エチレン/極性モノマー共ポリマー化 bis ((フェノキシイミン) Ti 複合体の振る舞い:極性モノマー共ポリマーの形成
Hiroshi Terao1, Seiichi Ishii, Makoto Mitani
1Research Center, Mitsui Chemicals, Inc., 580-32 Nagaura, Sodegaura, Chiba, 299-0265, Japan.
Journal of the American Chemical Society
|December 11, 2008
まとめ
特定のbis ((フェノキシイミン) リガンドを持つチタンの触媒は,エチレンと5-ヘクセン-1-イルアセテートの共聚化を促進する. これらのグループ4の移行金属複合体は,オレフィンポリメリゼーションにおいて有望であることが示されています.
科学分野:
- ポリマー化学のポリマー化学について
- 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
背景:
- グループ4の移行金属複合体は,オレフィンポリメリゼーションにおいて極めて重要です.
- Bis (((フェノキシ-イミン) リガンドは,触媒設計のために調整可能なステリックおよび電子特性を提供します.
- エチレンと機能化されたオレフィンとの共ポリメリゼーションは,ポリマーの微細構造を制御する上で課題を提示します.
研究 の 目的:
- 新型ビス ((フェノキシ・イミン) タイタニウム複合体の触媒活性を調べる.
- これらのチタン触媒を使用して,エチレンと5-ヘキセン-1-イルアセテートの共聚化を調査する.
- 触媒性能に対するリガンド構造の影響を理解する.
主な方法:
- ビス ((フェノキシ・イミン) タイタン複合物の合成と特徴付け.
- 様々な条件下でエチレンと5-ヘクセン-1-イルアセテートの共聚合反応.
- NMRスペクトロスコピーやGPCなどの技術を用いた結果のコポリマーの分析.
主要な成果:
- タイタニウム複合物は,エチレンと5-ヘクセン-1-イルアセテートの共ポリメリゼーションを効果的に媒介した.
- フェノキシ部分にオルトフェニルグループの存在は,触媒活性に影響を与えました.
- ポリエチレン鎖に5-ヘクセン-1-イルアセテートを組み込むことが達成されました.
結論:
- ビス ((フェノキシ-イミン) タイタン複合体は,エチレン/機能化されたオレフィン共ポリメリゼーションの活性触媒である.
- リガンドの設計,特にオルトフェニル置換は,触媒の性能に役割を果たします.
- これらの発見は,新しい機能的なポリオレフィンを作るための道を開きます.
関連する概念動画
01:17Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
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...
01:28Stability of Conjugated Dienes
Introduction
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
01:26Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
01:16Structure of Conjugated Dienes
Introduction
Conjugated dienes are compounds characterized by the presence of alternating double and single bonds. In a conjugated system like 1,3-butadiene, the unhybridized 2p orbital on each carbon overlaps continuously, allowing the π electrons to be delocalized across the entire molecule. In contrast, this type of overlap does not occur in cumulated and isolated dienes, such as 2,3-pentadiene and 1,4-pentadiene, respectively. Instead, the π electrons remain localized between the double...
Conjugated dienes are compounds characterized by the presence of alternating double and single bonds. In a conjugated system like 1,3-butadiene, the unhybridized 2p orbital on each carbon overlaps continuously, allowing the π electrons to be delocalized across the entire molecule. In contrast, this type of overlap does not occur in cumulated and isolated dienes, such as 2,3-pentadiene and 1,4-pentadiene, respectively. Instead, the π electrons remain localized between the double...