SPARC (SPARC Performs Automated Reasoning in Chemistry) chemical reactivity models were extended to calculate hydrolysis rate constants for carboxylic acid ester and phosphate ester compounds in aqueous non- aqueous and systems strictly from molecular structure. The energy differences between the initial state and the transition state for a molecule of interest are factored into internal and external mechanistic perturbation components. The internal perturbations quantify the interactions of the appended perturber (P) with the reaction center (C). These internal perturbations are factored into SPARC's mechanistic components of electrostatic and resonance effects. External perturbations quantify the solute-solvent interactions (solvation energy) and are factored into H-bonding, field stabilization and steric effects. These models have been tested using 1471 reliable measured base, acid and general base-catalyzed carboxylic acid ester hydrolysis rate constants in water and in mixed solvent systems at different temperatures.