Three series of forty-nine novel 4-(3-trifluoromethylphenyl)-2H-pyridazin-3-one derivatives are designed,synthesized,and evaluated through a Spirodela polyrrhiza test and a greenhouse test.Some compounds show > 80% chlorophyll inhibition of Spirodela polyrrhiza at 10 μg/mL and exhibit some herbicidal activities against Digitaria adscendens in the pre-emergence treatment at a rate of 150 g/ha.Moreover,the study of the structure-activity relationship(SAR) suggests that the appropriate bulky substituent at the right position is critical for the bleaching and herbicidal activities,which may be useful for the future design of new compounds.
