Ionic Liquid Forms of Mesotrione with Enhanced Stabilityand Reduced Leaching Risk

Mesotrione is one of the triketone herbicides that are widely used in corn fields to control broadleaf and some grass weeds because of its high herbicidal activity and crop safety. However, mesotrione is unstable during the progress of storage and application and can easily enter the groundwater to cause environmental pollution due to its high leakage in soil. In this study, 22 new salts based on mesotrione, most of which were defined as herbicidal ionic liquids (HILs), were synthesized by pairing with different structural cations to optimize the physicochemical properties for solving these problems of mesotrione. The results showed that the water solubilities of HILs were no longer limited by pH and could be decreased by selecting suitable paired cations. Also, HILs exhibited a higher thermal stability, lower surface tension, higher octanol-water partition coefficient, and better soil adsorption capacity and herbicidal activity than mesotrione. HIL-22 paired with cetylpyridinium could meet the requirements such as efficacy control, thermal stability, and reduction of environmental risk based on the physicochemical properties and biological activities. This study showed the novel HILs could make contributions to solve the problems existing in the practical applications and reduce the negative impact of herbicides on the environment.