用SO3进行电友芳香硫化:协调或经典的S(E) Ar机制?
Gergana Koleva1, Boris Galabov, Jing Kong
1Department of Chemistry, University of Sofia, Sofia 1164, Bulgaria.
Journal of the American Chemical Society
|November 9, 2011
概括
芳香硫化与三氧化硫 (SO3) 通过协调的2:1机制进行,而不是1:1的威兰德中间体,特别是在非极性溶剂中. 这一修订后的机制得到了计算支持,并解释了实验趋势.
科学领域:
- 物理化学 物理化学
- 计算化学的计算化学
- 有机化学 有机化学
背景情况:
- 电友芳香硫化是一种关键的有机反应.
- 该机制,特别是三氧化硫 (SO3) 的机制,一直在争论中,通常涉及威兰德中间体.
- 计算研究对于阐明反应途径至关重要.
研究的目的:
- 通过计算来研究电友芳硫化由SO的机制.
- 挑战人们对硫化机制的传统理解.
- 为了确定溶剂极性对反应路径的影响.
主要方法:
- 使用M06-2X和SCS-MP2理论水平进行电子结构计算.
- 激活能量和反应中间体的分析.
- 1:1和2:1反应机制的比较.
- 气相和溶剂相模拟 (非极性和极性).
主要成果:
- 使用威兰德中间体的1:1机制由于高激活能量,在能量方面不利.
- 在非极性介质中,一种直接的2:1硫化机制,涉及两个SO3分子,是最受青的.
- 在极性SO3复合溶剂中,采用2:1S3E) Ar机制,采用威兰德型二元中间体是最好的.
- 计算结果准确地预测了,和的实验反应性和区域选择性.
结论:
- 芳硫化与SO3的机制通常是2:1的过程,而不是传统的1:1路径.
- 溶剂的极性在很大程度上决定了具体的机械细节,包括中间体的参与.
- 这些发现为了解芳硫化动力学和区域选择性提供了更准确的理论框架.
相关概念视频
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Simple aryl halides do not react with nucleophiles. However, nucleophilic aromatic substitutions can be forced under certain conditions, such as high temperatures or strong bases. The mechanism of substitution under such conditions involves the highly unstable and reactive benzyne intermediate. Benzyne contains equivalent carbon centers at both ends of the triple bond, each of which is equally susceptible to nucleophilic attack. This 50–50 distribution of products is confirmed through isotopic...
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