SOMO-HOMO変換によるディストニックラジカルアニオン化:溶液中の実験試験で,EPRのラジカル均衡技術による
Paola Franchi1, Elisabetta Mezzina, Marco Lucarini
1Department of Chemistry "G. Ciamician", University of Bologna , Via San Giacomo 11, I-40126 Bologna, Italy.
Journal of the American Chemical Society
|January 14, 2014
まとめ
溶液中のヒドロキシラミンに対する結合解離エネルギーが測定されました. 研究では,溶媒の極性により,電荷とラジカルとの間の安定作用が排除され,理論的な予測と一致することがわかった.
科学分野:
- 物理化学 物理化学
- 有機化学 オーガニック・ケミストリー
- スペクトロスコーピーは,スペクトロスコーピーを用います.
背景:
- ヒドロキシラミンは,様々な化学反応における重要な中間物質です.
- 4-carboxy-TEMPOは,スピンラベルと抗酸化剤として使用される安定したニトロキシル基です.
- 結合解離エネルギー (BDE) を理解することは,反応性と安定性を予測する鍵です.
研究 の 目的:
- 溶液中の4-カルボキシ-TEMPOから派生したヒドロキシアミンのO-H結合解離エネルギー (BDE) を測定する.
- 遠隔電荷と安定基間の安定化相互作用に対する溶媒の極性の影響を調査する.
- 実験結果と,異なる段階におけるこれらの相互作用に関する理論的予測を比較する.
主な方法:
- 電子パラマグネティック共振 (EPR) のラジカル均衡技術を使用して,BDEを決定しました.
- 極性溶媒での実験:アセトニトリルとジメチル硫酸化物.
- 4-カルボキシ-テンポ誘導体の中性および脱プロトンの両方の形態の振る舞いを分析しました.
主要な成果:
- 実験的なBDEは,研究されたヒドロキシラミンにおけるO-H結合の測定に成功しました.
- 極性溶媒 (アセトニトリル,DMSO) の存在は,激素の安定化に大きく影響した.
- 遠隔の負の電荷と安定基間の安定相互作用の完全な喪失が溶液で観察されました.
結論:
- 安定したラジカルに対する遠隔負の電荷の安定効果は,ガス相で観察され,極性溶媒では減少します.
- 実験結果は,極性媒体におけるこれらの相互作用の喪失を予測する理論的計算を裏付けている.
- 溶媒効果は,根性種の電子特性と反応性を調節する上で重要な役割を果たします.
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