Thermodynamic and kinetic study of ibuprofen with hydroxyl radical: A density functional theory approach |
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| Authors: | Ruiyang Xiao Matthew Noerpel Hoi Ling Luk Zongsu Wei Richard Spinney |
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| Affiliation: | 1. Department of Civil, Environmental, and Geodetic Engineering, The Ohio State University, , Columbus, Ohio, 43210;2. Department of Chemistry and Biochemistry, The Ohio State University, , Columbus, Ohio, 43210 |
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| Abstract: | Ibuprofen, a frequently detected pharmaceutical in natural and engineered waters, was studied in both neutral and anionic forms using density functional theory at the B3LYP/6‐311++G**//B3LYP/6‐31G* level of theory in its reaction with hydroxyl radical ( ? OH). The reaction pathways included ? OH addition to aromatic ring, abstraction of a H‐atom, and nucleophilic attack on the carbonyl group. The results showed that H‐atom abstraction pathways are the most favorable. The free energy change for H‐atom abstraction reaction ranges from ?37.8 to ?15.9 kcal/mol; for ? OH addition ranges from ?3.85 to ?1.23 kcal/mol; and for nucleophilic attack on the carbonyl group is 13.9 kcal/mol. The calculated rate constant between neutral ibuprofen and ? OH, 6.72 × 109 M?1s?1, is consistent with the experimental value, 6.5 ± 0.2 × 109 M?1s?1. Our results provide direct evidence for byproduct formation and identification on the molecular level. © 2013 Wiley Periodicals, Inc. |
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| Keywords: | ibuprofen ibuprofen anion hydroxyl radical density functional theory H‐atom abstraction thermodynamic and kinetic study |
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