[Phytotoxic activity of asymmetric N,N-dialkylnaphthamides]

Asymmetric N,N-dialkylnaphthamides, prepared and tested in pre- and post-emergence tests against some representative weeds, showed good or excellent phytotoxicity often with selectivity of action against Echinochloa and Setaria. These amides are characterized by the presence on the amide nitrogen of a sec.butyl or a 1-methylbutyl or a 1-ethylpropyl group together with another alkyl substituent of varying weight and nature. As reference compounds we prepared and tested N,N-dialkyl-alpha-naphthamides, isomers of the compounds under test, bearing on the N atom an alkyl group of avrying composition and a ter.butyl in place of sec. butil or a 1-ethylprophyl or other alpha-branched alkyl in place of the 1-methylbutyl. The results show the importance of alpha-substitution on at least one of the alkyl groups on the amide N as regards the degree of phytotoxicity. Some of the alpha-naphthamides giving interesting results with the weed species tested were further studied using plants of agricultural interest.