了解L2Pd0和分子氧之间的旋转禁止反应
Clark R Landis1, Christine M Morales, Shannon S Stahl
1Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA. landis@chem.wisc.edu
Journal of the American Chemical Society
|December 17, 2004
概括
二氧化物与的反应 ((0)) 涉及一个阶段性过程,包括形和旋转交叉. 这种机制对于理解催化有氧氧化反应至关重要.
科学领域:
- 有机金属化学 有机金属化学
- 催化剂是一种催化剂.
- 计算化学计算化学
背景情况:
- 催化有氧氧化反应在有机合成中至关重要.
- 二氧化物 (O2) 和 () 0复合体之间的初始反应是一个关键的,但复杂的,步骤.
- 了解这种反应的自旋动力学对于优化催化效率至关重要.
研究的目的:
- 为了阐明(0) 复合物和二氧化之间的自旋禁止反应的机制.
- 分析旋转交叉在反应路径中的作用.
- 为了提供对氧复合物的形成的见解.
主要方法:
- 使用了自旋无限制密度函数理论 (DFT) 的计算.
- 反应途径被逐步分析.
- 研究了旋转密度移位的研究.
主要成果:
- 反应通过一个阶段性机制进行,涉及三重的eta1-superoxo-palladium (I) adduct.
- 从三联到单联表面的旋转交叉被确定为一个关键步骤.
- 单一的引体崩成一个eta2-peroxo-palladium (II) 复合体.
结论:
- 旋转密度转移到中心有助于旋转交叉.
- 这种机制阐明了二氧化碳转化为氧联结体的过程.
- 这些发现对于设计改进的催化氧化过程具有重要意义.
相关概念视频
Molecular Orbital Theory I
Overview of Molecular Orbital Theory
Molecular Orbital Theory II
Molecular Orbital Energy Diagrams
Preparation of Diols and Pinacol Rearrangement
Compounds bearing two hydroxyl groups are known as diols. When the hydroxyl groups are located on adjacent carbon atoms, the diols are called vicinal diols or glycols. Under acidic conditions, vicinal diols undergo a specific reaction called pinacol rearrangement.
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.
Radical Reactivity: Overview
Radicals, the highly reactive species, gain stability by undergoing three different reactions. The first reaction involves a radical-radical coupling, in which a radical combines with another radical, forming a spin‐paired molecule. The second reaction is between a radical and a spin‐paired molecule, generating a new radical and a new spin‐paired molecule. The third reaction is radical decomposition in a unimolecular reaction, forming a new radical and a spin‐paired molecule. These three...
Radical Reactivity: Steric Effects
The presence of electron-donating, electron-withdrawing, or conjugating groups adjacent to a radical center, imparts electronic stabilization to the radicals. Examples of such electronically-stabilized radicals are triphenylmethyl, tetramethylpiperidine‐N‐oxide, and 2,2‐diphenyl‐1‐picrylhydrazyl. These radicals are remarkably stable and are known as persistent radicals. Some of the persistent radicals can even be isolated and purified.
Along with electronic factors, steric factors also account...
Along with electronic factors, steric factors also account...
Radical Chain-Growth Polymerization: Overview
Chain-growth or addition polymerization is successive addition reactions of monomers with a polymer chain. In radical chain-growth polymerization, the reaction proceeds via a free-radical intermediate. The free radical is formed from radical initiators, which spontaneously generate free radicals by homolytic fission. Organic peroxides (such as dibenzoyl peroxide, as shown in Figure 1) or azo compounds are popular radical initiators. A low concentration ratio of radical initiator to monomer is...


