能否协调离子玛消除:通过循环布坦环计时内部位移
Uri Habusha1, Esther Rozental, Shmaryahu Hoz
1Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel 52900.
Journal of the American Chemical Society
|December 12, 2002
概括
这项研究量化了carbanion消除的速率,揭示了快速内部消除速率常数大约为3 x 10^10 s^-1. 计算分析表明,在特定条件下,这种消除无障碍地发生.
科学领域:
- 有机化学 有机化学
- 反应动力学反应动力学
- 计算化学计算化学
背景情况:
- 碳是有机合成中的关键中间体.
- 了解carbanion反应途径,包括质子化和消除,至关重要.
- 3-chlorobicyclobutane-carbonitrile作为一个模型基板来研究碳的行为.
研究的目的:
- 为了确定一个carbanion中间体的内部消除速率常数.
- 研究质子供体酸度对在质子化和消除之间进行的碳离子分离的影响.
- 通过计算建模卡尔巴尼消除机制,并评估溶解的作用.
主要方法:
- 使用一系列具有不同酸度的酒精来实验确定产品比率 (质子化/消除).
- 使用Eigen型图形分析实验数据的分析.
- 开始计算 (B3LYP/6-31G) 来建模消除过程.
- 模拟反应动态,包括溶解效应 (Onsager模型).
主要成果:
- 产品在质子化和淘汰之间进行分区,允许确定内部淘汰速率常数,大约为3 x 10^10 s^-1.
- 高酸性酒精 (三乙醇和六二醇) 导致扩散控制的反应速率.
- 计算研究表明,在没有溶解的情况下,模型卡巴尼昂的无障碍消除过程.
- 在二甲氧乙 (DME) 中的溶解效应被证明可以稳定卡巴尼,阻碍自发排泄.
结论:
- 研究的卡巴尼的内部消除是一个快速的过程.
- 溶解在控制carbanion反应性方面发挥着重要作用.
- 计算和实验数据提供了对carbanion反应途径的全面了解.
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