Computation of relative bond dissociation enthalpies (ΔBDE) of phenolic antioxidants from Quantum Topological Molecular Similarity (QTMS)

A recently proposed method called quantitative topological molecular similarity (QTMS) generated a model for the computation of the relative substituent effects on the bond dissociation enthalpies (ΔBDEs) for a set of 39 phenols. The data set includes a diverse set of substituents with monosubstituted and poly-substituted derivatives that exhibit different electronic and steric effects. Many share common structural features with already well-established antioxidants. QTMS reveals the active region of the substituted phenols and identifies the electronic descriptors that best explain the range of ΔBDEs observed. For substituents in the 4-X position (para) we find that our model requires a correction for radical stabilization enthalpy (RSE). Application of the QTMS methodology yields an unrivalled QSAR with r 2 = 0.98 and q2 = 0.85 for the bond dissociation enthalpies of this phenolic antioxidant data set. © 2006 American Chemical Society.