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Determination of the substituent effect on the O-H bond dissociation enthalpies of phenolic antioxidants by the EPR radical equilibration technique.
MedLine Citation:
PMID:  12098294     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Abstract/OtherAbstract:
The bond dissociation enthalpies (BDE) of several phenols containing electron-withdrawing substituents in the para position have been determined by means of the EPR radical equilibration technique. It has been found that CN, NO(2), CHO, COOR, and COOH induce an increase of the BDE value of the O-H bond, thus producing a worsening of the antioxidant activity of phenols, while Cl, Ph, and CH[double bond]CHPh show an opposite effect. The contributions of these substituents for the calculation of the BDE values in polysubstituted phenols by using the group additivity rule have also been derived. It is shown that this rule provides quite reliable predictions of bond strengths, so that the method can be conveniently used to estimate new data on substituted phenols.
Authors:
Giovanni Brigati; Marco Lucarini; Veronica Mugnaini; Gian Franco Pedulli
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of organic chemistry     Volume:  67     ISSN:  0022-3263     ISO Abbreviation:  J. Org. Chem.     Publication Date:  2002 Jul 
Date Detail:
Created Date:  2002-07-05     Completed Date:  2003-01-16     Revised Date:  2003-11-03    
Medline Journal Info:
Nlm Unique ID:  2985193R     Medline TA:  J Org Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4828-32     Citation Subset:  -    
Affiliation:
Dipartimento di Chimica Organica A. Mangini, Università di Bologna, Via S. Donato 15, I-40127 Bologna, Italy.
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