Abstract

In the present work we have studied photo-induced decomposition of iprodione on silica support with different additions of titanium dioxide. Both the experimental and theoretical (DFT) approaches have been applied. It was found that 16 hours visible light exposure of the samples with 0.1% and 1.0% of TiO₂ leads respectively to 48.28% and 21.05% of residual amounts of iprodione in these samples. A number of intermediates and end products were identified by means of GS-MS and LC-MS chromatography. The iprodione isomer (RP 30228) and its decay product 1-(3,5-dichlorophenyl)-5-isopropyl biuret (RP 36221) were identified among them. Our DFT calculations have revealed the detailed mechanisms of formation of the above products and the mechanism of accelerated proton-induced decomposition of iprodione molecules adsorbed on the TiO₂ surface. Also, the intra-molecular reasons for iprodione stability in acidic media were clarified together with the mechanism of hydantoin cycle opening under the action of hydroxyl anions.

摘要

在目前的工作中，我们研究了在二氧化硅载体上添加不同量的二氧化钛对异丙苯酮的光诱导分解。实验和理论（DFT）方法都已应用。发现用0.1％和1.0％的TiO ₂的样品的16小时可见光曝光。分别导致这些样品中异丙洛酮残留量的48.28％和21.05％。通过GS-MS和LC-MS色谱法鉴定了许多中间体和终产物。在其中鉴定出了异丙二酮异构体（RP 30228）及其衰变产物1-（3,5-二氯苯基）-5-异丙基缩二脲（RP 36221）。我们的DFT计算揭示了上述产物的形成的详细机理，以及质子诱导的吸附在TiO ₂表面上的异丙二酮分子加速质子分解的机理。另外，阐明了异丙醇在酸性介质中稳定性的分子内原因以及在羟基阴离子的作用下乙内酰脲循环开放的机理。