Pd触媒によるエアロビック酸化反応:触媒の寿命を延長する戦略
Wilson C Ho1, Kevin Chung1,2, Andrew J Ingram1,3
1Department of Chemistry, Stanford University , Stanford, California 94305, United States.
Journal of the American Chemical Society
|December 16, 2017
まとめ
パラジウム触媒の前駆者は,アルコールと炭水化物を酸素剤として空気で効果的に酸化する. 低負荷の有酸素酸化を可能にするために,触媒の安定性と効率を高める戦略が開発されました.
科学分野:
- カタリシス
- 有機化学
- 緑の化学
背景:
- パラジウム複合体はアルコール酸化のための効果的な触媒である.
- 末端酸化剤として空気を用いたエアロビック酸化は望ましいが,触媒の安定性に問題がある.
- ネオクープロインなどのリガンドの酸化分解は,高い触媒負荷を必要とします.
研究 の 目的:
- アエロビック酸化のためのパラジウム触媒の前駆体の寿命と効率を改善するための戦略を開発する.
- エロビック酸化中の触媒の無効化のメカニズムを理解する.
- アルコール,ポリオール,炭水化物の高効率な酸化を可能にする.
主な方法:
- パラジウム複合体の合成と応用 [[[ネオクープロイン]]Pd[[μ-OAc]]2[OTf]2.
- ラジカル・オート酸化を含む触媒の非活性化経路を調査するメカニズム研究.
- リガンドの改変と犠牲の水素原子のドナーまたはラジカルスキャバーの追加を実行します.
- 様々な基質の有酸素酸化のための反応条件の最適化.
主要な成果:
- パラジウム複合体は,アルコール,二酸化物,ポリオール,炭水化物の選択的酸化のための効果的な触媒前駆体である.
- アエロビック酸化は,当初,急性自己酸化メカニズムによるネオクープロインリガンドの分解によって制限された.
- リガンドの改変,犠牲のH原子ドナー (例えばベンジル水酸化物) の添加,またはスタイレンにより,触媒の寿命とターンオーバー数 (TON) が著しく改善された.
- ポリオールのアエロビック酸化は,0.25 mol % Pd の負荷で達成された.
結論:
- 開発された戦略は,有酸素酸化触媒の寿命と効率を効果的に高めます.
- 解消メカニズムの理解は,改良された触媒システムの設計に不可欠です.
- この研究は,特にポリオールと炭水化物の低負荷有酸素酸化触媒における重要な進歩を示しています.
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