Selenium analogs of phenoxypropionic and phenoxyacetic herbicides

Selenium analogs of phenoxyacetic herbicides, namely 2-(2,4-dichlorophenoxy)propionic acid (2,4-DP), 2-(2,4-dichlorophenoxy)acetic acid (2,4-D), 2-(4-chloro-2-methylphenoxy)propionic acid (MCPP), 2-(4-chloro-2-methylphenoxy)acetic acid (MCPA), 2-(2,4,5-trichlorophenoxy)propionic acid (2,4,5-TP), and 2-(2,4,5-trichlorophenoxy)acetic acid (2,4,5-T), were synthesized in two steps. Iodo aryl derivatives were dimerized with elemental selenium in the presence of CuO as catalyst to the corresponding diselenides. Diselenides were reduced with NaBH4 to a selenide anion and condensed with either propionic or chloroacetic acid to achieve the selenium analogs of phenoxyacetic herbicides. These selenium analogs show moderate herbicidal and fungistatic activity.