STRUCTURE-ACTIVITY-RELATIONSHIPS OF HERBICIDAL NITRODIPHENYL ETHERS

Thirty 4-(substituted phenoxy) nitrobenzenes were synthesized and exam ined for phytotoxicity against barnyard-grass in the light and dark. F rom the structure-activity relationships and light-requisition for the activity, they were classified into three groups. The diphenyl ethers of the first group, which required light for the activity, were chara cterized by ortho and para substitutions. The second group compounds h aving meta or ortho and meta substitutions were active even in the dar k. The third group involved compounds substituted at both meta and par a positions and their herbicidal activity was inhibited by light. p-Am ino analog of nitrofen showed high herbicidal activity.