Quantitative structure—activity relationships of light‐dependent herbicidal 4‐pyridone‐3‐carboxanilides I. Effect of benzene ring substituents at the anilide moiety

摘要

AbstractA number of substituted 4‐pyridone‐3‐carboxanilide derivatives show various degrees of light‐dependent herbicidal activity. The effects of substituents at the anilide moiety on the activity againstEchinochloa oryzicolawere analysed quantitatively with physicochemical substituent parameters. The activity was shown to vary parabolically with total hydrophobicity (Σπ) of the anilide ring substituents as well as with the steric parameter (Es) of theortho‐substituents. TheEsparameter for only the bulkierortho‐substituent, with the more negative value, but not for the two, was significant. The effect of substituents at the 1‐position was expressible by indicator variables assigned to each 1‐substituted series, the physicochemical rationalization being left fo