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Kinetics and mechanism of oxidation of aspirin by bromamine‐T, N ‐bromosuccinimide, and N ‐bromophthalimide
Author(s) -
Ramachandrappa R.,
Mayanna S. M.,
Made Gowda N. M.
Publication year - 1998
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/(sici)1097-4601(1998)30:6<407::aid-kin2>3.0.co;2-w
Subject(s) - chemistry , perchloric acid , n bromosuccinimide , oxidizing agent , decarboxylation , reaction rate constant , kinetics , ionic strength , reaction rate , acetic acid , aqueous solution , reaction mechanism , inorganic chemistry , medicinal chemistry , halogenation , catalysis , organic chemistry , quantum mechanics , physics
The kinetics of the oxidation of aspirin (ASP) by bromamine‐T (BAT), N ‐bromosuccinimide (NBS), and N ‐bromophthalimide (NBP) has been studied in aqueous perchloric acid at 303 K. The oxidation reaction follows identical kinetics with first‐order in [oxidant], fractional‐order in [ASP], and inverse fractional‐order in [H + ]. Under identical experimental conditions the extent of oxidation with different oxidizing agents is in the order: NBS>BAT>NBP. The rate decreased with decreasing dielectric constant of the medium. The variation of ionic strength and the addition of the reaction products and halide ions had no significant effect on the reaction rate. The solvent isotope effect was studied using D 2 O. Kinetic parameters were evaluated by studying the reaction at different temperatures. The reaction products were identified by GC–MS. The proposed reaction mechanism and the derived rate law are consistent with the observed kinetic data. Formation and decomposition constants for ASP‐oxidant complexes have been evaluated. Decarboxylation, bromination, and loss of acetic acid gave 2,4,6‐tribromophenol. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 407–414, 1998