Herbicidal Ionic Liquids: A Promising Future for Old Herbicides? Review on Synthesis, Toxicity, Biodegradation, and Efficacy Studies

[Image: see text] The transformation of agrochemicals into herbicidal ionic liquids (HILs) has been suggested as a solution to problems associated with commercial forms of herbicides. The aim of this review was to summarize the latest progress in the field of HILs, including their synthesis as well as physicochemical and biological properties, and to address the areas that require further research in order to ensure their safe commercialization (e.g., data regarding biodegradability, toxicity, and environmental fate). The first part of the review provides an in-depth summary of the current state of knowledge regarding HILs, particularly the anions and cations used for their synthesis. The second part highlights the employed synthesis methods and elucidates their respective advantages and limitations. The third section is focused on the characterization of HILs with emphasis on the methods and factors that are significant in terms of their practical application. Subsequently, the issues associated with the biodegradation and toxic effects of HILs are discussed based on the relevant literature reports. All sections include comprehensively tabulated data in order to enable rapid comparison of utilized approaches. Finally, all the findings are critically analyzed in terms of crucial disadvantages (especially the lack of standardization), which allowed us to establish future recommendations and basic guidelines that are presented in the last section.