Current Status of Organofluorine Compounds As Agrochemicals

Introduction

Inspired by the potential efficiency of fluoro-DDT as an insecticide, researchers were interested in organofluorine compounds as agrochemicals. This is because strong stability, physiological activity, fat solubility and hydrophobicity, and ability to adjust electronic and lipophilic parameters of organofluorine compounds make fluoro-agrochemicals with the characteristics of small dosage, low toxicity, high efficacy, and strong metabolic capacity. It is precisely because of this that fluoro-agrochemicals gradually show huge growth potential, and the research and development activities of fluoro-agrochemicals are increasingly active. Here, Alfa Chemistry introduces the situation of fluoro-agrochemicals on the market from the perspective of the chemical type, agrochemical type, the presence/absence of fluoro-functionalized heterocycles, the presence/absence of chirality center. The paper described here may can provide ideas for the development of new and economical fluoro-agrochemicals, and stimulate researchers to create new agrochemicals.

Fig.1. The structure of fluoro-DDT.

The Situation of Fluoro-agrochemicals

Ogawa et al. analyzed a database of fluoro-agrochemicals contains more than 400 fluoro-agrochemicals (300 compounds assigned with ISO common names and 44 compounds with non-ISO common names, 69 compounds with development codes and 11 experimental pesticides) (ISO: International Organization for Standardization)) ^[1]. According to their report, we summarized the situation of fluoro-agrochemicals on the market as of 2020 from the different perspective.

• The largest subdivision of fluoro-agrochemicals is the group that contains an "Ar-F" moiety (29%), followed by the groups that contain an "Ar-CF₃" moiety (22%), a "Het-(C_sp2)-CF₃" moiety (13%), or an "alkyl-CF₃" moiety (5%). It can be seen the preparation of aromatic compounds with F and CF₃ groups is more likely to furnish successful agrochemical candidates. In addition, the compounds that contain C-CF₃ moieties account for 42% of all fluorine-containing compounds. Compounds that contain monofluoro moieties such as C_sp2-F and C_sp3-F cover 35%  of all compounds. This suggests that the CF₃ fragment has greater advantages over the C-F fragment for agrochemicals.

Fig.2. Distribution of chemotypes of fluoro-agrochemicals.

• Organofluorine compounds can be used as various agrochemicals such as herbicides, insecticides, fungicides, acaricides, nematicides, plant growth regulators, rodenticides and many others. The most common types of agrochemicals used by organofluorinated compounds are: herbicides (40%), insecticides (25%), fungicides (17%) and acaricides (9.0%). However, in terms of the size of their respective sectors, fluorinated agrochemicals are relatively evenly distributed across all categories, with the amount of each category proportional to its size. When focused on the compounds with more than six fluorine atoms in their structures, the clear majority of fluoro-agrochemicals (total 75%) are insecticides (53%) and acaricides (22%).

Fig.3. Classification of fluoro-agrochemicals by agrochemical type.

• Heterocycles are extremely important scaffolds for the design of agrochemicals. Most launched agrochemicals (>70%) contain at least one heterocycle, in particular those heterocycles that contain nitrogen. However, only 61% of the fluoro-agrochemicals contain heterocyclic moieties, whereas heterocycles-free fluoro-agrochemicals account for an impressive 39%. This indicates that organofluorine compounds do not always require heterocyclic skeletons to be successful agrochemicals. In addition, among the fluoro-agrochemicals that contain heterocycles, the compounds whose fluorine or fluoro-functional groups are directly attached to the heterocyclic core are 52%, whereas 48% fluoro-agrochemicals have fluorine-free heterocyclic moieties, indicating fluorine is not always necessary directly attached to the heterocyclic skeletons.

Fig.4. (A) Distribution of fluoro-agrochemicals with or without heterocycles. (B) Classification of fluoro-agrochemicals with heterocycles based on whether fluorine or fluoro-functional groups directly attached to the heterocyclic core or not.

• Chiral compounds are already very common in agrochemicals. According to the proportion of fluoro-agrochemicals with chiral fragments in their structures. The number of fluoro-agrochemicals with an asymmetric carbon center account for 34%. However, the number of fluoro-agrochemicals with fluorine or fluoro-functional groups directly connected to a stereogenic carbon center, which includes racemic compounds, is extremely low (1.4%). This shows that there is still great potential t for the development of fluoro-agrochemicals with stereogenic carbon center(s).

The paper may can give you some ideas for the development of new and economical fluoro-agrochemicals. For over many years, Alfa Chemistry has deep research in the application of organofluorine compounds in agrochemicals. If you need any help about fluoro-agrochemicals, you can contact our engineers online and we will provide you with professional advice and solution. In addition, Alfa Chemistry offers a wide range of organofluorine products for the agrochemicals sector.

Reference

1. Ogawa Y., et al. Current contributions of organofluorine compounds to the agrochemical industry[J]. Iscience, 2020, 23(9).