Herbicidal selectivity of (E)-3-(2,4-dichlorophenoxy)acrylates: QSAR study with molecular connectivity indices

Soskic, M.; Sabljic, A.

Herbicidal selectivity of (E)-3-(2,4-dichlorophenoxy)acrylates: QSAR study with molecular connectivity indices

1993

Soskic, M. | Sabljic, A.

The aim of this study was to generate a quantitative model of the herbicidal selectivity of (E)-3-(2,4-dichlorophenoxy)acrylates against barnyard grass and rice. Molecular connectivity indices and other topological quantities were used as molecular descriptors. A solid and sound correlation (r = 0.91) was obtained between the selectivity index delta pI(50) (defined as logarithmic ratio of biological activities observed in the two tested plant species) and the three topological quantities: the first-order molecular connectivity index, the valence fifth-order path/cluster molecular connectivity index, and the presence of a cyclic alcohol moiety. Our QSAR analysis revealed that the size of a molecule accounts for a large part of the variation in the delta pI(50) data. However, the degree of branching and the presence of a cyclic group in the alcohol moiety have a significant influence on the selectivity of (E)-3-(2,4-dichlorophenoxy)acrylates. The derived selectivity model, when compared with the corresponding empirical model, based on the 1-octanol/water partition coefficient and Taft's polar constant, shows a far superior performance in accuracy.

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