含缺陷位TS-1催化氧化噻吩及甲基噻吩反应机理的量子化学研究

用ONIOM2方法 7T/45T模型优化了含缺陷位TS-1分子筛(TS-d)催化氧化噻吩及甲基噻吩各步反应的反应物、过渡态、中间体和产物的结构.我们结合实验数据,得到的路线如下:首先,TS-d吸附H2O2,然后经历质子转移生成单齿或双齿超氧化物中间体.质子转移有两条途径,单质子和双质子转移.研究表明双齿比单齿超氧化物中间体的能量更低,是更稳定的中间体.因此采用双齿中间体继续反应.噻吩和甲基噻吩氧化先形成亚砜,再进一步氧化生成砜.计算数据与实验结果一致.

Quantum Chemical Study on Oxidation of thiophene and methylthiophene over Defect Reaction Mechanism

The oxidative desulfurization of thiophene (Tp) and methylthiophene (mTp) over defect TS-1 (TS-d) catalyst was investigated using 7T/45T two-layered ONIOM2 method. The following oxidation mechanism at TS-d was hypothesized: First, H2O2 adsorbed to TS-d, then underwent proton transfer to generate monodentate titanium hydroperoxo complex. There are two ways to proton transfer, a single proton and double proton transfer. Studies have shown that the isomer of bidentate titanium hy-droperoxo complex is more reactive and slightly more stable. Therefore, the reaction was continued with bidentate titanium hydroperoxo complex. Tp and mTp were oxidized to sulfoxide, and further oxidized to sulfone. The calculated data are consistent with the experimental results.