リング開きアルキンメタテシスポリメリゼーションにおける結合ポリマートポロジーのイニシアター制御
Stephen von Kugelgen1, Donatela E Bellone1, Ryan R Cloke1
1Department of Chemistry, University of California , Berkeley, California 94720, United States.
Journal of the American Chemical Society
|April 28, 2016
まとめ
モリブデンカルビネ複合体は,リング開きアルキンメタテシスのポリメリゼーションを開始する. エンドグループのステリック差異は,線形または循環結合ポリマーが形成されるかどうかを決定する.
科学分野:
- 有機金属化学
- ポリマー化学
- 材料科学
背景:
- モリブデンカルビネ複合体はアルキンの転化のための効果的な触媒である.
- リング開きアルキンメタテシスポリメリゼーション (ROMP) は結合ポリマーの合成を可能にします.
- 制御されたトポロジーを持つ結合ポリマーの合成は重要な課題です.
研究 の 目的:
- ROMPにおけるポリマートポロジーに対するイニシアター構造の影響を調査する.
- モリブデンカルビネ複合体を用いて完全に結合されたポリ ((o-フェニレンエチニレン) を合成する.
- 線形と周期的ポリマー形成を制御するメカニズムを解明する.
主な方法:
- 5,6,11,12-テトラデヒドロベンゾ[a,e][8]アヌレンの環開きアルキンメタテシスポリマー化.
- メシチル (Mes) またはエチル (Et) 末端基を持つモリブデンカルビネ複合体を用いて開始する.
- ポリメリゼーションメカニズムを分析するための運動研究.
主要な成果:
- モリブデンカルビネ複合体は,ストレートサイクルアルキンの生体ROMPを成功裏に開始しました.
- エンドグループ (Mes vs. Et) はポリマートポロジーを決定した.
- [MesCMo ((OC ((CH3) ((CF3) 2)) ]は,純粋に線形ポリ ((o-フェニレンエチニレン) を生成したものです.
- [EtCMo ((OC ((CH3) ((CF3) 2)) ]は,生成されたサイクルポリマー (n=5〜20).
- エチル末端群の場合は,内分子裏切りが示された.
結論:
- 開始カルビネリガンドのステリック特性は,ポリマートポロジーを制御する上で決定的な役割を果たします.
- この研究は,線形および循環結合ポリマーの両方を合成するための方法を示しています.
- この発見は,ポリマー合成のためのROMPと触媒設計の仕組みについての洞察を提供します.
関連する概念動画
Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
3.3K
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...
3.3K
Olefin Metathesis Polymerization: Overview
2.7K
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...
2.7K
Cationic Chain-Growth Polymerization: Mechanism
3.0K
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...
3.0K
Radical Chain-Growth Polymerization: Mechanism
3.8K
The radical chain-growth polymerization mechanism consists of three steps: initiation, propagation, and termination of polymerization. The polymerization initiates when a free radical generated from the radical initiator adds to the unsaturated bond in the monomer. The unpaired electron of the free radical and one π electron in the unsaturated bond creates a σ bond between the free radical and the monomer. As a result, the other π electron in the unsaturated bond converts this species into...
3.8K
Free-Radical Chain Reaction and Polymerization of Alkenes
10.2K
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.
10.2K
Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)
2.3K
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...
2.3K


