### Mechanism of IBU damage induced by hydroxyl free radicals extracting P-isopropyl phenyl-H in water/liquid phase environment

LI Bing1, ZHUANG Yan2, WU Zihao3, MA Hongyuan4, PAN Yu4, MEI Zemin4, WANG Zuocheng4

1. 1. College of Mechanical Engineering, Baicheng Normal University, Baicheng 137000, China；
2. Computer Science College, Baicheng Normal University, Baicheng 137000, China；
3. School of Environment, Sun Yat-sen University, Guangzhou 510257, China；
4. College of Physics, Baicheng Normal University, Baicheng 137000, China
• Received:2019-12-11 Online:2020-07-25 Published:2020-07-25

Abstract: The title reaction was investigated in this paper. The dispersion corrected density functional method (WB97X-D) was applied, together with perturbation theory (MP2 method) and solvation model density (SMD) model based on self consistent reaction field theory. The study showed that benzene ring-H, methylene-H and methenyl-H abstraction by hydroxyl radicals can all induce ibuprofen molecule damage. The calculation of potential energy surface showed that the energy barrier of benzene ring-H abstraction by hydroxyl radicals at different positions was nearly the same with the values of ~123.0 kJ/mol, and the damaged ibuprofen molecule could be repaired. The energy barrier of methylene-H abstraction of hydroxyl radicals at different positions was almost the same, ~100.0 kJ/mol, and the damaged ibuprofen molecule was difficult to be repaired. Furthermore, the energy barrier of methenyl-H abstraction by hydroxyl radicals was 68.4 kJ/mol, and the damaged ibuprofen molecule cannot be repaired. The results showed that the reaction of ibuprofen molecule damage induced by methylene-H abstraction by hydroxyl radicals had an absolute advantage.

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