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相关概念视频

Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide02:44

Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide

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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.
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Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids02:04

Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids

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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.
5.7K
Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)00:53

Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)

1.9K
Acyclic diene metathesis polymerization or ADMET polymerization involves cross-metathesis of terminal dienes, such as 1,8-nonadiene, to give linear unsaturated polymer and ethylene. As ADMET is a reversible process, the formed ethylene gas must be removed from the reaction mixture to complete the polymerization process.
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
1.9K
Carboxylic Acids to Methylesters: Alkylation using Diazomethane01:33

Carboxylic Acids to Methylesters: Alkylation using Diazomethane

2.1K
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.
2.1K
Free-Radical Chain Reaction and Polymerization of Alkenes02:35

Free-Radical Chain Reaction and Polymerization of Alkenes

7.8K
The conversion of alkenes to macromolecules called polymers is a reaction of high commercial importance. The structure of the polymer is defined by a repeating unit, while the terminal groups are considered insignificant. The average degree of polymerization represents the number of repeating units in the polymer molecule and is denoted by the subscript n.
7.8K
Cycloaddition Reactions: MO Requirements for Photochemical Activation01:12

Cycloaddition Reactions: MO Requirements for Photochemical Activation

2.1K
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.
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Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions
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高效的低负荷PdOx/AlSiOx催化剂用于乙烯二元化.

Tatiana Otroshchenko1, Dmitry I Sharapa2, Elizaveta A Fedorova1

  • 1Department of Advanced Methods for Applied Catalysis, Leibniz-Institut für Katalyse e.V. (LIKAT), Albert-Einstein-Str. 29a, D-18059, Rostock, Germany.

Angewandte Chemie (International ed. in English)
|July 7, 2024
PubMed
概括

一种新型的异质催化剂与原子分散的使得高效的乙烯二元化. 这一突破为传统的同质催化剂提供了可持续的替代方案,提高了碳化合物生产的选择性和活动性.

关键词:
模度化 (Dimerization) 是一个过程.乙烯乙烯是一种不同质的催化剂.帕拉是什么意思?帕拉是什么意思?

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科学领域:

  • 催化剂是一种催化剂.
  • 材料科学 材料科学 材料科学
  • 化学工程是化学工程的重要组成部分.

背景情况:

  • 乙烯二聚化是一个关键的工业过程.
  • 目前的方法依赖于同质的催化剂,这给分离和环境带来了挑战.
  • 需要更高效和可持续的催化系统.

研究的目的:

  • 开发一种高度活性和选择性的异质催化剂,用于乙烯二聚化.
  • 了解催化活性背后的基本机制.
  • 为了集成二分化催化剂与转化催化剂进行连续反应.

主要方法:

  • 用原子分散的 (Pd) 合成异质催化剂.
  • 在工业相关条件下的乙烯二聚化反应研究.
  • 动力实验,催化剂表征 (例如,光谱,显微镜) 和密度函数理论 (DFT) 的计算.
  • 在单个反应器中,将Pd催化剂与含有 (Mo) 的烯转化催化剂集成.

主要成果:

  • 开发的异质Pd催化剂表现出高活性和对乙烯二聚变的选择性,性能优于现有的催化剂.
  • 在42%的乙烯转化时达到80%的C4碳化合物选择性,在200°C时达到42%的乙烯转化.
  • DFT计算和表征提供了对活跃地点 (孤立的Pd(II) Ox物种) 的见解.
  • 综合系统通过顺序二分化和转化实现了98%的烯选择性.

结论:

  • 在异质支上原子分散的Pd是乙烯二聚化的一种高度有效的催化剂.
  • 催化剂在没有辅助催化剂或激活剂的情况下工作,简化了这一过程.
  • 综合系统可从乙烯中有效地联合生产烯.