Stereoselective Degradation and Transformation Products of a Novel Chiral Insecticide, Paichongding, in Flooded Paddy Soil

Abstract

Paichongding is a chiral neonicotinoid insecticide currently marketed as racemate against sucking and biting insects. Under anaerobic condition, all paichongding stereoisomers underwent appreciable degradation in soil during 100 days of incubation, with estimated t values between 0.18 and 3.15 days. Diastereoselectivity in paichongding degradation was observed, with enantiomers (5S,7R)- and (5R,7S)-paichongding being more preferentially degraded in soils than enantiomers (5R,7R)- and (5S,7S)-paichongding. The half-lives of (5R,7R)- and (5S,7S)-paichongding were 3.05 and 3.15 days, respectively, as compared to 0.18 day for (5R,7S)- and (5S,7R)-paichongding. A total of nine intermediates were identified, of which depropylated paichongding was the predominant metabolite and appeared to be stable and recalcitrant to further degradation. Paichongding is degraded via denitration, depropylation, nitrosylation, demethylation, hydroxylation, and enol-keto tautomerism, producing chiral and biologically active products. These findings could have implications for environmental risk and food safety evaluations.

Simultaneous Determination of the Residues of Isopyrazam Isomers and Their Metabolites in Soil and Tomatoes by Ultraperformance Liquid Chromatography-Tandem Mass Spectrometry

“…25,47 Consistent with previous research by Li et al on the different degradation of Paichongding isomers in soil, isomer-specific degradation in soil could also be observed in their study. 48 In addition, they reported that the higher the content of organic matter in the soil, the higher the concentration of microorganisms, thus leading to accelerated pesticide dissipation.…”

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 1: new molecules, metabolism, fate, and transport

“…Major metabolites of flupyradifurone are difluoroethylamino-furanone and 6-chloronicotinic acid (Li et al 2016c). The latter is a common degradation derivative of imidacloprid, nitenpyram, acetamiprid, and thiacloprid (Simon-Delso et al 2015), and it is likely produced from degradation of paichongding and cycloxaprid as they also contain a chloropyridine moiety.…”

Uncatalyzed Addition and Cyclization of T_SN₃to 1,1-Enediamines: An Effective Green Route to Highly Functionalized 1,2,3-Triazole Compounds

“…1,1-Enediamines (EDAMs) are fascinating and versatile building blocks that are widely used to synthesize various heterocyclic compounds [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52]. Many of these compounds have a wide range of biological activities, such as antitumor [53][54][55], pesticide [56][57][58], and others.…”