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相关概念视频

Nitriles to Amines: LiAlH4 Reduction00:55

Nitriles to Amines: LiAlH4 Reduction

3.1K
Nitriles are reduced to amines in the presence of strong reducing agents like lithium aluminum hydride through a typical nucleophilic acyl substitution. The reaction requires two equivalents of the reducing agent. The reducing agent acts as a source of hydride ions.
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
3.1K
Reduction of Alkynes to trans-Alkenes: Sodium in Liquid Ammonia02:10

Reduction of Alkynes to trans-Alkenes: Sodium in Liquid Ammonia

9.0K
Alkynes can be reduced to trans-alkenes using sodium or lithium in liquid ammonia. The reaction, known as dissolving metal reduction, proceeds with an anti addition of hydrogen across the carbon–carbon triple bond to form the trans product. Since ammonia exists as a gas (bp = −33°C) at room temperature, the reaction is carried out at low temperatures using a mixture of dry ice (sublimes at −78°C) and acetone. 
When dissolved in liquid ammonia, an alkali metal,...
9.0K
Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation02:24

Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation

7.5K
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
7.5K
Amides to Amines: LiAlH4 Reduction01:20

Amides to Amines: LiAlH4 Reduction

4.4K
Amide reduction with strong reducing agents like lithium aluminum hydride proceeds through a nucleophilic acyl substitution to form amines. Primary, secondary, and tertiary amides yield primary, secondary, and tertiary amines, respectively.
Amide reduction requires two equivalents of the reducing agent, acting as a source of hydride ions. As shown in the figure, the reaction is initiated with a nucleophilic attack by the hydride ion at the carbonyl carbon to form a tetrahedral intermediate.
4.4K
Catalysis02:50

Catalysis

26.2K
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.
26.2K
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation02:17

Reduction of Alkenes: Asymmetric Catalytic Hydrogenation

3.2K
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
3.2K

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相关实验视频

Updated: May 10, 2025

Ammonia Synthesis at Low Pressure
08:14

Ammonia Synthesis at Low Pressure

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高效的低温氨裂解,通过在无Ru催化剂上的应力异构结构接口实现.

Pei Xiong1,2, Jiangtong Li1, Zhihang Xu1

  • 1Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, 999077, China.

Advanced materials (Deerfield Beach, Fla.)
|April 28, 2025
PubMed
概括

一种新型应力芯@催化剂有效地在低温下破解氨以储存. 这一突破避免了昂贵的催化剂,为实际的能解决方案铺平了道路.

关键词:
氨裂变是对氨的裂变造成的.核心@外催化剂的核心@外催化剂动态菌株演变的动态变化异构结构的接口接口.格子应变应变 格子应变

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Heterogeneous Removal of Water-Soluble Ruthenium Olefin Metathesis Catalyst from Aqueous Media Via Host-Guest Interaction
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Heterogeneous Removal of Water-Soluble Ruthenium Olefin Metathesis Catalyst from Aqueous Media Via Host-Guest Interaction
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科学领域:

  • 材料科学 材料科学 材料科学
  • 催化剂是一种催化剂.
  • 储能 储能 储能 储能 储能 储能

背景情况:

  • 氨 (NH3) 是一个有前途的 (H2) 载体.
  • (Ru) 催化剂对于低温NH3裂变来说是昂贵的.
  • 开发高效,低成本的催化剂对于H2技术至关重要.

研究的目的:

  • 开发一种具有成本效益的低温氨裂解催化剂.
  • 为了研究应力异构结构催化剂的性能和机制.
  • 提高用于储能应用的气生产率.

主要方法:

  • 一种应力异构 Co@BaAl2O4-x 核心@外催化剂的合成.
  • 在475至575°C的温度下对催化性能进行评估.
  • 利用同步X射线吸收光谱和衍射研究工作条件下的催化剂结构.
  • 进行动力学研究以了解反应机制.

主要成果:

  • 在低温下,Co@BaAl2O4-x催化剂的性能与基于Ru的催化剂相当.
  • 实现了高的转化率和64.6 mmol H2 gcat-1 min-1.的H2生产率.
  • 鉴定出增强的NH3吸附和N─H解离,这是由于Co.表面的拉力应变造成的.
  • 通过应变释放/恢复证明有效的脱,防止催化剂中毒.

结论:

  • 格子应变工程和强大的金属支接口是催化剂设计的有效策略.
  • 应力Co@BaAl2O4-x催化剂为Ru提供了一个可行的替代方案,用于低温NH3裂变.
  • 这项工作推动了使用氨的高效催化剂的开发,用于使用氨储存气.