的消除.
- 确定β-Cl消除是关键链转移和终结机制,导致寡烯形成并防止VC与烯的共聚合.
- 在特定条件下观察到VC的基聚聚合,产生具有特征性基质缺陷的聚乙烯 (PVC).
结论:
- β-Cl消除是4组金属催化反应与乙烯基化物的主要途径,大大限制了其在插入聚合和共聚合中的使用.
- 极端聚合提供了对PVC的替代途径,但由于潜在的副作用,需要特定的条件和仔细的控制.
- 了解这些相互竞争的途径对于设计催化剂和对受控乙烯聚合物的反应条件至关重要.
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