The Research On Toxicity Effect And Its Predicting Method For Organotin Compounds

Organotin compounds (OTCs) are extensively used in polymer stabilizers, fungicides, antifoulants, insecticides, organic catalysts, oil additives and so on. Due to the wide industrial applications considerable amounts of OTCs have entered various ecosystems, and destroy the aquatic environment. Therefore, research on their aquatic toxicity is of great significance to discussing toxic mechanism and ecological risk assessment.In this article, in order to assess the toxic effects of organotin compounds, with the method of static toxicity test, the acute toxicity of five organotin compounds to Scenedesmus obliquus and Daphnia magna was determined, and the influence of organotin compounds' structure and physicochemical properties on their toxic effects was elementarily discussed. The results indicated that all the organotin compounds had relatively strong toxicity to the two aquatic organisms with similar sequence of toxic action, viz. tri-n-butyltin>tetra-n-butyltin>di-n-butyltin >butyltin, on the other hand, due to species difference and influences of environmental factors such as degradation, the toxicity of the sameorganotin compound to the two aquatic organisms was greatly different. In the same time, the organotin compounds' physicochemical properties and molecular structure also affected their toxicity to the two aquatic organisms. In the same series, the more substituted alkyl was, the stronger the organotin compound's hydrophobicity was, and the higher toxicity was. However, when the number of substituted alkyl increased to more than enough, the toxicity became lower because of the bigger molecular volume.Moreover, the QSAR study was carried between toxicity data lgEC50 obtained by experiments and lgK0W, '%V. The results showed that in the same series, the more substituted alkyl was, the higher toxicity was, because the value of -igECso became bigger and bigger with lgKow fO '%v. However, when the volume of organotin was big enough, the toxicity became low. The reason was that organotin was difficult to penetrate the cell membrane and arrive at the center of active sites because of the large spatial resistance. Therefore, the toxicity of TeBT is similar to TBT.Finally, the QSAR between the acute toxicity of Scenedesmus obliquus and Daphnia magna by 16 organotin compounds and molecular structure parameters were established, like dipole(a), core-core repulsion(CC7ï¿¡), total energy(7F), LUMO energies^UMo), net atomic charges(g). The result showed that the toxicity of the organotin compounds to the aquatic organisms was related to the quantum chemical descriptors which characterized the molecular volume. When the values of Mr , CCR...