相关实验视频
Updated: Jul 6, 2026

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Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
在chlorocarbene/alkene添加反应中,度与度的对比
Robert A Moss1, Lei Wang, Min Zhang
1Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08903, USA. moss@rutchem.rutgers.edu
Journal of the American Chemical Society
|April 9, 2008
概括
这项研究测量了二碳 (CCl2) 和碳 (CClF) 添加到基的激活参数. 结果显示,对反应障碍的和贡献不同,对于高度反应性的基因,因素占主导地位.
科学领域:
- 有机化学 有机化学
- 物理化学 物理化学
- 计算化学计算化学
背景情况:
- 碳添加到基是有机合成中的基本反应.
- 了解激活参数 (和) 可以了解反应机制.
- 以前的研究还没有完全描述CCl2和CClF添加的动力学和热力学方面.
研究的目的:
- 报告二碳 (CCl2) 和碳 (CClF) 添加到简单的第一个测量激活参数.
- 对这些反应的吉布斯自由激活能量 (ΔG‡) 进行热和热贡献的研究.
- 为了比较CCl2,CClF和基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基基
主要方法:
- 测量反应速率和确定激活参数 (ΔH‡ 和 ΔS‡) 的实验动力学研究.
- 使用各种基,包括循环基,1-基和四甲基乙烯,以探测硬质和电子效应.
- 并行计算研究 (例如,DFT计算) 支持实验发现和阐明反应机制.
主要成果:
- 证明了对循环烯和1-烯的CCl2添加物的旋屏障的存在.
- 观察到这些基因的PhCCl添加是主导的,CCl2添加显示了可比的和贡献,CClF添加是主导的.
- 发现热因子控制了所有三种碳素 (CCl2,CClF,PhCCl) 的添加到高度反应性的基,四甲基乙烯.
结论:
- 碳添加到基的激活参数受到体和体因素的显著影响.
- 和的相对贡献取决于特定的碳和结构.
- 计算研究补充了实验数据,提供了对碳化合物添加机制和过渡状态结构的更深入的理解.
相关概念视频
Introduction to Electrophilic Addition Reactions of Alkenes
The double bond in a simple, unconjugated alkene is a region of high electron density that can act as a weak base or a nucleophile. The filled π orbital (HOMO) of the double bond can interact with the empty LUMO of an electrophile. A bonding interaction occurs when the electrophile attacks between the two carbons; the electrophile then accepts a pair of electrons from the π bond and undergoes addition across the double bond, yielding a single product.
Addition and elimination reactions can be...
Addition and elimination reactions can be...
Radical Anti-Markovnikov Addition to Alkenes: Thermodynamics
The anti-Markovnikov addition of hydrogen halides to an alkene is thermodynamically feasible only with HBr. The radical addition reaction with other hydrogen halides like HCl and HI is thermodynamically unfavorable.
Radical Halogenation: Thermodynamics
The thermodynamic favorability of a reaction is determined by the change in Gibbs free energy (ΔG). ΔG has two components- enthalpy (ΔH) and entropy (ΔS). The entropy component is negligible for alkane halogenation because the number of reactants and product molecules are equal. In this case, the ΔG is governed only by the enthalpy component. The most crucial factor that determines ΔH is the strength of the bonds. ΔH can be determined by comparing the energy between bonds broken and bonds...
Standard Entropy Change for a Reaction
Entropy is a state function, so the standard entropy change for a chemical reaction (ΔS°rxn) can be calculated from the difference in standard entropy between the products and the reactants.
Acid-Catalyzed Hydration of Alkenes
Alkenes react with water in the presence of an acid to form an alcohol. In the absence of acid, hydration of alkenes does not occur at a significant rate, and the acid is not consumed in the reaction. Therefore, alkene hydration is an acid-catalyzed reaction.
Electrophilic Addition of HX to 1,3-Butadiene: Thermodynamic vs Kinetic Control
The addition of a hydrogen halide to 1,3-butadiene gives a mixture of 1,2- and 1,4-adducts. Since more substituted alkenes are more stable, the 1,4-adduct is expected to be the major product. However, the product distribution is strongly influenced by temperature; low temperature favors the 1,2-adduct, whereas the 1,4-adduct is predominant at high temperature.

