Hydrolysis and Phytotoxic Activity of Cyclic Imides

In order to explain the close phytotoxic activities of N-aryl-3,4,5,6-tetrahydrophthalimides and their hydrolyzed products, N-aryl-3,4,5,6-tetrahydrophthalamic acids, five sets of both types of compounds possessing the same aryl residues were prepared. Their phytotoxic activity against sawa millett (E. utitts) and green microalga (S. acutus), and the relationship of interconversion between the imides and amide acids during the bioassay were investigated. In almost all cases, the imides showed stronger activity than the corresponding amide acids. The hydrolysis of the imides and the cyclization of amide acids were observed in respect of the aryl residues. The phytotoxicity caused by the imides and amide acids tested was influenced by this interconversion.