tailieunhanh - PREDICTION OF CHEMICAL REACTIVITY PARAMETERS AND PHYSICAL PROPERTIES OF ORGANIC COMPOUNDS FROM MOLECULAR STRUCTURE USING SPARC

Soil reactivity with chemical oxidants is also important when considering the costs of the use of chemical oxidation. Excessive loss of a chemical oxidant that is reacting with organics in soil, instead of reacting with the contaminants, may preclude the use of the technology as an economically viable approach to site remediation. Different chemical oxidation technologies are most appropriate for particular hydrogeologic conditions. For example, Fenton’s Reagant may not be ideal for groundwater with high concentrations of carbonate. The carbonate ion preferentially scavenges the hydroxyl radicals created by Fenton’s Reagant reactions before they have a chance to react with the petroleum contaminants. By contrast, the presence. | EPA 600 R-03 030 March 2003 PREDICTION OF CHEMICAL REACTIVITY PARAMETERS AND PHYSICAL PROPERTIES OF ORGANIC COMPOUNDS FROM MOLECULAR STRUCTURE USING SPARC By . Hilal and . Karickhoff Ecosystems Research Division Athens Georgia and . Carreira Department of Chemisty University of Georgia Athens GA National Exposure Research Laboratory Office of Research and Development . Environmental Protection Agency Research Triangle Park NC 27711 DISCLAIMER The United States Environmental Protection Agency through its Office of Research and Development partially funded and collaborated in the research described here under assistance agreement number 822999010 to the University of Georgia. It has been subjected to the Agency peer and administration review process and approved for publication as an EPA document. ABSTRACT The computer program SPARC SPARC Performs Automated Reasoning in Chemistry has been under development for several years to estimate physical properties and chemical reactivity parameters of organic compounds strictly from molecular structure. SPARC uses computational algorithms based on fundamental chemical structure theory to estimate a variety of reactivity parameters. Resonance models were developed and calibrated on more than 5000 light absorption spectra whereas electrostatic interaction models were developed using more than 4500 ionization pKas in water. Solvation models . dispersion induction dipole-dipole hydrogen bonding etc. have been developed using more than 8000 physical property data points on properties such as vapor pressure boiling point solubility Henry s constant GC retention times Kow etc. At the present time SPARC predicts ionization pKa in the gas phase and in many organic solvents including water as function of temperature carboxylic acid ester hydrolysis rate constants as function of solvent and temperature E1 2 reduction potential as function of solvents pH and temperature gas phase electron affinity and numerous physical .