Jove
Visualize
お問い合わせ

関連する概念動画

Thermal Electrocyclic Reactions: Stereochemistry01:17

Thermal Electrocyclic Reactions: Stereochemistry

2.7K
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.
2.7K
Heterogeneous Catalysis01:22

Heterogeneous Catalysis

111
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...
111
Photochemical Electrocyclic Reactions: Stereochemistry01:26

Photochemical Electrocyclic Reactions: Stereochemistry

2.4K
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
2.4K
Thermal and Photochemical Electrocyclic Reactions: Overview01:26

Thermal and Photochemical Electrocyclic Reactions: Overview

3.2K
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.
3.2K
Diels–Alder Reaction: Characteristics of Dienes01:29

Diels–Alder Reaction: Characteristics of Dienes

5.7K
The Diels–Alder reaction brings together a diene and a dienophile to form a six-membered ring. Both components have unique characteristics that influence the rate of the reaction.
Characteristics of the diene
Conformation
The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable,...
5.7K
Introduction to Mechanisms of Enzyme Catalysis01:13

Introduction to Mechanisms of Enzyme Catalysis

10.2K
10.2K
JoVE
x logofacebook logolinkedin logoyoutube logo
JoVEについて
概要リーダーシップブログJoVEヘルプセンター
著者向け
出版プロセス編集委員会範囲と方針査読よくある質問投稿
図書館員向け
推薦の声購読アクセスリソース図書館諮問委員会よくある質問
研究
JoVE JournalMethods CollectionsJoVE Encyclopedia of Experimentsアーカイブ
教育
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab Manual教員リソースセンター教員サイト
利用規約
プライバシーポリシー
ポリシー
  1. ホーム
  3. ヴァナディア/セリア触媒反応におけるユニークな電子および構造的効果
  1. ホーム
  3. ヴァナディア/セリア触媒反応におけるユニークな電子および構造的効果

関連する実験動画

Chemical Vapor Deposition of an Organic Magnet, Vanadium Tetracyanoethylene
08:25

Chemical Vapor Deposition of an Organic Magnet, Vanadium Tetracyanoethylene

Published on: July 3, 2015

12.2K

ヴァナディア/セリア触媒反応におけるユニークな電子および構造的効果

Xin-Ping Wu1, Xue-Qing Gong1

  • 1Key Laboratory for Advanced Materials, Centre for Computational Chemistry, and Research Institute of Industrial Catalysis, East China University of Science and Technology , Shanghai 200237, People's Republic of China.

Journal of the American Chemical Society
|October 7, 2015

PubMed で要約を見る

まとめ
この要約は機械生成です。

ヴァナディア/セリア触媒は,独自の電子的および構造的効果のために酸化脱水化 (ODH) に高い活性を示します. V-O-Ce インターフェースの酸素と新しい O2p 状態は,反応障壁を減らすための鍵です.

さらに関連する動画

Atomic Layer Deposition of Vanadium Dioxide and a Temperature-dependent Optical Model
11:10

Atomic Layer Deposition of Vanadium Dioxide and a Temperature-dependent Optical Model

Published on: May 23, 2018

12.6K
Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area
08:13

Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area

Published on: February 19, 2018

12.6K

関連する実験動画

Chemical Vapor Deposition of an Organic Magnet, Vanadium Tetracyanoethylene
08:25

Chemical Vapor Deposition of an Organic Magnet, Vanadium Tetracyanoethylene

Published on: July 3, 2015

12.2K
Atomic Layer Deposition of Vanadium Dioxide and a Temperature-dependent Optical Model
11:10

Atomic Layer Deposition of Vanadium Dioxide and a Temperature-dependent Optical Model

Published on: May 23, 2018

12.6K
Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area
08:13

Chemical Precipitation Method for the Synthesis of Nb2O5 Modified Bulk Nickel Catalysts with High Specific Surface Area

Published on: February 19, 2018

12.6K

科学分野:

  • カタリシス
  • 材料科学
  • 表面化学

背景:

  • ヴァナディア/セリアを支える触媒は,高い触媒活性で知られています.
  • 酸化脱水反応 (ODH) は化学合成において極めて重要です.
  • これらの触媒のメカニズムを理解することは最適化に不可欠です.

研究 の 目的:

  • ODH反応におけるヴァナジア/セリア触媒の基礎的なメカニズムを理論的な計算を用いて解明する.
  • 触媒の高い活性に寄与する主要な電子的および構造的要因を特定する.
  • 触媒サイクルにおける異なる酸素種と電子状態の役割を調査する.

主な方法:

  • 密度関数理論 (DFT) の計算を体系的に実行した.
  • 各種の酸素の触媒性能が評価された.
  • 新しいO2p状態を含む電子構造の変化を分析した.

主要な成果:

  • 独特の電子効果と構造効果の両方が触媒活動に不可欠です.
  • V-O-Ceインターフェースの酸素は,特にH吸収エネルギーが低いとき,強い構造効果を強調します.
  • ヴァナディア種を貯蔵すると,新しい空のO2p局所化状態が生じ,ODH反応に参加し,エネルギーバリアを下げます.

結論:

  • ヴァナディアとセリアの相互作用により,ODHの活性サイトが生成されます.
  • V-O-Ceインターフェースのような構造的特徴は,触媒性能に大きな影響を与えます.
  • 特定の電子状態 (O2p) の形成は,反応経路を促進し,活性化エネルギーを減らすために不可欠です.