フォスフォディエステルに対する核愛性の攻撃の効率的な分子内一般酸触媒
Anthony J Kirby1, Marcelo F Lima, Davi da Silva
1University Chemical Laboratory, University of Cambridge, Cambridge CB2 1EW, U.K.
Journal of the American Chemical Society
|December 21, 2006
まとめ
ディメチルアモニウム触媒は,リン酸エステル水解を100万倍以上加速する. この効率的な一般酸性触媒は,核性分子との反応に不可欠な分子内水素結合により,pHが7まで維持されます.
科学分野:
- 有機化学 オーガニック・ケミストリー
- バイオケミストリー バイオケミストリー
- 化学動力学 化学動力学
背景:
- リン酸エステル水解は,生物学的および化学的なシステムにおいて根本的な役割を果たします.
- 一般的な酸性触媒は,反応速度を大幅に高めることができます.
- 核ファイルの反応性を理解することは,反応結果を予測する鍵です.
研究 の 目的:
- メチル8-ジメチラミノ-1-ナフチルリン酸塩の水解の触媒機構を調査する.
- ダイメチルアモニウム群と分子内水素結合が反応速度に及ぼす影響を決定する.
- この水解反応における様々な核粒子の反応性を調査する.
主な方法:
- pH値の範囲におけるリン酸エステル水解の運動学的研究.
- ヒドロキシラミン誘導体を含む多様な核愛素による反応の調査.
- 機械的な提案を裏付けるために,ab initio計算を用いた計算分析.
主要な成果:
- ディメチルアモニウム触媒は,酸性pHで約10^6の速度加速を達成した.
- 分子内水素結合は,pH 7.まで触媒を保持した.
- 核性基本性は,0.29のブロンステッドベータ (nuc) を示し,これはリン酸エステルの中間値である.
- ハイドロキシラミンは明らかなアルファ効果を示し,特定の反応経路を示唆した.
結論:
- ヌクレオフィルのプロトネーションは,一般の酸触媒化リン酸エステル水解の速度を高めます.
- 分子内水素結合は,持続的な触媒活性に不可欠である.
- ヒドロキシラミンを含む反応機構は,おそらく均衡前のタウトメア経由で進行する.
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