O2およびH2Oとラベル付けされた酸素-18を用いた水溶液中のTiO2-光触媒性アリル環開き機構の決定
Xibin Pang1, Wei Chang, Chuncheng Chen
1Beijing National Laboratory for Molecular Sciences, Key Laboratory of Photochemistry, Institute of Chemistry, The Chinese Academy of Sciences , Beijing 100190, China.
Journal of the American Chemical Society
|May 23, 2014
まとめ
分子酸素 (O2) は,TiO2光触媒における芳香C-C結合を直接割って,単一の酸素原子を挿入します. この発見は,アロマティック汚染物質の分解メカニズムを明確にします.
科学分野:
- 環境化学 環境化学
- フォトカタリシスによる.
- 有機化学 オーガニック・ケミストリー
背景:
- 芳香C-C結合の分裂は,TiO2光触媒による芳香汚染物質の分解に不可欠である.
- この過程におけるO2とH2Oの正確な役割は,複雑な中間物質と限られた反応モデルのため,不明のままである.
研究 の 目的:
- アロマティック sp ((2) C-C 結合のTiO2光触媒分裂における分子酸素 (O2) と水 (H2O) の正確な役割を解明する.
- アロマティックリングの開きに関与する主要な中間産物と反応機構を特定する.
主な方法:
- O2とH2Oの両方の酸素-18同位体ラベルを使用しました.
- 3,5-di-tert-butylcatechol (DTBC) の光触媒分解を,アセトニトリル溶液中のTiO2を用いて研究した.
- 主要な中間製品の構造を分析し,具体的には7つ組の環無水化物を分析した.
主要な成果:
- O2から1つの酸素原子を芳香C-C結合に挿入し,O2を直接環開き剤として特定した直接的な証拠を提供した.
- リング開きメカニズムは,以前に提案されたO2.2の1,2添加ではなく,単一のO原子の組み込みを含むことが実証されました.
- イントラディオールとエクストラディオール製品の比率は,TiO2触媒の粒子の大きさによって影響され,O2活性化部位と表面調整部位との相関関係を示すことが観察されました.
結論:
- 分子酸素 (O2) は,TiO2光触媒における芳香環の割れ分を決定する決定的な要因である.
- このメカニズムは,O2から単一のO原子を組み込むことで,以前の仮説を明らかにします.
- 粒子の大きさや表面調整部位などのTiO2触媒の性質は,O2の活性化とそれに続く分解経路に大きな影響を与えます.
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