Organic Qsar And Applied Research

Quantitative structure-property/activity relationship(QSPR/QSAR) has been an important method for environmental risk assessments of chemicals. In this thesis, the study that QSPR/QSAR is used to assess the environmental behavior and ecological effect of organic chemicals was presented including both the theory and the application. The main content was concluded as follows:A new approach was proposed to quantify the Lewis acidity and basicity of organic chemicals. The logarithm difference values of partition coefficients of the compounds in butyl ether/water and in cyclohexane/water system were used for the measurement of the Lewis acidity, while the logarithm difference values of partition coefficients in trichloromethane/water and in tetrachloromethane/water system were used for the measurement of the Lewis basicity, and they were used successfully to differentiate the relative strength of Lewis acidity and basicity for 59 benzene and its derivates. Furthermore, they were introduced into QSPR/QSAR to study the relationship between the n-octanol/water partition coefficients, the water solubilities and the organic carbon-based sorption coefficients and their Lewis acidity and basicity for benzene and its derivates, which gave a good result.Hydrogen-bond donor acidity is an important parameter for the linear sorvation energy relationship (LSER) method, and is difficult to be obtained. According to the principle for the quantification of the Lewis acidity, a new method to estimate the solute hydrogen-bond donor acidity was proposed based on the conclusion that the solute Lewis acidity is mainly correlated with its hydrogen-bond donor acidity, and used successfully to estimate the hydrogen-bond acidity of 41 substituted aromatic compounds. This approch may extend the application of the LSER method.The water solubilities, the n-octanol/water partition coefficients and the organic carbon-based sorption coefficients of 18 phenylthiocarboxylates were determined by the shake method for the first time. Several QSPR equations were given by LSER method, which give a quantitative description for the domanint factors for these partition properties and is used successfully to predict the partition properties of some unknown phenylthiocarboxylatyes.The toxicity of 18 phenylthiocarboxylates was assessed by applying luminescent bacteria toxictiy test, and a corresponding classification method was given for these phenylthiocarboxylates. Hansch method was used to explain the toxicty, it concluded that hydrophobic and electron effect played an important rolein the toxicity. Furthermore, the relationship between the toxicty of these phenylthio-carboxylates and their molecular connectivity indices was established, which gave a simple and fast estiamtion method to assess the toxicity of phenykhiiocarboxylates.Based on toxicity mechanism, a QSAR model was established and used to explain the toxicity of organic chemicals to fathead minnow and Photobacterium phosphoreum, which showed good relationships with wide range of organic compounds.Based on root elongation method, a new test system using Cabbage seed was proposed to evaluate the toxicity of organic chemicals on higher plants. The toxictity of 14 substituted aromatic compounds on Cabbage seed were determined, and were analysed by several common QSAR methods, which showed that hydrophobic and electron effect played an important role in the toxicity of organic chemicals on higher plants as did in the toxicity on animals.Based on LSER method, the relationship between the acute toxicity of 26 substituted aromatic compounds on Photobacterium phosphoreum, Daphnia magna and fathead minnow and their theoritical sorvatochromic parameters , the high correlation were found, it provided an example to introduce the quantum chemical parameters into QSAR study.The hydrolysis of 10 phenylthiocarboxylates was studied in detail by HPLC under the experimental condition. We determined 50 hydrolysis rate constants and discussed the effects of pH, temperature on hydrolysis, which showed that base catalyzed hydrolysis of phenylthiocarboxylates would be a main degradation pathway under the environmental conditions. -The sorption of 35 substituted aromatic compounds and 8 phenylthiocarboxylates on natural soils was studied in detail, which showed that the sorption of organic chemicals on soils consisted of two contributions: a linear partition in soil organic matter and a nonlinear residual adsorption on soil minerals. Partition would often dominate the sorption process of organic chemicals at moderate to high relative concentrations because of their unfavorable competitive adsorption on polar minieral surfaces, and follow sorption partition theory, while for some polar compounds, both partition and residual adsorption may dominate the sorption process at low relative concentrations and give a nonlinear sorption isotherm..