フェノールは,銅で酸塩をNOに還元する (II):フェノールの酸化におけるプロトン反応性外協調球の役割
Aditesh Mondal1, Kiran P Reddy1, Jeffery A Bertke2
1School of Chemistry , Indian Institute of Science Education and Research Thiruvananthapuram (IISER-TVM) , Thiruvananthapuram 695551 , India.
Journal of the American Chemical Society
|January 9, 2020
まとめ
この研究は,銅複合体が窒素を酸化窒素と酸化フェノールにどのように促進するか明らかにしています. 陽子結合電子伝送経路が観察され,ユニークな無酸素フェノール窒素化が可能になった.
科学分野:
- バイオ有機化学
- 有機金属化学
- カタリシス
背景:
- 移行金属による反応は,窒素から酸化窒素への変換とフェノルの酸化を含む生理学的プロセスにとって極めて重要です.
- 銅複合体は,これらの重要な化学的変換を触媒する重要な役割を果たします.
- これらの反応のメカニズムを理解することは,新しい触媒システムの開発の鍵です.
研究 の 目的:
- 代用フェノールとニトリトコッパー (II) クリプタート複合体の反応性を調査する.
- 銅によって媒介された窒素から酸化窒素の放出のメカニズムを明らかにする.
- 反応経路と産物に対するプロトネーション状態の影響を調べる.
主な方法:
- 銅 (II) 暗号化複合体の合成と特徴付け
- 反応の中間物質とメカニズムを検知するためのスペクトロスコピック研究.
- 反応速度と順序を決定するための運動研究.
- 提案されたメカニズムをサポートする計算分析.
主要な成果:
- 銅 ([mC]Cu) 複合体 ([mC]Cu) から酸化窒素 (NO) への放出は,代替フェノールによる陽子結合電子移転 (PCET) 経路を経由する.
- 陽子化銅 ([mCH]Cu (II)) 複合体は,フェノールからの初期電子移転によってフェノールと反応する.
- 銅複合体の外部の調整球に陽子が存在することは,フェノール窒素化のための異常な無酸素経路を促進します.
結論:
- 窒素から酸化窒素への変換とフェノルの酸化のメカニズムは,銅触媒の陽子化状態に大きく依存しています.
- PCETは,コッパー・ナイトライト種からのNO放出の重要な経路です.
- 銅複合体は,新しい無酸素フェノール窒素反応を媒介することができる.
関連する概念動画
Oxidation of Phenols to Quinones
4.4K
In the presence of oxidizing agents, phenols are oxidized to quinones. Quinones can be easily reduced back to phenols using mild reducing agents. The electron-donating hydroxyl group enhances the reactivity of the aromatic ring, enabling oxidation of the ring even in the absence of an α hydrogen.
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox...
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox...
4.4K
Acidity and Basicity of Alcohols and Phenols
21.8K
Like water, alcohols are weak acids and bases. This is attributed to the polarization of the O–H bond making the hydrogen partially positive. Moreover, the electron pairs on the oxygen atom of alcohol make it both basic and nucleophilic. Protonation of an alcohol converts hydroxide, a poor leaving group, into water—a good one. The two acid–base equilibria corresponding to ethanol are depicted below.
21.8K
Reactions at the Benzylic Position: Oxidation and Reduction
4.8K
The benzylic position describes the position of a carbon atom attached directly to a benzene ring. Benzene by itself does not undergo oxidation. In contrast, the benzylic carbon is quite reactive in the presence of strong oxidizing agents such as KMnO4 or H2CrO4. Therefore, alkylbenzenes are readily oxidized to benzoic acid, irrespective of the type of alkyl groups.
4.8K
Hydrolysis of Chlorobenzene to Phenol: Dow Process
3.8K
Simple aryl halides do not react with nucleophiles under normal conditions. However, the reaction can proceed under drastic conditions involving high temperatures and high pressure to give the substituted products. For example, chlorobenzene is converted to phenol using aqueous sodium hydroxide at 350 °C under high pressure by the Dow process. The reaction follows an elimination-addition mechanism involving a benzyne intermediate. Here, the chloride ion is...
3.8K
meta-Directing Deactivators: –NO2, –CN, –CHO, –⁠CO2R, –COR, –CO2H
6.4K
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...
6.4K
Electrophilic Aromatic Substitution: Nitration of Benzene
8.0K
The nitration of benzene is an example of an electrophilic aromatic substitution reaction. It involves the formation of a very powerful electrophile, the nitronium ion, which is linear in shape. The reaction occurs through the interaction of two strong acids, sulfuric and nitric acid.
8.0K
![[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59739.jpg&w=3840&q=50)

