Conformational preferences of fluorine-containing agrochemicals and their implications for lipophilicity prediction

Daniela Rodrigues Silva,Joyce K Daré,Matheus P Freitas

doi:10.3762/bjoc.16.200

Abstract

Molecular polarity governs lipophilicity, which in turn determines important agrochemical and environmental properties, such as soil sorption and bioconcentration of organic compounds. Since the C–F bond is the most polar in organic chemistry, the orientation of fluorine substituents originating from the rotation around C–C(F) bonds should affect the polarity and, consequently, the physicochemical and biological properties of fluorine-containing agrochemicals. Accordingly, this study aims to determine the most likely conformers of some fluorine-containing agrochemicals and to correlate their molecular dipole moments with the respective n-octanol/water partition coefficients (log P), in order to investigate the dependence of the lipophilicity with the molecular conformation.

Highlights

Whilst in the last years the agrochemical industry has encountered a period of downturn affected by new regulations, low crop prices, biochemical resistance, among other variables, recent events have shown signs of recovery [1]
Given the high degree of freedom in the chemical structure of penoxsulam (I), the conformational analysis started with a Monte Carlo conformational search at the ωB97X-D/631G(d,p) [16,17] level of the density functional theory (DFT)
The overall molecular polarity is influenced by the nature of the substituent group, and by the orientation of the neat molecular dipole moment vector. Methods that ignore such influences result in reduced accuracy when predicting physicochemical properties of complex structures, such as the herbicides presented

Summary

Introduction

Whilst in the last years the agrochemical industry has encountered a period of downturn affected by new regulations, low crop prices, biochemical resistance, among other variables, recent events have shown signs of recovery [1]. The agrochemical industry focuses on introducing new efficient and more environmentally friendly products, that attend the new regulation requirements, for replacing those agrochemicals that were banned due to either their hazard or inefficiency in fighting persistent weeds and pathogens [1]. The process for designing, developing, and introducing new agrochemicals to the market is considerably challenging, since it involves many steps and the optimization of a range of properties. It is an expensive and time-consuming procedure [2].

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Conclusion