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関連する概念動画

ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH301:11

ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3

7.9K
All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons electron-rich. Consequently, the reactivity of the aromatic ring towards electrophilic substitution increases. For instance, the nitration of anisole is about 10,000 times faster than the nitration of benzene. The electron-donating effect of the methoxy group in anisole activates the ortho and para positions on the ring and stabilizes the corresponding...
7.9K
ortho–para-Directing Deactivators: Halogens01:24

ortho–para-Directing Deactivators: Halogens

7.1K
Halogens are ortho–para directors. They are more electronegative than carbon. Therefore, as ring substituents, they can withdraw electrons through the inductive effect and deactivate the aromatic ring towards electrophilic substitution. Halogens also have an electron-donating resonance effect on the ring, which influences the orientation of the incoming electrophile. If an electrophile attacks at the ortho or the para position, the halogen donates electrons and stabilizes the intermediate...
7.1K
Regioselectivity and Stereochemistry of Hydroboration02:36

Regioselectivity and Stereochemistry of Hydroboration

9.7K
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn stereochemistry.
9.7K
Acid-Catalyzed α-Halogenation of Aldehydes and Ketones01:21

Acid-Catalyzed α-Halogenation of Aldehydes and Ketones

5.1K
By replacing an α-hydrogen with a halogen, acid-catalyzed α-halogenation of aldehydes or ketones yields a monohalogenated product
In the first step of the mechanism, the acid protonates the carbonyl oxygen resulting in a resonance-stabilized cation, which subsequently loses an α-hydrogen to form an enol tautomer. The C=C bond in an enol is highly nucleophilic because of the electron-donating nature of the –OH group. Consequently, the double bond attacks an electrophilic halogen to form a...
5.1K
meta-Directing Deactivators: –NO2, –CN, –CHO, –⁠CO2R, –COR, –CO2H01:13

meta-Directing Deactivators: –NO2, –CN, –CHO, –⁠CO2R, –COR, –CO2H

7.0K
All meta-directing substituents are deactivating groups. These substituents withdraw electrons from the aromatic ring, making the ring less reactive toward electrophilic substitution. For example, the nitration of nitrobenzene is 100,000 times slower than that of benzene because of the deactivating effect of the nitro group. The first step in an electrophilic aromatic substitution is the addition of an electrophile to form a resonance-stabilized carbocation. The energy diagrams for...
7.0K
Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration02:34

Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration

10.0K
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.
10.0K

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関連する実験動画

Updated: Mar 26, 2026

Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides
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Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides

Published on: May 26, 2019

9.9K

表面制御モノ/ディセレクティブオーソC-H結合活性化

Qing Li1, Biao Yang1, Haiping Lin1

  • 1Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University , 199 Ren'ai Road, Suzhou, 215123, Jiangsu P. R. China.

Journal of the American Chemical Society
|February 9, 2016
PubMed
まとめ

研究者は,フェノール誘導体を用いて,Au{11}とAg{11}の表面での選択的C−H結合活性化を調査した. 異なる表面選択性が観察され,表面支援有機合成のための新しい経路を提供した.

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Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides CHIPS
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Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides CHIPS

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Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy
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Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy

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Last Updated: Mar 26, 2026

Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides
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Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides CHIPS
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Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy
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科学分野:

  • 有機化学
  • 表面科学
  • カタリシス

背景:

  • 選択的C−H結合の活性化は,高結合解離エンタルピーと低反応選択性により,有機化学における重要な課題である.
  • フェノール誘導体は,競合する反応経路により,C-H活性化のための複雑な基板を提示する.

研究 の 目的:

  • 選択的なオーソC−H機能化と,Au−""""とAg−""""の表面におけるフェノール誘導体のオーソ・オートコップリングを調査する.
  • 脱水と脱酸素が反応経路と選択性に与える影響を理解する.

主な方法:

  • 反応のプラットフォームとして,金属表面のAu{111}とAg{111}を使用しています.
  • スキャニング・トンネル顕微鏡 (STM) を使って表面をイメージする.
  • 機械的な計算のための応用密度関数理論 (DFT).
  • 表面分析のためにX線光電子スペクトロスコーピー (XPS) を使用した.

主要な成果:

  • Au ((111) 表面の非選択的なC−H結合活性化が観察された.
  • モノセレクティブのC−H結合活性化がAg−111表面で観察された.
  • 脱水と脱酸素の競争が反応経路を決定することを示した.

結論:

  • この研究は,異なる金属表面での単一および非選択的なC-H活性化経路を明らかにしています.
  • 発見は,制御されたC−H結合の活性化による表面補助有機合成のための新しい戦略を提供します.
  • この研究は,金属表面におけるフェノール誘導体の反応を制御するメカニズムに関する基本的な洞察を提供します.