10.1021/acs.jafc.6b04528
The research presents the synthesis, characterization, and evaluation of herbicidal ionic liquids (HILs) based on long alkyl chains and common herbicides like 2,4-D, MCPA, MCPP, and dicamba. The HILs were produced through an acid-base reaction between the herbicidal acids and hydroxides of hexadecyltrimetylamonium, octadecyltrimetylamonium, and behenyltrimethylammonium in an alcoholic medium, yielding products with over 95% efficiency. The study investigated the influence of alkyl chain length and anion structure on physicochemical properties such as thermal stability, solubility, surface activity, density, viscosity, and refractive index. The synthesized HILs showed high thermal stability and surface activity, with solubility varying based on carbon chain length and anion structure. Greenhouse and field experiments were conducted to assess the herbicidal efficacy against common lambsquarters and flixweed, comparing HILs to commercial herbicides. The results indicated that HILs had similar or higher efficacy than the commercial products, especially those containing phenoxyacids as anions. Analyses included NMR spectroscopy for structure confirmation, elemental analysis for purity, and various physicochemical measurements like density, viscosity, and surface tension. Thermal analysis (DSC and TGA) was also performed, along with solubility tests in different solvents and surface activity measurements to determine critical micelle concentration (CMC) and contact angle.