3D-QSAR And HQSAR Study On The Reaction Rate Constants Of Organic Pollutants With Gaseous Free Radicals

Organic pollutants have the characteristics of high toxicity,strong accumulation and difficult degradation.It is of great significance to study the degradation and transfer mechanism of organic pollutants in the atmosphere and water,assess the ecological risk of various organic compounds and establish the ecological evaluation system of organic pollutants.Quantitative structure activity relationship(QSAR)establishes quantitative relationship models between the molecular structure characteristic parameters of compounds and the biological activities through mathematical methods,so as to predict the activity of the compounds.Three QSAR(3D-QSAR)can establish the relationship between the structure and activity of compounds by calculating the spatial structure around the molecules,which has the characteristics of simple operation and high prediction accuracy.hologram QSAR(HQSAR)is an emerging and efficient QSAR method,which can easily generate QSAR models with higher prediction accuracy.Based on the3D-QSAR and HQSAR methods,QSAR models of the reaction rates of organic pollutants such as hydrocarbons,alcohols,ketones,esters,ethers and aromatics with oxidants were established to meet the needs of ecological risk assessment of organic chemicals.The main contents include:The Co MFA and HQSAR methods were used to study the QSAR models of the rate constants of the reactions of 161 hydrocarbon organic pollutants with hydroxyl radicals in the atmosphere.The prediction ability of the developed models were assessed by leave-one-out cross verification(LOO-CV)and external test verification,and the effect of the structure of the compounds on the reaction rate was analyzed by means of three-dimensional equipotential maps and molecular contribution maps.The research results show that both the HQSAR model and the Co MFA model have good predictive ability.The halogen atom can inhibit the reaction rate constant of the compounds,while the ether bond and sulfur atom in the molecule can increase the oxidation reaction rate of hydrocarbon organic pollutants and hydroxyl radicals.The Co MFA method and HQSAR method were used to study the QSAR models of the reaction rate constants of 68 kinds of organic pollutants with chlorine radicals in the atmosphere.The prediction ability of the developed models were assessed by LOO-CV and external test verification,and the effect of the structure of the compounds on the reaction rate was analyzed by means of three-dimensional equipotential maps and molecular contribution maps.The results show that both QSAR models can express the quantitative relationship between the structure information and the rate constant of the studied organic pollutants.The halogen atom can inhibit the reaction rate constant of compounds,while the carbonyl group,ester group and hydroxyl group in the compound molecule can increase the oxidation reaction rate constant of organic pollutants with chlorine radicals.The QSAR models of the reaction rate constants of 166 organic pollutants and nitro radicals in the atmosphere was established by the HQSAR method.The prediction ability of the developed models were assessed by LOO-CV and external test verification,and the effect of the structure of the compounds on the reaction rate was analyzed by molecular contribution maps.The results show that HQSAR model has good prediction ability and robustness.Halohydrocarbons,ketones,aldehydes,ethers,lipids and cyclic alkanes can inhibit the reaction rate,while sulfides and cyclic alkenes can improve the oxidation efficiency of organic pollutants with nitro radicals.The HQSAR method was used to establish the QSAR models of the reaction rate constants of123 organic pollutants with ozone/hydroxyl radicals.The prediction ability of the developed models were assessed by LOO-CV and external test verification,and the contribution maps of the HQSAR model was used to explore the influence of the molecular structure and rate constant of organic pollutants.The contribution maps of HQSAR model shows that halogen atoms can inhibit the reaction rate,while amino,hydroxyl,nitro and aromatic rings can improve the oxidation efficiency of organic pollutants.