Document Detail


Theoretical and experimental investigation on the oxidation of gallic acid by sulfate radical anions.
MedLine Citation:
PMID:  18211035     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Abstract/OtherAbstract:
By monitoring the decay of SO4*- after flash photolysis of aqueous solutions of S2O82- at different pH values, the kinetics of the reaction of SO4*- radicals with gallic acid and the gallate ion was investigated. The bimolecular rate constants for the reactions of the sulfate radicals with gallic acid and the gallate ion were found to be (6.3 +/- 0.7) x 10(8) and (2.9 +/- 0.2) x 10(9) M(-1) s(-1), respectively. On the basis of the oxygen-independent second-order decay kinetics and on their absorption spectra, the organic radicals formed as intermediates of these reactions were assigned to the corresponding phenoxyl radicals. DFT calculations in the gas phase and aqueous solution support formation of the phenoxyl radicals by H abstraction from the phenols to the sulfate radical anion. The observed recombination of the phenoxyl radicals of gallic acid to yield substituted biphenyls and quinones is also supported by the calculations. HPLC/MS product analysis showed formation of one of the predicted quinones.
Authors:
Paula Caregnato; Pedro M David Gara; Gabriela N Bosio; Mónica C Gonzalez; Nino Russo; María Del Carmen Michelini; Daniel O Martire
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Publication Detail:
Type:  Journal Article     Date:  2008-01-23
Journal Detail:
Title:  The journal of physical chemistry. A     Volume:  112     ISSN:  1089-5639     ISO Abbreviation:  J Phys Chem A     Publication Date:  2008 Feb 
Date Detail:
Created Date:  2008-02-08     Completed Date:  2008-04-11     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9890903     Medline TA:  J Phys Chem A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1188-94     Citation Subset:  -    
Affiliation:
Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina.
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