多产品反应中的机制的一般方法:产品特异性的分子间动态同位素效应
Shuhuai Xiang1, Matthew P Meyer
1Department of Chemistry and Biochemistry, University of California , Merced, California 95343, United States.
Journal of the American Chemical Society
|April 12, 2014
概括
一种新方法测量了自然丰富的碳-13动态同位素效应,用于具有多个产品的反应. 这项技术应用于催化反应,揭示了对竞争性循环添加和阿尔德烯通路的洞察力.
科学领域:
- 有机化学 有机化学
- 化学动力学 化学动力学
- 同位素效应的影响
背景情况:
- 动态同位素效应 (KIE) 对于阐明反应机制至关重要.
- 在自然丰度下测量KIE简化了实验程序.
- 由于产品混合,并发反应使机理学研究复杂化.
研究的目的:
- 开发一种用于测量碳-13 (13C) KIEs在自然丰富的一般方法.
- 将这种方法应用于具有竞争路径的复杂反应系统.
- 从高精度同位素效应数据中获得机械洞察力.
主要方法:
- 开发一种精确的分析方法来量化13C KIEs.
- 在环烯和1--1-烯之间进行催化反应的应用.
- 高精度同位素比质谱仪用于分子间13C KIE测量.
主要成果:
- 成功测量了自然丰富的分子间13CKIEs,用于多产品反应.
- 对主要 [2+2] 循环添加和次要烯产品的KIEs的量化.
- 证明该方法在区分反应路径方面的实用性.
结论:
- 开发的方法为复杂反应的机理学研究提供了强大的工具.
- 同位素效应数据支持对催化反应的具体机制解释.
- 这种方法促进了使用自然丰富的同位素研究并发反应途径.
相关概念视频
02:31Multi-Step Reactions
7.5K
Chemical reactions often occur in a stepwise fashion involving two or more distinct reactions taking place in a sequence. A balanced equation indicates the reacting species and the product species, but it reveals no details about how the reaction occurs at the molecular level. The reaction mechanism (or reaction path) provides details regarding the precise, step-by-step process by which a reaction occurs. Each of the steps in a reaction mechanism is called an elementary reaction. These...
7.5K
02:24Predicting Reaction Outcomes
9.1K
Kinetics describes the rate and path by which a reaction occurs. In contrast, thermodynamics deals with state functions and describes the properties, behavior, and components of a system. It is not concerned with the path taken by the process and cannot address the rate at which a reaction occurs. Although it does provide information about what can happen during a reaction process, it does not describe the detailed steps of what appears on an atomic or a molecular level. On the other hand,...
9.1K
03:06Reaction Mechanisms
24.3K
Chemical reactions often occur in a stepwise fashion, involving two or more distinct reactions taking place in a sequence. A balanced equation indicates the reacting species and the product species, but it reveals no details about how the reaction occurs at the molecular level. The reaction mechanism (or reaction path) provides details regarding the precise, step-by-step process by which a reaction occurs.
For instance, the decomposition of ozone appears to follow a mechanism with two steps:
For instance, the decomposition of ozone appears to follow a mechanism with two steps:
24.3K
02:14SN2 Reaction: Kinetics
8.5K
Kinetic Studies and Significance
In a chemical reaction, a relationship exists between the concentration of reactants and the rate at which the reaction proceeds. The study to measure this relationship is known as the kinetics of a chemical reaction. Kinetic studies are used to deduce the rate law of a chemical reaction, which provides information about the species involved during the transition state of the rate-determining step. Thus, kinetic studies help to derive the mechanism of a...
In a chemical reaction, a relationship exists between the concentration of reactants and the rate at which the reaction proceeds. The study to measure this relationship is known as the kinetics of a chemical reaction. Kinetic studies are used to deduce the rate law of a chemical reaction, which provides information about the species involved during the transition state of the rate-determining step. Thus, kinetic studies help to derive the mechanism of a...
8.5K
02:05SN1 Reaction: Kinetics
8.3K
In an SN2 reaction, the reaction rate depends on both the type of nucleophile and the substrate. A hindered tertiary alkyl halide is practically inert to the SN2 mechanism despite using a strong nucleophile.
However, Sir Christopher Ingold and Edward D. Hughes, who studied the kinetics of various nucleophilic substitution reactions, noticed that a tertiary alkyl halide does undergo a nucleophilic substitution reaction in the presence of a weak nucleophile. While studying the substitution...
However, Sir Christopher Ingold and Edward D. Hughes, who studied the kinetics of various nucleophilic substitution reactions, noticed that a tertiary alkyl halide does undergo a nucleophilic substitution reaction in the presence of a weak nucleophile. While studying the substitution...
8.3K
03:08Rate-Determining Steps
30.4K
Relating Reaction Mechanisms
In a multistep reaction mechanism, one of the elementary steps progresses significantly slower than the others. This slowest step is called the rate-limiting step (or rate-determining step). A reaction cannot proceed faster than its slowest step, and hence, the rate-determining step limits the overall reaction rate.
The concept of rate-determining step can be understood from the analogy of a 4-lane freeway with a short-stretch of traffic-bottleneck caused due to...
In a multistep reaction mechanism, one of the elementary steps progresses significantly slower than the others. This slowest step is called the rate-limiting step (or rate-determining step). A reaction cannot proceed faster than its slowest step, and hence, the rate-determining step limits the overall reaction rate.
The concept of rate-determining step can be understood from the analogy of a 4-lane freeway with a short-stretch of traffic-bottleneck caused due to...
30.4K