線形ポリマーの自己組み立てとトポロジー変換による選択的サイクルによるサイクリックポリマーへの合理的なエントリー
Daisuke Aoki1, Gouta Aibara1, Satoshi Uchida1
1Department of Chemical Science and Engineering, Tokyo Institute of Technology and ‡JST-CREST, Ookayama, Meguro, Tokyo 152-8552, Japan.
Journal of the American Chemical Society
|April 8, 2017
まとめ
研究者たちは サイクルポリマーを合成する簡単な方法を開発しました この新しいアプローチは独自の自己組み立てプロセスを用いて デイジーチェーンイニシアターを作り,効率的なポリマーサイクリングを可能にします
科学分野:
- ポリマー化学
- 超分子化学
- 有機合成
背景:
- サイクルポリマーには 線形ポリマーと比べて ユニークな特性があります
- サイクルポリマーの効率的かつスケーラブルな合成は,ポリマー科学における課題です.
- 既存の方法はしばしば複雑な手順を伴うか,一般性がない.
研究 の 目的:
- シンプルで効率的でスケーラブルな合成ルートをサイクルポリマーに開発する.
- トポロジーの変換によるサイクルポリマートポロジーの作成のための新しい方法を確立する.
- 新しい合成プロトコルの 汎用性と利点を示すために
主な方法:
- SEC-アンモニアを含むクラウンエーテルモノメアの選択的サイクル化により,デイジーチェーンイニシアターを形成する.
- 線形ポリマーを生成するイニシアターの生体ポリメリゼーション
- 線形ポリマーから周期性ポリマーへのトポロジー変換.
主要な成果:
- 定量的なサイクリングステップは,クラウンエーテル分子の自己組み立てによって達成されました.
- 開発された方法は,線形前駆体からサイクルポリマーを合成することを可能にします.
- グラムスケールの合成は成功裏に実証され,手順の簡素さと濃度の独立性を強調した.
結論:
- サイクルポリマーの新しい効率的な合成戦略が確立されています.
- この方法は,キーセルフアセンブリとトポロジー変換プロセスに依存しています.
- このアプローチは,サイクルポリマー合成のシンプルさとスケーラビリティの点で重要な利点を提供します.
関連する概念動画
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.
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.
01:16Cycloaddition Reactions: Overview
Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.
01:17Radical Chain-Growth Polymerization: Chain Branching
The skeletal structure of polymers synthesized via radical polymerization is always branched. For example, the polymerization of ethylene by radical polymerization results in a low-density grade of polyethylene with a heavily branched skeletal structure. Here, the radical site abstracts hydrogen from the growing chain, and the radical site shifts from the end (a primary carbon center) to anywhere within the growing chain (a secondary carbon center). Consequently, the part of the chain from the...
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...