在气相替代和消除中留下组效应
Scott Gronert1, Adelaide E Fagin, Keiko Okamoto
1Contribution from the Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, CA 94132, USA. sgronert@sfsu.edu
Journal of the American Chemical Society
|October 8, 2004
概括
研究气相反应,这项研究揭示了离开组的能力与S(N) 2和E2反应的反应外热度相关. 气相反应率遵循化物>三酸>化物,与凝结相趋势保持一致.
科学领域:
- 物理化学 物理化学
- 有机化学 有机化学
- 反应动力学 反应动力学
背景情况:
- 了解离开群体的影响对于预测反应结果至关重要.
- 气相反应研究提供了对内在反应性的见解,最大限度地减少了溶解效应.
- 之前的研究已经确定了凝聚相反应率趋势,但气相比较较少见.
研究的目的:
- 研究离开组对气相S,N和E2反应中的反应速率和产品分布的影响.
- 为了将气相反应率趋势与已建立的凝聚相数据进行比较.
- 为了确定替代效应是否源于基基质或溶解差异.
主要方法:
- 利用最近开发的方法来分析气相S(N) 2和E2反应产物分布.
- 检查了与各种基化物,化物和三乙酸盐的离子核友的反应.
- 在MP2/6-311+G(d,p)//MP2/6-31+(d) 级进行理论计算,以支持实验发现.
主要成果:
- 对于S(N) 2和E2反应的气相反应顺序被确定为化物>三酸>化物.
- 发现离开组的能力与气体和凝结相的反应外热度直接相关.
- 气相数据在很大程度上与冷凝相数据并行,这表明替代效应主要取决于基质.
结论:
- 在气相S(N) 2和E2反应中,离开组的能力是由反应外热度决定的.
- 观察到的气相反应率趋势与冷凝相反应率趋势一致,表明内在电子效应主导了溶解.
- 对这些反应的替代效应源于基基质的性质.
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