Dissociation energies of O-H bonds in natural antioxidants

The dissociation energies of O-H bonds in natural antioxidants were estimated from the kinetic data (rate constants of reactions of the antioxidants with the peroxy radicals). The calculations were performed using the method of intersecting parabolas. alpha-Tocopherol was used as a reference phenol with D (O-H) = 330 kJ mol(-1). The following groups of antioxidants were chosen for the estimation: tocopherols, their sulfur- and selenium-containing analogs, flavones, flavanones, and gallates. The discrepancy in the D (O-H) values for the same phenol by measurements of k(RO2 (center dot) + ArOH) of different authors does not exceed 2 kJ mol(-1). The D (O-H) values were calculated for 64 phenols.