用反应控制的相转移催化剂用于将烯环氧化为烯氧化物
1Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, Dalian 116023, People's Republic of China. huangw@dicp.ac.cn
Science (New York, N.Y.)
|May 12, 2001
概括
这项研究介绍了一种新的催化剂,用于使用过氧化 (H2O2) 来氧化烯酸. 催化剂结合了同质和异质的好处,使得高效的氧化生产具有高产量和没有副产品.
科学领域:
- 催化剂是一种催化剂.
- 绿色化学 绿色化学
- 有机合成 有机合成
背景情况:
- 传统的烯酸环氧化方法往往会产生有问题的副产品.
- 开发高效和可回收的催化系统对于可持续的化学品生产至关重要.
研究的目的:
- 用过氧化开发一种新的催化系统,用于使用过氧化进行烯酸环氧化.
- 结合同质和异质催化剂的优势,提高效率和可回收性.
- 为了实现无副产品的高产氧化物生产.
主要方法:
- 使用含的催化剂,用H2O2.2氧化烯酸氧化烯酸.
- 采用反应控制的相转移机制,催化剂在可溶性活性物种和沉形式之间过渡.
- 集成了2-乙烯甲基/2-乙烯甲基氧化还原过程,用于在现场生成H2O2.
主要成果:
- 催化剂在H2O2的存在下形成可溶性活性物种,并在H2O2耗尽后沉,从而促进易于回收利用.
- 使用O2从中获得了85%的氧化产量,基于2-乙烯甲化.
- 证明了无副产品的环氧化工艺,解决了工业氧化物合成的关键挑战.
结论:
- 开发的催化系统有效地结合了同质和异质的催化优势.
- 这种方法为氧化物生产提供了可持续和高效的途径,最大限度地减少了浪费.
- 反应控制的相转移和集成的H2O2生产是过程成功的关键.
相关概念视频
02:50Catalysis
The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
01:17Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
01:26Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
01:27Catalysis
Catalysis influences the rate of chemical reactions by providing an alternative reaction pathway with lower activation energy. A catalyst speeds up a reaction, but it is not consumed during the process. The fundamental principle of catalysis is the ability of a catalyst to alter the reaction mechanism, often introducing a more efficient pathway than the uncatalyzed process.In a catalyzed reaction, the catalyst participates directly in the reaction mechanism. It interacts with reactants to form...
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...