title: Synthesis and Reduction Kinetics of Five Ibuprofen-Nitroxides for Ascorbic Acid and Methyl Radicals.
abstract: The hybrid compounds 1-5 comprised of five nitroxides with ibuprofen were synthesized and their reduction rate for ascorbic acid (AsA) and methyl radicals were measured in comparison with 3-hydroxy-tetramethylpyrrolidine-1-oxyl (PROXYL) 6. The rate constants in reduction reaction with 200-fold excess of AsA were determined in following order: 1 (0.42±0.06), 3 (0.17±0.06), 2 (0.10±0.05), and 6 (0.09±0.02 M-1s-1). The remaining two sterically shielded nitroxides 4 and 5 scarcely reacted with AsA. In the reaction with the more reactive methyl radicals, produced by 200-fold excess of Fenton's reagent, the reduction rates of 2, 4, and 5 were in the following decreasing order: 2 (1.1±0.2), 4 (0.76±0.09), and 5 (0.31±0.03 M-1s-1).
authors.affiliation: Graduate School of Science and Engineering, Yamagata University.
authors.forename: Kota
authors.initials: K
authors.lastname: Sasaki
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Ito
authors.forename: Hirotada G
authors.initials: HG
authors.lastname: Fujii
authors.forename: Shingo
authors.initials: S
authors.lastname: Sato
mesh_terms: D001205:Ascorbic Acid / Q000138:chemical synthesis* / Q000737:chemistry; D005609:Free Radicals / Q000138:chemical synthesis / Q000737:chemistry; D007052:Ibuprofen / Q000737:chemistry*; D007700:Kinetics; D015394:Molecular Structure; D009589:Nitrogen Oxides / Q000138:chemical synthesis / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D005609:Free Radicals; D009589:Nitrogen Oxides; D001205:Ascorbic Acid; D007052:Ibuprofen