オレフィンメタテシス反応におけるルテニウムアルケンの中間物質のモデル化合物
Donde R Anderson1, Daniel D Hickstein, Daniel J O'Leary
1Arnold and Mabel Beckman Laboratories of Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
Journal of the American Chemical Society
|June 29, 2006
まとめ
研究者らは,ルテニウム-オレフィン複合体のモデルシステムを開発し,オレフィンメタテシスに不可欠である. 彼らは2つの横に結合した同位体を特定し,NMRとX線結晶学を使用してその動的相互変換バリアを測定した.
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
- オーガニック・シンセシス オーガニック・シンセシス
背景:
- オレフィンメタテシスは,有機合成における重要な反応である.
- ルテニウム触媒によるオレフィンメタテシスのメカニズムを理解することは,新しい触媒の開発の鍵です.
- ルテニウム-オレフィン複合体は,このメカニズムにおける重要な中間物質である.
研究 の 目的:
- ルテニウム-オレフィン複合体を研究するためのモデルシステムを開発する.
- これらの複合体の構造と動態を調査する.
- オレフィンメタテシスのメカニズムについての洞察を得るために.
主な方法:
- 1,2-ジビニルベンゼンとルテニウム前駆体を使用したルテニウム-オレフィン添加物の合成.
- 1H NMRスペクトロスコーピーを用いて複合体の特徴づけ.
- X線結晶学分析による複雑な構造の決定.
- ダイナミック・インターコンバージョン・バリアの測定は,スペクトロスコーピーを用いて行われます.
主要な成果:
- 2つのルテニウム-オレフィン添加物が形成され,横に結合したイソマーとして識別されました.
- オレフィンとH2IMesのリガンドは,相互に cis 調整されていることが判明しました.
- 2つの同位体間のダイナミックな相互変換は,19.1 +/- 0.1 kcal/molの測定されたバリアを持っています.
結論:
- 開発されたモデルシステムは,ルテニウム-オレフィン複合体の研究を効果的に可能にします.
- この発見は,オレフィン転化メカニズムに関連する貴重な構造的,動的情報を提供しています.
- この研究は,ルテニウムを含む触媒過程のより深い理解に貢献します.
関連する概念動画
02:35Free-Radical Chain Reaction and Polymerization of Alkenes
The conversion of alkenes to macromolecules called polymers is a reaction of high commercial importance. The structure of the polymer is defined by a repeating unit, while the terminal groups are considered insignificant. The average degree of polymerization represents the number of repeating units in the polymer molecule and is denoted by the subscript n.
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
01:57Preparation of Diols and Pinacol Rearrangement
Compounds bearing two hydroxyl groups are known as diols. When the hydroxyl groups are located on adjacent carbon atoms, the diols are called vicinal diols or glycols. Under acidic conditions, vicinal diols undergo a specific reaction called pinacol rearrangement.
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.
The reaction begins with transferring a proton from the acid catalyst to one of the hydroxyl groups, producing an oxonium ion.
01:13Olefin Metathesis Polymerization: Overview
Recently, the development of olefin metathesis polymerization advanced the field of polymer synthesis. Simply put, the reorganization of substituents on their double bonds between two olefins in the presence of a catalyst is known as the olefin metathesis reaction. The use of metathesis reaction for polymer synthesis is called olefin metathesis polymerization.
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
01:16Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
Ring-opening metathesis polymerization or ROMP involves strained cycloalkenes as starting materials. The mechanism of ROMP proceeds by reacting cycloalkene with Grubbs catalyst to give metallacyclobutane intermediate which undergoes a ring-opening reaction to form new carbene. The new carbene reacts with another molecule of cycloalkene. Repetition of these steps leads to the formation of an unsaturated open-chain polymer product. All these steps are reversible, however, relieving the ring...
00:53Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)
Acyclic diene metathesis polymerization or ADMET polymerization involves cross-metathesis of terminal dienes, such as 1,8-nonadiene, to give linear unsaturated polymer and ethylene. As ADMET is a reversible process, the formed ethylene gas must be removed from the reaction mixture to complete the polymerization process.
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...