Study On The Solubility In Water And N Octanol/Water Partation Coefficients Of Phenol Compounds

As widely used in the chemical industry, phenol compounds have become the main organic pollutants in nature water. The evaluation of environmental hazards and human health hazard of such compounds is necessary. As the two most important physical-chemical properties of organic substances, aqueous solubility and n-octanol/water partition coefficient (logKow) are essential for evaluating the safety of organic pollutants and are the hotspot in the environment. Experiment and theoretical calculation can be used in study the water solubility and logKow of phenol compounds. This can provide property data for evaluating the enviromental performance of phenol compounds and accumulate experience for stuty the property parameters of organic pollutants in the theory.Both the experimental and theoretical calculation methods have been used to study the water solubility and logKow of phenol compounds in this work.Using the flask method, the water solubility of five kinds of phenol compounds were determined separately during the temperature rang of 17~41℃. The results showed that the water solubility of the selected compounds all increased with the temperature, but the trend varied.To obtain the relationship equation between the water solubility and temperature, the experimental solubility data were correlated by ideal solution model, three parameter equation, polynomial equation andλH equation. The correlation effects of different models were investigated. To some systems, there are larger fitting error with the polynomial equation andλH equation. After a slight improvement, good correlation results can be obtained. The results showed that four equations can all give good agreement with experimental data. The fitting error obtained by improved polynomial equation was smallest, the average relatively error was only 1.75%.To predict the water solubility of phenol compounds in the theory, the structure and thermodynamic parameters of fifty kinds of phenol compounds were obtained by using density functional theory (DFT) at the level of B3LYP/6-31G(d, p). The relationship models between the water solubility (-logx) and the parameters were established. The correlation coefficients (R2) and the leave-one-out cross validated correlation coefficients (q2) were 0.955and 0.945, respectively. The model had better fitting ability and internal predictive ability.The logKow of six kind of phenol compounds were determined by the shake-flask method and R-HPLC methods. The results of the shake-flask method were more accurate, but the R-HPLC was much simpler. The logKow of some phenol compounds at different temperatures and different aqueous pH conditions were measured. The results showed that the logKow values did not change significantly at the range of 20~50℃, and with the pH value increasing, the logKow of some compounds decreased, but the other had no significant change.The HF and B3LYP in DFT methods and two basis sets 6-31G (d, p) and 6-311G (d, p) were used to calculate the structure and thermodynamic parameters of thirty-six phenol compounds. The relationship equations between logKow and parameters were established. Upon examination, all the models from the three methods had better fitting ability. Comparing with the models from the other two methods, the equation calculated at HF/6-31G (d, p) had better internal predictive ability and needed less computation time. The equation from HF/6-31G (d, p) was more robust and can well be used to predict the logKow of the phenol compounds.