Theoretical Study on the Selective Redox Mechanism of Benzaldehyde in Photo-catalyzed Reaction

作者：Huang Xiao; Gan Hanlin; Peng Liang^*; Gu Fenglong^*

来源：Chemical Journal of Chinese Universities, 2016, 37(2): 297-305.

DOI：10.7503/cjeu20150719

• Benzaldehyde
• Photocatalysis
• Mechanism of selective redox reaction
• Density functional theory

The photoelectron and photohole could be generated on the surface of TiO2 under the UV irradiation. Some reactive species could be produced indirectly. The photoelectron could be trapped by oxygen leading to yield the superoxide anion radicals, while the photohole can react with the solvent molecules to generate the hydroxyl radical and alcohol radical. The substrate may be reduced by the photoelectron directly, or by alcohol radicals. And it may be oxidized by the photohole directly, or by the reactive species of hydroxyl radicals and superoxide anion radicals. The M06-2X/6-311G* method was employed to investigate the selective redox mechanism of benzaldehyde in solution, which was reduced or oxidized by the reactive species generated during the photo-catalyzed process in different reaction conditions. According to the computation results, the photo-redox reaction of benzaldehyde would be happened in room temperature. In oxygen-free ethanol solvent, the ethanol molecules could react with the oxidizing species to yield the alcohol radicals, while benzaldehyde could be mainly reduced to benzyl alcohol. In oxygen-rich without ethanol condition, the reductive photoelectron is trapped by oxygen to prohibit the reduction of benzaldehyde, so benzaldehyde is mainly oxidized to benzoic acid.

• 单位
  华南师范大学