相关实验视频
Updated: Jul 18, 2026
11:15
HKUST-1 as a Heterogeneous Catalyst for the Synthesis of Vanillin
Published on: July 23, 2016
通过新型铁 (III) - 氧化复合物的循环聚合物的机械比较:单位与多位点催化剂
Brendan J O'Keefe1, Laurie E Breyfogle, Marc A Hillmyer
1Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA.
Journal of the American Chemical Society
|April 19, 2002
概括
铁和单核铁复合物有效催化循环聚合. 双铁复合体提供了卓越的控制和更快的传播速率,表明了不同的催化机制,并为未来的催化剂设计提供了信息.
科学领域:
- 有机金属化学 有机金属化学
- 聚合物科学 聚合物科学
- 催化剂是一种催化剂.
背景情况:
- 铁复合物越来越多地被探索为聚合物合成的催化剂.
- 了解单核和多核催化剂之间的机制差异对于优化聚合过程至关重要.
研究的目的:
- 为了结构性地表征二铁和单核铁氧化物复合物.
- 为了比较它们在周期性的聚合中的催化活性和机制,特别是 ε-caprolactone (CL) 和 D,L-lactide (LA).
主要方法:
- 铁复合物的结构特征. 铁复合物的结构特征.
- 使用Fe2(OCHPh2)6和L2FeOR催化剂进行CL聚合的动力学研究.
- 分析所产生的聚合物的分子量,多分散性和终端组分析.
主要成果:
- 两个Fe2(OCHPh2)6和L2FeOR复合体都是有效的聚合催化剂.
- 与单核L2FeOR相比,二铁复合体Fe2(OCHPh2) 6表现出优异的聚合控制和50倍以上的传播速率常数 (k(prop)) .
- 动力分析显示了不同的反应顺序与催化剂度,表明不同的聚合机制,包括单核复合物的活性链聚合.
结论:
- 由于更有效的机制,二铁复合体在循环聚合过程中表现出增强的催化性能.
- 这些发现为铁催化周期性聚合的机械细微差别提供了洞察力.
- 结果指导了用于改善聚合物合成的新型铁基催化剂的设计.
相关概念视频
02:51Metal-Ligand Bonds
The hemoglobin in the blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the manufacture of polyethylene all contain coordination compounds. Ions of the metals, especially the transition metals, are likely to form complexes.
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
02:34Structural Isomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
01:23Properties of Organometallic Compounds
Organometallic compounds are compounds that contain a carbon–metal bond. Carbon belongs to an organyl group like alkyl, aryl, allyl, or benzyl groups. The metal can be from Group I or Group II of the periodic table, a transition metal, or a semimetal.
01:19Complexation Equilibria: The Chelate Effect
In complexation reactions, metal atoms or cations interact with ligands to form donor-acceptor adducts called metal complexes. Ligands that bind through one donor site are monodentate, ligands with two donor sites are bidentate, and those with more than two donor sites are polydentate ligands. For example, ethylene diamine is a bidentate ligand that binds through two nitrogen donor atoms, forming a five-membered ring. EDTA is a polydentate ligand that binds through four oxygen and two nitrogen...
00:43Complexometric Titration: Ligands
Different monodentate and polydentate ligands are used as complexing agents in complexometric titration reactions. The formation of complexes by mono- and bidentate ligands involves two or more intermediate steps, limiting their use as complexing agents. In comparison, polydentate ligands can form complexes with metal ions in a single-step process, facilitating sharper end points. This means polydentate ligands, such as amino carboxylic acid derivatives, are most commonly employed in...
01:22Heterogeneous Catalysis
Heterogeneous catalysis involves a catalyst in a different phase from the reactants. It is a process where the catalyst and the reactants are in distinct phases, typically solid and gas or liquid.Most heterogeneous catalysts are metals, metal oxides, or acids. The list includes transition metals like iron (Fe), cobalt (Co), nickel (Ni), palladium (Pd), platinum (Pt), chromium (Cr), manganese (Mn), tungsten (W), silver (Ag), and copper (Cu). These metals possess partially vacant d orbitals that...