里奇的"恒定选择性关系"是多么的恒定? 对于n,pi和西格玛核爱好者的一般反应度
Shinya Minegishi1, Herbert Mayr
1Department Chemie der Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13 (Haus F), D-81377 Münich, Germany.
Journal of the American Chemical Society
|January 8, 2003
概括
这项研究量化了基离子与核友的反应性,建立了一个统一的核友性尺度. 它揭示了大多数核友的一致反应模式,有助于预测化学反应.
科学领域:
- 有机化学 有机化学
- 物理化学 物理化学
- 反应动力学反应动力学
背景情况:
- 基离子是有机反应中的关键中间体.
- 了解核反应性对于预测反应结果至关重要.
- 之前的研究 (Ritchie关系) 建立了碳酸反应的框架.
研究的目的:
- 为了确定与各种核友的离子反应的动力学.
- 为不同的核爱者类型开发一个全面的核爱度表.
- 评估现有的反应性模型和参数的适用性.
主要方法:
- 在20°C时,对82个与n核友的基离子反应进行了动态分析.
- 方程 log k = s 的应用 (N + E) 来推导核子参数 (N,s).
- 使用Ritchie方程 (log k = N(+) + log k(0) 的相关性分析来确定离子参数.
- 整合数据以计算其他碳酸的电友性 (E) 参数.
主要成果:
- 对于15个n核友的确定的反应性参数 (N,s).
- 证明大多数n核爱好者遵循Ritchie的常数选择性关系 (s ≈常数).
- 标识了水作为一个异常,具有不同的斜率参数 (s = 0.89).
- 开发了对基离子和Ritchie型核友的统计验证参数.
- 为三,三和三离子生成的电友性参数 (E).
- 表明三离子的E参数可以预测n核和化物转移反应,但不能预测pi核反应.
结论:
- 现在可以实现一个统一的核友性尺度,包括n,pi和sigma核友性.
- 这项研究完善了对碳酸的反应性和选择性的理解.
- 从里奇的关系偏离部分由特定的核友行为 (例如,水) 解释.
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