Radio And Stable Isotope Synthesis, Chiral Separation And Determination Of Cis-Neonicotinoids, And The Fate Characterization In Soil

Paichongding and Cycloxaprid are two novel cis-neonicotinoids with good industrialisation prospects for their high activities. Due to higher activity against imidacloprid-resistant brown planthopper (nilaparvata lugens), paichongding was jointly developed by East China University of Science and Technology (ECUST) and Jiangsu Kwin Company. Cycloxaprid has high activities against imidacloprid-resistant brown planthopper and whitefly (besimia tebaci), it has already obtained joint efforts from ECUST, Shanghai Shengnong Pesticide Co. Ltd and FMC Corporation. To improve the studies of modes of action, metabolism environment behavior, safety evolution and application, radio and stable isotopic synthesis of paichongding and cycloxaprid were studied, which will facilitate future research combined with isotopic tracer, high-resolution spectroscopy instrument, molecular biology and other related technologies. The contents were as follows:1) Semi-/micro-syntheses of6-Cl-PMNI were performed using three commercial radio or stable isotope labeled starting materials, NaBH4, nitromethane and ethylenediamine dihydrochloride, respectively. Cyclization of6-C1-PMNI with crotonaldehyde followed by etherification with propanol, or reaction with succinaldehyde affords paichongding or cycloxaprid, respectively. Four radio or stable isotope labeled compounds were obtained under the optimizing reaction condition. Chemical and radiochemical purities and special activities of radiolabeled compound were determined by HPLC or HPLC-LSC. All labeled compounds were characterized by1H,13C NMR or MS.2) Isomers of paichongding or cycloxaprid were separated by chiral HPLC with optical purities over99%. Chemical structures of these chiral isomers were characterized by1H,13C NMR,2D HSQC and HMBC. Configuration differences in four isomers of paichongding and two isomers of cycloxaprid were analyzed by2D NOESY, and finally determined by crystal structures. Then, chiral stability of the isomers in organic solvents, buffer solutions or soil water was explored, to stimulate the process of enantiomers analysis, pesticide formulation or soil metabolism research, and find suitable solvents for analysis and sample treatment.3)14C labeled cycloxaprid and its isomers were used to understand the transformation of cycloxaprid in flooded soils, and their differences in extractable residues (ER), bound residues (BR) and mineralization were compared. After100d incubation, ER for14C labels followed a similar dissipation trend, BR increased obviously with time, and mineralization to CO2also increased cumulatively. All these changed were depended closely on the soil type and showed correlation coefficients with properties of the soils. No significant difference in ER, BR and mineralization were observed between two isomers and racemates. All these findings would promote the process of environment risk assessment and commercialization.