| Abstract: | Good preparative procedures for 63 new dinitroanilines and dinitrochlorobenzenes have been developed. A total of 80 2,6-dinitroanilines was synthesized in order to determine the effect of steric, electronic, and hydrophobic factors on plant growth regulating activity. The UV, IR, ¹H nmr, and ¹⁹F nmr spectra of these dinitroanilines were investigated in different solvents. Several interesting phenomena were found. Mono-N-n-alkylation was found to inhibit resonance interaction between the amino group and one nitro group; the other nitro group, however, remained coplanar. On the other hand, di-N -alkylation forced both nitro groups from coplanarity. The propyl groups of 4-substituted-2,6-dinitro-N,N-din-propylanilines were found to lie over the plane of the benzene ring. A model representing the mode of herbicidal activity for these compounds was proposed. This model satisfactorily explains the herbicidal activity of a large number of dinitroanilines with a wide range of steric, electronic, and hydrophobic properties. New herbicides can be predicted from this model. |
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