Adjustment of the Structure of the Simplest Amino Acid Present in Nature—Glycine, toward More Environmentally Friendly Ionic Forms of Phenoxypropionate-Based Herbicides

Abstract

The use of chemicals for various purposes in agriculture has numerous consequences, such as the contamination of ecosystems. Thus, nowadays it is perceived that their development should adhere to the principles of green chemistry elaborated by Paul Anastas. Consequently, to create more environment-friendly herbicides, we elaborated a ‘green’ synthesis method of a series of ionic liquids (ILs) containing cations derived from glycine. The appropriately modified cations were combined with an anion from the group of phenoxy acids, commonly known as 2,4-DP. The products were obtained with high yields, and subsequently, their properties, such as density, viscosity and solubility, were thoroughly examined to elucidate existing structure–property relationships. All ILs were liquids at room temperature, which enabled the elimination of some serious issues associated with solid active forms, such as the polymorphism or precipitation of an active ingredient from spray solution. Additionally, the synthesized compounds were tested under greenhouse conditions, which allowed an assessment of their effectiveness in regulating the growth of oilseed rape, selected as a model dicotyledonous plant. The product comprising a dodecyl chain exhibited the greatest reduction in the fresh weight of plants, significantly surpassing not only a commercially used reference herbicide but also the potassium salt of 2,4-DP.

A comprehensive study demonstrating the influence of the solvent composition on the phytotoxicity of compounds, as exemplified by 2,4‐D‐based ILs with a choline‐type cation

“…However, the other recently popular strategy involves targeted modification of the structure of a.i. that results in formation of ILs (e.g., herbicidal ionic liquids (HILs) incorporating organic cations and anions exhibiting herbicidal activity) 7–10 . Interestingly, in the case of HILs, the phytotoxic effect towards plants is generally considered as an efficacy of eradication of undesirable vegetation.…”