Quantitative structure-activity relationships of herbicidal N-alkyl-N-(4-substituted benzyl)-4-chloro-2-pentenamides against Echinochloa oryzicola

The herbicidal activity of N-alkyl-N-(4-substituted benzyl)-4-chloro-2-pent enamides against a barnyard grass species, Echinochloa oryzicola, was evalu ated, and the potency variations were quantitatively analyzed using physico chemical parameters for the N-alkyl and the benzyl-benzene ring substituent s in the amide moiety. The results indicated that the herbicidal potency wa s parabolically related with the total hydrophobicity of the amide moiety. The electron-withdrawing property of the benzene-ring substituents as well as their hydrogen-bonding accepting ability was significant in potentiating the herbicidal activity.