![Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-(phosphinetriyl)tripiperidine]}palladium Under Mild Reaction Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F51444.jpg&w=3840&q=50)
オルガノランタニド触媒合成による,フォスフィン終末ポリエチレン. 適用範囲と仕組み
Amber M Kawaoka1, Tobin J Marks
1Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA.
Journal of the American Chemical Society
|April 28, 2005
まとめ
二次フォスフィンは,オルガノランタニドで触媒化されたエチレンポリメリゼーションを大幅に強化し,高い活性と狭いポリ分散性につながります. プライマリ・フォスフィンは低分子量オリゴマーのみを生成する.
科学分野:
- 有機金属化学 有機金属化学
- ポリマーサイエンスの科学
- カタリシス カタリシス カタリシス
背景:
- オルガノランタニド複合体は,オレフィンポリメリゼーションの活性触媒である.
- ポリマー分子量とポリ分散性を制御することは,ポリメリゼーションプロセスにおいて極めて重要です.
研究 の 目的:
- オーガノランタニド媒介によるエチレンポリメリゼーションにおけるチェーン転送剤としての一次性および二次性フォスフィンの役割を調査する.
- フォスフィン連鎖伝達効率と触媒構造と反応条件を相関させるため.
主な方法:
- エチレンポリメリゼーションは,ランタノセンの前触媒 ([Cp'{2}LnH{2}およびCp'{2}LnCH{3}SiMe{3}) {2}) を用いて,様々なフォスフィンで.
- ポリメリゼーション活動,ポリマーの分子量,およびポリ分散性の分析.
主要な成果:
- 二次性フォスフィン (例えばディフェニルフォスフィン,ディイソブチルフォスフィン) は,鎖移転効率が高く,高ポリメリゼーション活動と狭いポリ分散性をもたらします.
- チェーンの伝達効率は,リン酸化物によるLn-CH ((SiMe ((3)) ((2)) のプロトン分解の速度と相関しています.
- プライマリー・フォスフィンは低分子量オリゴーマーを産生し,鎖移転能力が限られていることを示している.
結論:
- 二次フォスフィンは,オルガノランタニドで触媒化されたエチレンポリメリゼーションの有効なチェーン転送剤であり,ポリマーの特性に対する制御を可能にします.
- このメカニズムは,Ln-アルキル結合のフォスフィン媒介のプロトノリシスを含む.
- プライマリーフォスフィンは,このメカニズムを通じて高分子量ポリマーを生産するのに適していません.
関連する概念動画
02:27Preparation of Alkynes: Alkylation Reaction
Introduction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
02:34Preparation of Alkynes: Dehydrohalogenation
Introduction
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
01:14Aldehydes and Ketones to Alkenes: Wittig Reaction Mechanism
The Wittig reaction, which converts aldehydes or ketones to alkenes using phosphorus ylides, proceeds through a nucleophilic addition‒elimination process.
The reaction begins with the nucleophilic addition between a phosphorus ylide and the carbonyl compound. Due to its carbanionic character, phosphorus ylide acts as a strong nucleophile and attacks the electrophilic carbonyl group. This generates a charge-separated dipolar intermediate called betaine. The negatively charged oxygen atom and...
The reaction begins with the nucleophilic addition between a phosphorus ylide and the carbonyl compound. Due to its carbanionic character, phosphorus ylide acts as a strong nucleophile and attacks the electrophilic carbonyl group. This generates a charge-separated dipolar intermediate called betaine. The negatively charged oxygen atom and...
00:57Cationic Chain-Growth Polymerization: Mechanism
The cationic polymerization mechanism consists of three steps: initiation, propagation, and termination. In the initiation step of the polymerization process, the π bond of a monomer gets protonated by the Lewis acid catalyst, which is formed from boron trifluoride and water. The protonation of the π bond generates a carbocation stabilized by the electron‐donating group. In the propagation step, the π bond of the second monomer acts as a nucleophile and attacks the generated carbocation,...
01:17Ziegler–Natta Chain-Growth Polymerization: Overview
Ziegler–Natta polymerization is another form of addition or chain‐growth polymerization used for synthesizing linear polymers over branched polymers. The catalyst used for polymerization is the Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, who developed it in 1953. This catalyst is an organometallic complex of titanium tetrachloride and triethyl aluminum, with the active form of the catalyst being an alkyl titanium compound. Using the Ziegler–Natta catalyst, high molecular...
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...