Correlating Molecular Structures and Properties of Emergin Contaminants with Environmental Fate Models

Abstract

A preliminary analysis of quantitative structure-activity relationships was conducted over six selected compounds: geosmin, 2-methylisoborneol, 2,4-dichlorophenol, acetaminophen, triclosan and atrazine. All six compounds have been widely distributed in the environment and have attracted increasing attention recently. These chemicals are all emerging contaminants likely to come under tighter regulations in the future. Multiple structural, thermodynamic, energy and fate descriptors were examined in regards to their correlations with biodegradation, oxidation and hydrolysis rate constants found for each of these compounds. These descriptors include values such as aqueous solubility, various partition coefficients, Henry's law constant, vapor pressure, enthalpy of vaporization, energy of highest occupied molecular orbital (EHOMO) and energy of lowest unoccupied molecular orbital (ELUMO). Most of these values were found through literature surveys while some were calculated using readily available software. Statistical analysis of the data suggested there are various potential descriptors available to predict the environmental activity of these chemicals. Most notably, the descriptors log octanol-air partition coefficient, EHOMO, ELUMO displayed the highest correlations for the biodegradation rate constant, oxidation rate constant and hydrolysis rate constant, respectively. These correlations can provide the basis for further development of models predicting the fate of these chemicals. Future areas of research might include the use of additional compounds, development of data for a particular measurement from references originating within the same laboratory and using identical measurements, and investigation of other techniques to build quantitative structure-activity relationships (QSARs) models.