在含有的石上用分子氧直接氧化烯
Weijie Li1, Guangjun Wu1,2, Wende Hu3
1Haihe Laboratory of Sustainable Chemical Transformations, School of Materials Science and Engineering, Nankai University, Tianjin300350, China.
Journal of the American Chemical Society
|February 22, 2022
概括
我们开发了一种新型的催化剂Co@Y, 这种催化剂具有高氧化物选择性和稳定性,提供更绿色的化学合成途径.
科学领域:
- 催化剂
- 材料科学
- 化学工程
背景情况:
- 使用分子氧的直接烯环氧化提供100%的原子经济,但面临过度氧化和异构化的挑战.
- 开发有氧环氧化的选择性催化剂对于有效的化学合成至关重要.
研究的目的:
- 构建和评估被封闭在化 (Co@Y) 中的均离子,以进行有氧氧化.
- 研究Co@Y催化剂的催化机制和性能.
主要方法:
- 封闭在石中的一致离子的合成 (Co@Y).
- 在773K的气氧化中对Co@Y进行催化试验.
- 用光谱分析 (例如,EPR,XAS) 来阐明反应机制.
- 密度函数理论 (DFT) 计算以研究反应途径.
主要成果:
- 在有氧烯环氧化中表现出前所未有的催化性能.
- 在773K时达到24.6%的氧化物选择性.
- 获得了4.7 mmol/gcat/h的最先进的氧化生产率.
- 催化剂在200小时内表现出极好的稳定性,没有活动损失.
- 光谱和DFT研究显示了参与氧化激活和环氧化形成的Co2+-Co2+-δ+-Co2+氧化还原循环.
结论:
- 在化物Y (Co@Y) 中封闭的均离子对选择性有氧氧化非常有效.
- 催化剂的设计能够有效地激活分子氧气,并最大限度地减少副产品的形成.
- 这项工作为选择性氧化反应的化金属催化剂设计提供了一个模型.
相关概念视频
Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
6.2K
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
6.2K
Preparation of Epoxides
8.2K
Overview
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of...
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of...
8.2K
Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
11.0K
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
11.0K
Sharpless Epoxidation
4.3K
The conversion of allylic alcohols into epoxides using the chiral catalyst was discovered by K. Barry Sharpless and is known as Sharpless epoxidation. The use of a chiral catalyst enables the formation of one enantiomer of the product in excess. This chiral catalyst is mainly a chiral complex of titanium tetraisopropoxide and tartrate ester (specific stereoisomer). The stereoisomer used in the chiral catalyst dictates the formation of the enantiomer of the product. In other words, the use of...
4.3K
Oxidative Cleavage of Alkenes: Ozonolysis
11.3K
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.
11.3K
Oxidation of Alkenes: Syn Dihydroxylation with Potassium Permanganate
13.5K
Alkenes can be dihydroxylated using potassium permanganate. The method encompasses the reaction of an alkene with a cold, dilute solution of potassium permanganate under basic conditions to form a cis-diol along with a brown precipitate of manganese dioxide.
13.5K


