揭示醇溶剂的"增强效应":聚合诱导的形状变化和合作增强的H键
Albrecht Berkessel1, Jens A Adrio, Daniel Hüttenhain
1Institut für Organische Chemie, Universität zu Köln, Greinstrasse 4, D-50939 Köln, Germany. berkessel@uni-koeln.de
Journal of the American Chemical Society
|June 29, 2006
概括
醇聚合物,而不是单体,显著提高了键供体的能力. 1,1,1,3,3,3-二醇 (HFIP) 的二元和三元是其催化作用的关键.
科学领域:
- 物理化学 物理化学
- 计算化学的计算化学
- 超分子化学 超分子化学
背景情况:
- 像HFIP和PhTFE这样的醇是具有强大的键捐赠能力的独特溶剂.
- 了解它们的溶剂特性对于催化和有机合成至关重要.
- 分子构成和聚合在溶剂行为中的作用尚未完全理解.
研究的目的:
- 调查对HFIP和PhTFE对键捐赠能力的构成和聚合的影响.
- 阐明这些溶剂中观察到的增强反应性的结构基础.
主要方法:
- 使用密度函数理论 (DFT) 进行理论计算.
- 通过核磁共振 (NMR) 光谱学进行实验验证.
- 对烯环氧化反应的动力学研究.
- 溶剂聚合物的单晶X射线衍射分析.
主要成果:
- DFT 揭示了 H 键捐赠能力与单体醇的 CO 键构成 (ap 与 sp) 有着强烈的依赖.
- 动力学表明,溶剂聚合物 (2-3个单体) 会激活像H2O2.2.这样的氧化剂.
- X射线晶体学证实了H键聚合物 (螺旋体,带,循环寡合物) 和主要的sp conformations.
- 对HFIP寡合体的DFT分析显示,二聚化和三聚化对H键供体能力的合作作用.
结论:
- 形状和聚合都显著影响了醇的键供体强度.
- HFIP的二元和三元体,与同周平面 (sp) 形状的单元体,主要负责观察到的溶解和催化效应.
- 与小型聚合物相比,单体物种在溶剂的活性中起的作用较小.
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