Herbicidal ionic liquids derived from alkylbetaines proved to be biodegradable, thermally stable and highly effective anti-weed agents.

Novel herbicidal ionic liquids (HILs) containing different anions and cations derived from ammonium esterquats were prepared by employing a simple, inexpensive pathway. The basic physicochemical properties of the synthesized salts (such as density, viscosity, refractive index, solubility and thermal stability) were determined.Additionally, their herbicidal efficacy was evaluated under greenhouse and field conditions with a subsequent assessment of biodegradability and toxicity (acute oral toxicity towards rats and rainbow trout, the growth inhibition test of green algae and the acute immobilization test using water flea). The results of greenhouse and field experiments revealed that the herbicidal activity of HILs comprising long alkyl chains has exceeded that of commercial plant protection products. The HIL containing the di(tallowoyloxyethyl)dimethylammonium cation exhibited notable biodegradability (63% after 28 days) and various toxicity classifications depending on the tested organism: category V towards rats with LC 50 4 2000 mg, category II towards fish with LC 50 /96 h at 10.62 mg L À1 , category I towards algae and daphnids with E r C 50 /72 h at 1.73 mg L À1 and EC 50 at 0.28 mg L À1 , respectively. These findings provide evidence that the synthesis of HILs with a specifically designed structure may be successfully employed for obtaining novel, efficient and environmentally friendly plant protection agents. † Electronic supplementary information (ESI) available: 1 H and 13 C NMR spectra, detailed testing procedures for: the acute toxicity test towards rats, the acute oral toxicity test towards rainbow trout, the growth inhibition test of green algae, the acute immobilization test using water flea. See

In this study, fourteen new herbicidal ionic liquids (HILs) based on MCPB with a 1-alkyl-1-methylpiperidinium cation were synthesized and characterized.

This study focused on the synthesis and subsequent characterization of herbicidal ionic liquids based on betaine and carnitine, two derivatives of amino acids, which were used as cations. Four commonly used herbicides (2,4-D, MCPA, MCPP and Dicamba) were used as anions in simple (single anion) and oligomeric (two anions) salts. The obtained salts were subjected to analyzes regarding physicochemical properties (density, viscosity, refractive index, thermal decomposition profiles and solubility) as well as evaluation of their herbicidal activity under greenhouse and field conditions, toxicity towards rats and biodegradability. The obtained results suggest that the synthesized herbicidal ionic liquids displayed low toxicity (classified as category 4 compounds) and showed similar or improved efficacy against weed compared to reference herbicides. The highest increase was observed during field trials for salts containing 2,4-D as the anion, which also exhibited the highest biodegradability (>75 %).

Herbicidal ionic liquids (HILs) have been demonstrated to have potential as highly effective herbicides that may also have different modes of action that their neutral precursors. Here, double salt herbicidal ionic liquids (DSHILs) containing at least two herbicidal anions selected from glyphosate, dicamba, or 4-chloro-2-methylphenoxyacetate (MCPA) paired with ammonium or phosphonium cations are reported along with their post-emergence herbicidal activity against several plant species, from both greenhouse and field study-based bioassays. The novel DSHILs were shown to integrate the advantages of two different herbicides into a single HIL, enhance herbicidal efficacy, and reduce the risk of weed resistance due to the various modes of action of the applied treatment. The formation of the DSHILs dramatically reduced melting points and modified the compound solubilities compared to the parent herbicides. Statistical analyses for the greenhouse efficacy tests demonstrated that DSHILs had significant positive differences against winter wheat (Triticum aestivum L.) and white mustard (Sinapis alba L.) as compared to commercial formulations. Biodegradability studies were also performed on selected DSHILs, and the compounds were found to be not readily biodegradable.

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 HILs demonstrated excellent efficacy. Laboratory regrowth tests established that the ionic liquids of glyphosate are efficiently translocated to rhizomes preventing the regrowth of plants.

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.

Ten sulfonylurea-based herbicidal ionic liquids (HILs) were prepared by combining the metsulfuron-methyl anion with various cation types including quaternary ammonium ([bis(2-hydroxyethyl)methyloleylammonium](+), [2-hydroxyethyltrimethylammonium](+)), pyridinium ([1-dodecylpyridinium](+)), piperidinium ([1-methyl-1-propylpiperidinium](+)), imidazolium ([1-allyl-3-methylimidazolium](+), [1-butyl-3-methylimidazolium](+)), pyrrolidinium ([1-butyl-1-methylpyrrolidinium](+)), morpholinium ([4-decyl-4-methylmorpholinium](+)), and phosphonium ([trihexyltetradecylphosphonium](+) and [tetrabutylphosphonium](+)). Their herbicidal efficacy was studied in both greenhouse tests and field trials. Preliminary results for the greenhouse tests showed at least twice the activity for all HILs when compared to the activity of commercial Galmet 20 SG, with HILs with phosphonium cations being the most effective. The results of two-year field studies showed significantly less enhancement of activity than observed in the greenhouse; nonetheless, it was found that the herbicidal efficacy was higher than that of the commercial analog, and efficacy varied depending on the plant species.