在使用盐复合物的二氧化碳和环氧化物的共聚合中,共催化剂的作用
Donald J Darensbourg1, Ryan M Mackiewicz, Jody L Rodgers
1Department of Chemistry, Texas A&M University, College Station, Texas 77843, USA. djdarens@mail.chem.tamu.edu
Journal of the American Chemical Society
|October 6, 2005
概括
这项研究研究了环氧化物和二氧化碳的盐催化共聚化. 它揭示了不同催化剂如何影响反应速率和机制,从而产生高度活跃和强大的催化系统.
科学领域:
- 聚合物化学 聚合物化学
- 有机金属化学 有机金属化学
- 催化剂是一种催化剂.
背景情况:
- 环氧化物和二氧化碳的共聚合对于生产聚碳酸盐至关重要.
- 盐复合物是有效的催化剂,但需要澄清同催化剂的作用.
- 之前的研究表明对联体电子和共催化剂类型的敏感性.
研究的目的:
- 为了阐明氧化环素和二氧化碳共聚合的机制.
- 详细说明各种可催化剂在盐催化反应中的作用.
- 解释不同类型的共催化剂观察到的动力差异.
主要方法:
- 在现场对共聚合反应的动态监测.
- 红外 (IR) 和31P核磁共振 (NMR) 光谱学.
- 机理学研究涉及盐衍生物和各种催化剂.
主要成果:
- 确定了N-异环胺,和离子盐作为有效的催化剂.
- 实现了高周转频率 (~1200 h-1),表明强大且活跃的催化剂.
- 观察到与中性可催化剂 (胺,) 的启动期,但没有与离子盐.
- 提出了一种涉及中性可催化剂内盐/zwitterions的机制.
结论:
- 催化剂的选择对共聚合物的动力学和机制产生重大影响.
- 离子盐通过离子六坐标中间体促进直接通路.
- 中性可催化剂形成反应性的内盐/,模仿离子盐的行为.
- 了解这些机制可以设计更高效的聚碳酸合成.
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