Preparation of Ionic Liquid Forms of l-Glufosinate for Improving the Physicochemical Property and Enhancing Efficacy

Glufosinate, a nonselective contact herbicide, has been widely applied in the global scope via its ammonium salt form for weed control in agricultural systems and noncultivated land. However, this herbicide with strong water solubility can be easily transferred into aquatic ecosystems, causing adverse impacts on nontarget organisms, and its performance in the field was shown to be susceptible to environmental conditions. As a promising solution to problems related to current herbicides, herbicidal ionic liquids (HILs) have not yet been applied to glufosinate. In this work, 12 HILs with different types of cations were first synthesized by using l-glufosinate (the active isomer of glufosinate) as an anion for optimizing the physicochemical property and enhancing the efficacy of this herbicide. The results showed that the IL forms of l-glufosinate could display good thermal stability, excellent surface activity, and high octanol–water partition coefficients by the selection of appropriate cations. The prepared HILs possessing improved lipophilicity can be dissolved in organic solvents such as methanol, acetone, and chloroform, suggesting less access to aquatic ecosystems. In the greenhouse experiment, l-glufosinate-based HILs had better herbicidal activities against Amaranthus retroflexus than l-glufosinate at different temperatures but had no effect on the enhancement of activities on Setaria viridis (L.) Beauv. Field testing demonstrated that when the treatment dose was 450 g AI ha–¹, the control efficacies (over 79%) of HIL6, HIL7, HIL9, and HIL10 on Chenopodium album L. were significantly higher than that (just 60%) of l-glufosinate. These results reported here offer a bright way for the optimization of the physicochemical properties of l-glufosinate and provide some new inspiration for the design of environmentally friendly formulations of l-glufosinate.