替代基化碳的碎片化机制的二元性
Robert A Moss1, Yan Ma, Ronald R Sauers
1Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, NJ 08903, USA. moss@rutchem.rutgers.edu
Journal of the American Chemical Society
|November 21, 2002
概括
产生了替代的基化碳化合物,并研究了它们的碎片化机制. 抛物线哈梅特相关性表明,基于替代电子效应,从异质分解转变为同质分解碎片化.
科学领域:
- 有机化学 有机化学
- 摄影化学的使用.
- 反应机制 反应机制
背景情况:
- 碳是有机合成中至关重要的反应性中间体.
- 了解碳碎裂途径是控制反应结果的关键.
- 基化碳为研究替代剂对反应性的影响提供了一个独特的系统.
研究的目的:
- 为了研究替代基化碳的碎片化机制.
- 为了确定电子替代剂对碳烯碎片化速率的影响.
- 为了将实验发现与理论预测相关联.
主要方法:
- 通过迪亚齐林前体的光化学分解生成替代的基化碳素.
- 使用激光闪光光电解的卡尔碎片的动态分析.
- 计算研究以支持机械解释.
主要成果:
- 对于各种替代的基碳酸,确定了碎片化速率常量 (kfrag).
- 观察到一个抛物线式哈梅特相关性 (log kfrag vs. sigma+).
- 电子捐赠的替代物有利于异质分解,而取电子的组则有利于同质分解.
结论:
- 替代基碳酸的碎片化机制从异质过渡到同质过渡,对替代剂的电子需求有所不同.
- 观察到的抛物线哈梅特相关性为过渡状态特征的逐渐转变提供了有力的证据.
- 计算研究证实了拟议的机械双重性.
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