Quantum chemical studies on protonation of some substituted thiazole derivatives

The acidity constants, pKa values for protonation of some substituted thiazole derivatives were calculated by using AM1 and PM3 basis sets of semi-empirical methods and B3LYP/6-31G(d) basis sets of density functional theory (DFT) calculated physical and thermodynamic parameters. Correlation search among the experimental and calculated acidity constants, pKa values, revealed that the best correlation exist between the experimental and ab initio calculated pKa values with a regression of R2 = 0.98.