ニッケル・ボラン・ユニット全体に逆戻り可能なH2添加は,触媒作用の有望な戦略である
W Hill Harman1, Jonas C Peters
1Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
Journal of the American Chemical Society
|March 3, 2012
まとめ
研究者らは,ディホスフィン-ボランリガンドを用いて,新しいニッケル複合体を合成した. これらの複合物,特にB-メシチル誘導体は,オレフィン水素化のための効率的な触媒活性を示し,化学合成におけるその可能性を強調しています.
科学分野:
- 有機金属化学 有機金属化学
- カタリシス カタリシス カタリシス
- ボロン化学 ボロン化学
背景:
- ディフォスフィン・リガンドは,協調化学と触媒作用において極めて重要です.
- ボラン機能化は,リガンドにユニークな電子およびステリック特性を提供します.
- ニッケル複合体は,様々な有機変異のための汎用的な触媒です.
研究 の 目的:
- ディフォスフィン・ボラン・リガンドをケラートすることによってサポートされる新しいニッケル複合体を合成し,特徴づけること.
- これらのニッケル複合体の調整行動と構造的特徴を調査する.
- 水素化反応で合成されたニッケル複合体の触媒活性を評価する.
主な方法:
- ArB ((o-Ph ((2) PC ((6) H ((4)) ((2)) リガンドを含むニッケル複合体の合成.
- 構造特性を示すために,X線 difraktion を用いて[Ph]DPB[Ph]Ni[THF]の構造特性を決定する.
- 溶液中のニッケル (II) 複合体の特徴を特定するための多核性NMRスペクトロスコーピー.
- オレフィン基板の触媒性水素化には[(Mes) DPB (((Ph) ]Ni.を用いるとする.
主要な成果:
- 準四面体ニッケル複合体の合成に成功し, η(2) -B,Cの協調を図った.
- 短いニッケル-リガンド相互作用のX線微分法による[Ph]DPB[Ph]Ni[THF]の特徴化.
- 擬似3座標ニッケル複合体, [(Mes) DPB (((Ph) ]Niの分離,可逆的な二水素酸化添加を示している.
- 温和な条件下で[Mes) DPB (Ph) ]Niによる効率的なオレフィン水素化触媒の実証.
結論:
- ディフォスフィン・ボラン・リガンド・フレームワークは,ニッケルに独特な協調幾何学を効果的にサポートしています.
- B-メシチルニッケル複合体は,水素化の効率的な触媒として作用し,有機合成における潜在的な応用を示しています.
- この研究は,有機金属化学と触媒のリガンド設計の範囲を拡大します.
さらに関連する動画
関連する概念動画
02:50Catalysis
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.
01:27Catalysis
Catalysis influences the rate of chemical reactions by providing an alternative reaction pathway with lower activation energy. A catalyst speeds up a reaction, but it is not consumed during the process. The fundamental principle of catalysis is the ability of a catalyst to alter the reaction mechanism, often introducing a more efficient pathway than the uncatalyzed process.In a catalyzed reaction, the catalyst participates directly in the reaction mechanism. It interacts with reactants to form...
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
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.
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
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...
03:08Hydroboration-Oxidation of Alkenes
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.