实验和理论研究中性氧化瓦纳集群与乙,乙烯和乙之间的反应
Feng Dong1, Scott Heinbuch, Yan Xie
1Department of Chemistry, and NSF ERC for Extreme Ultraviolet Science and Technology, Colorado State University, Fort Collins, Colorado 80523, USA.
Journal of the American Chemical Society
|January 18, 2008
概括
氧化瓦纳集群与乙烯和乙烯反应,但不与乙反应. DFT计算解释了观察到的反应性,显示了C=C键裂解和脱水反应的有利途径.
科学领域:
- 无机化学 无机化学
- 物理化学 物理化学
- 材料科学 材料科学 材料科学
背景情况:
- 中性氧化物集群在催化和材料科学中至关重要.
- 了解它们与碳化合物的反应性是设计新化学过程的关键.
研究的目的:
- 研究中性氧化瓦纳集群与小碳化合物 (C2H6,C2H4,C2H2) 的反应.
- 用实验和计算方法阐明反应机制并确定相对碳化合物的反应性.
主要方法:
- 使用极端紫外线 (EUV) 和真空紫外线 (VUV) 激光器进行单光子电离的实验研究.
- 使用密度函数理论 (DFT) 计算进行理论分析.
主要成果:
- 氧化瓦纳集群与C2H4结合,形成V (m) O (n) C2H4产物.
- 富含氧气的集群将C2H4的C=C键裂开,产生VO2CH2产物.
- C2H2经历协会反应,脱水反应产生VO2C2.2.
- C2H6与这些集群的反应性最小.
- DFT计算证实了关键反应的热力学有利性和无障碍性.
结论:
- 氧化瓦纳集群与C2碳化合物的反应性取决于碳化合物的结构和集群中的氧含量.
- DFT 的结合能量准确地预测了观察到的相对反应性.
- 该研究提供了对金属氧化物集群与不和碳化合物的相互作用的基本见解.
相关概念视频
Carboxylic Acids to Methylesters: Alkylation using Diazomethane
Carboxylic acids react with diazomethane in an ether solvent via alkylation at the carboxylate oxygen atom to give methyl esters of the corresponding acid with excellent yields.
Alkenes via Reductive Coupling of Aldehydes or Ketones: McMurry Reaction
The radical dimerization of ketones or aldehydes gives vicinal diols through a pinacol coupling reaction. However, the behavior of titanium metals used for the reaction as a source of electrons is unusual. When the reaction is carried out in the presence of titanium, diols can be isolated at low temperatures. Else titanium further reacts with diols, forming alkenes through the McMurry reaction.
Cycloaddition Reactions: MO Requirements for Photochemical Activation
Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.
Preparation of Alkynes: Alkylation Reaction
Introduction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Catalysis
The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.


