The solvent effect on the enthalpy of hydrolysis of cyclic adenosine 3′,5′‐monophosphate. A quantumchemical study

Abstract

AbstractThe solvent effect on the enthalpy of hydrolysis has been studied by the Extended‐Hückel method for the hydrolysis reactions of cyclic adenosine 3′,5′‐monophosphate (cyclic 3′,5′‐AMP) and related cyclic phosphate diesters. The results show that the difference in enthalpy of hydrolysis between cyclic 3′,5′‐AMP and related phosphate diesters is explained by the difference in net solvation enthalpy. The larger exothermic net solvation enthalpy of cyclic 3′,5′‐AMP can be ascribed to an extra stabilization of the hydrolysis product with respect to the reactants, which does not occur for the other cyclic phosphate diesters. The extra stabilization is due to hydrogen bonding with water between O(1′) and O(5′) in both adenosine 5′ ‐ and 3′‐monophosphate.