Xuewen Hua

Novel Anthranilic Diamide Insecticides: Design, Synthesis, and Insecticidal Evaluation

Three series of new anthranilic diamide derivatives containing sulfide, N-cyanomethylsulfilimine, and N-cyanomethylsulfoximine groups were designed and synthesized by coupling the active substructures of anthranilic diamides and sulfoxaflor. The structures of the synthesized compounds were confirmed by infrared spectroscopy, 1H and 13C NMR, and elemental analysis. Several unique structural characteristics were revealed via the crystal structure analysis of compound N-(2-(2-methyl-2-(methylthio)propylcarbamoyl)-4-chloro-6-methylphenyl)-3-bromo-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxamide 16e. Bioassay results indicated that most of the synthesized compounds showed superior insecticidal activities against Mythimna separata and Plutella xylostella when compared with the positive control cyantraniliprole. In particular, N-(2-(2-methyl-2-(N-cyanomethylsulfideimino)propylcarbamoyl)-4-chloro-6-methylphenyl)-3-bromo-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxamide 17e showed excellent insecticidal activity against Mythimna separata, with a mortality rate of 100 % at a concentration of 1 µg mL–1. These results indicated that sulfide, N-cyanomethylsulfilimine, and N-cyanomethylsulfoximine moieties, as important active substructures, could improve or maintain the activity of the anthranilic diamide and promote novel pesticide development.

Determination of Tiadinil and Its Metabolite in Flue-Cured Tobacco

A novel and sensitive method was developed for the determination of residues of tiadinil and its metabolite, 4-methyl-l,2,3-thiadiazole-5-carboxylic acid, in flue-cured tobacco. The pesticides were extracted with acetone and purified by gel permeation chromatography and solid-phase extraction. Analysis was performed by ultra-performance liquid chromatography-tandem mass spectrometry in negative ionization mode. Two precursor-product ion transitions were monitored for both compounds in the multiple reaction monitoring mode. Quantification was conducted by using matrix-matched standard calibration. Recovery values of the proposed method for tiadinil ranged from 72.5 to 98.2%, with relative standard deviations ranging from 3.8 to 9.5%; recovery values for 4-methyl-l,2,3-thiadiazole-5-carboxylic acid ranged from 75.4 to 103.3% with RSDs ranging from 3.7 to 9.3%. The limit of quantification for both compounds was 0.01 mg/kg. This method is valuable for residual analysis, quality control and monitoring of tiadinil and its metabolite, 4-methyl-l,2,3-thiadiazole-5-carboxylic acid, in tobacco.