In order to assess the fate of pesticide in the environment, the influences of both biotic and abiotic factors should be taken into account. Among the abiotic factors affecting the behaviors of pesticides, photochemical reactions are the most important. In aquatic systems, they play a dominant role in the conversion and degradation of pesticides[1].Novel pesticide brochlorfenapyr (proposal common name), test code: HNPC-A3061, chemical name:1-(2-chloroethoxy)methyl-4-bromo-2-(4-chlorophenyl)-5-tirfluoromethylpyrrol-3-nitrile, is a novel pyrrole class of insecticide which can be used to effectively control pest insects on the crops such as vegetables, rice and cotton with the application rate of 6~18g a.i./ha[2,3]. Little information is available about the degradation and fate of HNPC-A3061 in environment [4,5]. Therefore, it is very important to evaluate the degradation of HNPC-A3061 in the solutions under the irradiation of light in order to provide the references for its reasonable use and environmental safety assessment. In the study, the photolytic kinetics of HNPC-A3061 in n-hexane, methanol, acetone, acetonitrile and deionized water under the irradiation of ultraviolet and xenon light was evaluated in the room temperature using GC-ECD, and the results were presented in Table 1. Meanwhile photodegradation products of HNPC-A3061 at 50 minutes after irradiation were separated and identified by preparative HPLC and GC-MS, and the chemical identity of photodegradation products of HNPC-A3061 was presented in Figure1.The results showed that thepesticide HNPC-A3061 degraded very fast in the organic solvents under theirradiation of UV-light and simulated sun light. The photolysis of HNPC-A3061in n-hexane, methanol, acetonitrile and water could be described well by thefirst-order kinetics equation, and the photodegradation rate at the sameconcentration of 1mg/kg decreased with a order of n-hexane>methanol>water>acetonitrile>acetone,and among them, n-hexane exhibited a photosensitized effect on photodecompositionof the pesticide. However, HNPC-A3061 was very stable in acetone under theirradiation, and degraded 1% when it was irradiated for 48h under the UV-lightand xenon light, suggesting that acetone have a significant photoextinctioneffect on the photodecomposition of HNPC-A3061.When it was irradiated for 50minin acetonitrile solution, HNPC-A3061 was converted into two products A[3-bromo-5-(4-chloro phenyl)-4-isocyano-1-methyl-2-(trifluoromethyl)-1H-pyrrole] and B [1-((2-chloroethoxy) methyl)-2-(4-chlorophenyl)-3-isocyano-5-(trifuoromethyl)-1H-pyrrole] through two photolyticpathways such as debromination and O-dealkylation.References :[1]     Liu W P. Environmental Chemistry of Pesticides. Beijing: Chemical Industry Press, 2004.[2]     Ou X M, Liu A P, Huang M Z, et al. Discovery of new pesticide HNPC-A3061. in: Research Institute of China Chemical Science and Technology. Proceedings of the Seventh National Symposium on Pesticides Research and Development. Hangzhou,China. May 2007. pp7~12[3]     Pei H, Ou X M, Yu K, et al. Bioactivity of novel compound HNPC-A3061 against several insects in laboratory. China Modern Agrochemicals,2009,8(4):11-14[4]     Yang C H, Ou X M, Liu H Y, et al. Determination of Novel Insecticide HNPC-A3061 Residues in Cabbage and Soil by Gas Chromatography with ECD. Chinese Agrochemicals, 2014, 53(3): in press.[5]     Yang C H, Ou X M, Liu H Y, et al. Residues and persistence of novel insecticide HNPC-A3061 in Chinese cabbages and soils. Journal of Agro-environmental Science, 2014, 33(6): in press.

Photolysis of new pesticide HNPC-A3061 in organic solvents

248th National Meeting (2014)

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