Synthesis and herbicidal activity of novel N-(2,2,2)-trifluoroethylpyrazole derivatives.

A series of novel N-(2,2,2)-trifluoroethylpyrazole derivatives were synthesized, and their structures were characterized by IR, mass spectroscopy, (1)H NMR, and elementary analysis. The herbicidal activities of target compounds 10a-c and 11a-c were assessed. The bioassay results showed that these pyrazole derivatives exhibited good herbicidal activity. Compound 11a showed the best pre-emergence herbicidal effects against both dicotyledonous and monocotyledonous weeds with good safety to maize and rape at the dosage of 150 g a.i. ha(-1) in greenhouse. Field trials indicated that compound 11a exhibited better herbicidal activity by soil application than the commercial herbicide, metolachlor. Moreover, compound 11a showed the same level of safety to maize as metolachlor.