You are here:
ESTIMATION OF CARBOXYLIC ACID ESTER HYDROLYSIS RATE CONSTANTS
Citation:
Hilal, S H., S W. Karickhoff, L. A. Carreira, AND B. P. Shrestha. ESTIMATION OF CARBOXYLIC ACID ESTER HYDROLYSIS RATE CONSTANTS. QSAR & COMBINATORIAL SCIENCE 22(9/10):917-925, (2004).
Impact/Purpose:
Elucidate and model the underlying processes (physical, chemical, enzymatic, biological, and geochemical) that describe the species-specific transformation and transport of organic contaminants and nutrients in environmental and biological systems. Develop and integrate chemical behavior parameterization models (e.g., SPARC), chemical-process models, and ecosystem-characterization models into reactive-transport models.
Description:
SPARC chemical reactivity models were extended to calculate hydrolysis rate constants for carboxylic acid esters 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 and are factored into H-bonding, field stabilization and steric effects. These models have been tested using 1471 measured hydrolysis rate constants in water and mixed-solvent systems at different temperatures. The aggregate RMS deviation of the calculated versus observed values was 0.374 M(-1)s(-1); close to the intralaboratory experimental error.