title: Boosting effect of ortho-propenyl substituent on the antioxidant activity of natural phenols.
abstract: Seven new antioxidants derived from natural or synthetic phenols have been designed as alternatives to BHT and BHA antioxidants. Influence of various substituents at the ortho, meta and para positions of the aromatic core of phenols on the bond dissociation enthalpy of the ArO-H bond was evaluated using a DFT method B3LYP/6-311++G(2d,2p)//B3LYP/6-311G(d,p). This prediction highlighted the ortho-propenyl group as the best substituent to decrease the bond dissociation enthalpy (BDE) value. The rate constants of hydrogen transfer from these phenols to DPPH radical in a non-polar and non-protic solvent have been measured and were found to be in agreement with the BDE calculations. For o-propenyl derivatives from 2-tert-butyl-4-methylphenol, BHA, creosol, isoeugenol and di-o-propenyl p-cresol, fewer radicals were trapped by a single phenol molecule, i.e. a lower stoichiometric number. Reaction mechanisms involving the evolution of the primary phenoxyl radical ArO are proposed to rationalise these effects.
authors.affiliation: Université de Lille, Sciences et Technologies, Unité de Catalyse et de Chimie du Solide - UMR CNRS 8181 Bâtiment C6, F-59655 Villeneuve d'Ascq Cedex, France; International Flavors & Fragrances Research and Development, 61 rue de Villiers, 95253 Neuilly-sur-Seine Cedex, France.
authors.forename: Clémentine
authors.initials: C
authors.lastname: Marteau
authors.affiliation: Université de Lille, Sciences et Technologies, Unité de Catalyse et de Chimie du Solide - UMR CNRS 8181 Bâtiment C6, F-59655 Villeneuve d'Ascq Cedex, France.
authors.forename: Romain
authors.initials: R
authors.lastname: Guitard
authors.affiliation: Université de Lille, Sciences et Technologies, Unité de Catalyse et de Chimie du Solide - UMR CNRS 8181 Bâtiment C6, F-59655 Villeneuve d'Ascq Cedex, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Penverne
authors.affiliation: International Flavors & Fragrances Research and Development, 61 rue de Villiers, 95253 Neuilly-sur-Seine Cedex, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Favier
authors.affiliation: Université de Lille, Sciences et Technologies, Unité de Catalyse et de Chimie du Solide - UMR CNRS 8181 Bâtiment C6, F-59655 Villeneuve d'Ascq Cedex, France. Electronic address: veronique.rataj@univ-lille1.fr.
authors.forename: Véronique
authors.initials: V
authors.lastname: Nardello-Rataj
authors.affiliation: Université de Lille, Sciences et Technologies, Unité de Catalyse et de Chimie du Solide - UMR CNRS 8181 Bâtiment C6, F-59655 Villeneuve d'Ascq Cedex, France. Electronic address: jean-marie.aubry@univ-lille1.fr.
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Aubry
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D002084:Butylated Hydroxytoluene / Q000031:analogs & derivatives / Q000737:chemistry; D005054:Eugenol / Q000031:analogs & derivatives / Q000737:chemistry; D006860:Hydrogen Bonding; D010636:Phenols / Q000737:chemistry*; D012997:Solvents; D013816:Thermodynamics
chemical_list: D000975:Antioxidants; D010636:Phenols; D012997:Solvents; D002084:Butylated Hydroxytoluene; C042329:phenoxy radical; D005054:Eugenol; C036643:isoeugenol; C054527:2-tert-butyl-4-methylphenol
keywords: Antioxidant; Autoxidation; BDE; DPPH radical; Phenol; ortho-Propenyl group