Quantitative Correlations for the Estimation of Thermodynamic and Molecular Properties of Pyridines and 2,2′-Bipyridyines

Abstract

Standard heats of formation, entropies, ionization potentials, and molecular dipole moments of a series of pyridines have been calculated by MNDO, AM1 and PM3 methods. Linear relationship have been established which permit a priori estimation of thermodynamic and molecular characteristics of pyridines. Correlation have been found between the values of pK a for 2,2'-bipyridines for aqueous solutions and their gas phase proton affinities.

10.1007/s11178-008-1006-y

“…In the recent years, considerable progress was achieved in the calculations of acidity parameters (such as proton affinity ΔH H and basicity ΔG) of molecules of many organic compounds in the gas phase [21,[25][26][27][28][29]. Therefore, it became possible to draw reliable relations between ΔH H and structural parameters [31][32][33]36] or other properties [27,28,[30][31][32][33][34][35][36][37] and describe competing protonation processes involving multicenter molecules [27,28,34,35] and gas-phase tautomeric protontransfer equilibria [34,37]. In the past 5 years, the error in the calculation of the above acidity parameters for the gas phase was smaller than 1% [25,30,41,44].…”