Synthesis and herbicidal activity of substituted 2-(1-(3-chloropyridin-2-yl)-3, 5-dimethyl-1H-pyrazol-4-yl) acetic acid derivatives containing 1, 3, 4-thiadiazole

Nine novel 2-(1-(3-chloro pyridin-2-yl)-3, 5-dimethyl-1H-pyrazol-4-yl) acetic acid derivatives B1 - B9 were synthesized from acetylacetone, ethyl bromoacetate and 2, 6-dichloropyridine. The synthesis route included a series of reactions such as substitution, alkylation, cyclization, hydrolysis, and acidification condensation. The chemical structures were characterized by ¹H NMR and MS. Preliminary bioassay showed that most of the above compounds displayed herbicidal activities at the concentration of 150 g/hm². The inhibition rates of B2, B3, B6 and B8 against Abutilon theophrasti Medicus, Amaranthus retroflexus and Amaranthus lividus L. were nearly 100%.