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A kinetic study of the reactions of sulfate and dihydrogen phosphate radicals with epicatechin, epicatechingallate, and epigalocatechingallate
Author(s) -
Villata Laura S.,
Gonzalez Mónica C.,
Mártire Daniel O.
Publication year - 2010
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/kin.20492
Subject(s) - chemistry , radical , reaction rate constant , photoionization , activation energy , phosphate , sulfate , photochemistry , atmospheric temperature range , kinetics , organic chemistry , ion , ionization , physics , quantum mechanics , meteorology
The bimolecular rate constants for the reactions of sulfate radicals with epicatechin (EC), epicatechingallate (ECG), and epigallocatechingallate (EGCG) were found to be (1.46 ± 0.06) × 10 9 , (1.20 ± 0.08) × 10 9 , and (1.04 ± 0.07) × 10 9 , respectively. The activation energy [E A = 9 ± 3 kJ mol −1 ] and preexponential factor [A = (4.8 ± 0.6) × 10 10 ] for the reaction of EC with the sulfate radical were measured in the temperature range 288–303 K. The phenoxyl radicals of EC (λ max = 310 nm) were obtained both by the reaction of this flavonoid with the sulfate radicals and by photoionization. The measured bimolecular rate constants for the reactions of the dihydrogen phosphate radicals with EC, ECG, and EGCG were (7.8 ± 0.9) × 10 8 , (8.5 ± 0.4) × 10 8 , and (6.8 ± 0.4) × 10 8 , respectively. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 391–396, 2010