Glyphosate-Based Herbicidal Ionic Liquids with Increased Efficacy

Eight new glyphosate-based herbicidal ionic liquids (HILs), containing both mono- and dianions of glyphosate (benzalkonium glyphosate, bis(2-hydroxyethyl)-cocomethylammonium glyphosate, oleylmethylbis(2-hydroxyethyl)ammonium glyphosate, didecyldimethylammonium glyphosate, di(hydrogenated tallow)dimethylammonium glyphosate, 4-decyl-4-ethylmorpholinium glyphosate, di(benzalkonium) glyphosate, and di(bis(2-hydroxyethyl)cocomethylammonium) glyphosate) were prepared via acid base reaction between the corresponding ammonium hydroxides (some premade) and glyphosate free acid. The transformation of glyphosate free acid into ionic liquids led to an elimination of melting points in all but one compound and significant change in solubilities. All HILs exhibited higher thermal stability than glyphosate free acid. Greenhouse testing indicated that while at a higher application rate of 360 g/ha the efficacy of all the HILs was comparable to the commercial herbicide control, at a lower application rate of 180 g/ha, the efficacy of all HILs was as much as two and a half to three times higher when compared to the commercial formulation, and the dianionic glyphosates were the most effective. In field trials, all but one of the tested Has demonstrated excellent efficacy. Laboratory regrowth tests established that the ionic liquids of glyphosate are efficiently translocated to rhizomes preventing the regrowth of plants.