Abstract: A.DELTA..sup.1 - tetrahydrophthalic anhydride is reacted with an amine in the presence of lower fatty acid. Alternatively N-(4-hydroxyphenyl)-.DELTA..sup.1 -tetrahydrophthalimide or a salt thereof is reacted with an aralkyl halide. A N-substituted-.DELTA..sup.1 -tetrahydrophthalimide compound having herbicidal activity is produced. This compound has the formula ##EQU1## wherein R' is naphthyl; phenyl; phenyl substituted by 1-3 substituents selected from the group consisting of halogen, nitro, cyano, thiocyano, carboxyl, haloalkyl, lower alkyl and alkylthio; --CH.sub.2 Y wherein Y is phenyl, naphthyl or phenyl substituted by 1-5 substituents selected from the group consisting of halogen, nitro, lower alkyl and lower alkoxyl; or ##SPC1##Wherein Z is phenyl, naphthyl, or phenyl substituted by at least one substituent selected from the group consisting of halogen, nitro, lower alkyl and lower alkoxyl.