在V(100) 单晶表面上被吸附的化物中的合反应
1Department of Chemistry, University of California, Riverside, California, 92521, USA.
Journal of the American Chemical Society
|May 28, 2009
概括
表面上的甲通过两个不同的途径形成乙烯. 低温乙烯由甲基合形成,而高温乙烯需要二醇酸中间体.
科学领域:
- 表面科学是一门科学.
- 不同质的催化剂.
- 化学动力学 化学动力学
背景情况:
- 甲是化学中的一个关键的C1构建块.
- 了解甲表面反应对于催化是至关重要的.
- 表面在各种催化过程中都很重要.
研究的目的:
- 阐明甲在 (100) 表面上的反应机制.
- 为了确定导致乙烯形成的途径.
- 研究甲热化学中的中间体的作用.
主要方法:
- 温度编程消毒 (TPD) 是指温度编程消毒的方法.
- 在X射线光电子光谱学 (XPS) 中.
- 在超高真空 (UHV) 条件下的同位素标记实验.
主要成果:
- 在290 K和540 K的两个不同的温度下观察到乙烯脱吸.
- 低温乙烯的形成是在C-O键解离后通过甲基合进行的.
- 高温乙烯的形成需要二醇酸中间体 (-OCH(2) CH(2) O-).
- 观察到的化学成分是一般的,适用于协同吸收的化物.
结论:
- 两个不同的机制控制着从甲在上形成乙烯的形成.
- 表面的中间结构 (甲,二酸盐) 决定了反应路径和产品的分布.
- 这些发现为金属表面的合反应提供了洞察力.
相关概念视频
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.
Vicinal Diols via Reductive Coupling of Aldehydes or Ketones: Pinacol Coupling Overview
Wilhelm Rudolph Fittig discovered the pinacol coupling reaction in 1859. It is a radical dimerization reaction and involves the reductive coupling of aldehydes or ketones in the presence of hydrocarbon solvent to yield vicinal diols.
Aldehydes and Ketones to Alkenes: Wittig Reaction Mechanism
The Wittig reaction, which converts aldehydes or ketones to alkenes using phosphorus ylides, proceeds through a nucleophilic addition‒elimination process.
The reaction begins with the nucleophilic addition between a phosphorus ylide and the carbonyl compound. Due to its carbanionic character, phosphorus ylide acts as a strong nucleophile and attacks the electrophilic carbonyl group. This generates a charge-separated dipolar intermediate called betaine. The negatively charged oxygen atom and...
The reaction begins with the nucleophilic addition between a phosphorus ylide and the carbonyl compound. Due to its carbanionic character, phosphorus ylide acts as a strong nucleophile and attacks the electrophilic carbonyl group. This generates a charge-separated dipolar intermediate called betaine. The negatively charged oxygen atom and...
Oxidations of Aldehydes and Ketones to Carboxylic Acids
Oxidation of aldehydes and ketones results in the formation of carboxylic acids. Aldehydes, bearing hydrogen next to the carbonyl group, are easily oxidized compared to ketones. This is because an aldehydic proton can easily be abstracted during oxidation.
Aldehydes readily undergo oxidation in strong oxidizing agents such as potassium permanganate and chromic acid. The oxidation can also be carried out using mild oxidizing agents such as silver oxide. In fact, aldehydes can be easily oxidized...
Aldehydes readily undergo oxidation in strong oxidizing agents such as potassium permanganate and chromic acid. The oxidation can also be carried out using mild oxidizing agents such as silver oxide. In fact, aldehydes can be easily oxidized...
C–C Bond Formation: Aldol Condensation Overview
Aldol condensation is an important route in synthetic organic chemistry used to generate a new carbon–carbon bond under basic or acidic conditions. The aldol condensation reaction presented in Figure 1 constitutes an aldol addition reaction followed by the dehydration process.
Base-Catalyzed Aldol Addition Reaction
As depicted in Figure 1, base-catalyzed aldol addition involves adding two carbonyl compounds in aqueous sodium hydroxide to form a β-hydroxy carbonyl compound.


