Synthesis and herbicidal activity of cinnamic acid and related compounds

Abstract

Forty-seven substituted trans-cinnamic acids were synthesized by the condensation reaction malonic acid and selected aldehydes. The inhibitory effect of these well- characterized compounds were tested with Mimosa pigra Linn, and Echinochloa crus-galli (L.) The eight trans-cinnamic acids bearing, 3-F, 3-Cl, 2,6-di/cl, 2-Cl-6-F, 3-OMe, 3,4-OCH2O- and 3-No2 showed high inhibitory effect on growth of M.pigra. While the eleven trans-cinnamic acids containing 4-F, 2-CI, 4-CI, 2-, 3-and 4-Br, 2, 4-,2,6- and 3,4-diCI, 4-OMe and 4-t-C4H9 showed high inhibitory effect on growth of E. crus-galli. In addition, twelve cinnamamides, fifteen cinnamate esters, six sodium cinnamate and three calcium cinnamate derivatives were prepared. These well-characterized compounds were tested for antigrowth activity of M. pigra. N-(2,4-dichlorophenyl)-3,4-methylenedioxcinnamamide, 2,4-dichlorophenyl 3-nitro-cinnamate, sodium 3-fluorocinnamate, sodium 3-chlorocinnamate, sodium 3-methoxy- cinnamate, sodium 3-nitrocinnamate, calcium 3-fluoorocinnamate and calcium 3,4-methylenedioxycinnamate exhibited high activities. Besides, 3,4-methylenedioxycinnamic and 3-nitrocinnamic acids did not show germination inhibition activity against selected weeds. Several compounds displayed the activity comparable to various to various commercial herbicides in terms of growth inhibition activity test. Some of them revealed promising tendency for the development as new herbicides.