Antioxidant activity and pKa calculations of 4‑mercaptostilbene and some derivatives: A theoretical approach

Abstract The radicals scavenging activity of some mercaptostilbenes and their hydroxyl analogs were investigated with the density functional theory method. The HAT, SET–PT and SPLET mechanisms were studied in vacuum and some solvents and the BDE, AIP, PDE, PA, ETE were calculated. The SPLET process represents the most thermodynamically preferred reaction pathway in water and methanol, however, the HAT mechanism is preferred in both benzene and vacuum. The SET–PT mechanism is not preferred in all media studied, because AIP values are higher than BDE and PA values. The pKa values of the studied compounds were calculated. The results revealed that the acidity of the mercaptostilbenes was higher than those of the hydroxy analogs in all models studied, as was also indicated in experimental works. These results also can be used for both food and pharmaceutical industries.