在使用[(dippe) NiH]2在2-甲基-3-丁中竞争性裂解C-CN和C-H键时的溶剂效应和激活参数
Brett D Swartz1, Nicole M Reinartz, William W Brennessel
1Department of Chemistry, University of Rochester, Rochester, New York 14627, USA.
Journal of the American Chemical Society
|June 11, 2008
概括
溶剂的极性决定了化与2-甲基-3-丁二 (2M3BN) 的反应性. 极性溶剂有利于C-H激活,而非极性溶剂促进C-C裂变,影响反应途径和产品比率.
科学领域:
- 有机金属化学 有机金属化学
- 反应机制 反应机制
- 催化剂是一种催化剂.
背景情况:
- 化复合物的反应性在有机合成中至关重要.
- 了解反应途径,如C-H和C-CN激活,是控制产品选择性的关键.
- 溶剂效应在调节有机金属反应结果方面发挥着重要作用.
研究的目的:
- 为了研究溶剂极性的影响,在[(dippe) NiH]2和2-methyl-3-butenenitrile (2M3BN) 之间的反应.
- 阐明C-H和C-CN激活通路之间的机制差异.
- 确定控制这些相互竞争的反应的热力学和动力学参数.
主要方法:
- [度NiH]2与2M3BN在不同极性的溶剂中的反应.
- 对产品比率的分析以确定C-H与C-CN激活的选择性.
- 在和N,N-二甲基形式胺 (DMF) 中进行温度依赖的动力学研究,以计算Eyring激活参数.
- 使用硬质体积较大和协调较弱的溶剂来探测过渡状态溶解.
主要成果:
- 溶剂极性对2M3BN激活的选择性有显著影响,因为2M3BN激活的2.
- 在极性溶剂中有利于C-H激活,而在非极性溶剂中有利于C-CN (C-C) 激活.
- 耳环激活参数表明,C-H激活的激活度较低 (11.4 kcal/mol),但激活度更为负 (-45 e.u.) 与C-CN激活 (17.3 kcal/mol和-29 e.u.) 相比,它们具有较低的活性. ) 的情况.
结论:
- 过渡状态的微分解解解释了观察到的溶剂依赖性选择性.
- -H激活在度上受到青,这表明一个比-CN激活更有序的过渡状态.
- 这些发现为控制有机催化中的反应性和选择性提供了宝贵的见解.
相关概念视频
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Stability of Conjugated Dienes
Introduction
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
SN2 Reaction: Stereochemistry
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If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not observed.
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Conformation
The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable, the...
Characteristics of the diene
Conformation
The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable, the...


