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相关概念视频

Radical Reactivity: Steric Effects01:10

Radical Reactivity: Steric Effects

2.0K
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...
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Thermal Electrocyclic Reactions: Stereochemistry01:17

Thermal Electrocyclic Reactions: Stereochemistry

2.1K
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.
2.1K
Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule02:17

Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule

14.7K
If a set of reactants can yield multiple constitutional isomers, but one of the isomers is obtained as the major product, the reaction is said to be regioselective. In such reactions, bond formation or breaking is favored at one reaction site over others.
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
14.7K
Photochemical Electrocyclic Reactions: Stereochemistry01:26

Photochemical Electrocyclic Reactions: Stereochemistry

1.9K
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
1.9K
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration02:34

Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration

8.7K
The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.
8.7K
Complexation Equilibria: Factors Influencing Stability of Complexes01:09

Complexation Equilibria: Factors Influencing Stability of Complexes

494
In complexation reactions, metal cations are the electron pair acceptors, and the ligands are the electron pair donors. The stability of the metal complexes depends primarily on the complexing ability of the central metal ion and the nature of the ligands. Generally, the complexing ability of the metal ion depends on the size and charge of the ion. As the metal ion size increases, the stability of the metal complexes decreases, provided that the valency of the metal ion and the ligands remain...
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Updated: Sep 20, 2025

Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy
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通过有机子进行绝缘主导的中间稳定,使得高选择性CO2电还原成为可能.

Zishan Han1,2, Xinyu Wang1, Zhiguo Li1

  • 1Nanoyang Group, Tianjin Key Laboratory of Advanced Carbon and Electrochemical Energy Storage, School of Chemical Engineering and Technology, and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, 300072, China.

Angewandte Chemie (International ed. in English)
|May 28, 2025
PubMed
概括

这项研究引入了一种使用有机四级氨酸来增强电催化二氧化碳减排的新型固体效应策略. 这种方法通过调整铜表面的中间吸附来提高酸生产的选择性.

关键词:
吸附方式 吸附方式 吸附方式他们的评价.铜铜 铜铜 铜铜电化学 电化学 电化学

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科学领域:

  • 电化学 电化学 电化学
  • 材料科学 材料科学 材料科学
  • 催化剂是一种催化剂.

背景情况:

  • 控制中间约束能量对于选择性电催化二氧化碳减排 (CO2RR) 是至关重要的.
  • 已知酸通过静电相互作用稳定中间体.
  • 使用有机离子体的固体效应主导的策略提供了一种调整中间吸附的新方法.

研究的目的:

  • 研究使用有机四级氨酸 (CnTA+) 调节CO2RR中中间吸附的方法.
  • 阐明这些子影响反应通路的机制.
  • 提高酸生产的选择性和效率.

主要方法:

  • 在现场减弱的总反射率-表面增强红外吸收光谱 (ATR-SEIRAS) 来研究电极表面的离子行为.
  • 使用不同CnTA+离子修改的铜电极进行电触媒CO2减排实验.
  • 对酸生产法拉第效率 (FE) 的分析.

主要成果:

  • 较长的链CnTA+对铜表面具有较高的亲和力,并且在电双层中更有效地替代酸.
  • CnTA+的固体效应显著增强了关键反应中间体的吸附.
  • 八甲基三甲基 (C18TA+) 离子导致酸FE高达90%.

结论:

  • 有机四级酸,特别是具有较长链的酸,可以通过一种以固态效应为主导的机制有效地引导CO2RR通路向酸.
  • 这种分子工程方法提供了一种灵活的途径来优化CO2RR性能.
  • 这些发现为设计用于二氧化碳转换的先进电催化剂提供了新的策略.