[Asymmetric chlorobenzoic acid N,N-dialkylamides having phytotoxic activity]

In continuation of research on phytotoxic substances with selective activity, pre- and post-emergence tests against some weed species were made using a series of 3-chlorobenzamides substituted on the amide nitrogen with a sec.butyl or a 1-methylbutyl group, the second alkyl substituent being linear, branched, saturated or unsaturated. Asymmetric 3-chlorobenzamides with a tert.butyl in place of sec.butyl or with an 1-ethylpropyl in place of 1-methylbutyl and with a second alkyl residue of different nature and with variable weight, were prepared and tested for the purposes of comparison. The results show that amides with excellent phytotoxicity and selectivity of action are obtained if a sec.butyl, 1-methylbutyl or 1-ethylpropyl group is retained and the second substituent on the amide nitrogen is suitably varied. The results give further information on the importance of the steric characteristics of the substituents on nitrogen in the phytotoxic N,N-dialkylamides.