Estimation of Phosphate Ester Hydrolysis Rate Constants. I. Alkaline Hydrolysis

SPARC (SPARC Performs Automated Reasoning in Chemistry) chemical reactivity models were extended to allow the calculation of alkaline hydrolysis rate constants of phosphate esters in water. The rate is calculated from the energy difference between the initial and transition states of a molecule. This difference is a function of the reference rate and internal and external perturbations to the reference rate. The internal perturbations are comprised of electrostatic and resonance effects. The external perturbations quantify solute-solvent interactions based on the dielectric constant of the solvent and the steric effect of substituent groups. These perturbation models have been tested using 225 reliably measured second order hydrolysis rate constants over a variety of temperatures. The RMS deviation of the calculated versus observed values was 0.401 log M -1 s -1 .