相关实验视频
Updated: May 29, 2026

09:48
Original Experimental Approach for Assessing Transport Fuel Stability
Published on: October 21, 2016
关于周期性臭氧和强氧道的热稳定性的理论预测
1Department of Chemistry and Biochemistry, National Chung Cheng University, Chia-Yi, 621, Taiwan.
Journal of the American Chemical Society
|September 6, 2011
概括
循环臭氧由于显著的量子道效应,迅速异构成开放臭氧,解释了其难以捉摸的性质. 现在可以对循环臭氧进行实验性识别,特别是通过同位素标记.
科学领域:
- 理论化学 理论化学
- 化学动力学 化学动力学
- 量子力学就是量子力学.
背景情况:
- 循环臭氧是一种难以捉摸的分子.
- 它的稳定性是通过对正常 (开放) 臭氧的异构决定的.
- 实验性鉴定一直没有成功.
研究的目的:
- 研究循环臭氧对正常臭氧的异构反应.
- 在热条件下确定循环臭氧的稳定性.
- 解释实验识别中的挑战.
主要方法:
- 使用变量过渡状态理论进行双层动态计算.
- 包括多维道的使用.
- 来自MRCISD+Q/aug-cc-pVQZ的高水平潜在能量表面数据.
- 从B3LYP/cc-pVTZ. 的低级反应路径.
主要成果:
- 在300K以下观察到显著的道效应 (在300K时为~200,在200K时为>10^7).
- 异构化比以前想象的要快得多,因为道和潜在能量的表面穿越.
- 周期性臭氧的预计半衰期在200K时为10秒,在100K以下为70秒.
- 对于18O替代的计算动态同位素效应 (KIE) 高 (在低温下高达10).
结论:
- 量子道在循环臭氧的快速异构化中起着至关重要的作用.
- 计算出的短半衰期解释了实验检测的困难.
- 高KIE表明,循环臭氧的同位素标记可以促进实验性识别.
相关概念视频
Oxidative Cleavage of Alkenes: Ozonolysis
In ozonolysis, ozone is used to cleave a carbon–carbon double bond to form aldehydes and ketones, or carboxylic acids, depending on the work-up.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Stability of Substituted Cyclohexanes
This lesson discusses the stability of substituted cyclohexanes with a focus on energies of various conformers and the effect of 1,3-diaxial interactions.
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
Combustion Energy: A Measure of Stability in Alkanes and Cycloalkanes
The low reactivity in alkanes can be attributed to the non-polar nature of C–C and C–H σ bonds. Alkanes, therefore, were initially termed as “paraffins,” derived from the Latin words: parum, meaning “too little,” and affinis, meaning “affinity.”
Alkanes undergo combustion in the presence of excess oxygen and high-temperature conditions to give carbon dioxide and water. A combustion reaction is the energy source in natural gas, liquified petroleum gas (LPG), fuel oil, gasoline, diesel fuel, and...
Alkanes undergo combustion in the presence of excess oxygen and high-temperature conditions to give carbon dioxide and water. A combustion reaction is the energy source in natural gas, liquified petroleum gas (LPG), fuel oil, gasoline, diesel fuel, and...
Temperature Dependence on Reaction Rate
The Collision Theory
Atoms, molecules, or ions must collide before they can react with each other. Atoms must be close together to form chemical bonds. This premise is the basis for a theory that explains many observations regarding chemical kinetics, including factors affecting reaction rates.
The collision theory is based on the postulates that (i) the reaction rate is proportional to the rate of reactant collisions, (ii) the reacting species collide in an orientation allowing contact between...
Atoms, molecules, or ions must collide before they can react with each other. Atoms must be close together to form chemical bonds. This premise is the basis for a theory that explains many observations regarding chemical kinetics, including factors affecting reaction rates.
The collision theory is based on the postulates that (i) the reaction rate is proportional to the rate of reactant collisions, (ii) the reacting species collide in an orientation allowing contact between...
Hess's Law
There are two ways to determine the amount of heat involved in a chemical change: measure it experimentally, or calculate it from other experimentally determined enthalpy changes. Some reactions are difficult, if not impossible, to investigate and make accurate measurements for experimentally. And even when a reaction is not hard to perform or measure, it is convenient to be able to determine the heat involved in a reaction without having to perform an experiment.

