AcidBase Properties of Adenosine 5′‐Monophosphate, Guanosine 5′‐Monophosphate, and Inosine 5′‐Monophosphate in Aqueous Solutions of Methanol

Abstract

AbstractThe protonation constants of adenosine 5′‐monophosphate, guanosine 5′‐monophosphate, and inosine 5′‐monophosphate were determined in binary mixtures of H2O containing 0, 10, 15, 20, 25, 30, 35, 40, 45, and 50% MeOH, using a combination of potentiometric and spectrophotometric methods at a constant temperature (25°) and constant ionic strength (0.1 mol⋅dm−3 NaClO4). The protonation constants were analyzed using the normalized polarity parameter (E$\rm{{_{T}^{N}}}$), and Kamlet, Abboud, and Taft (KAT) parameters. A linear correlation of log K vs. the normalized polarity parameter was obtained. Dual‐parameter correlation of log K vs. π* (dipolarity/polarizability) and α (H‐bond‐donor acidity), as well as π* and β (H‐bond‐acceptor basicity) also gives good results in various aqueous organic solvent mixtures. Finally, the results are discussed in terms of the effect of solvent on the protonation equilibria.