Paul Seybold, Ph.D. (Advisor); Eric Fossum, Ph.D. (Committee Member); David Dolson, Ph.D. (Committee Member)
Master of Science (MS)
Acid dissociation constants, often expressed as pKa values, afford vital information with regards to molecular behavior in various environments and are of significance in fields of organic, inorganic, and medicinal chemistry. Several quantitative structure-activity relationships (QSARs) were developed that correlate experimental pKas for a given class of compounds with a descriptor(s) calculated using density functional theory at the B3LYP/6-31+G** level utilizing the CPCM solvent model. A set of carbon acids provided a good final QSAR model of experimental aqueous pKas versus ΔEH2O (R2 = 0.9647) upon removal of three aldehydes as outliers. A study of saturated alcohols offered a final QSAR model with R2 = 0.9594, which was employed to confirm the behavior of the three aldehydes as hydrated species in aqueous solution. Finally, a study restricted to ketones was conducted to estimate their pKas in dimethyl sulfoxide solution. QSAR models of experimental pKas versus ΔEDMSO for the keto and enol tautomers were modest at best (R2 = 0.8477 and 0.7694, respectively). A binary linear regression was employed to incorporate descriptors representing both the keto and enol tautomers, improving the final R2 to 0.9670 upon removal of one outlier. The QSAR models presented may be utilized to estimate pKas for related compounds not offered in the existing literature or that are challenging to measure experimentally.
Year Degree Awarded
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