克莱森重新排列:从QM/MM模拟中了解溶剂效应和"在水上的"反应性
Orlando Acevedo1, Kira Armacost
1Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, USA.
Journal of the American Chemical Society
|January 22, 2010
概括
在"在水"环境中的反应显示,由于水通过键稳定极性过渡状态,其速度提高. 反应物的疏水替代剂通过将分子定向到水面来增强这种效果.
科学领域:
- 物理有机化学 有机化学
- 计算化学计算化学
- 超分子化学 超分子化学
背景情况:
- 在"水上"环境中的反应可以比有机溶剂提供优势,包括增加速率,产量和特异性.
- 这些背后的精确机制.
- 在水上,在水上
- 效应,特别是溶剂相互作用的作用,需要进一步阐明.
研究的目的:
- 调查"在水上"环境中观察到芳香的克莱森重排的速度增强的起源.
- 为了确定溶剂相互作用的具体贡献,如结合和极性,反应加速.
主要方法:
- 使用量子力学/分子力学 (QM/MM) 蒙特卡洛模拟和自由能量扰动理论.
- 分析了溶解物-溶剂相互作用,包括键,并计算了辐射分布函数.
- 在16种不同的溶剂中进行了计算,以将溶剂特性与反应速率相关联.
主要成果:
- "在水上"的速率提升归因于接口水分子通过增强的键稳定了极性过渡状态.
- 反应物的疏水替代剂通过将反应中的氧气导向水面来促进更极性的溶剂环境.
- 观察到的速度加速与溶剂极性的增加相关,而疏水效应和溶剂极化性起到了微不足道的作用.
结论:
- 界面水在通过特定的键相互作用加速克莱森重组中发挥着关键作用.
- 在受反应剂替代剂影响的油/水界面上的分子定向是最大限度地提高"在水"速率的关键.
- 该研究强调了QM/MM方法在研究液体表面发生的反应中的实用性.
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