亜鉛-アニリド複合体によるアルキンの触媒的,Z選択的,半化
Greg J Baker1, Andrew J P White1, Ian J Casely2
1Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, 82 Wood Lane, White City, London W12 0BZ, United Kingdom.
Journal of the American Chemical Society
|March 27, 2023
まとめ
この研究は,不飽和化合物の水素化のために二水素 (H2) を活性化する新しい亜鉛複合体を詳細に説明しています. この発見により,アルキンの選択的半水素化が可能になり,新しい触媒経路が提供されます.
科学分野:
- 有機金属化学
- カタリシス
- 無機化学
背景:
- 二酸化水素 (H2) アクティベーションは,触媒性水素化に不可欠です.
- 選択的で効率的な触媒システムの開発は,化学における重要な課題です.
- 亜鉛複合体は新しい触媒変換の可能性を秘めている.
研究 の 目的:
- 分子亜鉛アニリド複合体を使用して二水素の可逆活性化について報告する.
- H2活性化およびその後の水酸化反応のメカニズムを解明する.
- アルキンの選択的半水素化のための触媒システムを開発する.
主な方法:
- 反応メカニズムの探査のためのステキオメトリック実験.
- 機械的な洞察のための密度関数理論 (DFT) の計算.
- 様々な不飽和基質 (アルキン,アルケーン,アルカディン) での水酸化試験
主要な成果:
- H2の活性化は,Zn-N結合添加を含む4つの成分の移行状態を経由して発生する.
- その結果生じる亜鉛水化物複合体は,C=C結合 (アルキン,アルケーン,1,3-ブタジーン) を効果的に水酸化する.
- アルキンの水酸化はステレオ特異性 (シン同位体) であり,アルケンよりも速い.
- 選択的アルキン半化のための高Z:E比率の触媒系が開発された.
結論:
- 亜鉛アニリド複合体は,可逆的なH2活性化と水亜鉛化を促進する.
- この研究は,亜鉛複合体を用いた選択的水素化触媒の最初の例を示している.
- 開発された触媒システムは,選択的なアルキンの変換に希望を示しています.
関連する概念動画
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
7.9K
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.
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.
7.9K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.4K
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...
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...
3.4K
02:13Reduction of Alkenes: Catalytic Hydrogenation
12.3K
Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
12.3K
01:28Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation
4.7K
Unlike the easy catalytic hydrogenation of an alkene double bond, hydrogenation of a benzene double bond under similar reaction conditions does not take place easily. For example, in the reduction of stilbene, the benzene ring remains unaffected while the alkene bond gets reduced. Hydrogenation of an alkene double bond is exothermic and a favorable process. In contrast, to hydrogenate the first unsaturated bond of benzene, an energy input is needed; that is, the process is endothermic. This is...
4.7K
02:35Electrophilic Addition to Alkynes: Hydrohalogenation
10.1K
Electrophilic addition of hydrogen halides, HX (X = Cl, Br or I) to alkenes forms alkyl halides as per Markovnikov's rule, where the hydrogen gets added to the less substituted carbon of the double bond. Hydrohalogenation of alkynes takes place in a similar manner, with the first addition of HX forming a vinyl halide and the second giving a geminal dihalide.
10.1K
02:40Alkynes to Aldehydes and Ketones: Acid-Catalyzed Hydration
8.8K
Introduction
Analogous to alkenes, alkynes also undergo acid-catalyzed hydration. While the addition of water to an alkene gives an alcohol, hydration of alkynes produces different products such as aldehydes and ketones.
Analogous to alkenes, alkynes also undergo acid-catalyzed hydration. While the addition of water to an alkene gives an alcohol, hydration of alkynes produces different products such as aldehydes and ketones.
8.8K